CN100438364C

CN100438364C - Broadcast audio communication from implantable medical device

Info

Publication number: CN100438364C
Application number: CNB011033908A
Authority: CN
Inventors: J·T·哈特劳布; D·L·汤普森; D·R·格里宁格
Original assignee: Medtronic Inc
Current assignee: Medtronic Inc
Priority date: 2000-01-25
Filing date: 2001-01-31
Publication date: 2008-11-26
Anticipated expiration: 2021-01-31
Also published as: CN1367587A

Abstract

A method and apparatus which broadcasts an implantable medical device by radio frequency emission of an audible sound generated by IMD, comprises the process of inquiring the programmed parameter value, the operational mode and operational detail, confirming the variational programme, inquiring the date in the IMD, warning of the patient and other information. IMD comprises a radio frequency emitter which broadacasts or transmits an audible sound, the audible sound comprises a voice statement or music tone storage in an analog memory, which is involved in an programming or inquiring arithmetic or a warning of trigger event. A wireless signal receiver receives a wireless signal and an audible sound, demodulates and reproduces the signal or sound to an apprehensible voice statement or music tone, which includes the IMD information and a warning or status messages of patients in other time generated during programming or dialog.

Description

Communication device and method for broadcasting audible sounds from an implantable medical device

The present invention relates generally to improved methods and apparatus for providing delivery of Implantable Medical Device (IMD) information and patient warnings or messages via broadcast radio signals capable of being received and reproduced as human understandable voiced statements or other audible sounds.

Early IMDs, such as implantable cardiac pacemakers, were designed to generally operate in a single operating mode, controlled by fixed operating parameters, and did not have the ability to change operating modes or otherwise communicate percutaneously with external devices. It will be apparent that it will be clinically desirable to change certain operating parameters and/or modes of operation throughout the day. The method originally used for implantable cardiac pacemakers involved the use of a miniature rheostat that was directly accessible by inserting a needle-like tool into the patient's skin to adjust the resistance in the pacing rate or pulse width setting circuit. Later, miniature reed switches were incorporated in the pacing rate or pulse width circuits, which were responsive to the magnetic field applied through the skin by an external magnet placed at the site of implantation. In this way, pulse width, pacing rate, and a limited number of pacing modes may be adjusted.

Observation of the operation of an implantable cardiac pacemaker may also be achieved, for example, by using a standard EKG machine and by the time interval between pacing pulse spikes in an ECG trace recorded from a patient's skin electrodes. The reed switch is closed using the applied magnet to change the pacing mode to the asynchronous pacing mode and translate the fixed pacing rate or pulse amplitude or width to a value that reflects the current operating parameters. One application of this technique is to monitor impending battery depletion from a preset or programmed pacing rate based on the voltage drop across the battery by observing changes in the pacing rate, for example, as described in U.S. patent 4,445,512. Of course, this approach can only provide one low-band data channel, avoiding interference with the primary function of pacing the patient's heart when necessary.

In addition, when the radio antenna is placed over the implanted lead, pacing pulses conducted through the elongated pacing lead conductor cause the electromagnetic signal to be heard as noise pulses on the amplitude modulated radio frequency band. It follows that the delivery of pacing pulses can be confirmed without the need for an EKG machine, and that the pacing rate can be roughly determined by timing successive noise pulses with a stopwatch. The output circuit sensor is incorporated into a particular model pacemaker, causing the sensor to "ring" when a pacing pulse is delivered for the entire period of the pacing pulse. The duration of the noise pulse retrieved by the radio is proportional to the pacing pulse width, and measuring the pacing pulse width from the duration of the noise pulse is at least theoretically possible.

It will be appreciated that as digital circuit technology advances, control of the operating modes and parameters of implanted medical devices may be implemented in digital or binary circuits that use stored control states or operating parameter values. To change an operating mode or parameter value, a "programmer" has been developed based on Radio Frequency (RF) downlink data communication from an external programmer transceiver to a telemetry transceiver and memory housed within the IMD.

By using such telemetry systems, it is possible to provide uplink data telemetry to transmit the contents of registers or memory within the IMD to a telemetry receiver within a programmer using the same RF transmission capabilities. Today, both analog and digital data may be transmitted from an implanted medical device to an external programmer via uplink RF telemetry. In the context of implantable cardiac pacemakers, analog data generally includes battery status, sampled intracardiac electrocardiogram amplitude values, sensor output signals, pacing pulse amplitude, energy and pulse width, and pacing lead impedance. The numerical data typically includes statistics regarding performance, event flags, current values of programmable parameters, implant data, and patient and IMD identification codes.

The evolution to the current widespread use of telemetry transmission systems depends on the formation of a low amplitude magnetic field by current oscillation in the LC circuit of the RF telemetry antenna in the transmit mode and the detection of induced currents in a closely located receive mode RF telemetry antenna. Short duration bursts (bursts) of carrier frequencies are transmitted in a variety of telemetry transmission formats. In MEDTRONIC

The RF carrier frequency is set to 175kHz on the manufacturing line, and the RF telemetry antenna of an IMD is typically a wire coil wound on a ferrite core inside a sealed enclosure. The RF telemetry antenna of the external programmer is contained in a programming head and permanent magnet that can be placed on the patient's skin over the IMD to create a magnetic field within the sealed enclosure of the IMD.

In uplink telemetry transmissions from implanted medical devices, it is desirable to limit the current leakage from the implanted battery as much as possible to extend the life of the device. However, as device operation and monitoring capabilities increase, it is desirable to be able to increase the data capacity of the transmission in real time or within the shortest possible transmission time with high reliability and immunity to spurious noise. As a result of these considerations, many RF telemetry transmission data coding schemes have been proposed or are currently used in an attempt to increase the data transmission rate.

Currently, a wide variety of IMDs are commercially available or proposed for clinical implantation, which can be programmed in a variety of operating modes and can be transmitted for interrogation using RF telemetry. Such medical devices include implantable cardiac pacemakers, cardioverter/defibrillators, pacemakers/cardioverter/defibrillators, drug delivery systems, cardiac muscle stimulators, cardiac and other physiological monitors, electrical stimulators (including nerve and muscle stimulators), brain (deep bridge) stimulators, and cochlear implants, as well as cardiac assist devices or pumps, and the like. As technology advances, IMDs have become more complex in possible programmable operating modes, available operating parameter menus, and monitoring capabilities that add to the variety of physiological conditions and electrical signals. These complexities place higher demands on programming and interrogation systems and the healthcare providers that use them.

In our legal invention registration H1347, we disclose an improvement on this type of programmer that adds audio voice statements in operation to assist the healthcare provider who uses them. For example, we propose to add voice statements, track programmer interactions with implanted medical devices during programming, and patient following sessions that can be heard by the healthcare provider using the programmer. Such voiced statements would augment or replace the visual display of such information or the minimal audible tone (e.g., buzzer sound) that is displayed or emitted when using an external programmer or pacing system analyzer.

Other methods have also been developed that rely on RF telemetry transmissions to provide real-time warnings to the patient when the IMD malfunctions or is detecting that therapy will be required. It has been proposed to incorporate an audible beep alarm into an IMD to alert the patient to battery depletion, such as disclosed in U.S. patent nos. 4,345,603 and 4,488,555, which are incorporated herein by reference. Similarly, it has been suggested in U.S. patents 4,140,131 and 5,076,272, and in the above-incorporated' 603 patent, to apply low energy stimulation to electrodes on or near the IMD to "sting" the patient when the battery is depleted, which patents are incorporated herein by reference. The use of an audible beep alarm incorporated into an implantable cardioverter/defibrillator to alert a patient to an impending cardioversion shock is disclosed in U.S. patent 4,210,149, which is incorporated herein by reference.

Furthermore, it has been suggested in us patent 4,102,346 to use a beeping audible warning of the depletion of the battery of the implantable cardiac pacemaker in an external monitor, which is obviously directly coupled to the implantable cardiac pacemaker. Acoustic voice recordings have been incorporated into external medical devices for providing warnings or instructions, as disclosed in U.S. patents 5,285,792, 4,832,033 and 5,573,506, which are incorporated herein by reference.

As mentioned above, the history of IMD development has marked an increasing amount of dexterity and complexity in design and operation. However, in some cases, it is desirable to provide a simplified IMD with limited features and controllable operating modes and parameters for use in developing countries or for control by the patient.

As an example of the above, a simplified and low cost programmable, single chamber cardiac pacemaker pulse generator is disclosed in commonly assigned U.S. patent nos. 5,391,188 and 5,292,342, which are hereby incorporated by reference, and are specifically intended to meet the requirements in the emerging country. To avoid the need for expensive external programmers, the low cost pacemaker disclosed in the patent was designed using a simplified programming scheme and a simple EKG display coupled to skin contact electrodes for simply displaying the artificial pacing pulses and the patient's ECG. In this low cost implantable cardiac pacemaker, programming is accomplished by repeatedly timing the application of magnetic fields to the IMD as described above to gradually increase or decrease the pacing rate, pacing pulse width amplitude, etc. The magnetic field may be applied or removed manually and the polarity of the magnetic field may be reversed. The magnetic field sensor and associated programming circuitry within the IMD varies incrementally depending on the applied magnetic field and polarity. The healthcare provider must closely observe the EKG display and calculate the change in pacing rate from the observed pacing interval changes and calibrate the change in pulse amplitude. This requires better hand-eye coordination and fast mental calculations to determine when the required rate or amplitude change has been achieved.

In the latter case, the neurostimulation device and drug delivery system may be implanted in the patient's body and an external programmer provided to the patient for providing limited adjustment of stimulation therapy and drug delivery to allow them to adjust the delivered therapy. Such means include MEDTRONIC

Itrel

Implantable neurostimulator and Synchromed

The drug penetrates the system. The patient is allowed to adjust stimulation and medication by transmitting "up" and "down" commands. The implanted medical device responds to the programming command but does not communicate back to the patient, who is also concerned about whether the required adjustments have been completed.

All of the above RF telemetry systems require complex circuitry and cumbersome antennas as described above and are expensive to implement into IMDs. An RF telemetry transceiver within the IMD consumes electrical energy from the device battery when in use. In addition, telemetry systems all require the use of expensive and complex external programmers that establish telemetry protocols, encode and transmit downlink telemetry transmissions, and receive, decode and display and/or record uplink telemetry transmissions. Recording and/or only visually displaying uplink telemetry data from IMD and device operation (such as delivery of pacing pulses by an implantable cardiac pacemaker) requires careful visual observation by the healthcare provider operating the programmer. Likewise, receiving an acceptable confirmation in an uplink telemetry transmission using a recorder or visual display confirms that only the operating mode or programmed change in parameter values can be observed. It is possible to transmit only a very simple alarm sound to the patient. There is a need to provide a simple method of communicating meaningful implantable medical device information to a patient or healthcare provider that does not require the use of dedicated RF telemetry equipment and RF telemetry capabilities in IMDs. It will be apparent from the following description that the present invention fulfills many of these needs.

Reference made to earlier publications or patents and incorporated by reference in any of the specification is intended to be simply indicative of the level of prior art and/or that certain conventional structures, circuits, etc. may be employed in the practice of the invention. The disclosure of these reference materials is not intended to limit the scope of the invention to the particular embodiments illustrated herein.

The present invention is directed to improvements in the above-described prior art systems for communicating with IMDs of the above-described type to communicate IMD information, such as operating mode, parameter values, operating conditions and stored data, and/or to provide timely messages or alarms to the patient regarding device-related operations or malfunctions.

In one aspect of the present invention, a simplified system is provided for uplink communications to a patient or healthcare provider that receives radio frequency signals, including a common radio that is tuned to the frequency of the signals played by the IMD and that can be heard by the patient and/or healthcare provider caring for the patient. The IMD includes a radio frequency transmitter and antenna that implements the playing or transmission of voiced statements or musical tones using amplitude or frequency modulation within the commercial amplitude or frequency modulation (AM or FM) band. Frequencies at the low frequency end of the AM or FM are generally not occupied by broadcast stations and are preferred so that simple, readily available and inexpensive AM or FM radios can be used to receive and reproduce broadcasts or transmissions. However, other broadcast frequency bands may be used, such as the CB, UHF/VHF television and weather broadcast radio bands and corresponding receivers.

Accordingly, the present invention provides a system and method for radio frequency transmission of audible voiced statements or other audible sounds (e.g., musical tones) from an IMD that are received by a radio that is capable of being tuned to a transmission frequency. The transmitted or broadcast radio frequency signal is received, demodulated and reproduced by the radio as voiced statements or musical tones. Audible voiced statements or other audible sounds reproduced by the radio convey human understandable IMD information during programming or interrogation sessions and alerts the patient at other times.

The message or alarm informs of IMD operation that has occurred or is about to occur, or informs of device or component malfunction or condition, or informs of a detected patient condition. In response to a device or patient condition or prior to emergency device operation, a voice alarm can be triggered, alerting the patient to take appropriate action or to comply with completed device operations, such as administering therapy. These alarms include depletion of battery power in any battery-powered IMD, depletion of a substance (e.g., a drug diagnostic or therapeutic agent) in an implantable substance delivery system, or detection of a fatal tachyarrhythmia and/or emergency delivery of a cardioversion/defibrillation shock in an ICD. A message can be played informing the patient to stop exercise when a cardiac arrhythmia is detected. In addition, time-related messages can be played periodically, informing the patient to take medications on time, or to make regular follow-up visits with the healthcare provider, etc.

It is advantageous for the audio drive signals that produce voiced statements or other audible sounds (e.g., musical tones) to be recorded in a solid-state non-volatile analog memory location having a prescribed memory address within the IMD. The voiced statements are preferably recorded at the time of manufacture or distribution in a language appropriate to the patient or the country or person in which the patient resides. In one embodiment where sufficient non-volatile memory is available, the voiced statements can be recorded in multiple languages, with the appropriate language being selectable by programmed selection commands. In more complex IMDs with rf telemetry capabilities, a particular language may be selected using downlink rf telemetry commands. In the low-cost IMD disclosed herein, a repetitive series of magnetic fields can be provided, which can be used to select a language when decoding. The ability to record voice statements in a locally popular language or select pre-recorded voice statements allows for more flexible, less error prone and safer audible feedback and control. If the patient is moved to a country or place in a popular language different from the popular language of the patient when the patient is away from the country or place, the doctor or other healthcare provider can select the language of the voiced statement.

A plurality of audio drive signals conveying or indicating voiced statements or musical tones of IMD information of the types listed above are stored in analog memory. In one hardware embodiment, the appropriate audio drive signal is accessed in two sequences of interrogation or programming by a logic circuit that generates a unique memory address for the audio drive signal. In one embodiment based on a microprocessor, an operating algorithm is employed to sequentially generate addresses appropriate for the audio drive signal. A suitable audio drive signal is retrieved or applied to the radio frequency transmitter to produce an AM or FM transmission during the interrogation and programming sequence. At other times, the monitored condition, status or emergency or completed operation of the implantable medical device, or the condition or status of the patient, causes a message trigger signal to be generated based thereon. The unique memory address of the message or alarm to be broadcast is determined by the message trigger signal.

To conserve energy, AM or FM transmissions are low power, short duration, and have a range of a few feet or meters in order to conserve energy, avoid the use of awkward components in IMDs, and avoid interference. The antenna may comprise a discrete radio frequency antenna within the IMD housing or an elongated lead of a lead body if such an elongated lead is employed by the IMD. The rf telemetry antenna of more complex rf telemetry systems may also be employed or modified for use in the practice of the present invention. Low power radio frequency signals can be retrieved or transmitted by a body located within a few feet or meters of the patient wearing a low cost radio receiver.

These and other advantages and features of the invention will be better understood similarly by reference to the following detailed description of preferred embodiments of the invention when considered in conjunction with the accompanying drawings in which like reference characters designate like parts throughout the figures thereof and wherein:

FIG. 1 shows a simplified schematic diagram of communication between a programmable IMD in a patient and a healthcare provider, for which interrogation and programming is carried out using audible voiced statements or musical tone feedback transmitted by an external radio device receiving AM or FM transmissions from the IMD;

FIG. 2 is a block diagram of an exemplary pacemaker Implantable Pulse Generator (IPG) for use in the system of FIG. 1, operating in accordance with FIGS. 3A-3C and 4 when a magnet is applied to the skin of a patient above the IPG;

fig. 3A-3C are timing diagrams depicting the sequential application of magnets to the IPG of fig. 2, and the response of the IPG to the applied magnetic field, including device operation and voiced statements generated during an interrogation and programming sequence:

FIG. 4 is a diagram depicting memory address locations of voiced statements uttered by an IMD in the interrogation and programming sequences shown in FIGS. 3A-3C;

fig. 5 is an expanded block diagram of the audio feedback circuit block of fig. 2 illustrating how an audio drive signal is generated, modulated in an AM/FM transmitter, to play or transmit voice statements shown in the interrogation and programming sequences shown in fig. 3A-3C;

FIG. 6 is a block diagram of the analog storage/playback Integrated Circuit (IC) of FIG. 5;

FIG. 7 is a timing diagram depicting the generation of a two word message in the block diagram of FIG. 5;

FIG. 8 is a block diagram of a microcomputer based IMD operating system, intended for use with a controller and monitor or a therapy delivery system of the type shown in FIG. 10, capable of being interrogated or programmed by successive application of magnetic fields and capable of transmitting IMD information received by a radio;

FIG. 9 is a block diagram of a microcomputer based IMD operating system, intended for use with a controller and monitor or a therapy delivery system of the type shown in FIG. 10, capable of being interrogated or programmed using an RF telemetry transmission system and capable of transmitting IMD information received by a radio;

FIG. 10 is a block diagram of a digital controller/timer circuit that may be used with the operating system of FIG. 8 or FIG. 9 and with one of the monitor and therapy delivery device shown;

fig. 11 is a diagram depicting memory address locations of audio drive signals for voiced statements or musical tones issued in an interrogation and programming sequence of the implantable drug delivery device of fig. 10 with the operating system of fig. 8 or 9; and

fig. 12 is a diagram depicting memory address locations of audio drive signals for voiced statements or musical tones issued in an interrogation and programming sequence of the implantable electro-stimulation device of fig. 10 with the operating system of fig. 8 or 9.

The preferred embodiment of the present invention discloses the use of audible voice statements or musical tones transmitted by conventional low cost AM or FM or other band radio devices that receive the rf transmissions or broadcast signals of an IMD during a communication session involving interrogation or programming of device operating modes or parameters or providing patient warnings or messages. The doctor or other healthcare provider may hear a musical tone or voice statement to add to or replace the visual display, or confirm a programming change, or be listened to by the patient to confirm that the patient has begun programming. The present invention may be implemented in all of the above-referenced IMDs that provide monitoring and/or delivery of therapy to a patient. The present invention may be implemented in a simplified, low-cost programming scheme to provide dedicated uplink transmission of IMD information. The audio voice statement preferably also assists the healthcare provider in following programming or interrogation protocols during initial implantation or later.

The present invention may also be implemented into sophisticated RF telemetry programming and interrogation methods and protocols to selectively replace or augment uplink RF telemetry transmissions of device operating modes, states, operations and parameter values. In this case, the modulation of the transmitted acoustic drive signal may be at the usual RF carrier frequency transmitted by these RF telemetry, for example at 175 kHz. Alternatively, the radio may be incorporated into a programmer using the AM or FM band telemetry systems described herein.

The following description with reference to fig. 1-7 is directed to various preferred embodiments of the invention implemented in the housing of a low cost, single chamber, implantable pacemaker IPG that is programmed using a permanent magnet. This implementation may be incorporated into a more complex, dual chamber, programmable pacemaker or pacemaker/cardioverter/defibrillator IPG (as described with reference to fig. 8-10). Additional applications of audio communication accompanying programming or interrogation of an IMD identified in fig. 10 are then described. Fig. 11 and 12 illustrate particular uses of implantable substance delivery systems and implantable electrical stimulators, respectively. Teaching of the IMDs listed herein and other IMDs to be designed in the future will be readily adapted by those skilled in the art.

Fig. 1 is a simplified schematic illustration of audio feedback of data from an IMD100 implanted in a patient 102, which occurs during interrogation or programming to confirm changes in device operating modes or parameter values or the generation of alarms at other times. For purposes of illustration, IMD100 is preferably a cardiac pacemaker including a pacemaker IPG 110 and a pacing lead 120 extending from an IPG connector 112 to one or more pacing/sensing electrodes disposed in or on an atrium or ventricle of a patient in a conventional manner. Thus, pacemaker IPG 110 is shown operating either in a programmable, single-chamber atrial IPG operating in an atrial pacing mode or in a programmable, single-chamber ventricular IPG operating in a ventricular pacing mode. Further, in the preferred embodiment described below, pacemaker IPG 110 has an operating configuration that incorporates the audio feedback features of the present invention described below in the low cost, single chamber pacemaker IPG disclosed in the commonly assigned '188 and' 342 patents referenced above.

In the embodiment of fig. 2-7, a telemetry or communication session with the IMD is established by the physician or other healthcare provider by applying or removing permanent magnet 130 from the patient's skin above IPG 110, according to the protocol described below. The magnetic field constitutes a communication link signal that is detected by the IPG 110 to establish a communication session. Interrogation of IMD information and programming of pacemaker IPG 110 operating modes and parameter values are performed during a communication session.

The magnetic field polarity is sensed by the magnetic field sensor 70 within the pacemaker IPG 110 housing. The interrogation and programming protocols are identified by decoding and logic circuitry coupled to the magnetic field sensors in the following manner. According to a preferred embodiment of the low cost pacemaker of the present invention, each protocol causes the stored voiced statements to be capable of being transmitted as radio frequency signals by a radio frequency transmitter 31 (e.g., an AM or FM band transmitter). Transmitter 31 works with an antenna, which may comprise a discrete radio frequency antenna within the IMD housing, or in the case of cardiac pacemakers, ICDs, and nerve or muscle stimulation devices, may comprise an elongated conductor lead of a lead body, such as lead 120. Transmitter 31 may take the form of a MOTOROLA tuned to the appropriate frequency band

MC 13176 in the form of a single chip AM/FM transmitter.

In the sequence established by the protocol, when magnet 130 is applied to the patient's skin or removed, the doctor or other healthcare provider tunes AM or FM radio 142 to the appropriate AM or FM radio frequency transmission frequency and listens for voiced statements or musical tones emitted by radio speaker 144. Although not specifically illustrated, it is understood that the healthcare provider may also use an EKG display or recorder to view the artificial pacing pulses in the manner described in the commonly assigned '188 and' 342 patents referenced above. AM or FM transmissions 146 use low power to save energy and minimize IMD size and avoid interference problems, so radios 142 may need to be close to or worn on the patient's body.

This same process can be used by the patient to provide therapy, or to monitor conditions, or to change parameters of the therapy, such as to initiate or change the intensity of electrical nerve stimulation or to dispense a quantity of pain pills to control the affliction.

Fig. 2 is a block diagram depicting a small, lightweight, limited function, implantable pacemaker IPG circuit 10 according to one embodiment of the present invention and is a modification of fig. 1 of the above-referenced commonly assigned '188 and' 342 patents. Modifications include the addition of battery monitor circuit 17, audio feedback circuit 25, RF transmitter 31, RF antenna 117 (or coupled to lead terminal 12 via capacitor 129), filter and amplifier circuit 33, optional activity sensor 116 and activity rate response circuit 35, and connections to certain other circuit blocks. It should be understood that even numbered circuit blocks in fig. 2 may take the form of and be equivalent to those circuits disclosed in detail in the commonly assigned '188 and' 342 patents referenced above. Specific embodiments of these circuits have been identified in the commonly assigned '188 and' 342 patents cited above, with reference to the prior patents for illustrative purposes only. Reference to these circuits is not intended to limit the scope of the invention to the particular embodiments of these circuits. The inventors believe that the choice of particular circuits is not critical to the invention as long as they function as a whole to accomplish the operation of the invention.

Pacemaker IPG circuitry 10 is enclosed in a sealed enclosure of an IPG 110 implanted in patient 102, coupled to an atrial or ventricular cardiac pacing lead 120 (as shown in fig. 1) at IPG connector 112. Pacemaker IPG circuit 10 provides single chamber pacing and may be used in conjunction with a ventricular pacing lead or an atrial pacing lead to provide ventricular pacing or atrial pacing in conventional VVI or AAI and related programmable pacing modes.

It should be understood that throughout this disclosure, various internal electronic components including the pacemaker IPG circuit 10 are coupled to a battery 13 (e.g., commercially available manganese dioxide (MnO)₂) Camera battery, etc.) power supply 11. For clarity, the connections of all circuit blocks to the power supply 11 are not shown in fig. 2. However, power source 11 is shown coupled to battery monitor 17 to provide (in this case) a warning trigger signal representative of the battery voltage to the electrical override indicator (ERI) input of audio feedback circuit 25 during device interrogation to trigger a voice battery state (as described below with reference to FIGS. 3A-3C). In accordance with another aspect of the present invention, the alert trigger signal may also be used to periodically trigger the external radio 142 to play and generate RF alerts that are received by it. Audible sounds emitted by the speaker 144 of the radio 142 can be heard by the patient 102 to alert the patient that the battery voltage is depleted and that appropriate action is to be taken. Other messages may also be communicated from the IMD to the patient in this manner.

The battery monitor 17 periodically compares the output voltage of the battery 13 with a reference voltage therein and selects the provision of an ERI warning trigger signal to the ERI input when the battery voltage falls below the reference voltage. Such a battery monitor 17 follows the teachings of commonly assigned U.S. patent 4,313,079, which is incorporated herein by reference. Although not depicted in this embodiment, it will be appreciated that the ERI signal may also be applied to the up-down control circuit 90 to adjust the pacing rate to a percentage of the programmed pacing rate, and to the activity rate response circuit 35 (if present) to inhibit its operation. For example, the up/down control circuit 90 adjusts the programmed 70ppm pacing rate to decrease to a 58ppm ERI rate based on the ERI signal, e.g., during normal VVI or AAI pacing.

Pacemaker IPG circuit 10 includes an output and pump circuit 14 that delivers pacing pulses to terminal 12 and either an atrial pacing lead or a ventricular pacing lead attached thereto in accordance with a pacing trigger signal generated by a pulse width one shot circuit 16. In general, the output and pump circuit 14 corresponds to a pacing pulse output circuit disclosed in commonly assigned U.S. patent 4,476,868, which is hereby incorporated by reference, or other conventional pacing pulse output circuit. The output and pump circuit 14 further includes a programmable amplitude control circuit, disclosed in detail in the above-referenced' 342 patent, that allows the pacing pulse amplitude to be programmed with an amplitude programming signal applied to the pump (P) input. In a preferred embodiment, the pacing pulse amplitude can be programmed between high, medium, and low amplitudes.

The activity of the electronic heart in the patient is monitored by means of a conventional filter circuit 18 and sense amplifier 20 coupled to terminal 12, which filter circuit and sense amplifier serve to filter and amplify intrinsic cardiac electrical signals from the patient's heart. The filter circuit 18 performs a basic band-pass filtering operation on the raw atrial or ventricular cardiac electrical signal and provides a conditioning signal to the input of a conventional sense amplifier 20. SENSE amplifier 20 is configured to detect either P-waves or R-waves and provide a SENSE output signal on line 21. The sense output of the sense amplifier 20 is directed on line 21 to the Clock (CL) input of the D flip-flop 46.

In accordance with this embodiment of the present invention, the slow (e.g., 10Hz) master timing clock signal generated by the 10Hz oscillator circuit 22 controls the timing operation of the pacemaker IPG circuit 10, with one output from the rate limit decoding circuit 26 starting the oscillator circuit 22 via line 40. Referring to fig. 10 of the above-referenced commonly assigned '188 and' 342 patents, a 10Hz oscillator circuit 22 is shown and described in detail. Whenever the 10Hz oscillator circuit 22 is activated, it emits 4 10Hz pulses over a time period of 400 milliseconds; then it remains inactive until it is activated again. The 10Hz timing clock signal generated by oscillator circuit 22 is applied via line 24 to the negative CL (clock) inputs of rate limit decoding circuit 26, blanking decoding circuit 28 AND refractory period (refresh) decoding circuit 30, AND to one input of AND gate 32. Rate limit decoding circuit 26, blanking decoding circuit 28, and refractory period decoding circuit 30 define an upper rate limit period, a blanking period, and a refractory period, respectively, by counting the 10Hz clock cycles provided to their negative CL inputs on line 24.

A blanking interval (e.g., 100 milliseconds corresponding to one 10Hz clock cycle) extends therefrom when a pacing pulse is delivered or when a sensing signal is generated, and conventional blanking decoding circuitry 28 provides a blanking signal to sense amplifier 20 via line 29. It will be appreciated that depending on the length of the blanking interval required and the actual oscillation rate of oscillator circuit 22, a blanking period may be defined that includes a greater number of clock cycle counts. The blanking signal effectively disconnects the sense amplifier input from terminal 12 during the blanking time period to allow the artificial pacing pulse to disappear (otherwise saturating sense amplifier 20) and avoid double sensing the internal P-wave or R-wave.

Refractory period decoding circuitry 30 defines a refractory period that tracks each sensed or paced cardiac event. Refractory period decoding circuit 30 measures the refractory period by counting 10Hz clock cycles from line 24 as blanking decoding circuit measures the blanking interval. In the preferred embodiment of the present invention, it is believed that a refractory period on the order of 300 milliseconds or so is appropriate. In this case, refractory period decoding circuit 30 may define the refractory period to last 3 10Hz clock cycles.

During the refractory period, refractory period decoding circuit 30 provides a logic low refractory period output signal on line 44 and applies it to the D input of D flip-flop 46. The output of sense amplifier 20 on line 21 is applied to the CL input of flip-flop 46. The Q output of D flip-flop 46 remains at a logic low level and cannot transition to a logic high level as long as the refractory period decoding circuit 30 provides a logic low refractory period output signal to the D input. However, after the refractory period has expired, the refractory period signal applied to the D input on line 44 returns to a logic high level. At this point, assertion of one sense signal on line 21 (caused by a sensed event, as described below) causes the Q output of D flip-flop 46 on line 48 to toggle to a logic high, non-refractory period sense signal.

A logic level high or logic low on line 48 is applied to one input of and gate 32; and a 10Hz clock signal is applied to the other input of and gate 32 (as described above). If the refractory period has not expired, the output of AND gate 32 and the signal level on line 50 remain at a logic low level. If the refractory period has expired, line 48 will go to a logic high level when a "sense" event is detected. The "sense" signal generated on line 21 after the expiration of the 300 millisecond refractory period causes the Q output of D flip-flop 46 to transition to a logic high level. A positive offset of the next 10Hz clock signal will then cause the output of and gate 32 to transition to a logic high level. The output of and gate 32 is directed to the reset (R) input of flip-flop 46 on line 50. Thus, the Q output of D flip-flop 46 transitions to a logic low level when the signal on line 50 goes to a logic high level at the next clock signal following the sense signal (which is generated after the expiration of the refractory period).

The non-refractory period sensing signal on line 48 is also applied to one input of an OR gate 52 and the pulse width trigger signal on line 55 is applied to the other input of the OR gate 52. The output of or gate 52 is directed on line 56 to the set (S) input of rate limit, blanking and refractory period decoding circuits 26, 28 and 30. The logic high pulses on line 56 corresponding to the non-refractory period sensing signal or pulse width trigger signal set and restart the upper rate limit interval, blanking interval and refractory period interval. In addition, when the rate limit decode circuit is set, its logic high enable signal applied on line 40 can enable the 10Hz oscillator circuit 22, which again sends 4 10Hz clock pulses.

Rate limit decoding circuit 26 defines an upper rate limit for stimulation pulses delivered by pacemaker IPG circuit 10. In the disclosed embodiment of the present invention, it is believed that an upper rate limit of one pacing pulse every 400 milliseconds, or a maximum pacing rate of 150PPM, is appropriate. In this case, rate limit decoding circuit 26 defines an upper rate limit time interval that lasts for 4 consecutive cycles of the 10Hz clock (applied to its CL input). When a logic high signal on line 56 is applied to the S input of rate limit decoding logic 26 after each "sense" and "pace" event as described above, the output O of rate limit decoding circuit 26 goes to a logic low level for a period of about 400 milliseconds. This logic low level signal is applied on line 62 to the D input of D flip-flop 54, which prevents the output Q of the D flip-flop from transitioning from a logic low level to a logic high level in response to a logic high level or transition at the CL input of D flip-flop 54. After the rate limit time interval has elapsed on 400 milliseconds, the O output signal from rate limit circuit 26 returns to a logic high level on line 62.

Rate one shot and TMT circuit 58 (hereinafter referred to simply as rate/TMT circuit 58) determines the basic pacing rate at which pacing pulses are delivered to terminal 12 when no sensing output is present on line 21 during a pacing escape interval. The pacing escape interval between output pulses produced at output O of rate/TMT circuit 58 is programmable, with programmable pacing rates being established in increments of 10PPM in the range from 460 to 1200 milliseconds, e.g., between 130PPM and 50PPM, respectively. Rate/TMT circuit 58 comprises a retriggerable one-shot multivibrator that generates an output signal at its output (O) and applies that output signal via line 60 to the CL input of D flip-flop 54 when the programmed escape interval time has elapsed. If the 400 millisecond rate period time has elapsed, the Q output of D flip-flop 54 is switched to a logic high level based on the output signal on line 60, and a pulse width trigger signal is provided on line 55 to the trigger (T) input of pace pulse one shot 16. During the 400 millisecond up-rate time interval, the output signal on line 60 from rate/TMT circuit 58 is unable to transition the Q output of D flip-flop 54 to a logic high level and generate a pulse width trigger signal.

At this point it should be noted that the logic high pulse width trigger signal on line 55 is also directed to the S inputs of rate limit, blanking and refractory period decoding circuits 26, 28 and 30 through or gate 52 and line 56. After the 400 millisecond rate limit interval expires and the pacing escape interval expires, the logic high pulse width trigger signal on line 56 restarts the upper rate limit interval, the blanking interval, and the refractory period interval.

The programmed pacing escape interval is automatically restarted within rate/TMT circuit 58 when an output pulse is generated on line 60. Programmed pacing escape intervals are also restarted within rate/TMT circuit 58 in accordance with the "sense" event. The rising edge transition of the reset signal from the output of and gate 82 appearing on line 84 is applied to the R input of rate/TMT circuit 58 to restart the pacing escape interval. The non-refractory period sensing signal on line 48 from the Q output of D flip-flop 46 is coupled to one input of and gate 82, and the normal logic high output of NOR (NOR) gate 76 is coupled to the other input of and gate 82. After expiration of the refractory period time interval indicating a non-refractory period sensed event, the Q output of D flip-flop 46 goes to a logic high level based on the sensed event on line 21. The rising edge transition is communicated to the R input of rate/TMT circuit 58 via line 48, and gate 82 and line 84 and the pacing escape interval is restarted. As long as the rising edge transitions occur at the R input of rate/TMT circuit 58 more frequently than the programmed pace escape interval, the output signal on line 60 will stay at a logic low level and will inhibit the generation of the pulse width trigger signal at output Q of D flip-flop 54.

The pulse width trigger signal output by flip-flop 54 is directed on line 55 to the T input of pulse width one shot 16, and pulse width one shot 16 responds by generating a pacing trigger pulse on line 64 having a duration that determines the pulse width of the pacing pulse generated by output and pump circuit 14. The pacing pulse width is programmable in a range from 0.1 to 1.0 milliseconds, for example, in the manner described in more detail in the commonly assigned '188 and' 342 patents referenced above. The pacing trigger pulse output from pulse width one shot 16 is applied via line 64 to the T input of output and pump circuit 14, which in response applies a programmed amplitude pacing pulse through coupling capacitor 66 to terminal 12 and the pacing lead attached thereto. The pacing trigger pulse from the pulse width one shot 16 is also applied to the R input of the D flip-flop 54 on line 64 to terminate the pulse width trigger signal by terminating the latched or stored logic high level at the Q output of the D flip-flop 54.

In this manner, pacing pulses are generated and applied to the pacing lead depicted in fig. 1 on demand. In the present embodiment, programming of pacing rate and pacing pulse amplitude and width is accomplished in the manner described and illustrated in detail in the commonly assigned '188 and' 342 patents referenced above. To eliminate commonly used, expensive, bulky, and energy-consuming RF telemetry circuitry and components, the programming circuitry and protocols disclosed herein use solid-state semiconductor devices that are sensitive to applied external magnetic fields. Solid state magnetic field sensor (MAGFET)70 suitable for use in IMD telemetry is disclosed in commonly assigned U.S. Pat. No. 5,438,990 to Wahlstrand et al, which is incorporated herein by reference in its entirety. Both the N and S output signals on lines 72 and 74 are at a logic zero or low level when no magnetic field is applied. As described in the' 990 patent, MAGFET circuit 70 is capable of discriminating between two external magnetic fields of different polarity orientations (e.g., between a north-south oriented magnetic field and a south-north oriented magnetic field). Accordingly, MAGFET circuit 70 generates two logic high output signals, N (north) on line 72, and S (south) on line 74. For example, the N signal is asserted in accordance with the detection of the applied magnetic field by MAGFET circuit 70 for the N-S orientation. Likewise, an S signal is established based on detecting the S-N orientation of the applied magnetic field.

Logic circuit 78 receives a logic high N or S signal on line 72 or 74 from MAGFET circuit 70. The logic circuit 78 detects the application and removal of a magnetic field oriented in an N-S or S-N magnetic field, respectively. As described below with reference to fig. 3B, the logic circuit 78 sends control signals to the up/down control circuit 90 via a plurality of control lines (collectively shown at 92 in fig. 2). The logic circuit 78 includes digital logic for detecting and counting magnet removal and replacement cycles, as described in the commonly assigned '188 and' 342 patents referenced above, and for programming pacing rate, pacing pulse width, and pacing pulse amplitude in accordance with the assertion of various control signals therefrom.

For example, upon detection of a magnet removal/replacement cycle, the logic circuit 78 asserts a control signal to the up/down control circuit 90 causing it to enter the pacing rate programming mode. In rate programming mode, another control signal is derived from the N or S magnet polarity signal on lines 72 or 74, which commands a gradual increase or decrease in pacing rate, respectively.

The up/down control circuit 90 generates a plurality of output signals that are directed to the program (P) inputs of the rate/TMT circuit 58, the pulse width one shot 16, and the output/pump circuit 14 on lines 94, 96, and 98, respectively. The signals on lines 94, 96 and 98 are analog reference currents, which are described in detail in the commonly assigned '188 and' 342 patents referenced above. The reference currents on lines 94 and 96 determine the duration of the output pulse from rate/TMT circuit 58 and pulse width one shot 16, respectively, and thus the programmed pacing rate and pulse width. The reference current on line 98 determines the output pulse amplitude from the output/pump circuit 14 by producing a reference voltage on resistor 15. This reference voltage is used with a comparator and charging circuit in the output/pump circuit 14 to charge the output capacitor to a programmed voltage magnitude (as is well known in the art).

For example, in the case of a pacing rate parameter, up/down control circuit 90 provides a reference current on line 94 to the P input of rate/TMT circuit 58. The reference current level is gradually decreased on line 94 causing the pacing escape interval established by rate/TMT circuit 58 to increase. Likewise, the reference current level is increased in steps on line 94, causing the pacing interval established by rate one shot 58 to be decreased in steps. The pulse width one shot 16 is controlled in a similar manner by the reference current on line 96. The pacing pulse amplitude of the pacing pulses produced by output/pump circuit 14 is directly controlled by the voltage developed across resistor 15, which in turn is controlled by the voltage developed on line 98 by up-down control circuit 90.

The interrogation and programming protocol of this embodiment of the present invention is based on the initial detection of the application of an external magnetic field and the initial entry into TMT mode as shown in fig. 1. After the TMT and interrogation modes are completed, the external magnet 130 is removed and then reapplied in accordance with the protocol disclosed in the commonly assigned '188 and' 342 patents referenced above (for programming operating modes and parameter values, etc.). The number of programmable modes and parameter values of the pacemaker IPG circuit 10 is relatively more limited than is typical with more complex programmable cardiac pacemakers. For example, in this embodiment, the basic pacing rate, pacing pulse width, and pacing pulse amplitude parameters are programmable within selected ranges. The single chamber asynchronous and triggered pacing modes and other parameters may be programmed, such as sense amplifier sensitivity, refractory period and activity thresholds and gain factors as described in the above-referenced commonly assigned' 096 patent. In the case of a programmable dual chamber pacemaker, pacing upper rate limits and A-V delay intervals may also be programmed. Some arrangement must be made to select which parameter or mode to program in order to program the different parameter values and operating modes separately. Identification of the parameter or mode to be programmed has been achieved in some existing pacemakers by sending an identification code to the receiver of the implanted pacemaker via downlink RF telemetry, along with a new value or a new mode.

In TMT mode, rate/TMT circuit 58 provides a preset number (e.g., 3), outputs pulses to D flip-flop 54 at the TMT pacing rate on line 60, and provides 3 corresponding pulse width trigger pulses at its Q output. The non-refractory period sense event signal generated by D flip-flop 46 in response to the sense signal is blocked and cannot reset rate/TMT circuit 58. And gate 82 is blocked by a logic low signal on line 80 output from the nor gate 76 due to a logic high (N or S) level on one input of the gate. In this manner, amplifier circuit 20 continues to operate, but effectively disables its output signal as long as MAGFET70 senses the magnetic field.

The asynchronous TMT sequence helps the healthcare provider determine whether the currently programmed pacing pulse width and pulse amplitude settings are sufficient to achieve "pickup" of the patient's heart, i.e., sufficient to cause it to contract. In the presently disclosed embodiment of the invention, the TMT sequence may be one as disclosed in commonly assigned U.S. patent 4,273,132 to Hartlaub, which is incorporated herein by reference in its entirety. The pacing pulses generated during the TMT sequence may have a higher than normal pacing rate to distinguish the TMT sequence from asynchronous pacing pulses preceding and following it. The amplitude or pulse width of at least one TMT pacing pulse is reduced to a percentage of the programmed amplitude or pulse width. In the conventional programming system described in the above-referenced '132 patent, during this time, the healthcare provider observes the patient's heart activity on the EKG monitor and observes whether 3 pacing pulses all cause systoles. If one (or more) TMT pacing pulses are not targeted to the heart, the healthcare provider may increase the programmed pulse width or pulse amplitude and again execute the TMT sequence to verify that the pacing pulse energy is sufficient to target the heart and leave an appropriate safety margin.

After rate/TMT circuit 58 performs TMT, IPG circuit 10 begins asynchronous pacing at a nominal rate (e.g., 70PPM), or at a programmed rate, or at an ERI rate, provided this function is used, so long as the N or S magnetic field continues to be detected by MAGFET 70. In accordance with the modes of operation described in the above-referenced commonly assigned '188 and' 342 patents, a protocol is followed to program the pacing rate, pulse width and/or amplitude that provides for the manual removal or reapplication of the N or S magnetic field by appropriate movement of the magnetic pole 130 in fig. 1.

Referring to fig. 2, the following operations are implemented in audio feedback circuit 25, as will be described in more detail below. In brief, when an N or S signal is generated on line 72 or 74, the output signal of nor gate 76 is applied to audio feedback circuit 25 on line 80 as a MAGNET (MAGNET) signal. The magnet signal causes power to be applied from the power supply 11 to the components of the audio feedback circuit 25 described below, which are typically not powered in order to conserve the energy of the battery 13. The audio feedback circuit 25 includes logic circuitry for specifying memory addresses of analog music tones or voiced statements retrieved from analog memory and applied as audio drive (a-D) signals to the AM/FM transmitter 31 which transmits as described below. To conserve battery power, the AM/FM transmitter 31 is powered only by the SW signal and is coupled to the Audio Drive Signal (ADS) output when necessary during an interrogation or programming session or to deliver a message to the patient.

The pace trigger signal on line 64 and the non-refractory period SENSE output signal of flip-flop 46 on line 48 are directed to respective pace and SENSE (pace and SENSE) inputs of audio feedback circuit 25. Signals representing pacing pulse amplitude, pacing RATE and pacing pulse width, established in the up/down control circuit 90, are directed to the AMP, RATE and PW inputs of the audio feedback circuit 25 on lines 91, 93 and 95, respectively. As described above, the upper ERI signal on line 23 is applied to the ERI input of audio feedback circuit 25 when the battery voltage drops below the reference voltage in battery monitor 17.

Audio feedback circuit 25 also includes a pace/SENSE event counter that is activated to count the number of pace trigger pulses and sensed event signals generated after receipt of the magnet signal. The event counter initially counts the pacing trigger pulses of the TMT sequence whenever a magnet signal is present, and then counts the asynchronous pacing trigger pulses during the asynchronous interrogation mode. In the illustrated embodiment, the pace/sense counter counts a fixed number of pace trigger signals and sense signals when the magnet signal is terminated. The Count (CNT) is applied to the logic circuit 78 on line 73 as the timing for reapplying the magnetic field. The voiced statements emitted at times synchronized to each paced and sensed event are addressed using the counts of the pace/sensed event counters.

According to this embodiment of the invention, audio feedback circuit 25 and AM/FM transmitter 31 are energized during the TMT, the voiced statement "pace" is retrieved from analog memory and transmitted on each pacing pulse of the TMT, and the voiced statement "TMT pace" is transmitted on delivery of the final reduced energy pacing pulse of the sequence. The correct voiced statements are appended to the pacing pulses delivered in the TMT sequence using pace/SENSE event counter counts. Then, regardless of whether the magnetic field continues to be applied, a series of voiced statements are retrieved and transmitted in an interrogation sequence that begins after the TMT and continues until completion. In the embodiment of fig. 2-4, the voiced statements include manufacturer, device model and serial number identifiers, battery status, and parameter values including pacing rate, pacing pulse width, and pacing pulse amplitude. However, if pacing modes and other operating parameters, such as sense amplifier sensitivity, refractory period, activity threshold values, etc., are made programmable, the voiced statements may include other statements of these programming modes and parameter values.

Fixed rate pacing pulses are delivered after this TMT sequence is complete, as long as the magnetic field is not disturbed. According to this embodiment, the delivery of each pacing pulse is accompanied by a "pacing" statement that is retrieved and emitted until the magnetic field is removed. In another variation, only a fixed number of "pacing" statements may be retrieved and emitted, and the magnetic field may be retained to maintain fixed rate pacing for extended diagnostic or therapeutic purposes. When the pace/sense event counter reaches a fixed count (e.g., 10), the RF emission of the "pace" statement is stopped. At which point the pace/sense event counter may be turned off or the pacing trigger signal may continue to be counted. Further, when the magnetic field is removed thereafter, a fixed number of asynchronous pacing pulses accompanied by a retrieved and emitted "pace" statement may be delivered to assist in the timing of reapplying the magnetic field into the programming mode.

The pacing mode returns to the programming mode, which is typically an AAI or VVI mode, but may be a trigger mode (AAT or VVT) if a magnetic field is not reapplied and sensed during delivery of a fixed number of asynchronous mode pacing pulses. It is possible to temporarily place the IPG in a disabled mode to determine whether an intrinsic cardiac event is sensed, but such testing may not be safe for the patient. Preferably, after the magnetic field is removed and the asynchronous mode is terminated, the retrieved and emitted "paced" or "sensed" statement is transmitted by a pace/sense event counter counting again at a fixed number (e.g., 10) of pace trigger or sense event signals. In the absence of a non-refractory period sensed event, at the end of the pacing escape interval, the pacing trigger pulse continues with the "pace" statement retrieved and emitted until the count is reached. As shown in fig. 2, non-refractory period sensing events are counted and the RF emission of the "sense" statement is triggered, but it is possible to alternately count and emit the "sense" statement on both the refractory period and non-refractory period sensing events.

A preferred embodiment in the sequence of events involved in interrogating and/or programming pacemaker IPG 10 may be better understood with reference to the timelines of fig. 3A, 3B and 3C. In FIGS. 3A, 3B and 3C, represented by P₀、P₁The vertical solid line of the etc. represents the pacing pulse, denoted by S₁、S₂Etc. the vertical dashed lines represent sensed events. Fig. 3A depicts a pacemaker IPG identifier, programmed pacing rate and pulse amplitude, battery condition, and interrogation of retrieved and emitted paces and sensed events. In fig. 3A, it is assumed that pacemaker IPG 10 is generally operating to time T1 at which time magnet 130 (as shown in fig. 1) is applied. For example, upon detection of the programming magnet at T1, pacemaker IPG circuit 10 begins delivering 3 pacing pulses P at an asynchronous rate of 100PPM₁、P₂、P₃. Pacing pulse P₁And P₂At the programming pulse amplitude, however, pacing pulse P₃At a reduced pulse amplitude to determine whether the patient's heart is being delivered via reduced energy pacing pulses. The healthcare provider may view the 3 artificial pacing pulses on an EKG monitor and also show a PQRST combined image resulting from the pacing pulses if the pacing pulse energy exceeds the patient's pacing threshold. The retrieved "START TMT" statement is transmitted by AM/FM transmitter 31 shortly after the magnet signal is generated. "pace", "pace" and "TMT pace" states that the retrieval and transmission is synchronized with the next 3 pacing trigger signals of the TMT sequence.

In fig. 3A, after the TMT sequence is completed at time T2, pacemaker IPG circuit 10 remains in asynchronous (AOO or VOO) mode, in which pacing pulses P are delivered at a programmed or nominal asynchronous rate (e.g., 70PPM)₄To P_n. Alternatively, if the ERI signal is present and applied to the up/down control circuit 90 (as described above), the asynchronous rate may be 58ppm of the reduction rate. It will be appreciated that the time interval between asynchronous pacing at time T2 and time T3 in fig. 3 may last for an indeterminate period of time as long as programming magnet 130 remains in place. However, the "pacing" statement retrieved and transmitted can only continue until a predetermined number "n" is retrieved and transmitted, and then stop to conserve battery power. The magnet is removed at time T3 and the pacemaker IPG (e.g., AAI or VVI mode) returns to the programmed pacing mode, (at the programmed pacing rate and pacing pulse amplitude and width). Alternatively, after T3 and before returning to the programmed pacing mode, yet another number, e.g., 10 asynchronous pacing pulses, may be delivered. This feature allows removal of the magnet at any time after T1 and allows TMT, uplink telemetry, and asynchronous pacing to continue until completed after such magnet removal as described above.

Returning to time T2, in the depicted interrogation sequence, audio feedback circuit 25 begins retrieving the a-D signal and applying it to AM/FM transmitter 31, causing AM/FM transmitter 31 to transmit analog voice statements. In this example, the retrieved and transmitted voiced statements comprise a number of phrases selected from the list of memory addresses depicted in FIG. 4. The pacemaker manufacturer, model number and unique serial number are retrieved and transmitted, followed by a phrase of retrieval and transmission stating programmed pacing rate, programmed pulse width, high, medium or low programmed pacing pulse amplitude and battery status. If the logic level at the ERI input to audio feedback circuit 25 indicates normal, beginning of life, battery energy, then the battery status statement "Battery Normal" is retrieved and transmitted. If the battery monitor 17 generates an ERI signal in response to the detection of depletion, end of life, battery energy, the battery status statement "battery depleted" is retrieved and transmitted. It should be noted thatThe care provider may leave the magnet 130 in place (as shown in fig. 1) or remove it at any time during the interrogation sequence described above. Retrieval and transmission of voiced statements can continue to be completed even if the magnet is removed prior to retrieval and transmission of all statements of the query sequence. For example, in retrieving and transmitting these identifiers and state statements for the interrogation sequence, at pacing pulse P₄To P₇The statement inhibits "pacing". The "pace" statement is retrieved and transmitted after the interrogation sequence is completed, as long as the magnet continues to be applied or until a predetermined count "n" is reached.

At time T3 in fig. 3A, magnet 130 is removed from patient 102 shown in fig. 1; and no magnet signal is applied at the magnet input of audio feedback circuit 25. As shown in fig. 3A, audio feedback circuit 25 starts an internal event counter for 10 paced or sensed events, e.g., continues to program pacing rate, pulse width, or amplitude in one or more reapplied magnetic fields that must be sensed by MAGFET 70. Sense amplifier 20 is no longer effectively disabled and the non-refractory period sense signal that passes through and gate 82 and the reset pacing escape interval is clocked in rate/TMT circuit 58. The expiration of each escape interval (due to a non-refractory sensed event or expiration of the escape interval time) is applied to the sensing and pacing inputs of audio feedback circuit 25 which counts them. Audio feedback circuit 25 continues to retrieve the A-D signal from memory and provide it to AM/FM transmitter 31, delivering each pacing pulse (e.g., P)_n+1And P_N+10At) and deliver each sense signal (at S)_n+2And S_n+3Where) modulates and emits the statement "pace" or "sense" (as shown in fig. 3A). During this sequence, the healthcare provider may use the radio to receive, demodulate, and emit "paced" and "sensed" voiced statements (or musical tones representing it) and correlate them with a visual display of the same event. Retrieval and transmission of voiced statements is stopped when a predetermined count of "paced" and "sensed" events are accumulated in the event counter of audio feedback circuit 25.

The illustration of fig. 3A assumes that the magnetic field is no longer applied during the 10 pacing and sensing events (counted by the event counter and provided to logic block 78 on line 73) after time T3. Fig. 3B depicts a programming protocol sequence that is initiated by a single reapplication of the permanent magnet providing a magnet signal on line 80 after T3 but during the sequence before counting 10 paced or sensed events. During this time period, the healthcare provider or doctor can hear and count several "pace" and "sense" statements retrieved and transmitted by the radio and determine the time at which magnet 130 is reapplied to the patient's skin. At the completion of the 10 event windows, a single reapplication of the magnetic field in the 10 event windows is decoded in logic circuit 78 to begin the pacing rate programming sequence (in which the base pacing rate is programmed).

FIG. 3C depicts a programming protocol sequence initiated by two re-applications of a permanent magnet that provides a signal N or S on lines 72 or 74 during the procedure described above after T3 but before counting 10 events. Two reapplications of the magnetic field within the 10 event count windows are decoded in logic circuit 78 to begin a pacing pulse amplitude programming sequence in which the pacing pulse amplitude is programmed. Likewise, three reapplications of the magnetic field within the 10 event count windows are decoded in logic circuit 78 to begin the pacing pulse width programming sequence in which the pacing pulse width is programmed.

Programming of any of these three programmable parameters is accomplished by first initiating a TMT and interrogation sequence (as described above with reference to fig. 3A). Then, after time T3, the appropriate number (1, 2, or 3) of magnet removal/replacement cycles must be performed within the 10 event count window to switch the logic circuit 78 to the programming mode for programming the desired parameters. This method and ability to hear the retrieve and transmit "pace" and "sense" statements issued by the radio device makes it easy to reliably apply or remove the permanent magnet 130 to the patient's skin as many times as desired after the permanent magnet 130 is initially removed from the patient's skin at time T3 to select the desired parameters for reprogramming.

In the magnet removal/reapplication cycle depicted in fig. 3B and 3C, it can be observed that the reapplication magnet 130 is held in place to provide a selected N-S or S-N magnetic field to MAGFET70 during the subsequent programming mode. Accordingly, the continuously generated N or S signal is applied to one input of AND gate 82 through NOR gate 76 to effectively disable sense amplifier 20 and begin pacing in asynchronous mode. The pacing pulses are then delivered at the currently programmed pacing rate, pacing pulse width, and pulse amplitude. The logic circuit 78 decodes the number of applications of magnet 130 removals and replacements and provides a corresponding programming mode control signal to the up/down control circuit 90 via line 92.

Once in the decoded programming mode, the up/down control circuit 90 adjusts the corresponding parameter value to increase or decrease depending on the polarity of the detected magnetic field by an increment over each asynchronous pacing cycle. For example, the rate programming mode is initiated by completing the TMT and interrogation modes, and then removing and replacing the magnet once (as shown in FIG. 3B). As long as the N signal remains present on line 72, indicating detection of an N-S oriented magnetic field, the up/down control circuit 90 increases the pacing rate by one increment (e.g., 5PPM or 10PPM) per pacing cycle. Conversely, as long as the S signal remains present on line 74, indicating an S-N oriented magnetic field, the up/down control circuit 90 decreases the pacing rate by the same increment for each pacing cycle. The pacing rate is therefore programmed to the desired value by maintaining the S-N or N-S oriented magnetic field on MAGFET circuit 70 for a sufficient pacing period to achieve the desired degree. When the desired rate is reached, the magnet is simply removed to terminate the rate programming.

In the above-referenced commonly assigned '188 and' 342 patents, verification of pacing rate variation is validated by observing the delivery of redundant pacing pulses that indicate parameters that are programmed by their number on the running EKG display. In rate programming, two such pacing pulses are generated at the end of each pacing cycle, separated by 5 milliseconds (also shown in fig. 3B). In pulse amplitude programming, three such pacing pulses are generated at the end of each pacing cycle, separated by 5 milliseconds (also shown in fig. 3C). Assume that 4 such pacing pulses are generated at the end of each pacing cycle in order to indicate that the pacing pulse width is programmed. The number of redundant pacing pulses shows which parameter is being programmed, but does not reveal the programmed parameter value. Errors may occur in the counting of pacing cycles and incremental changes in these parameter values are not easily observed or measured from the EKG trace being printed or displayed on a video screen. It is necessary to know what the starting parameter is and to mental count the change from this value by counting the slip interval until the final parameter value is obtained. If the starting pacing pulse width or amplitude or pacing rate is not known and cannot be measured, it may be necessary to follow a programming sequence to increase or decrease the programmed parameter value to its upper or lower limit. The upper or lower limit is reached by counting the maximum number of slip intervals corresponding to the total number of possible incremental values. The new parameter values are then programmed by incrementally subtracting the parameter values from the maximum value or incrementally adding the parameter values from the minimum parameter values by a sufficient number of increments to achieve the desired programmed value.

According to yet another feature of the present invention, at the end of each runaway interval, audio feedback circuit 25 and AM/FM transmitter 31 are used to retrieve and transmit a statement of the programmed parameter value. In this manner, there is no need to use redundant and energy-wasting pacing pulses, and there is no need to calculate the correct number of pacing cycles required to make the parameter value change correctly, or to count out the pacing cycles. This results in a simpler, more reliable, and less prone to erroneous programming functions, with the advantages of reduced cost and increased patient safety.

Thus, the redundant pacing pulses used in the commonly assigned '188 and' 342 patents referenced above are depicted in fig. 3B and 3C, but it will be understood that they are not required in the practice of the present invention. When entering the programming mode through a removal/replacement cycle of one, two or more magnets, voiced statements of the parameter being programmed (e.g., "programming rate" or "programming amplitude") are retrieved from analog memory, transmitted and retrieved and reproduced by an external radio device.

In addition, at each incremental change, a pacing rate, pulse width, or pulse amplitude change is retrieved and transmitted, as depicted in fig. 3B and 3C. In this embodiment, especially at high pacing rates, it may be desirable to make incremental programming changes and transmission change values only at the end of every second or third or fourth escape interval to provide sufficient time to transmit and hear the entire phrase from the radio receiving it. Or the phrase may be shortened to summarize a 5 or 10 pacing rate and pulse width stated in milliseconds. Further, an upscale or downscale musical tone may be transmitted and emitted by the radio before or after each incremental increase or decrease, respectively, in the programmed parameter value to indicate that the parameter value is being changed. As described below, in some IMDs, one or more upshifted or downshifted musical tones may be transmitted after each parameter value is increased or decreased without having to retrieve and transmit the actual values in the transmitted voiced statements.

Fig. 4 shows an exemplary list of pacing rates, pulse widths, and pulse amplitudes that are retrieved and transmitted in the programming mode and encoded as memory addresses for an analog memory array, which is described below with reference to fig. 6. For example, voiced statements of pulse width in increments of 0.1 ms, ranging from 0.1 ms to 1.0 ms, and voiced statements of pacing rate in increments of 5PPM, ranging between 50PPM and 100PPM, are stored in memory. For example, "low amplitude," "medium amplitude," and "high amplitude" voiced statements of pacing pulse amplitudes of three programmable amplitudes are also stored in memory.

Fig. 5 is an expanded block diagram of audio feedback circuit 25 of fig. 2, including analog memory/playback integrated circuit IC 200, timing control logic 202, and address generation logic 204. Further, an acoustic input block 206 is shown in dashed lines, illustrating analog retrieval and transmission of voiced statementsAnd/or storage of musical tones in analog memory of the analog storage/playback IC 200. The recording is typically performed during manufacture of the pacemaker IPG or other IMD, although such recording may be performed after manufacture of the pacemaker IPG is complete. The analog storage/playback IC 200 is preferably an ISD33000 series ChipCoder

One of the monolithic voice recording/playback Devices, sold by information storage Devices, located in Los Alton Hills, california, usa, particularly model ISD33060 shown in fig. 6. Such an analog storage/playback IC is disclosed in U.S. patent 4,890,259, which is hereby incorporated by reference, and other related ISD patents.

In fig. 5, the timing control circuit 202 and IPG circuit are interconnected to receive a pacing trigger pulse on line 64, a sensed event signal on line 48, and a magnet signal on line 80 whenever an N (up) or S (down) signal is present on lines 72 and 74, respectively. The timing control circuit 202 establishes the protocols shown in fig. 3A-3C and described above and generates the commands shown in fig. 5, which are applied to the address generation circuit 204 or the AM/FM transmitter 31 and logic 78. These commands are generated in particular during the TMT mode, the asynchronous interrogation mode and the subsequent normal operating mode shown in fig. 3A. To save energy, the SW signal generated by the timing control circuit 202 causes the power of the AM/FM transmitter 31 to increase only during the transmit time window.

The address generation circuit 204 also receives the ERI signal on line 23 from the battery monitor 17 and also receives the pulse Amplitude (AMP), pacing RATE (RATE) and Pulse Width (PW) programmed operating parameter values on lines 91, 93 and 95 from the up/down control circuit 90, respectively. During the asynchronous interrogation mode of FIG. 3A, the AMP, RATE and PW programming parameters and the ERI signals are converted to the memory addresses listed in FIG. 4 as programmed values and battery conditions. These command hint ADDRESS generation circuits 204 select and apply the voiced statement memory addresses described above and listed in fig. 4 to the ADDRESS (ADDRESS) input line of the analog store/playback IC 200.

It is possible to combine voiced statements taken in tandem from two memory addresses to form a retrieve and transmit phrase as shown in fig. 7. For example, a voice phrase to "pace XX PPM" (where "XX" is the current programmed value) may be selected in cascade from a "pace" statement and a "XX PPM" rate statement at two addresses depicted in fig. 4 using a pacing signal and a programmed pacing rate value.

During the programming mode illustrated in fig. 3B and 3C, the increased or decreased Amplitude (AMP), RATE (RATE), and Pulse Width (PW) programming parameter values are likewise converted to the memory addresses listed in fig. 4 and applied to the address inputs of the analog storage/playback IC 200.

To initiate or trigger playback at an address provided to the "address" bus, address generation circuitry 204 also provides a "not chip able" (NEC) command and a "play" command to analog storage/playback IC 200. The addressed recorded voiced statements or other audible sounds are provided as a-D signals to the AM/FM transmitter 31 of fig. 2 through a playback filter and amplification stage 208. When the retrieved A-D signal statement is complete, the logic level on the "message not end" (NEOM) line transitions to alert timing control circuit 202, queuing the next command to address generation block 204. The above-described sequence of device identification, operating conditions and modes or states, and retrieval and transmission of programming parameter values are sequentially generated in an interrogation mode through "hand-off" cooperation between the timing control 202 and the analog storage/playback IC 200. Likewise, each device operation, i.e., either a pacing trigger pulse or a sensed event signal, causes timing control 202 to instruct address generation circuitry 204 to provide the address of the retrieved and emitted "pace" or "sense" statement to the address input of analog storage/playback IC 200. To place analog storage/playback IC 200 in a "zero power" mode when not in use, address generation circuit 204 also provides a "power down" (PWR _ DWN) logic level to analog storage/playback IC 200.

At a predetermined address in the analog storage/playback IC 200, voiced statements and/or musical tones are recorded over line 211 using the sound input block 206. The sound input block 206 provides an address, and provides a record command signal on the play/record line and a chip not enable (NCE) signal on the NCE line. The NCE input receives an enable logic level to begin recording of the voiced statements (or musical tones) addressed on the address bus.

Figure 5 also includes an additional circuit for retrieving the recorded message or alert as an a-D signal when it is appropriate to transmit an alert to the radio indicating that the device is malfunctioning or that treatment is urgently administered where appropriate. A variety of IMD monitoring devices may be provided for periodically or continuously monitoring the condition, status or emergency operation of the implantable medical device, or the condition or status of the patient, and providing a message trigger signal based thereon. Voiced statements informing the patient to contact his/her doctor or healthcare provider may also be stored and transmitted.

The ERI signal is a message trigger signal that will trigger the address generation and retrieval of the aforementioned "battery-empty" A-D signal transmitted by AM/FM transmitter 31. A timer is used in the address generation block which is responsive to the ERI signal and is capable of periodically generating the address of this warning to the patient (e.g. once per hour) so that it is no longer continuously generated. The ERI warning may be automatically set OFF when an interrogation or programming sequence is performed to allow these functions to be completed according to FIGS. 3A-3C. Further, in various more sophisticated programmed embodiments than illustrated in FIG. 2, the healthcare provider may use the programmer to transmit appropriate programming commands, with or without programming this function.

Fig. 6 is a simplified block diagram of an analog storage/playback IC 200 that includes elements to record voiced statements or sounds in a non-volatile analog storage array 210. The analog storage/playback IC 200 also retrieves the recorded statements and sounds and passes them on the analog outputs a-D + and a-D-to the filter and amplifier stage 208, which processes them and provides the a-D signals to the AM/FM transmitter 31. ISD33060 Chip Corder

Analog storage/playback IC 200 is a CMOS device that operates at 3 volts and provides 60 second playback of analog voice recordings stored in non-volatile analog storage array 210. The analog voice recording is addressed by a decoder 212 coupled to an address buffer 214, as described below, and provided to an analog output amplifier 226. The analog memory array is a multi-level memory, EEPROM dedicated to ISD, described in detail in the ISD' 259 patent referenced above.

The CMOS device includes a power conditioning circuit 230, which is intended to be coupled to an external component to form a regulated power supply coupled to the power supply 11 for supplying power to the other circuits depicted. Device control circuitry 232 is also coupled with the other circuitry depicted and controls device operation according to a predetermined application. In accordance with the present invention, the PWR _ DWN signal from the address generation block 204 is applied to the PD input of the device control circuitry to enter a zero power mode, minimizing battery drain at all times except during voice recording or playback. It can be concluded that the audio or voice statements stored in the non-volatile analog memory array 210 can be retained for 100 years without consuming any power. During playback or recording of voiced statements, the "play" or "record" logic levels are applied to the P/NR input. The NCE input receives an enable logic level to begin recording voiced statements in memory at the specified address of the voiced statement playback, the voiced statements being addressed on the address bus. The NEOM logic level signal is output from device control circuitry 232 and applied to timing control 202 when a voiced statement or phrase is complete to allow the next voiced statement or phrase to be addressed (as described above).

An on-chip oscillator is provided by internal clock 234, which may also be driven by external clock XCLK (not used in the practice of the present invention). The internal clock 234 provides a clock signal to an internal timing circuit 236 that provides a sampling frequency to a sampling clock 238 and the 5-pole active anti-alias filter 222 and the 5-pole active smoothing filter 218.

The audio sound or voice recording portion of the CMOS device includes a speech or audio input amplifier 220 for amplifying the audio input signal at ANA IN and coupling the amplified signal to an anti-aliasing filter 222. The filtered input signal is sampled by a sample clock 238 so that the sampled analog values are stored directly by the analog transceiver 216 to memory cells for later retrieval by the decoder 212 when addressed. The manner of address storage and assignment is as described in the ISD' 259 patent referenced above. Preamplifier 240 and AGC circuit 242 are also provided on the IC, but are not used in the practice of the present invention.

In accordance with one feature of the present invention, the voiced statements are recorded in a specific human language after fabrication of the pacemaker IPG circuit 10 (or other IMD circuit) is completed, but before the circuit 10 is enclosed in the IPG housing. Alternatively, a sound or voice statement recording is provided to the manufacturer (ISD in this example) and recorded in the analog storage array 210 prior to shipment of the analog storage/playback IC 200. In another approach, a pacemaker IPG or other IMD with a feedthrough may be provided for direct coupling with the ANAIN terminal of amplifier 220 for recording voiced statements (in the manner described in the above-referenced commonly assigned' 096 patent). In this variant, it is possible for the vendor or doctor implanting the medical device to store the voiced statements in a given country or region using a local language. In accordance with yet another aspect of the present invention, musical tones may also be recorded at certain memory locations by audio input amplifier 220 for use with voiced statements.

According to another feature of the invention, voiced statements may be recorded in more than one language, and the healthcare provider or doctor may select the language to be used. In more complex IMDs with RF telemetry capabilities, the particular language may be selected by downlink RF telemetry commands. In the low cost pacemaker IPG 10 described above, further repetitive sequences of successive removal and replacement of the magnet 130 over a specified period of time can be detected by appropriate circuitry in the logic circuit 78 and applied to the address generation circuit 204 to select the language to be used.

Regardless of how the voiced statements are recorded in the analog memory array 210, the retrieval of analog speech samples that are not to be transmitted is always done sequentially from memory locations in the analog memory array 210 when they are addressed by the decoder 212. Analog voice samples are sequentially retrieved by analog transceiver 216 at the sample clock frequency and applied to 5-pole active smoothing filter 218 to recombine the words of the phrase in natural prosody and phonetic form. The recombined voiced statements pass through multiplexer 224 and are applied to the input terminals of output amplifier 226, amplified in the amplifier and output at output terminals A-D + and A-D-. The auxiliary input to multiplexer 224 is not used in the present invention.

It will be appreciated that this preferred embodiment of the invention can be modified to provide different programming and interrogation sequences. MEDTRONIC

Champion^TMThe single chamber pacemaker IPG system shares a similar structure and operating system as the preferred embodiment described above, but is programmed and instructed to program operating modes and parameters in a different manner by successively removing and reapplying the magnet. The system comprises a MEDTRONIC

A model 9710 programmer that detects only pacing intervals and displays them on a display, which facilitates ECG interpretation using the method described in commonly assigned U.S. patent 4,226,245 to Bennett, which is incorporated herein by reference. Even when intervals are displayed, it is difficult to program the pacing rate while observing and translating the pacing interval display in order to count the pacing intervals and synchronize the generation of programming commands to the counted intervals. This method is long term and has errors. The invention can be implemented into Champion^TMIn the system, in the inquiry sequenceDuring which voiced statements are transmitted, as well as "pace" and "sense" statements that are received by the radio to aid in understanding TMT operation and time reprogramming.

At Champion^TMIn an IPG, a medical provider may observe the current rate and translate battery depletion from the observed pacing rate by a measurable percentage decrease in the programmed pacing rate in response to an ERI signal. For example, when the battery voltage drops below the ERI threshold voltage, the programmed pacing rate of 75PPM may decrease to 58 PPM. In addition to the MAGFET, a reed switch is included that is closed by the applied magnetic field to initiate an interrogation sequence that ends with TMT after the magnet is removed rather than beginning with the TMT sequence. The applied magnet closes the reed switch and switches the pacing mode to asynchronous mode, restoring the programmed pacing rate in the initial sequence of 3-4 asynchronous pacing pulses. If the battery voltage is below the ERI threshold, the asynchronous pacing rate is changed to the ERI rate or remains at the programmed pacing rate for the second sequence of asynchronous pacing pulses. The healthcare provider observes the artificial pacing on the ECG display and compares the observed escape intervals to determine if there is a significant difference and to conclude if the battery voltage is depleted and the IPG needs to be replaced. Then, for example, the magnet is removed, the pacing mode is returned to the disabled mode at a preset escape interval corresponding to 75PPM, and a fixed number of pacing escape intervals are counted in a third sequence. At the end of this count, a TMT sequence of 4 asynchronous pacing pulses at an elevated pacing rate and a programming window sequence including the TMT sequence and more than 7 pacing pulses begin, and the healthcare provider again observes the ECG display to determine whether the reduced-energy pacing pulses of the TMT sequence are targeted for the heart.

In this embodiment of the invention, at the programmed pacing rate, in the initial sequence of fixed rate pacing pulses, the retrieval and transmission of voiced statements (including battery status) during the interrogation mode of FIG. 3A may be initiated and completed. The second sequence may be incremented by the retrieved and transmitted "pace XX PPM" statements (where "XX" is the current programmed value) issued by the radio in synchronization with each pacing trigger. Likewise, the pacing pulses of the TMT sequence may be increased by the retrieved and transmitted "pace" and "TMT pace" statements issued by the radio, and the pacing pulses of the programming window sequence may be increased by the retrieved and transmitted "pace" and "sense" statements issued by the radio.

At Champion^TMIn a pacemaker IPG, only the pacing rate and pacing pulse amplitude are programmable. At Champion^TMIn the programming sequence of the pacemaker IPG, the pacing rate and pulse width are programmed using N-S and S-N magnetic fields, respectively. In the incremental window between 3 successive pacing pulses, the programming parameter value increases when the magnetic field is rapidly applied and removed twice in rapid succession. When the magnetic field is applied and removed once quickly, the value of the programming parameter decreases. In each case one has to wait until 3 escape intervals have elapsed together with the pacing trigger pulse before the parameter value can be increased or decreased again. Once the desired parameter value is obtained, the magnetic field is no longer applied and the pacing mode returns to the inhibit pacing mode after 10 pacing pulses have been delivered since the last application of the magnetic field.

In this embodiment, the invention may be implemented in voice with the statement "pace" issued, thereby aiding the timing for applying the magnetic field sufficiently far from and within the increment window to avoid programming errors. The retrieved and transmitted "pace" statement may increase the delivery of the last 10 pacing pulses.

The above-described embodiments of the pacemaker IPG are implemented as custom integrated circuits or more sophisticated microcomputer based operating systems that incorporate the analog memory IC 200 and distribute the timing control and address generation functions of fig. 5 among other system elements. This approach may be used with many other IMDs, such as the type of electrical stimulator disclosed in commonly assigned U.S. patent 4,520,825 to Thompson et al, which is hereby incorporated by reference.

Fig. 8 and 9 are block diagrams of such a microcomputer-based IMD operating system, intended for use with a controller and monitor or one of the types of therapy delivery systems depicted in fig. 10. The system of fig. 8 is programmed and interrogated using a simple magnet application and removal method as described above, while the system of fig. 9 employs RF telemetry programming and interrogation techniques that are well known in the art. The microcomputer based system of fig. 8 and 9 includes a microprocessor 152 coupled through a data and command bus 150 to a RAM 154, a ROM156, an analog storage/playback IC 200, a filter and amplifier stage 208, the battery monitor 17, and the digital controller/timer circuit 158 of fig. 10. The digital controller/timer circuit 158 is coupled to a particular monitor or therapy delivery system 160a-160i as shown in figure 10. Other components or circuit blocks used in a particular IMD may also be coupled to data and control bus 150.

The analog storage/playback IC 200 is configured as described above with reference to fig. 6. The audio drive signals for transmitting voiced statements or musical tones are stored in the analog memory array 210 of fig. 6 using the sound input block 206 and associated signals in the manner described above. If a-D signals are recorded during manufacture of the IMD and no option is provided to allow the distributor or physician to make the recordings, sound input block 206 may not be present in the IMD or may be disabled. If a voice input block 206 is present and enabled, it will be coupled with the data and control bus 150 to allow its use (particularly in the embodiment of fig. 9 where appropriate commands may be received in the downlink telemetry transmission).

In these embodiments, it is not necessary to use the timing control circuit 202 or the address generation circuit 204 of FIG. 5 to control the operation of the analog storage/playback IC 200. In this microcomputer based operating system, the timed operation of the analog storage/playback IC 200, as described above, is controlled by interrogation and programming algorithms stored in the ROM156 and initiated by the microprocessor 152. In the ROM156, the memory location addresses of the A-D signals stored in the analog memory array 210 are also stored and selectively retrieved and applied to the address buffer 214 according to interrogation and programming algorithms.

The IMD of fig. 8 or 9 in conjunction with fig. 10 is powered by battery 13 in power supply 11 and the battery voltage is monitored by battery monitor 17. Either the battery voltage is encoded in the battery monitor 17 and provided to the data and command bus 150 or an ERI warning trigger signal is generated in the battery monitor 17 in the manner described above and encoded and provided to the data and command bus 150 to the microprocessor 152. During the interrogation sequence, a simplified voiced statement of the battery voltage itself, or the battery voltage "normal" or "exhausted", is transmitted by the AM/FM transmitter 31, as described above.

At other times, if the encoded battery data indicates that the battery 13 is depleted to the ERI voltage, the microprocessor 152 initiates a warning routine causing the AM/FM transmitter 31 to emit a warning voiced statement or musical tone in an audible amount that can be heard by the patient. During the alert procedure, the microprocessor periodically (e.g., once per hour) retrieves the address of the appropriate A-D signal and directs it to the address buffer 214 of the analog storage/playback IC 200 over the data and control bus 150. NCE and NEOM commands are also applied on the data and control bus 150. The filter and amplifier stage 208 amplifies the a-D signal and applies it to the AM/FM transmitter 31 for transmission to the radio.

Other alert programs may also be included in the microcomputer based operating system for providing such audible sound alerts emitted by the radio to the patient upon the occurrence of a triggering event. The trigger event may include certain operations of the IMD or other changing conditions or states of the IMD. For example, in the case of an implantable drug delivery system, the patient may be alerted to the exhaustion of the drug supply. In the case of an implantable heart monitor or cardioverter/defibrillator, the patient may be presented with the arrhythmia detected by the arrhythmia detection algorithm and appropriate action taken. A patient is detected for an emergency of malignancy and an alert trigger signal is generated based on the detection. The patient is alerted to seek medical assistance or take other precautions by the RF emission of an audible alert. In the case of cardioverter/defibrillator, the patient may be advised to rest prior to delivery of the cardioversion/defibrillation shock.

In each case, the triggering event causes the microprocessor 152 to retrieve and apply the command for operating the analog storage/playback IC 200 and the address providing the appropriate A-D signal to retrieve the signal from the non-volatile analog storage array 210 of RAM 154 or ROM 156. The analog storage/playback IC 200 retrieves the addressed a-D signal and applies it through a filter and amplifier stage 208 to the AM/FM transmitter 31, which transmits an AM or FM voice statement or musical tone alert to the patient.

An interrogation and programming system responsive to the continuous application of the magnetic field of MAGFET70 is shown in fig. 8 for interrogating IMD information and for programming device operating modes and parameter values. MAGFET70 detects the polarity of the applied magnetic field and generates corresponding N and S signals on lines 72 and 74, respectively (in the manner described above with reference to fig. 2). The N and S signals are applied to the logic circuit 78, and the logic circuit 78 forms the appropriate coded signals which are applied to the microprocessor 152 over the data and control bus 150 to initiate the programming or interrogation algorithm. Thus, as shown and described in FIG. 1, a communication session is established by applying magnet 130 to the skin of the patient. The magnetic field constitutes a communication link signal that is detected by MAGFET70 to establish a communication session.

In fig. 9, a communication session is established using a programming and interrogation system based on RF telemetry transmission for interrogating IMD information and for programming device operating modes and parameter values, typically a programming head (not shown) of a programmer (not shown) includes a permanent magnet which closes reed switch 166 and generates a downlink RF telemetry signal which is received by RF telemetry antenna 168 and applied to RF telemetry transmitter/receiver circuit 164. The RF telemetry transmitter/receiver circuit 164 decodes and then re-encodes the received downlink RF telemetry signals for transmission over the data and control bus 150 and to form the communication link signals. An uplink RF telemetry transmission of IMD information received on the data and control bus 150 is generated in the RF telemetry transmitter/receiver circuit 164 and applied to the RF telemetry antenna 168 in an uplink telemetry transmission procedure. The microprocessor 152 begins the uplink RF telemetry transmission program and provides data and control signals on the data and control bus 150 to the RF telemetry transmitter/receiver circuit 164.

The system of fig. 9 can be configured in many different ways to share the uplink communication capability of the audible sounds produced by AM/FM transmitter 31, with the AM/FM transmitter 31 having high speed RF telemetry uplink transmissions received by the programmer. In a simple application, an RF telemetry transmission system may be used to receive programming and interrogation commands and to reflect interrogation data and programming confirmation back at frequencies in the AM or FM band, for reception by a radio or separate radio housed within the programmer. It should be noted that a 175kHz telemetry antenna within an IMD may be employed to transmit AM or FM frequency signals, and a single antenna may be designed with switching circuitry to operate optimally at both RF frequencies depending on the switching conditions.

In the system of fig. 8, a magnet is provided to the patient for limited operating modes and programming of parameter values, and audible acoustic feedback is received confirming such programming or interrogating certain IMD information. It will be appreciated that the interrogation and programming system of fig. 8 may be included in the working system of fig. 9 to allow the patient to use the magnet for the same purpose. Or the patient may be provided with a limited function programmer for RF telemetry downlink transmission of limited interrogation and programming commands (audible sound emissions in response to corresponding IMD information).

In this regard, high volume audible RF transmission capability may also be used during programming or interrogation procedures that allow the patient to initiate himself. For example, if the patient is provided with a limited programmer or magnet for increasing or decreasing drug dosage or symptom-relieving electrical stimulation, programming changes can be confirmed by RF transmission of voice statements or musical tones that are received and played back over the air. In each case, the change in programming causes the microprocessor to retrieve or apply the commands for operating the analog storage/playback IC 200 and the addresses of the appropriate A-D signals. The analog storage/playback IC 200 retrieves the addressed a-D signal and applies it to the AM/FM transmitter 31 through the filter and amplifier stage 208, which transmits a voice statement or musical tone confirming the change to the patient. Some examples are described below with reference to fig. 11 and 12.

Figure 10 is a block diagram of a digital controller/timer circuit 158 that may be used with the operating system of figures 8 or 9 and that has therapy delivery devices 160a-160h or a physiological monitor 160 i. It will be appreciated that many equivalent therapy delivery devices 160a-160h also have monitoring capabilities for accumulating physiological data for later interrogation. It will be appreciated that the logic 78 and the RF telemetry transmitter/receiver 164 of fig. 8 and 9 may be incorporated within the digital controller/timer circuit 158 in any particular therapy delivery apparatus and monitoring configuration. In the case of each IMD configuration, digital controller/timer circuitry 158 and a suitable programmable operating algorithm 162 control all operating functions.

With respect to the therapy delivery device configuration, the IMD may be configured to operate an implantable heart assist device or pump 160a implanted in a patient awaiting a heart transplant procedure. In this case, the resulting relative blood pressure and/or body temperature values may be used to adjust the action of the pump to maintain proper cardiac output. Or it may be configured to include one or a set of anti-tachycardia pacemakers 160b, anti-bradycardia pacemakers 160c, cardioversion devices 160d, and/or defibrillation devices 160e, with appropriate leads and electrodes extending from the implantable therapy-delivering medical device 100 to the patient's heart 10 for sensing Electrocardiograms (EGMs) and delivering pacing pulses or cardioversion/defibrillation shocks. The IMD may be configured to include a substance delivery device 160f coupled to a suitable conduit extending to a location on the patient's body for delivering a substance, such as a therapeutic or diagnostic agent or drug, from a substance reservoir. For example, a medication for treating hypertension may be delivered to the patient's heart 10 or vascular system.

In accordance with one aspect of the invention, the memory stores an audio drive signal indicative of the delivery of the substance to the body tissue. An acoustic drive signal associated with the delivery of the substance is applied to the radio frequency transmitter. The radio frequency transmitter plays a modulated radio frequency signal that can be detected or demodulated by the radio receiver, producing human understandable voiced statements or other audible sounds indicative of the delivery of the substance. According to another aspect of the invention, the depletion of the material reservoir is periodically monitored or interrogated. An audio drive signal representing the amount of released substance or the amount of substance remaining in the substance reservoir is stored in a memory location having a defined memory address. The delivery of the dosing substance is monitored. The amount of substance transferred or remaining in the reservoir is measured or calculated at each transfer or upon receipt of a substance-quantity interrogation command, and a stored audio drive signal indicative of the amount of substance transferred or remaining in the reservoir is retrieved from a memory location. The radio frequency transmitter plays a modulated radio frequency signal that can be detected and demodulated by the radio receiver to produce a human understandable voiced statement or other audible residual message that indicates the amount of substance delivered or remaining in the reservoir.

IMD may be configured as a MEDTRONIC

Transform^TMA cardiac stimulator 160g having suitable leads extending to the patient's heart and the skeletal muscles surrounding the heart to sense cardiac EGMs and to deliver muscle stimulation pulses periodically. Also, the resulting relative blood pressure and/or body temperature values may be used to adjust the muscle stimulation rate to maintain proper cardiac output. The IMD may also be configured as an electrical stimulator 160h, including nerve and muscle stimulators, brain stimulators, and cochlear implants, for applying electrical stimulation therapy to electrodes in appropriate locations in the patient's body.

Finally, the IMD may also be configured as an implantable monitoring system that monitors physiological conditions, such as an EGM for monitoring the heart of a patient and/or a heart monitor that monitors blood pressure, temperature and blood gas (blood gas) or pH. MEDITRONIC when the patient feels an arrhythmia and the recording function is activated by applying a magnet to the implant

Reveal^TMAn implantable loop recorder has surface electrodes and an EGM that records a 42 minute period. MEDTRONIC

Chronicle^TMImplantable hemodynamic recorders record EGMs and absolute blood pressure values at predetermined time intervals using leads and circuits disclosed in commonly assigned U.S. patent nos. 5,535,752 and 5,564,434, which are hereby incorporated by reference.

In any of these therapy delivery systems or monitoring systems, a variety of IMD information may be conveyed by means of retrieved and transmitted voiced statements or musical tones stored in analog storage array 210 of analog storage/playback IC 200. Two specific examples are shown in fig. 11 and 12, illustrating how the present invention may be used to simplify interrogation and programming of IMDs that typically provide limited functionality for patient programming to alleviate symptoms felt by the patient.

In these embodiments, the patient is typically provided with a patient activator or programmer to turn the therapy on or off and/or increase or decrease the therapy parameters. In particular, MEDTRONIC, referenced above, is provided in conjunction with such patient activator

Itrel

Implantable neurostimulator and Synchromed

The drug penetrates the system to allow the patient to adjust stimulation and medication to relieve the symptoms of the affliction. In accordance with the following embodiments of the present invention, musical tones are transmitted by the IMD to the radio when the patient is programmed with such patient actuators or magnets to adjust stimulation and medication. Upon use of patient actuators or magnets to deliver increased stimulation energyIn volume or dosing medication, a series of ascending scale tones may be transmitted to the radio. Similarly, a series of downshifting musical tones may be transmitted through the radio upon delivery of reduced stimulation energy or a metered dose of medication, depending on the patient's actuator or magnet. In addition, musical tones or harmonics accompanying the ascending or descending scale may also retrieve and transmit a programmed dose of stimulation energy or timed medicament to the radio.

Fig. 11 is a diagram depicting memory address locations of a-D signals for transmitting voiced statements or musical tones in an interrogation and programming sequence of the implantable drug delivery device 160f of fig. 10 having the operating system of fig. 8 or 9. The memory address locations are depicted in the diagram of fig. 11, for retrieving and transmitting voiced statements or musical tones in the current IMD information interrogation sequence at analog memory addresses "00" - "0D", followed by a programming sequence for increasing or decreasing the drug permeation rate at addresses "0E" - "0F". In the interrogation and programming sequence, the healthcare provider may initiate an interrogation, using either the programmer in the case of the configuration using the working system of FIG. 9, or the magnet 130 in the case of the configuration using the working system of FIG. 8.

Assuming the latter case, and assuming IMD100 of FIG. 1 is a drug delivery system incorporating drug delivery device 160f, the healthcare provider applies magnet 130 to MAGFET70, which generates an N or S signal on line 72 or 74 of FIG. 8. In response, the logic circuit 78 provides an interrupt to the microprocessor 152 to begin the interrogation process. Analog memory address "01" is provided on bus 150 to analog storage/playback IC 200, which transmits the voiced statement "data start" or musical tone at a discernible audible frequency. The inquiry routine then sequentially selects one of the programmed addresses "02" - "05" as the current permeation rate, selects "06" - "0A" as the remaining drug amount, and selects "0B" - "0C" for the battery condition. In these cases, the A-D signal causes RF transmission of voiced statements. An "end data" statement or a further music tone is then transmitted on the bus 150 to the analog storage/playback IC 200 by providing the address "0D" at the same or a different frequency than the "data start".

During the interrogation sequence, the battery voltage is monitored and the designated point in the sequence provides the appropriate one of addresses "0B" or "0C" to the analog storage/playback IC 200. Detection of the magnet 130 causes the microprocessor 152 to suspend the periodic RF transmission of a battery depletion alarm that may occur at other times when the battery 13 is draining to ERI voltage. Likewise, detection of the magnet 130 causes the microprocessor 152 to suspend the periodic RF transmission of the drug depletion alarm, which would otherwise occur if the amount of drug had been depleted to "a dose below 2 days" or a lower amount. However, it will be appreciated that during normal operation, these voiced statements or musical tone alerts are transmitted to the radio at addresses "0A" and "0C".

The magnet 130 may be removed to end the interrogation sequence or it may be left in place or rotated from end to begin the programming sequence to increase or decrease the rate of administration. In each case, the programming sequence begins in a rate increase mode by providing the address "0F" causing an "rate increase" voiced statement or RF transmission of an upshifted musical tone. The healthcare provider may then either leave magnet 130 in place to continue the rate increase mode or flip it from end to transition the programming sequence to the rate decrease mode for a few seconds. In the former case, after a few seconds, the command provided from the microprocessor 152 causes the rate to be incrementally increased and the currently programmed rate to be stored in the RAM 154 for periodic use by the digital controller/timer circuit 158 in the drug administration program. Microprocessor 152 then applies the analog memory address of the a-D signal of the increased rate voiced statement to analog storage/playback IC 200 over data and control bus 150, causing the retrieval and RF transmission of the voiced statement to the radio to confirm the change in rate. At this point, assuming the maximum rate has not been reached, the healthcare provider may choose to increase the rate by leaving the magnet 130 in place for a few seconds and repeating the process through the next rate increment. Alternatively, the healthcare provider may choose to terminate the programming sequence at the new programming rate, simply removing magnet 130 before retrieving and transmitting the next rate change. A similar process follows, by flipping the magnetic field and using the memory address "0F" if a reduction in the drug delivery rate is required, to produce a downpitched musical tone or "rate reduced" voiced statement.

With the configuration of the programming and interrogation system of FIG. 8, for example, the patient 102 may also be provided with the magnet 130 and follow instructions to increase or decrease the administration of the medication to treat the affliction. In this case, assume that the IMD is programmed with musical tones at manufacture using audible sound input 206 at addresses "00", "0A", "0D" (rather than equivalent voiced statements). The patient 102 is advised to apply the magnet 130 and follow the procedure described above until the ascending musical tone is heard. The rate may then be increased or decreased by following the steps described above. For safety, the maximum rate that the patient can program may be limited in a manner such as described in commonly assigned U.S. patent 5,443,486 to Hrdlicka et al, which is incorporated herein by reference.

Fig. 12 is a diagram depicting memory address locations of a-D signals for transmitting voiced statements or musical tones in an interrogation and programming sequence of the implantable electrical stimulator 160h of fig. 10 having the working system of fig. 8 or 9 or a hard-lead equivalent system thereof. Such implantable electrical stimulators include, but are not limited to, stimulators that electrically stimulate the spinal cord, peripheral nerves, muscles and muscle groups, diaphragm, various parts of the brain, body organs, etc., where the electrical pulses are delivered to electrodes at the desired stimulation site. Commercially available electrical stimulators of this type include MEDTRONICItrelII

Electrical stimulator, ItrelIII

Electrical stimulator and Matrix

Electrical stimulator and two-channel Itrel

An electrical stimulator.

The table of fig. 12 depicts the memory addresses of the a-D signals for transmitting voiced statements or musical tones in the interrogation sequence of the current IMD information at address locations "00" - "1D" and in the programming sequence of programmable parameter values and patterns at address locations "00" - "14" and "18" - "1D". The table of fig. 12 also shows memory address locations "0E" and "1F" for emitting an upshifting and downshifting musical tone in a programmed sequence of increasing or decreasing stimulation parameters (e.g., pulse amplitude or pulse width or pulse rate or electrodes) at address locations "00" - "14" and "18" - "1D". In an interrogation and programming sequence, a healthcare provider may initiate interrogation using a programmer, using the configuration of the working system of FIG. 9, or using the magnet 130, using the configuration of the working system of FIG. 8. The patient may be provided with a limited function programmer for programming one or more programmable parameter values and operating modes.

The following description assumes the use of a magnet programming and interrogation system and assumes that the IMD100 of FIG. 1 is an electrical stimulator 160h with leads 120 applied to muscles other than the heart. The healthcare provider applies magnet 130 to MAGFET70, which generates an N or S signal on line 72 or 74 of fig. 8. In response, the logic circuit 78 provides an interrupt to the microprocessor 152 to begin the interrogation process. Memory address "15" is provided on bus 150 to analog store/playback IC 200, which retrieves the stored voiced statement identifying the IMD. The interrogation program then sequentially selects one of the programmed addresses "00" - "06" for the current pulse rate, "07" - "0E" for the current (i.e., previously programmed) pulse width, "0F" - "14" for the current pulse amplitude. The inquiry continues to select address "16" or "17" for the battery condition, address "18" or "19" for cycling on or off states, and addresses "1A" - "1D" for programming the electrode configuration. In these cases, the A-D signal is applied to AM/FM transmitter 31, causing RF transmission of voiced statements. In the illustration of fig. 1, these retrieved voice statements are transmitted and received, demodulated and transmitted by radio 142, and heard by the healthcare provider.

During the interrogation sequence, the battery voltage is monitored and the appropriate one of addresses "16" or "17" is provided to the analog storage/playback IC 200 at the specified point in the sequence. Detection of the magnet 130 causes the microprocessor 152 to suspend the periodic RF transmission of a battery depletion alarm that may occur at other times when the battery 13 is draining to ERI voltage. However, it will be appreciated that during normal operation, voiced statements or musical tone alerts at address "16" are applied to AM/FM transmitter 31, causing RF transmission of voiced statements. In the illustration of fig. 1, these retrieved voice statements are transmitted and received, demodulated and transmitted by radio 142, and heard by the healthcare provider.

At this point, the magnet 130 may be withdrawn to end the interrogation sequence, or it may be left in place or rotated from end to begin the programming sequence to increase or decrease any programmable parameter (i.e., pulse rate, width, amplitude, period status, and electrodes). The programming sequence begins in the rate increase mode by providing an address "1E" to cause an RF transmission of an "increased value" voiced statement or an ascending musical tone. The healthcare provider may then either leave magnet 130 in place to continue the increase mode or flip it from end to transition the programming sequence to the decrease mode for a few seconds. A system can be used to program each parameter value and operating mode in succession that causes the magnet to be placed and removed in succession, similar to the system used in the procedure illustrated in figures 3A-3C.

Assuming that the stimulation pulse rate is being programmed to an increased pulse rate, the pulse rate is increased in steps by commands provided by the microprocessor 152 after a few seconds of continued application of the magnet. The new current programmed pulse rate is stored in RAM 154 for periodic use by digital controller/timer circuit 158 in the stimulus delivery program. The address "1E" of the A-D signal for the increased rate voiced statement is then applied by microprocessor 152 to analog storage/playback IC 200 over data and control bus 150, causing RF transmission of the voiced statement or the upshifted musical tone, confirming the rate change. At this point, assuming the maximum pulse rate has not been reached, the healthcare provider may choose to increase the rate by leaving the magnet 130 in place for a few seconds and repeating the process through the next rate increment. Alternatively, the healthcare provider may choose to terminate the programming sequence at the new programming pulse rate, simply removing magnet 130 before retrieving and transmitting the next rate change. If a reduction in the rate of administration is required, a similar procedure is followed.

With the configuration of the programming and interrogation system of FIG. 8, for example, the patient 102 may also be provided with the magnet 130 and follow instructions to increase or decrease the administration of the therapy to treat the affliction. In this case, assume that the IMD was programmed with musical tones instead of equivalent voiced statements at manufacture using audible sound inputs 206 at analog memory addresses "1E" and "1F". The patient 102 is advised to apply the magnet 130 and follow the procedure described above until the ascending musical tone is heard. The magnet can then be left in place to increase the velocity or to reverse the polarity of the magnetic field to decrease the velocity and hear the downpitched musical tone.

In the context of a microcomputer-based IMD operating system, the embodiments of the present invention shown in fig. 8-10 and employing IC 200 of fig. 6 are described above, wherein the programming and interrogation sequences are controlled by algorithms stored in ROM156 and by logic circuits and registers incorporated in digital controller/timer circuit 158. The algorithm utilizes timing control circuit 202 and address generation circuit 204 and the interconnections between them and with analog storage/playback IC 200 of fig. 5. It will be appreciated that in a microcomputer based operating system, such a circuit of fig. 5 may be used. Conversely, it will be appreciated that the embodiments may also be implemented in a hardware-based system that sequentially addresses analog memory addresses in the sequences described above with reference to FIGS. 11 and 12 and other sequences in which the therapy delivery and monitoring system of FIG. 10 may be designed for use.

It is therefore to be understood that the foregoing specific embodiments are illustrative of the many ways in which the principles of the invention may be practiced. It is therefore to be understood that other approaches known to those skilled in the art or disclosed herein may be used without departing from the scope of the invention or the appended claims.

It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described without actually departing from the spirit and scope of the present invention.

Claims

1. A communication system for transmitting implantable medical device information from an implantable medical device through a patient's body to a radio receiver outside the patient's body, the implantable medical device further comprising:

a power source for supplying power;

a battery monitor coupled to a power source;

an audio feedback device coupled to the battery monitor;

a radio frequency transmitter coupled to the audio feedback device;

a radio frequency antenna to transmit a signal;

a filter and amplification circuit coupled to the activity sensor for filtering and amplifying the signal;

a rate of action response circuit coupled to the amplification circuit;

a memory storing at least one audio drive signal capable of being reproduced as a human understandable voiced statement or sound conveying medical device information;

the radio frequency transmitter playing a radio frequency signal modulated by an audio frequency driving signal, the radio frequency signal capable of being received and demodulated by a radio receiver located outside the patient's body;

the audio feedback device retrieves at least one audio drive signal from the memory and applies the retrieved audio drive signal to the radio frequency transmitter causing the radio frequency transmitter to play a modulated radio frequency signal whereby the radio frequency signal can be detected and demodulated by the radio receiver to produce human understandable voiced statements or other audible sounds.

2. The system of claim 1, wherein: the medical device information is selected from a group of information further comprising:

a medical device manufacturer;

a medical device identifier;

a patient identifier;

the date of implantation;

last query date;

stored physiological data;

a battery condition;

real-time device operation;

a current programmed mode of operation;

a current programmed operating parameter value;

depletion of a material reserve;

an emergency device operation; and

the detected condition of the patient is determined,

when reproduced by the radio receiver, it constitutes a human understandable voiced statement or audible sound belonging to one or all of the medical device information selected from the set of information.

3. The system of claim 1, wherein:

the memory further includes a plurality of memory locations represented by memory addresses, storing a plurality of audio drive signals at specified memory addresses; and

the audio feedback device further comprises:

address generating means for selectively generating memory addresses of stored audio drive signals; and

means responsive to the generated memory address for retrieving an audio drive signal from the addressed memory location and applying the retrieved audio drive signal to the radio frequency transmitter for causing the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver to produce human understandable voiced statements or other audible sounds.

4. The system of claim 3, wherein: the medical device information stored at the prescribed memory address in the audio drive signal is selected from the group of information further comprising:

a medical device manufacturer;

a medical device identifier;

a patient identifier;

the date of implantation;

last query date;

stored physiological data;

a battery condition;

real-time device operation;

a current programmed mode of operation;

a current programmed operating parameter value;

depletion of a material reserve;

an emergency device operation; and

the detected condition of the patient is determined,

when reproduced by a radio receiver, it constitutes a human understandable voiced statement or other audible sound.

5. The system of claim 1, wherein:

the implantable memory device further includes a monitoring device that monitors a condition, status or emergency operation of the implantable medical device or a condition and status of the patient and provides a message trigger signal in response thereto; and

an audio feedback device responsive to the message trigger signal and transmitting the message from the implantable medical device by retrieving the audio drive signal and applying the retrieved audio drive signal to the radio frequency transmitter to cause the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver to produce human understandable voiced statements or other audible sounds.

6. The system of claim 5, wherein:

the memory further comprises a plurality of memory locations represented by memory addresses, storing an audio drive signal at a defined memory address, the audio drive signal conveying a message related to a condition, status, or emergency operation of the implantable medical device or a condition or status of the patient; and

the audio feedback device further comprises:

in response to the generated memory address, an audio drive signal is retrieved from the addressed memory address and the retrieved audio drive signal is applied to the radio frequency transmitter causing the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver to generate a means for communicating human understandable voiced statements or other audible sound messages to the patient.

7. The system of claim 6, wherein: the patient message stored at the prescribed memory address in the audio drive signal is selected from the group of messages further comprising:

the physiological condition of the patient;

a battery condition;

depletion of a material reserve;

an emergency device operation; and

the operation of the apparatus has been completed,

when reproduced by a radio receiver, it constitutes a human understandable voiced statement or audible sound.

8. The system of claim 1, wherein: the implantable medical device is powered by a battery and further comprises:

a monitoring device that monitors a level of battery energy consumed by the implantable medical device and provides a message trigger signal; wherein,

the memory stores an audio drive signal that can be reproduced as a human understandable voiced statement or sound conveying a battery energy level; and

an audio feedback device responsive to the message trigger signal and generating a human understandable voiced statement or other audible sound alarm indicative of the battery energy level by retrieving an audio drive signal related to the battery energy level and applying the retrieved audio drive signal to the radio frequency transmitter to cause the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver.

9. The system of claim 1, wherein: the implantable medical device further comprises:

a physiological condition monitoring device for monitoring a physiological condition of a patient;

means for determining from the monitored physiological condition or state of the patient the onset of a fatal condition in the patient and providing a message trigger signal; and wherein:

the memory stores an audio drive signal capable of being reproduced as a human understandable voiced statement or sound conveying an alert of the onset of the determined fatal condition to the patient; and

an audio feedback device responsive to the message trigger signal and generating a human understandable voiced statement or other audible alarm of the fatal condition by retrieving an audio drive signal associated with the determined fatal condition and applying the retrieved audio drive signal to the radio frequency transmitter to cause the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver.

10. The system of claim 1, wherein: the implantable medical device further comprises:

a heart monitoring device for monitoring the heart of the patient;

means for determining from the monitored heart a fatal tachyarrhythmia episode of the heart and providing a message trigger signal; and wherein:

the memory stores an audio drive signal capable of being reproduced as a human understandable voiced statement or sound conveying to the patient an alert of the onset of the determined fatal tachyarrhythmia; and

an audio feedback device responsive to the message trigger signal and generating a human understandable voiced statement or other audible alarm indicative of a fatal tachyarrhythmia by retrieving an audio drive signal associated with the determined fatal condition and applying the retrieved audio drive signal to the radio frequency transmitter to cause the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver.

11. The system of claim 1, wherein: the implantable medical device further comprises:

a heart monitoring device for monitoring the heart of the patient;

a cardiac therapy delivery device for delivering a cardioversion/defibrillation therapy to the patient in response to the detected tachyarrhythmia;

means for determining a fatal tachyarrhythmia episode of the heart from the monitored heart and providing a message trigger signal conveying the determined fatal tachyarrhythmia episode and emergency delivery of cardioversion/defibrillation shock therapy; and wherein:

the memory stores audio drive signals associated with determining the onset of a fatal acute arrhythmia and delivering emergency cardioversion/defibrillation shock therapy; and

an audio feedback device responsive to the message trigger signal and generating a human understandable voiced statement or other audible alarm indicative of a fatal tachyarrhythmia condition and an emergency delivery of cardioversion/defibrillation shock therapy by retrieving an audio drive signal associated with the determined fatal condition and applying the retrieved audio drive signal to the radio frequency transmitter to cause the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver.

12. The system of claim 1, wherein: the implantable medical device is a cardiac pacemaker that delivers cardiac pacing pulses to a heart of a patient, and wherein:

the memory stores an audio drive signal indicative of delivery of a pacing pulse;

an audio feedback device responsive to the delivery of the pacing pulse and generating a human understandable voiced statement or other audible alarm indicative of the delivery of the pacing pulse by retrieving an audio drive signal associated with the delivery of the pacing pulse and applying the retrieved audio drive signal to the radio frequency transmitter to cause the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver.

13. The system of claim 12, wherein:

the cardiac pacemaker further comprises means for sensing cardiac events and providing cardiac sensed event signals;

the memory stores an audio drive signal indicative of providing a cardiac sensing event signal; and

an audio feedback device responsive to the delivery of the cardiac sensing event signal and generating a human understandable voiced statement or other audible sound alarm indicative of the cardiac sensing event by retrieving an audio drive signal indicative of the provision of the cardiac sensing event signal and applying the retrieved audio drive signal to the radio frequency transmitter causing the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver.

14. The system of claim 1, wherein: the implantable medical device is an electrical stimulator for delivering electrical stimulation to human tissue, and wherein:

the memory stores an audio drive signal indicative of delivery of electrical stimulation to human tissue; and

an audio feedback device responsive to the delivery of the electrical stimulation and generating an audible statement or other audible alarm indicative of the comprehensible voice of the person delivering the electrical stimulation by retrieving an audio drive signal associated with the delivery of the electrical stimulation and applying the retrieved audio drive signal to the radio frequency transmitter to cause the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver.

15. The system of claim 1, wherein: an implantable medical device is a substance delivery system for delivering a substance to a patient's body, further comprising:

means for metered release of the substance from the substance reservoir onto the patient's body; and wherein:

the memory stores an audio drive signal indicative of the release of the substance into the body tissue; and

an audio feedback device responsive to the release of the substance and generating a human understandable voiced statement or other audible alarm indicative of the release of the substance by retrieving an audio drive signal associated with the release of the substance and applying the retrieved audio drive signal to the radio frequency transmitter to cause the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver.

16. The system of claim 1, wherein: an implantable medical device is a substance delivery system for delivering a substance from a reservoir having a defined volume onto a patient's body, further comprising:

means for metered release of the substance from the substance reservoir onto the patient's body; and

monitoring means for monitoring the amount of material released or remaining in the reservoir and providing a message trigger signal when the reservoir is depleted; and wherein:

the memory stores an acoustic drive signal indicating depletion of the remaining substance in the memory; and

an audio feedback device responsive to the message trigger signal and generating a human understandable voiced statement or other audible alarm indicative of depletion of the remaining substance in the reservoir by retrieving an audio drive signal associated with depletion of the remaining substance in the reservoir and applying the retrieved audio drive signal to the radio frequency transmitter to cause the radio frequency transmitter to play a modulated radio frequency signal capable of being detected and demodulated by the radio receiver.