CN110051929B - Implantation detection circuit, implantation detection method and device of cardiac pacing system - Google Patents
Implantation detection circuit, implantation detection method and device of cardiac pacing system Download PDFInfo
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- CN110051929B CN110051929B CN201910472944.1A CN201910472944A CN110051929B CN 110051929 B CN110051929 B CN 110051929B CN 201910472944 A CN201910472944 A CN 201910472944A CN 110051929 B CN110051929 B CN 110051929B
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/362—Heart stimulators
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/362—Heart stimulators
- A61N1/37—Monitoring; Protecting
- A61N1/3706—Pacemaker parameters
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/372—Arrangements in connection with the implantation of stimulators
Abstract
The invention relates to an implantation detection circuit, an implantation detection device and an implantation detection method of a cardiac pacing system. The implantation detection circuit comprises a detection module and a voltage comparison module, wherein the detection module is connected with the pacing circuit and is used for detecting the voltage of the pacing pulse before and after discharging successively and outputting voltage difference signals before and after the pacing pulse discharges, the voltage comparison module is used for judging whether the voltage difference exceeds a preset threshold voltage, and the voltage comparison module is also connected with a control module of the cardiac pacing system so as to transmit a comparison result to the control module. Compared with the traditional implantation detection technology, the implantation detection circuit of the cardiac pacemaker system does not need to accurately measure the current value or the electrode impedance or the voltage difference value, thereby being beneficial to reducing the design difficulty and simplifying the circuit structure. Furthermore, the detection module can be realized by a detection capacitor with a specific connection relation and four switch elements, and has the advantages of high detection precision, simple structure and low power consumption.
Description
Technical Field
The invention relates to the field of integrated circuits, in particular to an implantation detection circuit, an implantation detection device and an implantation detection method of a cardiac pacing system, and further relates to a readable storage medium and the cardiac pacing system.
Background
Cardiac pacing systems have evolved since the fifties of the last century, whether they are therapeutic indications or functions, and in addition to pacing functions, cardiac pacing systems have also been used to perform a variety of diagnostic techniques related to cardiac arrhythmias.
The known cardiac pacing system comprises a pacemaker (cardiac pacemaker) and an electrode lead, wherein the pacemaker and the electrode lead are implanted into a human body in an implantation operation, the pacemaker is powered by a battery, a tiny electric pulse (namely a pacing pulse) powered by the battery can be delivered to the heart through a pulse generator when needed, and the pacing pulse is transmitted to the heart through the conduction of the electrode lead, so that the heart is excited and contracted to fulfill the aim of treating the heart dysfunction caused by certain arrhythmia.
In the manufacturing process of the cardiac pacing system, a worker needs to perform performance detection on the pacing circuit and each component so as to meet the factory requirements. After leaving the factory, a doctor performs a pacemaker implantation operation to implant a pacemaker and an electrode lead into the body of a patient. The specific implantation procedure generally includes the steps of local anesthesia, venipuncture (placement of a guidewire), transvenously placing and testing an electrode lead, making a pouch and placing a pacemaker, and suturing. In an implantation test before delivery and a pacemaker implantation operation after delivery, it is a trend that an implantation operation is simplified by fully utilizing medical electronic equipment in order to improve implantation efficiency and accuracy, wherein after an electrode lead is placed and a pacemaker is placed, an implantation detection technology for determining whether a cardiac pacing system is in an implantation state by detecting whether the pacemaker, the electrode lead and cardiac muscle form a current loop (hereinafter referred to as a loop) belongs to one of important automatic functions.
Conventional techniques for implant detection of cardiac pacing systems include two types. One is to detect whether the pacemaker has an electrode load by measuring the impedance value of the pacing electrode position, and when the measured electrode impedance value is within a set range, the pacemaker has the electrode load, so as to judge that the pacing electrode is connected with the cardiac muscle, and the pacemaker, the electrode lead and the cardiac muscle form a loop, namely, the cardiac pacing system is in an implantation state. The method for measuring the electrode impedance has certain requirements on the amplitude and the width of a pacing pulse, and needs to detect the small variation of a high pacing voltage (up to 7.5V) after pulse discharge, in order to accurately measure the small variation, an analog-to-digital converter with high resolution precision needs to be configured, and the analog quantity of the pacing voltage is converted into a digital quantity by the analog-to-digital converter so as to facilitate subsequent calculation and data storage. However, the analog-to-digital converter needs to be matched with a sampling circuit, an amplifying circuit, a comparing circuit, a control logic circuit and the like, so that the circuit design is complex and the power consumption is large.
Another implant detection technique for conventional cardiac pacing systems is to determine whether the pacemaker has an electrode load by measuring whether the total current in the loop of pacemaker, electrode lead and myocardium has increased. In order to determine whether the total current is increasing, it is often necessary to add a series resistance in the power supply and pacemaker operating circuitry, and to determine whether the pacing electrode is connected to the myocardium by measuring whether the current in the resistance is increasing. When the pacing electrode is determined to be connected with the cardiac muscle, the pacemaker, the electrode lead and the cardiac muscle form a loop, namely, the cardiac pacing system is in an implantation state, the resistor can be shorted through an additional circuit. This kind of detection technique needs additionally to increase off-chip high accuracy resistance components and parts and set up the aftertreatment circuit who is used for detecting the current change on the pacemaker circuit board, has increased the design degree of difficulty of circuit, and the consumption is great.
Therefore, the conventional implantation detection technology of the cardiac pacing system has a complex circuit structure and high power consumption, and is not favorable for the design of the long service life of the cardiac pacing system.
Disclosure of Invention
The invention provides an implantation detection circuit of a cardiac pacing system, which is used for detecting the implantation state of the cardiac pacing system without obtaining accurate current values, electrode impedance values or voltage difference values, and is beneficial to simplifying the circuit structure and reducing the design difficulty. The invention further provides an implantation detection method and device of the cardiac pacing system, the cardiac pacing system and a readable storage medium.
According to a first aspect of the invention, there is provided an implant detection circuit of a cardiac pacing system, the implant detection circuit comprising:
the detection module is electrically connected with a pacing circuit of the cardiac pacing system and is used for sequentially sampling the voltage before and after discharge of pacing pulses delivered by the pacing circuit and outputting voltage difference signals before and after the pacing pulses are discharged; and the voltage comparison module is electrically connected with the detection module and used for comparing the voltage difference between the pacing pulse before and after discharge with a preset threshold voltage and outputting a comparison result, the voltage comparison module is also connected with the control module of the cardiac pacing system, and the voltage comparison module transmits the comparison result to the control module of the cardiac pacing system.
Optionally, the detection module is connected to a pacing capacitor of the pacing circuit, and the detection module detects a voltage stored by the pacing capacitor before and after discharge of a pacing pulse, so as to sample a voltage before and a voltage after discharge of a pacing pulse delivered by the pacing circuit, respectively.
Optionally, the detection module includes a detection capacitor, a first switch element, a second switch element, a third switch element and a fourth switch element, wherein the first switch element is connected between the first end of the detection capacitor and the ground, the second switch element is connected between the second end of the detection capacitor and the ground, the third switch element and the fourth switch element are connected in parallel between the first end of the detection capacitor and the second end of the pacing capacitor, the first end of the pacing capacitor is grounded, and the second end of the detection capacitor is connected to the voltage comparison module.
Optionally, the voltage comparison module includes a voltage comparator, a first input end of the voltage comparator is connected to the second end of the detection capacitor, and a second input end of the voltage comparator is connected to the threshold voltage.
Optionally, the detection capacitor is an on-chip capacitor.
Optionally, the implantation detection circuit is designed for full on-chip integration.
Optionally, at least one of the first switching element, the second switching element, the third switching element and the fourth switching element is one of a transistor, a MOSFET, a JFET and an IGBT.
According to a second aspect of the present invention, there is provided an implantation detection method of a cardiac pacemaker system, using the above implantation detection circuit, the implantation detection method comprising the following steps performed in sequence during one pacing pulse transmission period:
in a first time period before the pacing pulse is sent, only the first switching element and the second switching element are switched on, and the first end and the second end of the detection capacitor are short-circuited; in a second time period before the pacing pulse is sent, the voltage of the second end of the pacing capacitor is the voltage before discharge of the pacing pulse, only the second switching element and the third switching element are switched on, the voltage before discharge is sampled, the voltage of the first end of the detection capacitor is the voltage before discharge, and the voltage of the second end of the detection capacitor is 0; in a third time period after the pacing pulse is sent, the voltage of the second end of the pacing capacitor is the voltage of the pacing pulse after discharge, only the fourth switching element is switched on, the voltage after discharge is sampled, the voltage of the first end of the detection capacitor is the voltage after discharge, and the voltage of the second end of the detection capacitor is the inverse value of the voltage difference between the voltage before discharge and the voltage after discharge; and comparing whether the voltage difference is greater than a set threshold voltage or not by using a voltage comparison module, and outputting a comparison result, wherein when the voltage difference is greater than the preset threshold voltage, the cardiac pacing system is in an implanted state when the voltage difference is greater than the threshold voltage, and otherwise, the cardiac pacing system is in a non-implanted state.
According to a third aspect of the invention, there is provided a readable storage medium having stored thereon computer instructions which, when executed by a processor, perform the implantation detection method of the cardiac pacing system described above.
According to a fourth aspect of the present invention, there is provided an implant detection device of a cardiac pacing system, the implant detection device comprising the above-described implant detection circuit and/or the above-described readable storage medium.
According to a fifth aspect of the invention, there is provided a cardiac pacing system comprising the implant detection circuit described above.
The invention provides an implantation detection circuit of a cardiac pacing system, which comprises a detection module and a voltage comparison module, wherein the detection module is electrically connected with the pacing circuit and is used for sequentially sampling a voltage before discharge and a voltage after discharge of a pacing pulse issued by the pacing circuit and outputting a voltage difference signal before and after the discharge of the pacing pulse, the voltage comparison module is connected with the detection module and is used for comparing the voltage difference before and after the discharge of the pacing pulse with a preset threshold voltage and outputting a comparison result, the voltage comparison module is also connected with a control module of the cardiac pacing system, and the voltage comparison module transmits the comparison result to the control module of the cardiac pacing system. Compared with the traditional implantation detection technology, the implantation detection circuit of the cardiac pacemaker system does not need to accurately measure the current value or the electrode impedance value or the voltage difference value before and after pulse discharge in the cardiac pacemaker system, thereby being beneficial to reducing the design difficulty and simplifying the circuit structure.
Further, in the implantation detection circuit of the cardiac pacing system, the detection module includes a detection capacitor, a first switch element, a second switch element, a third switch element, and a fourth switch element, where the first switch element is connected between a first end of the detection capacitor and ground, the second switch element is connected between a second end of the detection capacitor and ground, the third switch element and the fourth switch element are connected in parallel between the first end of the detection capacitor and a second end of the pacing capacitor, the second end of the detection capacitor is connected to the voltage comparison module, and the voltage comparison module may include a voltage comparator. Among the above-mentioned detection circuitry of implanting, detection module can carry out real-time detection, convenient to use to every pace-making pulse that pacemaker provided to, the difference in voltage signal before and after pace-making pulse that detection module output discharged carries out the comparison through the second end direct input voltage comparison module of detection electric capacity, avoids quantization error, can realize high accuracy and detect. In addition, compared with the traditional implantation detection technology, the implantation detection circuit does not need an analog-to-digital converter and a matching circuit, does not need to increase extra discrete components and matching circuits outside the chip, is simple in structure and contributes to reducing power consumption, can adopt an on-chip fully integrated implementation mode, contributes to reducing cost, and can reduce the design complexity and increase reliability of a hybrid circuit board.
The implantation detection method of the cardiac pacing system provided by the invention comprises the steps of initializing the detection capacitor, sampling the voltage before discharging of the pacing pulse and sampling the voltage after discharging of the pacing pulse in sequence in a pacing pulse period by using the implantation detection circuit, and comparing whether the voltage difference is greater than the preset threshold voltage by using the voltage comparison circuit according to the characteristic that the voltage after the second sampling of the second end of the detection capacitor reflects the voltage difference before and after discharging of the pacing pulse, thereby obtaining the information whether the cardiac pacing system is in an implantation state. The computer instruction in the readable storage medium realizes automatic implantation detection of the cardiac pacing system by using the implantation detection circuit with a simple structure, has high detection precision and low power consumption, and simultaneously has lower current of the circuit, thereby being beneficial to prolonging the service life of the cardiac pacing system.
The present invention provides a readable storage medium having stored thereon computer instructions that, when executed by a processor, perform the implant detection method described above, thereby having the same or similar advantages as the implant detection method described above.
The implantation detection device of the cardiac pacing system provided by the invention comprises the implantation detection circuit and/or the readable storage medium, and therefore, the implantation detection circuit and the readable storage medium have the same or similar advantages.
The cardiac pacing system provided by the invention comprises the implantation detection circuit, thereby having the same or similar advantages as the implantation detection circuit.
Drawings
Fig. 1 is a schematic of a voltage waveform of a single pacing pulse in an embodiment of the present invention.
Fig. 2 is a circuit diagram of an implant detection circuit of a cardiac pacing system in an embodiment of the present invention.
Fig. 3 is a timing diagram of a pacing control signal of a pacing circuit and a control signal of an implant detection circuit in an embodiment of the invention.
Fig. 4 is a flow chart of computer instructions executed by a readable storage medium during a pacing pulse period in an embodiment of the present invention.
Description of the reference numerals:
100-implant detection circuitry; 110-a detection module; 120-voltage comparison module.
Detailed Description
The implantation detection circuit, the implantation detection method and the implantation detection device of the cardiac pacing system of the present invention are further described in detail in conjunction with the accompanying drawings and the specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
The physiological basis of cardiac pacing systems is that the myocardium can produce a contractile response to any form of electrical current stimulation, and with this, the pacemaker of the cardiac pacing system can deliver direct electrical stimulation to the diseased heart as needed to artificially normalize the heart. The cardiac pacing system can be divided into an external temporary pacing type for emergency temporary pacing and an implanted type (or permanent or embedded type) for long-term pacing. The present embodiment is primarily described in terms of an implantable cardiac pacemaker system, i.e., a cardiac pacemaker system in general.
The cardiac pacing system generally includes a pacemaker and an electrode lead, wherein the pacemaker includes a pulse generator connected to the electrode lead, wherein after a tip end (i.e. a pacing electrode) of the electrode lead contacts a cardiac muscle, an output signal of the pulse generator can be guided to the cardiac muscle for pacing, and a sensed signal of a heart beat can be fed back to a control module of the cardiac pacing system to control delivery of a pacing pulse. Cardiac pacing systems are typically set to a "transport mode" in which pacing pulses are delivered at a rate of about 60-70 times per minute, which is the fundamental rate of a cardiac pacemaker, before shipping and implantation into the body. Generally, after the pacemaker is implanted into a human body, a doctor sets appropriate pacing parameters according to the condition of a patient, and starts functions of parameter measurement, data statistics and the like. During the manufacturing process of the cardiac pacing system, the implantation process of the pacemaker and the electrode lead can be simulated to evaluate the performance of the pacing system, wherein a manual or automatic detection circuit can be adopted to judge whether the cardiac pacing system is in an implantation state, wherein the implantation state refers to a state that the pacemaker, the electrode lead and the 'myocardium' contacted with the head end of the electrode lead form a loop.
With the development of automation technology, in order to reduce the operation burden and operation time of a doctor in a pacemaker implantation operation in clinical practice, the pacemaker is required to automatically detect whether an electrode contacts with the cardiac muscle of a patient, if the electrode contacts with the cardiac muscle, a pacemaker working circuit, the electrode and the cardiac muscle form a loop, the cardiac pacing system is in an implantation state, and after the cardiac pacing system is judged to be in the implantation state, a control module can control the pacemaker to switch the working mode. After the cardiac pacing system is in an implanted state, the heart is electrically stimulated through a discharge circuit formed by a switch, an electrode lead and the cardiac muscle according to needs, so that the heart generates contraction pulsation.
In the pacing circuit of the pacemaker, since the voltage of the battery as the power source is lower than the pacing voltage of the pulse generator, a settable pacing voltage, that is, the pre-discharge voltage V of the pacing pulse is generated by the voltage boosting circuit H1 . The pacing circuit may further include a pacing capacitor C H The pacing capacitance C H The pre-discharge voltage V of each pacing pulse may be reduced H1 And a voltage V after discharge H2 And storing the data.
Fig. 1 is a voltage waveform schematic of a single pacing pulse in accordance with an embodiment of the present invention. Referring to FIG. 1, specifically, a pacing capacitor C is used before a pacing pulse is discharged H The voltage on is the pre-discharge voltage V of the pacing pulse H1 After a pacing pulse is discharged, the capacitor C is paced H The voltage on is converted into a post-discharge voltage V of the pacing pulse H2 . Pacing capacitor C H The value of the change in charge amount above is equal to the product of the discharge current and the discharge time of the pacing pulse, and can be expressed by equation (1):
ΔQ＝C(V H1 -V H2 )＝I*Δt (1)
wherein C is pacing capacitor C H Capacitance value of (V) H1 The pre-discharge voltage (i.e., pacing voltage), V, of the pacing pulse H2 The post-discharge voltage of the pacing pulse, I is the pacing average current, and Δ t is the pacing pulse width.
The impedance at the electrode in the discharge circuit can be derived from the above equation as formula (2):
wherein R is pacing loop impedance, (V) H1 -V H2 ) The voltage difference before and after the pacing pulse discharge.Pacing pulses and a pacing capacitor C, typically prior to electrode implantation H Is fixed, i.e. the pacing voltage V H1 The pacing pulse width Δ t and the pacing capacitor C are fixed values, and it is seen that when the electrode does not contact the myocardium, the discharge circuit of the pacing pulse is open circuit, and the impedance of the discharge circuit is large, so that the voltage difference (V) of the pacing pulse before and after discharge is at this time H1 -V H2 ) Small (meaning that the absolute value of the voltage difference is small). After the electrodes properly contact the myocardium, the impedance of the discharge circuit decreases, at which time the voltage difference (V) of the pacing pulse before and after discharge H1 -V H2 ) Becomes large, thereby a voltage difference (V) before and after the discharge of the pacing pulse H1 -V H2 ) Increases as the impedance of the pacing circuit decreases. When the voltage difference exceeds a preset threshold voltage, the cardiac pacing system is indicated to be in an implantation state. That is, the voltage difference of the pacing pulse before and after discharging increases with the decrease of the impedance of the discharging circuit, so that whether the cardiac pacing system is in an implanted state can be determined by determining the change of the voltage difference of the pacing pulse before and after discharging, and in addition, considering that a non-replaceable battery is generally adopted for supplying power for a pacemaker, the determination process should be as low as possible.
Fig. 2 is a circuit diagram of an implant detection circuit of a cardiac pacing system according to an embodiment of the present invention. Referring to fig. 2, a voltage difference (V) of a pacing pulse before and after discharging is accurately detected for low power consumption H1 -V H2 ) The change of avoiding adopting complicated circuit design such as adc, the implantation detection circuitry 100 of the cardiac pacing system of this embodiment includes detection module 110 and voltage comparison module 120, wherein detection module 110 is connected with the pacemaker, detection module 110 is used for successively detecting the voltage before discharging and the voltage after discharging of the pace-making pulse that pace-making circuit provided and exports the voltage difference signal before and after the pace-making pulse discharges, voltage comparison module 120 with detection module 110 connects for judge whether the voltage difference before and after the pace-making pulse discharges exceeds predetermined threshold voltage, if, then judges the cardiac pacing system is the implantation state, otherwise judges for non-implantation state.
In this embodiment, the pacemaker includes pacingCapacitor C H The pre-discharge voltage V of each pacing pulse delivered by the pacemaker H1 And the voltage after discharge is stored in the pacing capacitor C H Said pacing capacitor C H Is connected to ground, and the detection module 110 detects the pacing capacitor C H Voltage of the second terminal (corresponding to voltage V) H ) To obtain a pre-discharge voltage V of the pacing pulse H1 And a voltage V after discharge H2 . Therefore, the voltage before and after discharge of the pacing pulse can be conveniently sampled, and the sampling efficiency is improved. In further embodiments, detection module 110 may provide the pre-discharge voltage V for each pacing pulse by interfacing with a pacing circuit H1 And a voltage V after discharge H2 Is electrically connected to obtain a pre-discharge voltage V for each pacing pulse H1 And a voltage V after discharge H2 。
In particular, referring to FIG. 2, the detection module 110 of the implant detection circuit 100 may include a detection capacitor C S A first switch element S1, a second switch element S2, a third switch element S3 and a fourth switch element S4, wherein the first switch element S1 is connected with the detection capacitor C S Between the first terminal of (a) and ground, the second switching element S2 being connected to the detection capacitor C S Between the second terminal of (b) and ground, the third switching element S3 and the fourth switching element S4 are connected in parallel to the detection capacitor C S First terminal and pacing capacitor C H Between the second terminals of the detection capacitor C S Is connected to the voltage comparison module 120.
The voltage comparing module 120 may include a voltage comparator, the circuit of which compares two analog voltage signals respectively input from two input terminals, and the output signal (COMP _ OUT) is a binary signal 0 or 1, and when the difference between the voltages input from the two input terminals increases or decreases and the signs are not changed, the output thereof remains constant. The voltage comparing module 120 of this embodiment is configured to determine whether the voltage difference before and after the pacing pulse discharge exceeds a set threshold voltage, so as to obtain information of the implantation state of the cardiac pacing system, and therefore, the voltage comparator may be utilized to compare the voltage difference before and after the pacing pulse discharge with a preset threshold voltage.
In this embodiment, the detection module 110 detects the capacitance C S Is used for outputting the voltage difference between the sampled pacing pulse and the voltage before and after the discharge, therefore, the first input end of the voltage comparator can be connected with the detection capacitor C S The second input end of the voltage comparator is connected with the set threshold voltage V th . Conveniently, the first end of the detecting capacitor Cs is used as the upper plate of the detecting capacitor Cs, and the second end of the detecting capacitor Cs is used as the lower plate (corresponding to the output voltage V) p ) Wherein the upper plate is connected to a pacing capacitor C H The lower plate is connected to the first input end of the voltage comparator.
The detection capacitor C S Preferably, the on-chip capacitor may be formed between conductive layers on a semiconductor substrate (e.g., a silicon substrate, a silicon-on-insulator substrate, or a multilayer substrate including silicon, silicon germanium, a iii-v compound semiconductor, and combinations thereof), the electrode material of the on-chip capacitor may be a metal (e.g., copper, titanium, tantalum), a conductive compound (e.g., titanium nitride, tantalum nitride), or the like, and the dielectric material between the electrodes may be, for example, silicon oxide, hafnium oxide, lead zirconate titanate (PZT), barium Strontium Titanate (BST), or the like. The design of the on-chip capacitor is beneficial to improving the detection sensitivity and reducing the power consumption. Furthermore, the implantation detection circuit may be designed as a System on a chip (SoC), in which the detection module 110 and the voltage comparison module 120 are integrated on one chip, so as to reduce power consumption and improve detection sensitivity, and on the other hand, the System on a chip may not be designed as a complex circuit board, but may be manufactured by calling the standard of the processor in the device library through an accurate language comprehensive time sequence design, and may be embedded with other functional modules on the chip of the implantation detection circuit.
Fig. 3 is a timing diagram of a pacing control signal of a pacing circuit and a control signal of an implant detection circuit according to an embodiment of the invention. Referring to fig. 2 and 3, the present embodiment further includes an implantation detection method of the cardiac pacemaker system, which determines whether the cardiac pacemaker system is in an implanted state during a pacing pulse sending period by using the implantation detection circuit. The implantation detection method comprises the following steps.
First, before the pacing pulse is sent, the detection capacitor Cs is initialized. Specifically, in a first time period before the pacing pulse is sent (a time period after the time point t 1), only the first switching element S1 and the second switching element S2 are turned on, so that the first end and the second end of the detection capacitor Cs are short-circuited.
The pacing pulse refers to the pacing pulse to be detected. The implantation detection circuit of the embodiment can detect each pacing pulse delivered by the pacemaker before electrode implantation, and can also detect only part of the pacing pulses according to the requirement so as to reduce the power consumption. In the first time period, only the first switching element S1 and the second switching element S2 are turned on (at this time, the third switching element S3 and the fourth switching element S4 are in an off state), a path is formed between the first end and the second end of the detection capacitor Cs and the ground, that is, the first end and the second end are short-circuited, at this time, the net charges on the upper plate and the lower plate of the detection capacitor Cs are 0, and the first switching element S1 and the second switching element S2 are turned off after the initialization is completed.
Next, a first voltage sampling is performed. The first time of voltage sampling is specifically a second time period (a time period after the time point of t 2) before the pacing pulse is sent, at which time the pacing capacitor C H The voltage of the second terminal of (2) is the pre-discharge voltage V of the pacing pulse H1 Switching on only the second switching element S2 and the third switching element S3 to sample the pre-discharge voltage V of the pacing pulse H1 Making the voltage of the first end of the detection capacitor Cs be the voltage V before the discharge of the pacing pulse H1 And the voltage at the second terminal is 0.
In this embodiment, the pacing circuit is provided with a pacing capacitor C H Pacing capacitor C H The pre-and post-discharge voltages of each pacing pulse, the pacing capacitor C, may be stored H Is grounded at a first endThus, the first end of the detecting capacitor Cs and the pacing capacitor C can be connected H To obtain a pre-discharge voltage V of the pacing pulse H1 I.e. the pacing voltage. Slave pacing capacitor C using the capacitor's hold pressure characteristics H Sampling the pre-and post-discharge voltages of the pacing pulses to be detected helps to extend the sampleable time. The pacing voltage is determined according to the specifications or specific parameters of the cardiac pacemaker, for example, in the range of 2V to 7.5V.
At the first voltage sampling, only the second switching element S2 and the third switching element S3 are turned on (at this time, the first switching element S1 and the fourth switching element S4 are in an off state), so that the pacing capacitor C is connected to the first terminal of the detection capacitor Cs H A path is formed between the first end of the detection capacitor Cs and the pre-discharge voltage V of the pacing pulse H1 A path is also formed between the second terminal of the detection capacitor Cs and ground, and the voltage at the second terminal of the detection capacitor Cs is 0. After the first voltage sampling is completed, the second switching element S2 and the third switching element S3 are turned off.
The pacing pulse is delivered after the first voltage sample. In conjunction with fig. 1 and 3, it is possible to control timing for sending a pacing pulse by a pacing control signal after the above initialization and the first voltage sampling are completed (t 3 time point). The pulse width of the pacing pulse is about 400-1500 mus, which may be determined according to the specifications or parameters of the particular pacemaker. In this embodiment, the post-discharge voltage V of the pacing pulse after pulse delivery H2 Is also stored in the pacing capacitor C H Thus the post-discharge voltage V of the pacing pulse H2 The pacing capacitor C at the moment can also be sampled H The voltage of the second terminal of (1) is obtained.
Then, a second voltage sampling is performed. Referring to fig. 2 and 3, a pacing capacitor C is provided at a third time period (a time period after the t4 time point) after the pacing pulse is delivered H The voltage of the second end of the pulse is the voltage V after the discharge of the pacing pulse H2 Only the fourth switching element S4 is turned on (at this time, the first switching element S1, the second switching element S2, and the third switching element S3 are all off) to sample the post-discharge voltage V of the pacing pulse H2 Making the voltage of the first end of the detection capacitor Cs be the voltage V after the discharge of the pacing pulse H2 The voltage at the second terminal is- (V) H1 -V H2 ) That is, the voltage at the second end is the inverse value of the voltage difference between the pre-discharge voltage and the post-discharge voltage of the pacing pulse. And the fourth switching element S4 is turned off after the second voltage sampling is completed.
Detecting the first end of the capacitor Cs and the pacing capacitor C at the time of the second voltage sampling H The second terminal of (2) forms a path with a voltage of V H2 However, since the second end (lower plate) of the detection capacitor Cs has no current path, the amount of charge on the detection capacitor Cs remains the same after the first voltage sampling, and the voltage at the second end is — (V) H1 -V H2 ). It can be seen that the voltage signal at the second end of the detection capacitor Cs reflects the voltage difference before and after the discharge of the detected pacing pulse, and the change information of the voltage difference can be obtained by detecting the change of the voltage at the second end of the detection capacitor at this time.
Next, it is compared whether the voltage difference before and after the discharge of the pacing pulse is larger than a set threshold voltage. Specifically, the voltage comparison module 120 may be used to compare the absolute value of the voltage difference with a set threshold voltage, and output a comparison result, where when the voltage difference is greater than the set threshold voltage, it is determined that the cardiac pacing system is in an implanted state, and otherwise, it is determined that the cardiac pacing system is in a non-implanted state.
In this embodiment, the voltage comparison module 120 may compare the absolute value of the voltage difference with the set threshold voltage by using a voltage comparator, wherein the second terminal of the detection capacitor Cs is connected to the first input terminal of the voltage comparator, the second input terminal of the voltage comparator inputs the set threshold voltage, and the output terminal of the voltage comparator may output the comparison result. The set threshold voltage may be specifically set according to the specification or parameters of the pacemaker. Since the impedance of the discharge circuit due to the pacing pulse is significantly reduced after the electrode contacts the myocardium, the voltage difference (V) before and after the discharge of the pacing pulse H1 -V H2 ) Increase, and thus the voltage difference (V) before and after discharge H1 -V H2 ) Greater than a set thresholdWhen the voltage is applied, information about whether the cardiac pacing system is in an implanted state or not may be further output according to the comparison result (i.e., the COMP _ OUT signal) output by the voltage comparison circuit.
Specifically, when the cardiac pacing system is judged to be in an implantation state, the information can be fed back to an operator or a control module of the cardiac pacing system, so that the implantation detection circuit can be turned off, and other work of the cardiac pacing system can be started; when the cardiac pacing system is determined to be in the non-implantation state, the above process can be performed in a cycle of the following pacing pulse period until the cardiac pacing system is determined to be in the implantation state.
In the above detection process, since the second end of the detection capacitor Cs is disconnected from the ground after the first voltage sampling, the charge amount of the lower plate of the detection capacitor Cs remains unchanged, and after the second voltage sampling, the voltage of the second end of the detection capacitor Cs reflects the voltage difference before and after the discharge of the tested pacing pulse, an accurate value of the voltage difference does not need to be obtained, but the voltage difference is directly compared with the preset threshold voltage by using the voltage comparison module 120 connected with the second end of the detection capacitor Cs, so as to obtain information whether the electrode contacts with the myocardium, that is, information whether the cardiac pacing system and the myocardium form a loop, so as to determine whether the cardiac pacing system is in an implantation state. The implantation detection circuit 100 does not include an analog-to-digital converter or additional resistor components and supporting circuits, and as shown in fig. 2, implantation detection can be performed only by one detection capacitor Cs, one voltage comparator and four switch elements, so that the structure is simple; because complex circuits such as an analog-digital converter and the like are not included and the on-chip full-integration design can be adopted, the power consumption is lower compared with the traditional implantation judgment circuit; in the implantation detection circuit 100 of this embodiment, the second end of the detection capacitor Cs is directly connected to the first input end of the voltage comparison module 120, that is, the voltage of the second end of the detection capacitor Cs is directly compared with the preset threshold voltage, so that compared with the conventional implantation detection method, a multi-bit high-precision large dynamic range analog-to-digital converter is adopted to measure the voltages before and after discharge of the pacing pulse respectively, and then calculation is performed to obtain a tiny voltage change value, the implantation detection method of this embodiment avoids quantization errors, and can realize high-precision detection; in addition, the implantation detection method of the embodiment has low power consumption of the implantation detection circuit, can detect each pacing pulse in real time before judging the implantation state, can specifically detect whether the cardiac pacing system is in the implantation state after the electrode lead is placed for 1s (about one pacing pulse), and has high real-time performance. The implantation detection circuit 100 can adopt a full-on-chip integrated implementation mode, does not need a complex analog-to-digital converter, does not need to add extra off-chip discrete components, reduces the cost, and can reduce the design complexity and reliability of a hybrid circuit board.
The first switch element S1, the second switch element S2, the third switch element S3, and the fourth switch element S4 in the implantation detection circuit 100 may be selected from a Transistor, a MOSFET (Metal-Oxide-semiconductor field-Effect Transistor), a JFET (junction field-Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), and other switch elements, that is, at least one of the first switch element, the second switch element, the third switch element, and the fourth switch element may be implemented by one of a Transistor, a MOSFET, a JFET, and an IGBT, on one hand, automatic control may be conveniently implemented, and on the other hand, all switches of the implantation detection circuit 100 may be fabricated on the same chip through an integrated circuit process, so that parasitic capacitance is small and control is convenient. In some embodiments, one or more of the first switching element S1, the second switching element S2, the third switching element S3, and the fourth switching element S4 may also employ a passive switching device, such as a magnetic control switch, which does not need to consume electric energy in a non-operating state, which helps to reduce power consumption of the circuit. It should be noted that although the first switching element S1, the second switching element S2, the third switching element S3, and the fourth switching element S4 are provided as switches in this embodiment, the detection capacitor Cs in this embodiment keeps the charge unchanged after the first voltage sampling until the next initialization, and therefore, factors such as parasitic capacitance that easily consume the charge amount on the detection capacitor Cs should be avoided in selecting the switching elements.
In practice, in a pacemaker implantation operation, a dual-chamber implantation may be performed in an atrium and a ventricle, or only a single-chamber implantation of the atrium or the ventricle may be performed, and a cardiac pacing system may include more than one electrode lead, in order to detect whether a tip (i.e., a pacing electrode) of each electrode lead contacts a myocardium, i.e., to detect an implantation state of the cardiac pacing system, more than one set of the implantation detection circuits may be used for detection, and for each set of the implantation detection circuits, information about whether the cardiac pacing system forms a loop at each electrode position may be obtained by detecting a change in a voltage difference before and after a corresponding pacing pulse discharge.
The step of performing implant detection using the implant detection circuitry described above is preferably performed in an automated fashion. Fig. 4 is a flow chart of computer instructions executed by the implant detection circuitry for one pacing pulse cycle in accordance with one embodiment of the present invention. Referring to fig. 2 to 4, the present embodiment further includes a readable storage medium, on which computer instructions are stored, and when the computer instructions are executed by a processor, the implantation detection method may be executed by the implantation detection circuit, which specifically includes the following steps:
the first step is as follows: in a first time period before sending of a pacing pulse, only the first switching element S1 and the second switching element S2 are switched on, and the first end and the second end of the detection capacitor Cs are in short circuit;
the second step: the voltage of the second end of the pacing capacitor is the pre-discharge voltage V of the pacing pulse in a second time period before the pacing pulse is sent H1 Only the second switching element S2 and the third switching element S3 are turned on, and the voltage V before discharge is sampled H1 Making the voltage of the first end of the detection capacitor Cs be V H1 The voltage of the second end is 0;
the third step: in a third time period after the pacing pulse is sent, the voltage of the second end of the pacing capacitor is the discharged voltage V of the pacing pulse H2 Switching on only the fourth switching element S4, sampling the discharged voltage V H2 So that the detection capacitance CsThe voltage of the first terminal is V H2 The voltage at the second terminal is- (V) H1 -V H2 ) That is, the voltage at the second end of the detection capacitor Cs is the voltage V before discharge H1 And said post-discharge voltage V H2 The inverse value of the voltage difference of (d);
the fourth step: and comparing whether the voltage difference is greater than a set threshold voltage by using a voltage comparison module 120, and outputting a comparison result, wherein when the voltage difference is greater than the threshold voltage, the cardiac pacing system is in an implanted state, otherwise, the cardiac pacing system is in a non-implanted state and enters the next pacing pulse period to circularly execute the steps.
In this embodiment, the sending frequency of the pacing pulse may be a basic frequency of the cardiac pacemaker, so that the length of each pacing pulse cycle and the sending time of each pacing pulse signal may be determined, and further, the implantation detection circuit 100 may be controlled to perform the above steps in a part of or all of the pacing pulse cycles before detection through the implantation state.
The readable storage medium provided by the invention, when the computer instructions stored thereon are executed by the processor, can control the implantation detection circuit to sequentially execute the implantation detection method in one pacing pulse period, and output information whether the cardiac pacing system is in an implantation state. The computer instruction in the readable storage medium realizes automatic implantation detection of the pacemaker by using the implantation detection circuit with a simple structure, has high detection precision and low power consumption, and simultaneously has lower current of the circuit, thereby being beneficial to prolonging the service life of the pacemaker; in addition, the automatic implantation detection enables the detection to be efficient, and the operation burden and operation time of a doctor can be reduced.
The present embodiments also include an implant detection device for a cardiac pacing system. The implant detection device includes the implant detection circuit 100 described above and/or the readable storage medium described above. That is, the implantation detection apparatus includes at least one of the implantation detection circuit 100 and the readable storage medium to detect whether the cardiac pacing system and the myocardium form a loop in an implantation state. The readable storage medium and the implantation detection circuit controlled by the readable storage medium can be integrated in the same chip so as to simplify the structure and reduce the power consumption.
The implantation detection device can be used as a part of a pacemaker of a cardiac pacing system to perform automatic implantation detection through the implantation detection circuit and/or the readable storage medium, and the implantation detection device can also be separately arranged and used for implantation detection. The detection result of the implantation detection device can be fed back to a control module of the cardiac pacing system or can be notified to a doctor in a text or prompt tone mode and the like so as to control the cardiac pacing system to execute operation modes such as switching. The implantation detection device is used for detecting the implantation state of the cardiac pacing system, and is beneficial to improving the operation efficiency.
This embodiment additionally includes a cardiac pacing system including the implant detection circuit described above. By utilizing the implantation detection circuit, the manufacturer of the cardiac pacing system can simulate the functions of a pacemaker and a pacing electrode, and in addition, when a doctor carries out a pacemaker implantation operation, the implantation detection circuit can be utilized to obtain the information about whether the electrode correctly contacts with the cardiac muscle and the implantation state of the cardiac pacing system, so that the detection efficiency is improved. After the implantation detection is finished, the pacemaker is switched to a normal pacing working mode, and at the moment, the implantation detection circuit can be set to be forbidden according to needs without increasing the power consumption of the pacemaker.
In different circuit implementations, the structures of the detection capacitor, the switching device and the voltage comparison circuit of the present invention may be different, but it should be understood that circuits formed by changing their implementations without departing from the technical principles of the present invention also belong to the protection scope of the present invention.
The above description is only for the purpose of describing the preferred embodiments of the present invention and is not intended to limit the scope of the claims of the present invention, and any person skilled in the art can make possible the variations and modifications of the technical solutions of the present invention using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention, and therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention belong to the protection scope of the technical solutions of the present invention.
Claims (11)
1. An implant detection circuit for a cardiac pacing system, the implant detection circuit comprising:
the detection module is electrically connected with a pacing circuit of the cardiac pacing system and used for successively sampling the voltage before and after discharge of pacing pulses delivered by the pacing circuit and outputting voltage difference signals before and after discharge of the pacing pulses, the detection module comprises a detection capacitor, and the detection capacitor is configured to: before the pace pulse is sent, the voltage of the first end of the detection capacitor is the voltage before discharging and the voltage of the second end of the detection capacitor is 0, and after the pace pulse is sent, the voltage of the first end of the detection capacitor is the voltage after discharging and the voltage difference between the voltage after discharging and the voltage before discharging; and
and the voltage comparison module is electrically connected with the detection module and used for comparing the voltage difference before and after the pacing pulse discharges with a preset threshold voltage and outputting a comparison result, wherein when the voltage difference is greater than the threshold voltage, the cardiac pacing system is in an implanted state, otherwise, the cardiac pacing system is in a non-implanted state, the voltage comparison module is also connected with a control module of the cardiac pacing system, and the voltage comparison module transmits the comparison result to the control module of the cardiac pacing system.
2. The implant detection circuit of claim 1, wherein the detection module is coupled to a pacing capacitor of the pacing circuit, the detection module detecting a pre-discharge voltage and a post-discharge voltage, respectively, of the pacing capacitor prior to discharge of a pacing pulse to sample the pre-discharge voltage and the post-discharge voltage, respectively, of the pacing pulse delivered by the pacing circuit.
3. The implant detection circuit of claim 2, wherein the detection module comprises a first switching element, a second switching element, a third switching element, and a fourth switching element, wherein the first switching element is connected between the first terminal of the detection capacitor and ground, the second switching element is connected between the second terminal of the detection capacitor and ground, the third switching element and the fourth switching element are connected in parallel between the first terminal of the detection capacitor and the second terminal of the pacing capacitor, the first terminal of the pacing capacitor is grounded, and the second terminal of the detection capacitor is connected to the voltage comparison module.
4. The implant detection circuit of claim 3, wherein the voltage comparison module comprises a voltage comparator, a first input of the voltage comparator is connected to the second terminal of the detection capacitor, and a second input of the voltage comparator is connected to the threshold voltage.
5. The implant detection circuit of claim 3, wherein the detection capacitance is an on-chip capacitor.
6. The implant detection circuit of claim 5, wherein the implant detection circuit is of a fully on-chip integrated design.
7. The implant detection circuit of claim 3, wherein at least one of the first switching element, the second switching element, the third switching element, and the fourth switching element is one of a transistor, a MOSFET, a JFET, and an IGBT.
8. An implant detection method for a cardiac pacing system, using an implant detection circuit according to any one of claims 3 to 7, comprising the following steps performed in sequence during a pacing pulse delivery cycle:
in a first time period before sending of the pacing pulse, only the first switching element and the second switching element are switched on, and the first end and the second end of the detection capacitor are short-circuited;
in a second time period before sending the pacing pulse, the voltage of the second end of the pacing capacitor is the voltage before discharging of the pacing pulse, only the second switching element and the third switching element are switched on, the voltage before discharging is sampled, the voltage of the first end of the detection capacitor is the voltage before discharging, and the voltage of the second end of the detection capacitor is 0;
in a third time period after the pacing pulse is sent, the voltage of the second end of the pacing capacitor is the voltage of the pacing pulse after discharge, only the fourth switching element is switched on, the voltage after discharge is sampled, the voltage of the first end of the detection capacitor is the voltage after discharge, and the voltage of the second end of the detection capacitor is the inverse value of the voltage difference between the voltage before discharge and the voltage after discharge; and
and comparing whether the voltage difference is greater than a preset threshold voltage by using a voltage comparison module, wherein when the voltage difference is greater than the threshold voltage, the cardiac pacing system is in an implanted state, and otherwise, the cardiac pacing system is in a non-implanted state.
9. A readable storage medium having stored thereon computer instructions which, when executed by a processor, perform the implant detection method of claim 8.
10. An implant detection device for a cardiac pacing system, wherein the implant detection device comprises an implant detection circuit according to any one of claims 1 to 7 and/or a readable storage medium according to claim 9.
11. A cardiac pacing system comprising an implant detection circuit as claimed in any one of claims 1 to 7.
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