JPH0649078B2 - Programmable and automatic implantable cardioverter / defibrillator and pacemaker system - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates generally to automatic implantable cardioverter / defibrillators and implantable programmable pacemakers, and more particularly to non-programmable, automatic. And an implantable cardioverter / defibrillator programmable pacemaker and a system for combining non-programmable cardioverter / defibrillator actuation in a manner that allows the pacemaker to, at least in part, allow programmable control. .

An automatic implantable cardioverter / defibrillator (hereinafter "AICD") is used (1) when the AICD detects that the heart is beating too fast (tachycardia), or (2) the AICD. When the heart detects that the heart is not beating at all (fibrillation), it gives the heart one or more high energy stimulation pulses. In the case of tachycardia, the delivery of high energy stimulation pulses is commonly referred to as "cardioversion" and the stimulation is delivered synchronously with the QRS wave of the heart. This synchronization is done to avoid stimulation of the heart during the T-wave portion of the P-QRS-T heart cycle.

In fibrillation, the heart is stopped, so
There is no QRS complex. Therefore, it is not necessary to synchronize the delivered high energy stimulation pulse with any cardiac event. The purpose of delivering high-energy stimulation pulses to the heart, as well as to shock the heart back to beat at a more normal rate, that is, to interrupt tachycardia or fibrillate the fibrillating heart. It is in. The high energy stimulation pulses generated by the AICD are commonly referred to as "cardioversion" or "defibrillation" pulses.

AICD devices known in the prior art primarily include an embedded sensor circuit that detects the rate at which the heart beats through an attached sensing electrode. If the detected heart rate exceeds a high fixed rate threshold, the AICD is triggered to deliver a cardioversion pulse to the heart through a separate stimulation electrode. If the detected heart rate is below the low fixed rate threshold, the AICD is triggered to deliver a defibrillation version pulse to the heart through the stimulation electrodes. By using a non-programmable rate threshold fixed in this way, the detection and stimulation circuitry of the AICD device can be kept simple and compact.

The physician implanting the AICD device must determine the correct high fixed rate threshold and low fixed rate threshold needed for a particular patient. For example, only the high rate threshold is important. Because the low rate threshold is usually just a long escape interval that must time out without any cardiac activity being detected. However, for patients with bradycardia, the low rate threshold must also be carefully selected.

Once the correct threshold is determined, the physician must obtain an AICD device with the desired threshold built into its design. Unfortunately, this requires that the AICD device be specifically ordered from the manufacturer, or that the implanting physician maintain a large inventory of AICD devices that cover a wide threshold range. In addition, the correct high rate threshold for a patient may change after implantation, especially if the patient is on the prescribed medication. Therefore, there is a need in the prior art for programmable AICD devices whose high and low rate thresholds can be easily modified.

In addition, considering existing AICD devices with fixed high and low rate thresholds, a programmable program for changing the fixed rate thresholds associated with these devices, if desired. There is a need in the prior art for means or systems. The present invention advantageously addresses these and other needs. That is, it is an objective to achieve all of the above advantages and objectives without any substantial drawbacks.

SUMMARY OF THE INVENTION The above drawbacks and limitations are overcome by the present invention. In accordance with the present invention, an implantable programmable pacemaker provides a fixed rate AICD in a manner that allows the fixed rate threshold of the AICD device to be replaced by a programmable threshold contained within the pacemaker device.
Combined with the device.

More particularly, the present invention provides an implantable, programmable pacemaker, preferably a pacemaker that includes means for recognizing and treating bradycardia and / or tachycardia using low energy output pulses. Then combine it with the normal AICD. This is detected whenever the combined unit fails in low energy tachyarrhythmia or other stimulation pulses from the pacemaker to terminate the tachycardia or bradycardia condition and also by the pacemaker's programmable detection circuitry. It makes it possible to trigger the desired high-energy stimulation pulse from the AICD whenever various other thresholds, such as

Stated somewhat differently, it is not possible to allow the flexibility and flexibility of modern programmable pacemakers, especially their detection and response to various cardiac activities, as used with conventional non-flexible AICD devices. This is a feature of the present invention. The result is a highly flexible pacing / stimulation system that can deliver one or more high energy stimulation pulses as required based on programmable thresholds.

Thus, the present invention can be characterized as a programmable cardioverter / defibrillator containing three basic elements. The first of these elements is an automatic implantable cardioverter / defibrillator (AI).
CD) and the AICD is a high / low rate detection means for detecting when the heart beats above a fixed high threshold rate or below a fixed low threshold rate,
High energy cardioversion / defibrillation whenever the high / low rate detection means detects that the heart is beating above a fixed high threshold rate or below a fixed low threshold rate Means for delivering pulses to the heart.

The second of the three elements is an implantable programmable pacemaker, which includes a heart rate detection means for detecting the rate at which the heart is beating, and a heart rate program in which the detected heart rate is acceptable. Means for processing the detected heart rate to determine whether it is within a programmed range, and for allowing a programmed range of acceptable heart rates to be programmed into the processing means. And programming means.

The third element is coupling means for coupling the actuation of the AICD to the pacemaker, the coupling means being within a defined range of acceptable heart rates for the heart rate detected by the pacemaker heart rate detection means. When not present, it includes means for triggering the generation of cardioversion / defibrillation pulses from the AICD. This combination allows the fixed high and low threshold rates of the AICD to be replaced by the programmed range of implantable programmable pacemaker heart rates.

In the first embodiment of the invention, the coupling means for coupling the actuation of the AICD to the pacemaker is a direct electrical connection.
According to this first embodiment, the pacemaker circuit is
It has been modified to include an ICD trigger circuit. Otherwise, the sensing electrodes of a conventional AICD are then directly connected to the available connection points on the pacemaker's output connector. The trigger circuit provides an appropriate trigger signal to the connection point at the pacemaker output connector to which the AICD detection electrodes are connected. These trigger signals or their absence are detected by the detection circuitry of the AICD, thereby causing the AICD to generate the appropriate high energy stimulation pulses.

The AICD trigger circuit included in the pacemaker is a rate threshold circuit that can be programmed in the same manner as the other parameters of the pacemaker. That is, when the pacemaker's normal detection circuitry detects that the heart rate is within the programmed range of acceptable heart rate values, the heart rate is acceptable and a high energy stimulation pulse is required. An appropriate signal indicating that it is not is sent to the AICD device through its sensing electrode.

However, when the pacemaker detects that the heart rate is not within the programmed range of acceptable heart rates, that is, the detected heart rate is excessively high compared to the programmed high and low values. When fast or too slow, the appropriate trigger signal is sent to the AICD device through a direct electrical connection to evoke the desired response, i.e. one or more high energy stimulation pulses from the AICD. In this way, an otherwise conventional AICD device with a fixed rate threshold is converted into an AICD device with a programmable threshold.

In a second embodiment of the invention, an indirect electrical connection is made between the pacemaker device and the AICD device.
According to this second embodiment, the sense amplifier of the AICD device is coupled to the pacemaker through the use of a low energy (typically narrow) pulse sequence delivered to the heart by the pacemaker through the pacemaker's standard stimulation mechanism. There is. Although these low energy pulse sequences do not have enough energy associated with them to stimulate the heart, they do not have enough energy to be detected by the detection electrodes and detection circuitry of the AICD device. And has AI as cardiac activity
It is designed to be interpreted by a CD detection circuit.

Preferably, various sequences of such narrow non-stimulating pulses are programmed into the pacemaker,
It has also been used to signal the AICD that various events have been detected, such as tachycardia, bradycardia or fibrillation conditions. The detection circuitry in the AICD device is modified as necessary to discriminate between various sequences of pulses, and an appropriate response is evoked in relation to the signaled condition.

For example, if a fibrillation condition is detected by the pacemaker and is signaled to the AICD device through the generation of a specific sequence of narrow, non-stimulating pulses, the AICD device will attempt to defibrillate the heart and will be very high energy. Can be responded by the delivery of a stimulation pulse of In contrast, if a tachycardia condition is detected by the pacemaker and is signaled to the AICD device through the generation of a different sequence of narrow unstimulated pulses,
The AICD device may respond by delivering a single high energy stimulation pulse.

This second embodiment of the invention thus provides a programmable implantable medical device designed to deliver one or more high energy stimulation pulses to the heart whenever the heart rate exceeds a programmable threshold rate value. It can be described as a system. The system includes a detection means in its AICD portion for detecting when the heart rate is above a fixed high threshold rate value and / or below a fixed low threshold rate value. Is included. The AICD part of the device is
The heart rate exceeds a fixed high threshold rate value,
Or it also includes means for delivering a high energy stimulation pulse to the heart whenever the detection means detects a fixed low threshold rate value or less.

The system includes within its pacemaker portion an implantable pacemaker device having four components. These elements are detection means for detecting the heart rate, programming means for programming a specified range of rates into the processing means, and when the heart rate is not within the specified range. A pulse sequence of low energy pulses to the heart in response to the determination of the means for processing or monitoring the detected heart rate to determine the heart rate and the processing means that the heart rate is not within its specified range. And means for sending.

The pulse sequence of the low energy pulses delivered by the pacemaker must have an energy level sufficient to be detected by the AICD detection means, but insufficient to stimulate the heart. Therefore, the pulse sequence of low energy pulses is AICD
Detected by the detection means and also interpreted as a heart rate exceeding the fixed high threshold rate of the AICD,
In response, the delivery means of the AICD device delivers ordered high energy stimulation pulses to the heart.

Alternatively, the present invention may be viewed as a combination of an AICD device and an implantable programmable pacemaker device in either embodiment. The AICD device includes a first detection means for detecting when the heart is beating above a fixed high threshold rate or below a fixed low threshold rate and a fixed high heart rate. To deliver one or more high energy stimulation pulses to the heart whenever the first detection means detects beating above a threshold rate or below a fixed lower threshold rate And means of. The pacemaker device has a second detection means for detecting the rate at which the heart is beating, programming means for allowing a range of heart rates to be programmed into the processing means, and a heart rate is acceptable. Means for processing the detected heart rate to determine whether it is within a programmed range of different heart rates.

The combination further includes signal means within the pacemaker device for sending a trigger signal to the AICD device and one or more high energy energy sources to the heart for receiving the trigger signal and in response to receiving the trigger signal. Receiving means within the AICD device for initiating delivery of stimulation pulses. In one embodiment of the invention, the AICD device may be a conventional AICD device with detection electrodes. In this case, the pacemaker signal means is the trigger circuit described above, and the AICD receiving means is simply the detection electrode of the AICD device connected to the output of the pacemaker trigger circuit.

Further, the present invention includes a method of converting a fixed high or low rate threshold of an AICD device into a programmable high or low rate threshold. The AICD device used in this method is set to 1 whenever the heart rate detected by the detection means in the AICD device exceeds a fixed high rate threshold or is less than a fixed low rate threshold. It includes means for generating one or more high energy cardioversion / defibrillation pulses.

The method comprises two steps, the pacemaker includes a heart rate detection means for detecting when the heart rate exceeds a programmable upper limit or is less than a programmable lower limit. The first step is to couple the programmable pacemaker to the AICD device. The second step is to include one or more high energy cardioversion / defibrillation whenever the pacemaker's heart rate detection means detects a rate above a programmable upper bound or below a programmable lower bound. To trigger the generation of a pulse.

The invention also includes a method of combining the actuation of a non-programmable AICD with the actuation of an implantable programmable pacemaker. The AICD used in this method detects a first heart rate condition in which the detected heart rate exceeds a fixed upper rate value, and the detected heart rate is lower than the fixed lower rate value. Means for detecting a small second heart rate condition. The first cardiac rate condition is considered to be a tachycardia condition with an excessively fast cardiac rate, and the second cardiac rate condition is considered to be a bradycardia condition with an excessively slow cardiac rate or a fibrillation condition with a cardiac arrest. .

The AICD further includes means for generating one or more high energy cardioversion / defibrillation pulses that are automatically delivered to the heart in response to a first or second cardiac condition. There is. Pacemakers used with this method have a means to detect if the heart rate exceeds a programmable high or low rate threshold and a specified number of times to keep the heart at a programmed rate. Means for delivering stimulation pulses of controlled energy to the heart.

The method of combining AICD and pacemaker operation involves four steps. The first of these steps is to program the desired rate threshold into the pacemaker. The second step is to monitor the heart rate to determine if the rate threshold has been exceeded. The third step is to send a trigger signal from the pacemaker to the AICD in response to the determination in the second step that the heart rate exceeds the rate threshold. Finally, the fourth step is to generate a high energy cardioversion / defibrillation pulse in response to receiving the trigger signal sent in the third step.

DESCRIPTION OF THE DRAWINGS The above and other advantages of the invention are best understood with reference to the drawings.

FIG. 1 is a conventionally known AICD having a patch electrode and a detection electrode connected to a signal.

FIG. 2 is a functional block diagram of the AICD of FIG.

FIG. 3 is a previously known programmable implantable pacemaker that includes an external programmer used to program the pacemaker.

FIG. 4 is a pictorial view of the AICD and pacemaker combination of the present invention.

FIG. 5 is a functional block diagram of a programmable pacemaker modified for use with an AICD in accordance with the present invention.

FIG. 6 shows that a predetermined cardiac condition has been detected,
Also, two typical pulse codes that may be used with the modified pacemaker of at least one embodiment of the present invention to signal to the AICD device that one or more high energy stimulation pulses are required. It is a waveform diagram showing.

FIG. 7A is a typical ECG waveform diagram showing the P-QRS-T cycle of the heart detected by the pacemaker detection circuit and also used to transmit the desired pulse code in synchronization with the heart cycle. It shows possible timing relationships to obtain.

FIG. 7B is an ECG waveform diagram for a fibrillating heart and also illustrates possible timing relationships that may be used to transmit the fibrillation pulse code.

FIG. 8 is a flow chart of the basic program used in the modified pacemaker of the present invention for use with a conventional AICD device.

FIG. 9 is a flow chart of an alternative program used in the modified pacemaker of the present invention for use with a modified AICD device.

FIG. 10 is a block diagram of a modified AICD device.

Detailed Description of the Preferred Embodiments The preferred embodiments of the present invention are described below. This description is not intended to limit the scope of the invention, but merely to illustrate the general principles of the invention. The scope of the invention should be ascertained with reference to the claims.

Before describing the present invention, it will be helpful to review the basic operation of conventional AICD devices and conventional programmable pacemakers. Therefore, reference is first made to FIGS. 1 to 3, in which these devices are shown. FIG. 1 shows, for example, a schematic diagram showing an implanted AICD 12 connected to a heart 14. mainly,
AICD 12 includes separate stimulation electrodes 15, 16 and detection electrodes 18, 20. Stimulation electrodes 15 and 16
Is, for example, a large area electrode that is in physical contact with the outside of the heart 14. Often, these electrodes are referred to in the art as "patch electrodes." Other types of cardioversion or defibrillation electrodes could be used, including deployable electrodes that contact the inside or outside of the heart.

Detection electrodes 18 and 20 are shown in FIG. 1 as separate from stimulation electrodes 15 and 16. However, it will be appreciated by those skilled in the art that the sensing electrode may be the same as the stimulation electrode, as is usual in pacemaker technology. In this case, AICD 12 is
A suitable multi-pole isolation switch (not shown) is included at its output to isolate the detection circuit of D12.

As shown in FIG. 1, one sensing electrode 18 is in contact with the heart 14. The other detection electrode 20, which is mainly called the return electrode, is placed near the AICD 12. It has a unipolar configuration and the electrical path between the two detection electrodes 18 and 20 is via body fluid. In effect, the return electrode 20 may be part of the case of the AICD 12. Of course, bipolar detection electrodes may also be utilized where both electrodes 18 and 20 are placed at the desired tissue location where cardiac activity is being detected. Unipolar and bipolar sensing electrodes are well known and described in the art.

Referring now to FIG. 2, here is the AICD 1 of FIG.
Two functional block diagrams are shown. As can be seen in this figure, the AICD includes a sense amplifier 22 connected to leads 24 and 26 which are connected to sense electrodes 18 and 20, respectively. The output terminal of the detection amplifier 22 is connected to the fixed threshold circuit 28. The function of the fixed threshold circuit 28 is to determine whether the detected heart rate exceeds the fixed upper limit rate or is less than the fixed lower limit rate.

If the detected heart rate exceeds a fixed upper rate, a trigger signal "C" is generated indicating that one or more cardioversion high energy stimulation pulses are required. If the detected heart rate is less than the fixed lower threshold, a trigger signal "D" is generated indicating that one or more defibrillation high energy stimulation pulses are required. For a simple AICD device, the "C" and "D" trigger signals are the same and the same high energy stimulation pulse occurs regardless of whether tachycardia or bradycardia / fibrillation conditions are detected. To be done. More sophisticated AICD devices discriminate between cardiac conditions and deliver a high energy stimulation pulse of a particular type or pattern in relation to the cardiac condition being detected. The fixed threshold circuit 28 is typically a simple oscillator (clock),
Whether the heart rate is detected during a defined time interval (to determine if the heart is beating at a minimum rate at which tachycardia or fibrillation conditions exist, at least below) Decision, and if this decision is positive, how much after the last heart rate was detected (to determine the cycle of the heart rate as a decision as to whether the upper heart rate limit has been exceeded) And a counter circuit that determines if time has elapsed. Alternatively, a simple capacitor charging circuit used in conjunction with an analog threshold circuit can be used to perform this timing function. Such timing and measurement circuits are well known in the art.

Still referring to FIG. 2, it is shown that the "C" and "D" trigger signals are provided to the AICD control circuit 30. For a simple AICD device, the AICD control circuit 30 need not be more than an OR gate or wire which provides the appropriate "C" and / or "D" trigger signals to the pulse amplifier 32. A more advanced AICD device is A
Generates in ICD control circuit 30 a desired pattern and / or frequency of low level trigger signals that may be sent to output pulse amplifier 32 depending on whether a "C" or "D" trigger signal is received. Means for doing so may be included.

The low level trigger signal from the AICD control circuit 30 is received by the pulse amplifier 32 via the signal line 31. The purpose of the pulse amplifier 32 is simply to pass the low level trigger signal received from the AICD control circuit 30 to the two conductive paths 3.
Stimulation electrodes 15 and 16 via 4 and 36 (FIG. 1)
Is converted into high energy stimulation pulses that can be delivered to In practice, such a circuit is simply a suitable charging path and circuit so that the capacitor can be charged to a large voltage level and discharged to the stimulation electrodes 15 and 16 through the conductive paths 34 and 36 upon receipt of the trigger signal. May be a large capacitor having

AICD12 described in connection with FIG. 1 and FIG.
The above description of is related to function and various variations on the actual circuits and techniques used to achieve the desired stimulation of the heart when defined cardiac conditions that guarantee high energy stimulation pulses are detected. It will be appreciated that examples exist in the art.

Referring now to FIG. 3, a schematic diagram of a conventional programmable pacemaker 40 is shown along with the heart 14 to which the pacemaker is connected by suitable bipolar stimulation leads 42. Bipolar stimulation lead 42 is right ventricle 48
It includes a tip electrode 44 in contact with the inside (one of the four chambers of the heart 14). Ring electrode 46 is spaced a short distance from tip electrode 44. The heart activity occurring in the right ventricle 48 is the tip electrode 44 / ring electrode 46.
, And low-level stimulation pulses are delivered from the pacemaker 40 to the right ventricle 48 on demand through this same electrode combination.

Other lead and electrode combinations are also commonly used with programmable pacemakers that are additionally implantable on the bipolar stimulation lead 42 shown in FIG. The pacemaker 40 shown in FIG. 3 is a single chamber pacemaker configured for pacing the right ventricle 48 with the bipolar stimulation lead 42. Edge pole pacing leads are also commonly used in the art, as is the case with dual chamber pacemakers. The dual chamber pacemaker has monopolar and / or bipolar pacing leads directed to the right atrium 50 as well as monopolar and / or bipolar pacing leads directed to the right ventricle 48.
All such pacemaker configurations can be used with the present invention. Therefore, the configurations shown in FIG. 3 and other figures are merely exemplary.

An external programmer 52 is also shown in FIG. The programmer 52 is shown on one side of the skin or skin 51 in the schematically shown layers and the pacemaker 40 and the heart 14 are shown on the other side whereby the pacemaker 40 is implanted. On the other hand, the programmer 52 symbolically represents the fact that it is external (not implanted). Programmer 52
Communicate with the implanted pacemaker 40 using any suitable communication link, such as through a radio frequency (RF) telemetry link, or through the use of other modulated electromagnetic fields. The communication link between the pacemaker 40 and the external programmer 52 is the wavy line 5 passing through the skin 51.
4 is represented in FIG.

Notably, communication link 54 is bidirectional.
That is, data is sent from the programmer 52 to the pacemaker 40 and received from the pacemaker 40 over this communication link 54. The data sent to the pacemaker 40 sets parameters within the pacemaker 40 that control its operation. Furthermore, this communication link 54
Through the pacemaker 40 to the programmer 52. The data from pacemaker 40 includes information regarding detected heart activity and status information regarding the operation of pacemaker 40.

It is through this link 54 that the pacemaker 40 is thus "programmed" to operate in the desired manner, including the manner required for the present invention. The programming methods for the various programmable pacemakers currently available and the various programming options available are well known in the art and described in the literature. See, for example, Sonnanda et al., US Pat. No. 4,712,555 and Mann et al., US Pat. No. 4,788,980.

Referring now to FIG. 4, there is shown a schematic block diagram of one embodiment of the present invention. The present invention includes a modified programmable pacemaker that is used in combination with an otherwise conventional AICD device 12. The AICD device 12 includes stimulation electrodes 15 and 16 in contact with the heart 14 as described above in connection with FIG. Pacemaker 60 includes a bipolar lead 42 having a tip electrode 44 and a ring electrode 46 located in the desired chamber of heart 14, eg, the right ventricle. (As indicated above and repeated here for emphasis, this pacemaker 60 / bipolar lead 4
It should be understood that the two configurations are exemplary only. This is because any type of lead wire (bipolar or monopolar) can be used with any type of pacemaker, dual or single chamber to form part of the present invention. However, unlike previously known pacemakers, the pacemaker 60 modified in accordance with the present invention includes a special connection port 64 included in the pacemaker connector 62. This port 64 is designed to receive the detection electrode 18 of the AICD device 12. A special trigger circuit 66 in the modified pacemaker 60 is electrically connected to the port 64, whereby the sensing electrode 1
8 to make an electrical contact.

It should be noted that the other detection electrode 20 of the AICD device 12 also forms part of the AICD case and may be placed in the vicinity thereof, in which case the AICD
The connection between the device 12 and the pacemaker 60 is essentially a unipolar connection, as shown in FIG. Alternatively, electrode 20 may be connected to pacemaker connector 62, in which case a bipolar connection between the two devices is established. The exact type of connection between the AICD device 12 and the pacemaker 60 is not important for the purposes of the present invention.

FIG. 5 is a functional block diagram of the pacemaker 60 modified according to the present invention. This modified pacemaker 60
Is almost the same as a normal programmable pacemaker, but with the addition of a trigger circuit 66 and a port 64. Further, as will be described below, the operating program stored in the pacemaker 60 has been modified slightly to accommodate the trigger circuit 66 or to make other contacts with the AICD device 12.

As seen in FIG. 5, the pacemaker 60, in addition to the trigger circuit 66, includes a microprocessor 70 and a memory 7, which may be both ROM and RAM, for example.
2, a telemetry circuit 74, a detection amplifier 76, a pulse width / amplitude control circuit 78, a pulse amplifier 80, and a crystal oscillator 82. These circuits and elements operate and cooperate with each other in the manner known and described in the art. Therefore, only a brief overview of their operation will be given here.

During operation, microprocessor 70 controls the operation of pacemaker 60 as determined by the programs stored in memory 72. The basic operating program is received from external programmer 52 via communication link 54 via telemetry circuit 74 and programmed into RAM. Primarily, the basic function of the pacemaker 60 is to provide stimulation pulses to the heart 14 (FIG. 4) on demand.

For this purpose, a sense amplifier 76 having its input terminals coupled to the tip electrode 44 and the ring electrode 46 monitors cardiac activity. When a heartbeat is detected, which appears as an electrical signal on the tip electrode 44 and the ring electrode 46, the signal is sent to the microprocessor 70 by the detection amplifier 76. If the heartbeat is not detected within a defined time period (typically referred to as the "escape interval"), the microprocessor sends a trigger pulse through the pulse width / amplitude control circuit 78 and a stimulation pulse through the tip electrode 44 and It is sent to the pulse amplifier 80 which supplies the ring electrode 46.

The energy of the stimulation pulse delivered is set by the pulse width / amplitude control circuit 78 based on information programmed into the microprocessor 70 and memory 72. The crystal oscillator 82 is the microprocessor 70
Provides a basic clock signal for use by which all timing measurements are made. While the stimulation pulse is being delivered to the heart by the pulse amplifier 80, and for a defined period of time thereafter, the detection amplifier 76 is effectively turned off by the blanking signal received from the microprocessor 70.

As will be apparent to those skilled in the art, the above description of pacemaker 60 and its operation is functional. Therefore,
The exact circuitry that may be used by a particular programmable pacemaker to accomplish the functions described may vary from the above description. For example, not all programmable pacemakers use microprocessors as shown in FIG. Rather, many programmable pacemakers use dedicated circuitry that has the same functionality as a microprocessor.
However, any of these pacemakers could be effectively used as part of the present invention.

Moreover, it should be noted that many modern pacemakers advantageously not only detect when the heart is contracting within a defined escape interval, but also when the heart is too fast (tachycardia) or It includes a means for determining whether it is acting too late (bradycardia). In such cases, an attempt is made by the pacemaker to interrupt the tachycardia or bradycardia condition by delivering a defined sequence or pattern of stimulation pulses. See, for example, Mann et al., U.S. Pat. No. 4,788,980, cited above. The contents of which are incorporated herein by reference.

Unfortunately, however, such attempts by pacemakers to interrupt tachycardia or bradycardia conditions may not be successful. In such a case, the combination of the present invention selectively and programmable interrupts, and also ensures that a higher energy stimulation pulse is delivered to the heart whenever a selected programmed reference is detected. The detected condition (eg tachycardia)
Can be attempted to be interrupted.

Still referring to FIG. 5, trigger circuit 66 need only include trigger signal generator 84 and buffer amplifier 86. The purpose of the trigger signal generator 84 is simply:
A logic signal generated by the microprocessor 70, which is designated by reference numeral AICD in the figure, is used as a signal that a high energy stimulation pulse should be generated.
Converting to a pulse or trigger signal that can be detected by the ICD device 12 through its detection electrodes 18.
In this regard, it should be noted that in the case of detected bradycardia, it is the absence of a signal on the sensing electrode 18 that triggers the generation of a high energy stimulation pulse by the AICD device 12.

Therefore, in the case of a detected bradycardia, it is the function of the trigger signal generator 84 to prevent any signal from being sent to the AICD device 12 through its detection electrode 18. However, in the case of detected tachycardia, especially those tachycardia that are limited by programmable thresholds in the pacemaker, a logic signal identifying the tachycardia condition is applied to the fixed rate. It is the function of the trigger signal generator 84 to translate into a train of pulses that is interpreted by the AICD device as an over-threshold heart rate. At all other times, for example when the heart rate is detected as "normal", the logic signal identifying the acceptable heart rate is converted into a train of pulses which is interpreted by the AICD device as the normal heart rate. That is the function of the trigger signal generator 84.

The buffer amplifier 86 of the trigger circuit 66 provides a trigger pulse from the trigger signal generator 84 so that the signal appears at the AICD device 12, even though the signal originates at the heart 14 or other location where the sensing electrode 18 is located. Amplify and puff the signal. Any suitable operational amplifier or its equivalent can be configured by those skilled in the art to perform this function.

Those skilled in the art will appreciate that trigger signal generator 84 and buffer amplifier 8
It will be appreciated that the functions performed by 6 can be performed by suitable programming of microprocessor 70. Accordingly, variations of the present invention may have the trigger circuit 66 fully implemented in software or firmware (ie, in a control program) in combination with the microprocessor 70.

Referring now to FIG. 8, there is shown a flow chart illustrating the basic program or manner in which the modified pacemaker 60 of FIG. 5 operates. Only the operations relevant to the present invention are shown here. Other pacemaker features included in most modern demand pacemakers but not relevant to the present invention have been omitted for simplicity. FIG. 8 assumes that the desired pacing mode has been initiated (block 90). For example VVI, D
The type of pacing mode, such as DI, AVI, etc., is not important for the purposes of this description.

Once in the desired pacing mode, the escape interval is then initiated (block 94) and whether the pacemaker's detection circuitry causes a P wave (indicating contraction of the atrium) or an R wave (indicating contraction of the ventricle). Is allowed to be monitored (block 96). If the decision is positive, that is, if the P / R wave is detected before the escape interval times out,
A determination is then made as to whether tachycardia is present (block 98). If the result of the decision is negative, then control returns to block 94 and the process is repeated. That is, the escape interval is reset (restarted).

The determination made at block 98 as to whether tachycardia has been detected is performed in a conventional manner, and may include, for example, the heart 14 (fourth) over one or more cardiac cycles.
Figure) monitoring is required. However, this decision is made based on the programmable threshold programmed into the pacemaker rather than the fixed threshold built into the AICD device (block 1).
00) is advantageous.

The decision that a tachycardia condition exists is decision block 98.
If so, then appropriate trigger pulses are generated at a rate that exceeds the fixed threshold of the AICD device (block 102). These pulses are A
It is applied to the sensing electrode 18 of the ICD device and is also interpreted by the AICD device as the heart beating at a rate above the fixed threshold. Therefore, in an attempt to interrupt the detected tachycardia, a high-energy stimulation pulse is delivered to the AIC.
Evoked by device D. This process is repeated as many times as necessary to break the tachycardia.

If no P / R wave is detected at decision block 96, then monitoring of cardiac activity continues for the remainder of the escape interval (block 104). If the escape interval times out without detecting a P / R wave, then a determination is made as to whether a bradycardia condition exists (block 106). If the determination is negative, an atrial (A) or ventricular (V) stimulation pulse is generated in the usual demand pacemaker manner (block 108). Control returns to block 94 where the escape interval is reset and the process repeats.

The decision that a bradycardia condition exists is decision block 10
6 (this decision can be made in the usual way, but advantageously it is done using a programmed norm (block 110) rather than a non-programmable low rate threshold combined with an AICD device. is there),
The shutdown cycle is then invoked (block 11
2) During that time, the trigger pulse is not generated by the trigger circuit 66. This shutdown cycle ensures that the sensing electrode 18 of the AICD device 12 does not detect any cardiac activity for a defined activity, thereby ensuring that a high energy stimulation pulse is generated by the AICD device, High-energy stimulation pulses likely disrupt bradycardia or successfully defibrillate the heart.

Notably, for the purposes of the present invention, bradycardic and fibrillation conditions are detected and treated in the same manner. That is, a fibrillated or quiescent heart is treated by the present invention in the same manner as an overly fast beating heart.

The above description with respect to FIGS. 4, 5 and 8 is
It relates to the first embodiment of the present invention in which the detection electrode 18 of the ICD device 12 is directly connected to the pacemaker 60. In the second embodiment of the invention, the connection between the AICD device 12 and the pacemaker 60 utilizes an indirect connection rather than a direct electrical connection. This indirect connection is achieved between the sense electrodes 18 and 20 of the AICD device and between the tip electrode of the pacing mode line 42 of the pacemaker 60 and the sense electrode 20.

The schematic diagram of the components of this second embodiment may simply be the combination of FIG. 1 and FIG. That is, AI
The CD device 12 may be coupled to the heart 14 in a conventional manner, such as a pacemaker 40. However, pacemaker 40
Would modify the program stored therein, especially to complete the indirect connection between the two devices.

According to this second embodiment, the pacemaker 40 has insufficient energy to stimulate the heart upon detection of tachycardia or bradycardia conditions, but is detected by the sensing electrodes and circuitry of the AICD device 12. Generate a low energy pulse train or sequence with sufficient energy to suffice. In practice, such a low energy pulse
It appears on the tip electrode 44 and the ring electrode 46 and can be considered as a code detected by the detection circuit of the AICD device 12.

The typical code used is shown in FIG. Two such codes, Code 1 and Code 2, are shown in FIG. Also included in FIG. 6 is a typical stimulation pulse 118. This stimulation pulse 118 is much wider and has a much greater energy associated with it than the narrow pulse contained in pulse codes 1 and 2. The pulse code is carefully very narrow, on the order of a few microseconds, eg 10-30 microseconds, for which a typical stimulation pulse is
It may be 2-5 milliseconds wide to prevent the pulse code from actually stimulating the heart tissue.

The amplitude of the stimulation pulse shown in FIG. 6 is approximately the same as the amplitude of the stimulation pulse, which is, for example, 3-5 volts. However, this is merely an example, and any suitable amplitude that can be detected may be used. In practice, only a limited amplitude range, for example within the range of 2.8 to 10 volts, is readily available in pacemaker devices.

Referring now to Figures 7A and 7B, some typical cardiac waveforms are shown. FIG. 7A shows the normal P-QRS-T heart cycle that occurs within a normally beating heart. FIG. 7B shows the cardiac cycle for a fibrillated (non-beating) heart. These waveforms are shown for the purpose of showing a preferred timing relationship relative to the cardiac cycle over which the pulse code can be delivered.

The waveforms shown in Figure 7A are for a single cycle. If the heart 14 (FIG. 3) is beating normally, the cycle repeats for each heartbeat. Successive R
The time between waves represents the period of the heartbeat frequency. For a typical heart beating at 70 beats per minute, this period is approximately 8
60 milliseconds. Thus, there are approximately 860 ms between successive R waves. The time separating the P wave from the R wave may be on the order of 50-120 milliseconds.
Therefore, there is usually at least 700 between the R wave and the next P wave.
There are milliseconds. Thus, these times change as the heart rate changes, with correspondingly shorter time periods at higher heart rates.

For the purposes of the second embodiment of the present invention, it is desirable that the pulse code not be transmitted at one time during a cardiac cycle when the pulse code is undetectable or otherwise causes problems. . This means that it should not be transmitted at the same time as the P or R wave. Furthermore, it does not transmit stimulation pulses during cardiac tissue repolarization (ie, during the T-wave portion of the cycle), even if these pulses are of insufficient energy to stimulate cardiac tissue. Is desirable.

Therefore, it is necessary to synchronize the supply of pulse code with the cardiac cycle. The approach to achieve such synchronization is to wait a time T1 after the R wave before transmitting the pulse code, as shown in FIG. 7A. The time T1 is set long enough to guarantee that the T-wave has ended, but short enough to precede the P-wave. T1 on the order of 200-300 milliseconds
Values of satisfy generally these norms. However, these times can be adjusted somewhat shorter for tachycardia conditions and significantly longer for bradycardia conditions. Pacemaker 60
The existing circuits therein can be easily modified to allow a low stimulation pulse to occur at any selected time after a synchronization event, such as the occurrence of an R wave, eg, simply through reprogramming.

In Figure 7B, where there is a fibrillating heart condition,
The timing of the pulse code, eg pulse code 2 (used to signal fibrillation conditions), is not critical. The fibrillating heart is a nearly stationary heart, and there are no cardiac events for which synchronization can occur. Therefore, the preferred approach is to generate an appropriate pulse code at the end of the escape interval T _E (or alternatively at the end of two or three escape intervals) and then repeat the pulse code every T2 thereafter. .

If the heart responds to detecting the pulse code,
Or in response to not detecting any cardiac activity A
If the ICD device begins to beat as a result of transmitting a high energy defibrillation pulse, then the repeating pulse code is harmless. After a suitable time period, once the heart is beating again, the transmission of this code sequence can be terminated.

FIG. 9 is a flow chart of a program that can be executed in the pacemaker according to this second embodiment. This flow chart, and in particular its upper half, is very similar to the flow chart of FIG. Accordingly, steps or blocks of the flowchart of FIG. 9 that are equivalent to the flowchart of FIG. 8 are numbered the same except for the addition of the “prime” symbol (′) after the number in FIG. Has been done. Therefore, much of the description made above in connection with FIG. 8 applies equally to FIG. 9 and need not be repeated here.

The main difference between the program shown in FIG. 9 and the program shown in FIG. 8 is that a tachycardia condition exists (block 98 ') or a bradycardia condition exists (block 106'). Is an action that is made in response to the decision.
If a tachycardia condition is detected, a suitable pulse code corresponding to such a decision, eg Code 1, is
It is generated after time T1 from the last R wave, as described above in connection with FIG.

Similarly, if a bradycardia condition is detected (block 1
06 '), a suitable pulse code corresponding to such a decision, for example code 2, is generated (block 109),
The occurrence is also repeated every T2 seconds, as described above in connection with FIG. 7B (block 111).
If an R wave is detected during the T2 period (block 113), normal demand pacemaker operation is restarted (block 94 '). If time interval T2 times out prior to detection of the R wave, then code 2 is transmitted again (block 109) and the process repeats until the R wave is detected.

AICD devices are usually fibrillated (no heartbeat)
Since it also detects a very slow heartbeat (which is also interpreted as no heartbeat since the heartbeat is not detected within a defined time interval), Moreover, since the AICD responds to such detection by the delivery of high energy defibrillation pulses, it may be definitively questioned as to what is needed in the present invention for programming the lower limit of the AICD device. In other words, it could be shown that the fixed lower bound of the AICD device is appropriate for most patients and does not require programming.

However, for the first embodiment of the invention, the detection electrodes of the AICD do not detect fibrillation conditions (or other conditions) because the detection electrodes are not in contact with the heart. It is in contact with the pacemaker. Also, it can only detect what the pacemaker allows. Therefore, programming of both the upper and lower bounds of the AICD is required and is preferably included in the preferred embodiment in practice.

For the second embodiment of the invention, the AICD sensing electrode is in contact with the heart and thus also senses cardiac activity.
Thus (as determined by its programmed threshold rather than the AICD's fixed threshold)
All that the pacemaker needs to do to signal to the AICD that a tachycardia has been detected is that the combination of natural heart activity and the injected pulse is AICD.
Injecting sufficient pulses into the detection circuit during the cardiac cycle so that it appears as a heart rate that exceeds its fixed tachycardia threshold.

In this regard, the pacemaker includes a single low-energy stimulation pulse at the appropriate time in the cardiac cycle to give the AICD an indication that the heart rate is above a fixed upper limit. It is sufficient to inject any pulse code that is present. Furthermore, this allows a conventional AICD device without special discrimination circuitry to be used with this second embodiment of the invention.

However, the use of normal AICD for this second embodiment is considered undesirable (unless the AICD is only used for the purpose of providing tachycardia support). This is because only the rate upper limit of AICD can be effectively controlled. This is true because at or near the lower limit of AICD, the demand pacemaker is stimulating the heart in an attempt to beat it at a programmed rate. These stimulation pulses are disadvantageously interpreted by the AICD detection circuit as cardiac activity. Thus, even if the heart is experiencing bradycardia conditions or, worse, fibrillation conditions, the AICD will generate this fact by the pacemaker at a programmed rate (according to normal demand pacemaker operation). The stimulation pulses are present and therefore not detected, these stimulation pulses are AICD
Is interpreted as a heartbeat.

Therefore, it is not recommended to use the second embodiment unless the special pulse code is transmitted by the pacemaker so that it can be correctly interpreted by the AICD detection circuit. Otherwise, the AICD can be disabled in performing its most critical function, namely delivering the defibrillation pulse to the fibrillating heart.

Using a pulse code with the second embodiment allows these detection circuits to detect the pulse code and also to detect other detected activities, such activities including natural cardiac events or demand. The detection circuitry of the AICD needs to be modified in order to distinguish (from normal stimulation pulses generated by the pacemaker). FIG. 10 shows a functional diagram of a modified example of such a detection circuit. In FIG. 10, the basic threshold circuit 28 (FIG. 2) of the ordinary AICD device 12 is shown as a discrimination circuit 130.
You can see that it has been changed to include.

Basic threshold circuit 28 primarily includes sense amplifier 150, decode timer 152, counter 154 and decode logic 156. The detection of any activity by the sense amplifier 150, which may include a filter, initiates a time period (which may be considered as an escape interval). If this time period times out without being reset by a subsequent detected event, then the decode logic then generates a defibrillation ("D") trigger on signal line 158. In addition, all detected events are counted in counter 154 during this time period. If a defined number of such events are counted during this interval, then this count gives an indication that the heart is beating too fast, and the decode logic 156 causes the signal line to Generate a Cardiovert (“C”) trigger on 160.

Discrimination circuit 130 modifies the above operation by providing means for detecting and distinguishing the receipt of the desired pulse code, such as Code 1 or Code 2. As can be seen in FIG. 10, the circuit 130 (to be able to detect a narrow pulse width combined with a pulse code).
It includes a sense amplifier 132 having the desired bandpass characteristics. The sense amplifier 132 thus detects the pulse codes, amplifies and preprocesses them, and provides them to the logic circuits 134 and 136 for further processing.

Logic circuit 134, shown in FIG. 10 as a code 1 timer and logic circuit, determines whether the signal being detected by amplifier 132 matches code 1. If the determination is positive, the C1 signal is generated and also provided on signal line 138. Similarly, a logic circuit 136, shown as a code 2 timer and logic circuit, determines whether the signal detected by amplifier 132 matches code 2. If the decision is positive, the C2 signal is generated and signal line 140
Given above.

If, for example, Code 1 matches the determination that a tachycardia condition has been detected by the pacemaker, then the C1 signal is in OR gate 142 (on signal line 160 from basic threshold circuit 28) "C.""Combined with a trigger signal. The output of OR gate 142 outputs A to generate the appropriate high energy cardioversion pulse.
Trigger 1 signal used to signal the ICD.

Following this same example, if Code 2 matches the determination that a bradycardia or fibrillation condition is being detected, then a blank signal is used to effectively disable or blank the sense amplifier 150. The C2 signal is sent from 136 and the "D" trigger (on signal line 158) is combined with the signal in OR gate 144. The output of OR gate 144 outputs A to generate the appropriate high energy defibrillation pulse.
Trigger 2 signal used to signal the ICD.
Blanking of sense amplifier 150 is provided by the AICD detection circuit (also provided to the heart during Code 2 conditions).
This is done to prevent any pacemaker stimulation pulse from being interpreted as cardiac activity. Many alternative designs can be made in this regard to prevent the detection circuitry from falsely concluding that the pacemaker stimulation pulse was cardiac activity.

As mentioned above, the present invention advantageously takes advantage of the flexible programming features of pacemakers to
Allows it to be combined with non-programmable AICD devices or programmable pacemakers in a transfer to ICD manner, thereby allowing the AICD / pacemaker combination to serve both pacemaker and AICD functions in an efficient and programmable manner.

While exemplary embodiments of the present invention have been illustrated and described, it will be obvious to those skilled in the art that many modifications and alterations can be made to the invention described herein without departing from the scope of the invention. Let's do it. All such modifications and alternatives should be considered within the scope of the present invention. Therefore, the true scope of the invention should be determined with reference to the following claims.

Claims (18)

[Claims] 1. A programmable cardioverter / defibrillator system comprising: (a) an automatic implantable cardioverter / defibrillator (AICD), said AICD having a fixed heart and a high threshold rate. High / low rate detection means for detecting when beating above or below a fixed low threshold rate, and a heart above or below a fixed high threshold rate. High / beating below rate
Including a means for delivering high energy cardioversion / defibrillation pulses to the heart whenever the low rate detection means detects, (b) including an implantable programmable pacemaker, said pacemaker comprising: A heart rate detection means for detecting a rate at which the heart is beating, and a detected heart rate to determine if the detected heart rate is within a programmed range of acceptable heart rates. The AICD for processing rates and by triggering whenever the heart rate detected by the heart rate detection means of the pacemaker does not fall within a defined range of acceptable heart rates.
For triggering the generation of cardioversion / defibrillation pulses from the AICD such that the fixed high and low threshold rates of the ACD are replaced by programmed ranges of the implantable programmable pacemaker heart rate. And (c) programming means for allowing the programmed range of acceptable heart rates to be programmed into the processing means, and (c) for coupling actuation of the AICD to the pacemaker. A programmable cardioverter / defibrillator system including coupling means. 2. The method of claim 1 wherein said coupling means includes a direct electrical connection between said processing means of said pacemaker and said high / low rate detection means of said AICD. Programmable cardioverter / defibrillator system. 3. The high / low rate detection means of the AICD includes detection electrodes, the processing means of the pacemaker includes a trigger circuit, and the direct signal connection includes the trigger circuit and the trigger circuit. 3. A programmable cardioversion / defibrillator system according to claim 2, characterized in that it is between the detection electrode. 4. The high / low rate detection means when the trigger circuit determines that the processing means of the pacemaker determines that the detected heart rate exceeds a programmed range of acceptable heart rates. Means for generating a pulse of the first train at a rate that exceeds a fixed high threshold rate, whereby the AICD
Said high / low rate detection means of detecting said first train of pulses and interpreting said first train of pulses as a heart rate exceeding a fixed high threshold rate of AICD, thereby 4. A programmable cardioverter / defibrillator system according to claim 3, characterized in that it delivers said high energy cardioversion / defibrillation pulse. 5. The pacemaker further includes means for delivering a low energy stimulation pulse to the heart on demand to assist in pulsing the heart at a rate that is at least a programmed rate, and The processing means of the pacemaker is programmed to deliver a first sequence of low energy pulses through the delivery means to the heart according to a first defined pattern upon detection of a fast heart rate by the heart rate detection means. , The fast heart rate indicates a tachycardia condition, and the first
Of pulses of the sequence are designed to interrupt the tachycardia condition and cause the heart to beat at a slower rate, and the processing means further comprises the first of the low energy pulses generated by the pacemaker. Sequence is not able to interrupt the tachycardia condition, the AICD is
5. A programmable cardioverter / defibrillator system according to claim 4, wherein the programmable cardioverter / defibrillator system is programmed to provide a defibrillation pulse. 6. Every pulse for a defined time period when the trigger circuit determines that the processing means of the pacemaker determines that the detected heart rate is less than a programmed range of acceptable heart rates. Means for inhibiting the occurrence of a heart rate, so that the high / low rate detection means of the AICD do not detect any heart rate during the defined time period, and Interpreted as a heart rate below the fixed low threshold rate of the AICD,
4. A programmable cardioverter / defibrillator system according to claim 3, wherein the programmable cardioverter / defibrillator system is programmed to provide the high energy cardioversion / defibrillation pulse. 7. The pacemaker further includes means for delivering a low energy stimulation pulse to the heart on demand to assist in pulsing the heart at a rate that is at least a programmed rate, and The processing means of the pacemaker is programmed to deliver a sequence of low energy pulses to the heart through the delivery means according to a pattern defined upon detection of a slow heart rate by the heart rate detection means, the fast heart rate Indicates a bradycardia condition, the pulses of the sequence are designed to stop the bradycardia condition and cause the heart to beat at a faster rate, and the processing means further comprises a low-rate pulse generated by the pacemaker. Events in which the sequence of pulses of energy fails to stop the bradycardia condition Programmable cardioverter / defibrillator system according to claim 6, wherein said AICD is characterized in that it is programmed to provide a cardioversion / defibrillation pulse of the high-energy only. 8. The pacemaker further includes means for generating and delivering a low energy stimulation pulse to the heart on demand to assist in pulsing the heart at a rate that is at least a programmed rate. The coupling means generate a very low energy stimulation pulse of specified energy generated by the pulse generating means of the pacemaker, delivered to the heart, and detected by the high / low rate detecting means of the AICD. Including,
The programmable cardioverter / according to claim 1, characterized in that the specified energy of said low energy stimulation pulse is insufficient to stimulate the heart.
Defibrillator system. 9. The processing means of the pacemaker is further of very low energy when the processing means determines that the detected heart rate is above the programmed range of acceptable heart rates. Generating a first code sequence of stimulation pulses, and a very low energy stimulation when the processing means determines that the detected heart rate is below the programmed range of acceptable heart rates. Is programmed to generate a second code sequence of pulses, and the AIC
D high / low rate detection means further includes the first and second
9. The programmable cardioverter / defibrillator system of claim 8 including means for detecting and distinguishing between the code sequences of. 10. A programmable implantable medical system for delivering high energy stimulation pulses to the heart whenever the heart rate exceeds a programmable threshold rate value, said system comprising an automatic implantable cardioverter. A defibrillator (AICD) device, the AICD device comprising: an AICD detection means for detecting when the heart rate is above a fixed high threshold rate value; Means for delivering a high-energy stimulation pulse to the heart whenever the AICD detection means detects that a predetermined high threshold rate value has been exceeded, and also includes an implantable pacemaker device. The pacemaker device is a pacemaker detector for detecting a heart rate. Means, means for processing a detected heart rate to determine whether it exceeds a programmed norm, and programming for programming said specified norm into said processing means Generating a sequence of very low energy pulses at a rate that exceeds a fixed threshold rate of the AICD in response to a decision by the processing means that the heart rate exceeds the programmed norm. An energy level sufficient to be detected by the AICD detection means but insufficient to stimulate the heart. And said sequence of very low energy pulses is detectable by AICD detection means, whereby A programmable, implantable medical system characterized in that the delivery means of the AICD device is responsive to delivery of the high energy stimulation pulse to the heart. 11. The AICD detection means of the AICD device further includes means for detecting when the heart rate is less than a fixed threshold rate value, and the supply means includes: It includes means for delivering a high energy stimulation pulse to the heart whenever the AICD detection means detects that it is less than the fixed low threshold rate value, whereby the heart rate is above Whenever the AICD detection means detects less than a fixed low threshold rate value, and whenever the heart rate exceeds the programmed norm, the AICD device causes the heart to energize high energy stimulation pulses. A programmable and implantable medical system according to claim 10, characterized in that: 12. The implantable pacemaker device programmed reference includes a heart rate upper limit, above which the heart rate value above which an undesirable cardiac condition is considered to exist. 12. The programmable and implantable medical system of claim 11 including, and wherein the rate cap comprises a programmable value less than a fixed high threshold rate value of the AICD device. 13. A combination of an automatic implantable cardioverter / defibrillator (AICD) device and an implantable programmable pacemaker device, the pacemaker device for detecting the rate at which a heart is beating. A heart rate detection means, means for processing the detected heart rate to determine if the heart rate is within a specified range of acceptable heart rates, and the specified range is Programming means for allowing it to be programmed into the processing means, and triggering the AICD device upon determination by the processing means that the detected heart rate is not within the specified range of acceptable heart rates. Signaling means within said pacemaker device for sending a signal, said A A CDD means for detecting when the heart is beating above a fixed high threshold rate or below a fixed low threshold rate, and in response to receiving the trigger signal. Or in response to the AICD detection means detecting that the heart is beating above a fixed high threshold rate or below a fixed low threshold rate. Means for providing a stimulation pulse and receiving means in the AICD device for receiving the trigger signal, the trigger signal sent by the signal means being at least the fixed of the AICD device. A pulse train having a frequency greater than the determined high threshold rate, the pulse train having a heart rate detected by the heart rate detection means of the pacemaker. When above the defined range of acceptable heart rates, it is sent directly to the AICD receiving means, the trigger signal being the heart rate acceptable by the heart rate detection means of the pacemaker. An automatic implantable cardioverter, characterized in that it comprises means for inhibiting all pulses sent directly to said AICD receiving means for a defined time when below said defined range of rates. A combination of a defibrillator (AICD) device and an implantable programmable pacemaker device. 14. The signal means of the pacemaker includes a trigger circuit for generating or inhibiting the train of pulses, and the receiving means of the AICD device includes a sensing electrode coupled to the AICD sensing means. The detection electrode is further electrically connected to the trigger circuit by a direct electrical connection.
The combination described. 15. A combination of an automatic implantable cardioverter / defibrillator (AICD) device and an implantable programmable pacemaker device, wherein the pacemaker device detects the rate at which the heart is beating. A heart rate detection means, means for processing the detected heart rate to determine if the heart rate is within a specified range of acceptable heart rates, and the specified range is Programming means for allowing it to be programmed into the processing means, and triggering the AICD device upon determination by the processing means that the detected heart rate is not within the specified range of acceptable heart rates. A signal means in the pacemaker device for sending a signal, and the processing means And a means for generating and delivering low energy stimulation pulses, the AICD device wherein the heart beats above a fixed high threshold rate or below a fixed low threshold rate. AICD detection means for detecting when the heart is pulsing, in response to receiving the trigger signal, or pulsing the heart above a fixed high threshold rate or below a fixed low threshold rate. Responsive to the AICD detecting means detecting that the heart is present, including means for delivering a high energy stimulation pulse to the heart, and receiving means within the AICD device for receiving the trigger signal. The signal means of the pacemaker device is the AICD
A very low energy pulse train delivered to the heart by the stimulation pulse delivery means of the pacemaker device at a rate above the fixed high threshold rate of the detection means, wherein the receiving means in the AICD device is Including the AICD detection means, the very low energy pulse has a sufficient energy level to be detected by the AICD detection means, but is insufficient to stimulate the heart, whereby the AICD detection means is An extremely low energy pulse train is detected and interpreted as the heart beating at a rate above the fixed high threshold rate, whereby the delivery means of the AICD device delivers the high energy stimulation pulse to the heart. Implantable, characterized by responding by feeding Cardioverter / defibrillator (AICD) device and a combination of an implantable programmable pacemaker apparatus. 16. The detection means, processing means and pulse generation and supply means included in the pacemaker device further include each pulse of the train of low energy pulses which is detected by the AICD detection means. A means for controlling the delivery of said very low energy pulse by the rhythm of the heart so that it occurs within the heart's beating cycle at a time that is allowed to occur. The combination according to range 15. 17. The trigger signal delivered by the signaling means comprises one of a plurality of different burst patterns of very low energy pulses generated and delivered by the pulse producing and delivering means of the pacemaker device. And further, the receiving means in the AICD device includes a discriminating means for discriminating between the different burst patterns, whereby each of the different burst patterns is received and received in the AICD device. 16. The combination according to claim 15, which can be detected and fixed by a discriminating means. 18. A first of said plurality of very low energy burst patterns has a heart rate lower than a specified range of acceptable heart rates programmed into said processing means. And a second one of the plurality of very low energy burst patterns signals that the heart rate is higher than a specified range of acceptable heart rates programmed into the processing means. The combination according to claim 17, characterized in that