CN109589499B - Cardiac pacing system - Google Patents

Abstract

The invention provides a cardiac pacing system, which comprises a sensing module, a pacing module and a control module; under the condition of normal atrioventricular conduction, the control module controls the cardiac pacing system to work in a first mode and detects whether atrioventricular conduction block occurs; by sensing and comparing the PR interval and the absence of ventricular events, various atrioventricular conduction block events can be accurately judged; when the atrioventricular conduction block occurs, the control module controls the work of the cardiac pacing system to be switched into the second mode, so that the cardiac pacemaker can work in a proper mode in time, and the cardiac pacemaker can provide proper AV time sequence and ventricular rhythm.

Description

Cardiac pacing system

Technical Field

The invention relates to the field of medical instruments, in particular to a cardiac pacing system.

Background

A cardiac pacemaker (cardiac pacemaker) is an electronic therapeutic apparatus implanted in a body, which delivers electric pulses powered by a battery through a pulse generator, and stimulates the cardiac muscle contacted by an electrode through conduction of a lead electrode, so that the heart is excited and contracted, thereby achieving the purpose of treating heart dysfunction caused by certain arrhythmia. Cardiac pacemakers may be generally classified into single chamber pacemakers and dual chamber pacemakers. A single chamber pacemaker can sense and/or pace the atrium or ventricle. The AAI mode of a conventional pacemaker provides only basic atrial timing and is suitable for patients with sinus/atrial dysfunction. However, for patients with concurrent AVB (atrioventricular Block), AAI cannot provide AV (a is an abbreviation for Atria-Atria and V is an abbreviation for ventricles) timing and proper Ventricular rhythm to meet the needs of such patients, and therefore, cardiac pacemakers operate in other modes while AVB is occurring.

AVB (atrioventricular block) refers to abnormal conduction of electrical activation between atria and ventricles during electrical conduction in the heart, which can lead to arrhythmia, resulting in abnormal contraction and pumping of the heart. Atrioventricular block may occur at various sites such as the atrioventricular node, the bundle of his, and the bundle branch. Currently, pacemakers classify AVB differently depending on the degree of block, but the current pacemakers do not detect AVB accurately, resulting in the pacemakers not working in a proper mode in time for patients with symptoms of AVB and thus not providing proper AV timing and proper ventricular rhythm.

Disclosure of Invention

The invention aims to provide a cardiac pacing system to solve the problems that the existing cardiac pacemaker is inaccurate in AVB detection, not physiological in the detection process, incapable of working in a proper mode in time and the like.

In order to solve the technical problem, the invention provides a cardiac pacing system, which comprises a control module, a sensing module and a pacing module; under the condition of normal atrioventricular conduction, the control module controls the cardiac pacing system to work in a first mode, and under the condition of normal atrioventricular conduction, the control module detects whether atrioventricular block occurs;

the atrioventricular conduction block comprises a first type of atrioventricular conduction block or a second type of atrioventricular conduction block; the first type of atrioventricular block is: the PR interval exceeds a first set value in each of S successive cardiac cycles; the second type of atrioventricular block is: when the sensing module senses that in two consecutive cardiac cycles, a ventricular event is absent in the first cardiac cycle and a ventricular event is absent when the second cardiac cycle reaches the first set value; wherein S is a natural number greater than 2;

the control module controls the cardiac pacing system to switch to a second mode of operation when the control module detects an atrioventricular conduction block.

Optionally, in the case that the second type of atrioventricular conduction block is detected, the control module controls the pacing module to deliver electrical stimulation to the ventricles when the second cardiac cycle reaches the first set point.

Optionally, the first setting value is a sum of an average value of PR intervals and the first increment value in R consecutive cardiac cycles before the current cardiac cycle, or a sum of a maximum value of PR intervals and the first increment value, where R is a natural number greater than 2.

Optionally, when an atrioventricular conduction block occurs, the control module periodically performs atrioventricular conduction recovery detection, and when the atrioventricular conduction recovers to be normal, the control module controls the cardiac pacing system to switch to the first mode operation.

Optionally, the control module performs atrioventricular conduction recovery detection via AV interval extension; the AV interval extension is: taking the sum of the atrioventricular interval and the second increment value as an extended atrioventricular interval;

in detecting whether atrioventricular conduction is restored, the control module controls the cardiac pacing system to operate in the second mode at the extended atrioventricular interval; in the process of detecting whether the atrioventricular conduction is recovered, if continuous T ventricular sensing events occur in continuous Q cardiac cycles, the atrioventricular conduction is judged to be recovered to be normal; if continuous T ventricular sense events do not occur in continuous Q cardiac cycles, judging that the atrioventricular block continues to exist, and controlling the cardiac pacing system to recover to work in the second mode at the atrioventricular interval by the control module; wherein T is a natural number greater than 2, and Q is a natural number greater than T.

Optionally, during the operation of the cardiac pacing system in the second mode, if the sensing module senses that ventricular sensed events occur within atrioventricular intervals of consecutive U cardiac cycles, the control module determines that atrioventricular conduction is restored to normal, and controls the cardiac pacing system to switch to the first mode; wherein U is a natural number greater than 2.

Optionally, when the control module determines that the atrioventricular conduction is restored to normal and controls the cardiac pacing system to switch to the first mode to work, the sum of the maximum value of the PR conduction time and the third increment value in the W cardiac cycles before the cardiac pacing system is switched to the first mode to work is taken as the first set value; wherein W is a natural number greater than 2.

Optionally, the first mode is configured such that the control module controls the pacing module to deliver electrical stimulation to the atrium when the sensing module senses the absence of an atrial event; the pacing module follows the sensing module to sense the atrial event at an atrioventricular interval according to the control of the control module, or the pacing module sends electrical stimulation to the atrium, and if the ventricular event is absent in the atrioventricular interval, the pacing module does not send pacing electrical stimulation to the ventricle and marks the atrial event as a virtual pacing event.

Optionally, the second mode is configured to: and the pacing module follows the sensing module to sense the atrial event or the pacing module to deliver the electrical stimulation to the atrium at an atrioventricular interval according to the control of the control module, and delivers the electrical stimulation to the atrium if the ventricular event is absent in the atrioventricular interval.

Optionally, the atrioventricular conduction block further comprises a third type of atrioventricular conduction block, the third type of atrioventricular conduction block being: not less than M ventricular events are absent in N consecutive cardiac cycles, where M is a natural number greater than 2 and N is a natural number greater than M.

In summary, in the cardiac pacing system provided by the present invention, the cardiac pacing system includes a sensing module, a pacing module, and a control module; under the condition of normal atrioventricular conduction, the control module controls the cardiac pacing system to work in a first mode and detects whether atrioventricular conduction block occurs; by sensing and comparing the PR interval and the absence of ventricular events, various atrioventricular block events can be accurately and physiologically judged; when the atrioventricular conduction block occurs, the control module controls the work of the cardiac pacing system to be switched into the second mode, so that the cardiac pacemaker can work in a proper mode in time, and the cardiac pacemaker can provide proper AV time sequence and ventricular rhythm.

Drawings

It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. Wherein:

FIG. 1 is a schematic diagram of a workflow of a cardiac pacing system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a cardiac pacing system according to an embodiment of the present invention in which ventricular events are absent from two consecutive cardiac cycles;

FIG. 3 is a schematic diagram of a cardiac pacing system according to an embodiment of the present invention in which no less than M ventricular events are absent for N consecutive cardiac cycles, where N is 16 and M is 4;

FIG. 4 is a schematic diagram of a cardiac pacing system according to an embodiment of the present invention in which S consecutive PR intervals exceed a first set point, where S is 8;

FIG. 5 is a diagram illustrating a cardiac pacing system seeking atrioventricular conduction restoration through AV interval expansion according to an embodiment of the present invention;

FIG. 6 is a diagram illustrating a cardiac pacing system according to an embodiment of the present invention recovering from atrioventricular conduction without searching for AV interval extension;

fig. 7 is a block diagram of hardware components of a cardiac pacing system according to an embodiment of the present invention.

In the drawings:

01-a main control unit; 02-a time control unit; 03. 04-data/information interaction interface; 05-a pacing module; 06-a perception module; 07-a program control unit; 08-a control module; 09-digital/analog module.

Detailed Description

To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be noted that the drawings are in greatly simplified form and are not to scale, but are merely intended to facilitate and clarify the explanation of the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.

As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise, the term "front" or "back" generally referring to front and back in chronological order.

Dual chamber pacemakers typically sense and/or pace the atrium and also the ventricle. The traditional double-cavity pacemaker can generally work in double-cavity pacing modes such as DDD, DDI, DOO, ODO, DVI, VDD and the like according to user settings. The coding significance of each of the above modes of operation can be seen in the NASPE/BPEG pacemaker identification code, where NASPE stands for North American pacing and electrophysiology society and BPEG stands for British pacing and electrophysiology organization. See table 1 below for details:

table 1: NASPE/BPEG pacemaker identification codes

The first three identification codes are typically used to identify the pacing site, sensing site, and response pattern to sensing (P-wave, R-wave, or both) of the pacemaker. According to the NASPE/BPEG pacemaker identification code, the DDD pacing mode is also called atrioventricular full-function pacing, and is a pacing mode with atrioventricular dual-chamber sequential pacing, atrioventricular dual sensing, triggering and inhibiting dual responses. DDD pacing mode is the most commonly used pacing mode, and can provide AV synchronization as well as pacing guarantees. The DDD-type synchronous dual-chamber pacing mode may sense or pace both the atria and ventricles, while ventricular pacing may follow the atrial event at an atrioventricular interval, thereby achieving atrioventricular synchronization. The use of DDD is very effective for patients with complete atrioventricular block. However, for patients with incomplete block, the continuous operation of the pacemaker in the DDD operation mode may increase the right ventricular pacing, which is likely to cause adverse reactions such as heart failure.

Referring to fig. 1 to 7, fig. 1 is a schematic diagram illustrating a working process of a cardiac pacing system according to an embodiment of the present invention, figure 2 is a schematic diagram of a cardiac pacing system according to an embodiment of the present invention in which ventricular events are absent from two consecutive cardiac cycles, figure 3 is a schematic diagram of a cardiac pacing system according to an embodiment of the present invention in which no less than M ventricular events are absent for N consecutive cardiac cycles, figure 4 is a schematic diagram of a cardiac pacing system according to an embodiment of the present invention in which consecutive S PR intervals exceed a first set point, figure 5 is a schematic diagram of a cardiac pacing system according to an embodiment of the present invention searching for atrioventricular conduction restoration through AV interval extension, fig. 6 is a schematic diagram of the cardiac pacing system according to an embodiment of the present invention recovering from atrioventricular conduction without searching through AV interval extension, and fig. 7 is a structural diagram of hardware of the cardiac pacing system according to an embodiment of the present invention. Wherein arrows to the right in fig. 2 to 6 each indicate a direction along the passage of time.

An embodiment of the present invention provides a cardiac pacing system, including: the digital/analog module is in signal connection with the control module through a data/information interaction interface; the digital/analog module comprises a sensing module and a pacing module. The sensing module is configured to Sense cardiac events including atrial events (As-Atria Sense) and Ventricular events (Vs-Venturiular Sense); the pacing module is used to deliver electrical stimulation to the Atria (Atria) or ventricles (ventricles).

When the sensing module senses the absence of the atrial event (As), the control module controls the pacing module to deliver electrical stimulation (AP-Atria Pace) to the atrium; wherein the atrial event (As) is an atrial sensing event, particularly an atrial activation event, and the ventricular event (Vs) is a ventricular sensing event, particularly a ventricular activation event, both occurrences of which are sensed by the sensing module.

When atrioventricular conduction is normal, the control module controls the cardiac pacing system to work in a first mode (preferably an ADD mode), the pacing module follows the sensing module to sense the atrial events (As) at an atrioventricular interval according to the control of the control module, or after the pacing module delivers electrical stimulation (AP) to the atrium, if Ventricular events are absent in the atrioventricular interval and the atrioventricular interval is ended, the pacing module does not deliver pacing electrical stimulation to the ventricle and marks the atrial event As a virtual Ventricular pacing event (virtual Ventricular Pace, abbreviated As VVP); i.e., the subsequent escape intervals are calculated only from the ventricular pacing time points, without actually delivering the true electrical stimulation. In this manner, ventricular pacing can be minimized, and unnecessary ventricular pacing is avoided as much as possible. Meanwhile, in case of normal atrioventricular conduction, the control module also detects whether atrioventricular block occurs.

When atrioventricular block (AVB) occurs, the control module controls the cardiac pacing system to switch to a second mode of operation (preferably, DDD mode), and the pacing module follows the sensing module at an atrioventricular interval to sense the atrial event (As) according to the control of the control module, or delivers electrical stimulation to the atrium (VP-Ventricular Pace) if the Ventricular event (Vs) is absent at the atrioventricular interval after the pacing module delivers electrical stimulation to the atrium (AP-Atria Pace);

wherein the atrioventricular block (AVB) comprises at least one of:

atrioventricular block of the first type: the PR interval exceeds a first set value in each of S successive cardiac cycles;

the second category of atrioventricular block: when the sensing module senses that in two consecutive cardiac cycles, a ventricular event is absent in the first cardiac cycle and a ventricular event is absent when the second cardiac cycle reaches the first set value; wherein S is a natural number greater than 2;

atrioventricular block of the third type: not less than M ventricular events are absent in N consecutive cardiac cycles, where M is a natural number greater than 2 and N is a natural number greater than M.

The first setting may be set by real-time calculation based on the value of the continuously monitored PR interval. In other embodiments, the first mode is not limited to the ADD mode, and may be other suitable operating modes of the pacemaker. Similarly, the second mode is not limited to the DDD mode, and may be other suitable operating modes of the cardiac pacemaker.

Preferably, as shown in fig. 2, when the sensing module senses that a ventricular event (Vs) is absent in a first cardiac cycle and sensing continues until the first set value is reached in a second cardiac cycle in two consecutive cardiac cycles, the ventricular event (Vs) is also absent, and the control module controls the pacing module to deliver electrical stimulation (VP) to the ventricles. In practice, it is generally considered that the long PR interval is also a feature of AVB, so that the ventricular download detection window in the first cardiac cycle is the length of the AA interval (the interval between the current atrial event and the previous atrial event), and if there is no ventricular download event in the first detection window, the next ventricular download detection window is adjusted to the first set value (i.e., the standard detection value of the long PR interval). By this method, no descending atrioventricular conduction block is detected in two consecutive cardiac cycles, which is more physiological than the mode that the ventricular descending detection windows in the two cardiac cycles are AA intervals. That is, a certain degree of waiting occurs during the second cardiac cycle until the first set point is reached, and ventricular pacing is not delivered, thereby maximizing the detection of AVB events and minimizing the delivery of ventricular pacing. And under the condition that the AVB event really occurs, the safe pacing can be ensured to be delivered, and the adverse condition of losing ventricular pacing is avoided.

In this embodiment, when atrioventricular conduction is normal, the cardiac pacing system operates in a first mode (ADD mode) to not deliver electrical stimulation to the ventricles and to detect whether atrioventricular block occurs, and when atrioventricular block (AVB) occurs, the cardiac pacing system may physiologically switch to a second mode (DDD mode) to deliver electrical stimulation (VP) to the ventricles. The mode conversion process becomes more important in physiology because the ADD mode and the DDD mode adopt the same atrioventricular interval and have the same set of operation mechanism, seamless conversion on time sequence can be realized during mode conversion, the mode conversion is quicker and more physiological, the cardiac pacemaker can work in a proper mode in time, and the cardiac pacemaker can provide proper AV time sequence and ventricular rhythm. In addition, by sensing and comparing the absence of PR intervals and ventricular events, various atrioventricular conduction block events can be accurately determined, thereby enabling more reliable and more physiological pacing of the heart.

In particular, the DDD pacing mode provides atrioventricular synchronization and pacing assurance for patients when atrioventricular block (AVB) occurs, and the DDD synchronous dual-chamber pacing mode senses or paces both atria and ventricles while ventricular pacing follows an atrial event at an atrioventricular interval, thereby achieving atrioventricular synchronization. While the ADD mode is an AAI mode with ventricular sensing, all timing and behavior in the ADD mode is equivalent to DDD, but in this mode no real ventricular pacing electrical stimulation (VP) is delivered to the ventricle, but only the subsequent escape intervals, labeled as virtual ventricular pacing events (VVPs), are calculated from the ventricular pacing time points. The workflow for the ADD pacing mode may also be implemented with reference to a workflow using the DDD pacing mode. The processing after sensing an atrial event and after sensing a ventricular event is completely equivalent to the workflow of the DDD pacing mode, but the processing during pacing signal delivery adds some selection paths on the basis of the DDD mode processing, and in particular, refer to fig. 1, which shows the workflow of the cardiac pacing system provided by this embodiment, and specifically includes:

step 1: expiration between escapes; in practice, the cardiac pacing system begins a cycle of pacing delivery at the expiration of the escape interval;

step 2: judging whether the next pacing cavity is a ventricle; because a cardiac cycle is divided into an atrial cycle and a ventricular cycle, the current chamber needing pacing needs to be judged, if the cardiac cycle is the atrial cycle, thestep 3 is carried out, and if the cardiac cycle is the ventricular cycle, the step 4 is carried out;

and step 3: delivering Atrial Pacing (AP);

and 4, step 4: determining whether a real Ventricular Pace (VP) needs to be delivered; judging whether real Ventricular Pacing (VP) needs to be delivered according to the control of the control module, if the real ventricular pacing does not need to be delivered, enteringstep 5, and if the real ventricular pacing needs to be delivered, entering step 6;

and 5: marking as a virtual ventricular pacing event (VVP) and resetting the VA interval;

step 6: delivering true Ventricular Pacing (VP);

and 7: and finishing the pacing and delivering work of one cycle.

In a cardiac cycle, when the sensing module senses the absence of the atrial event (As), the control module determines that pacing for the atrium is needed, and the operating path of the cardiac pacing system is As follows: 1- >2- >3- > 7; where the heart is actually being acted upon,step 3, the pacing module delivers electrical stimulation (AP) to the atrium. This completes the pacing of the atrium. Furthermore, when atrioventricular conduction is normal, the cardiac pacing system operates in the ADD mode by: 1- >2- >4- >5- > 7; during this procedure, the cardiac pacing system does not deliver electrical stimulation to the ventricle, the cardiac pacing system marks the occurrence of a virtual ventricular pacing event (VVP), and resets the VA (V is an abbreviation for ventricular, a is an abbreviation for Atria, and the VV interval refers to the interval from an atrial event to a ventricular event) interval, which is not actually delivering electrical stimulation to the ventricle in this mode of operation. And when an atrioventricular block (AVB) occurs, the operational pathways of the cardiac pacing system are: 1- >2- >4- >6- > 7; it can be seen that this process is comparable to the ADD mode described above, with only step 6 replacingstep 5, while the other parts are identical, and since the ADD mode and the DDD mode have the same atrioventricular interval and AV timing, the cardiac pacing system can switch seamlessly to the DDD mode instantaneously. The cardiac pacing system works in an ADD mode under the condition of normal atrioventricular conduction, monitors the atrioventricular conduction condition at any moment through the sensing module, and immediately switches to a DDD mode to work once atrioventricular block occurs. So configured, compared to existing cardiac pacemakers, one aspect can provide sensed ventricular events (Vs) and provide an AV timing reference for the pacing system, which can improve hemodynamics. On the other hand, the whole work flow is based on the behavior mode of the DDD, and only virtual ventricular pacing needs to be converted into real electrical stimulation when the ADD mode is switched to the DDD mode, so that the conversion transition process can be more physiological and faster, and in addition, the work flow has inherent flexibility in the aspect of function expansion of a cardiac pacing system, particularly expansion under the influence of ventricular events (Vs). In yet another aspect, by distinguishing and comparing missing instances of ventricular events (Vs), or by comparing PR intervals, different degrees of AVB events can be distinguished, i.e., different degrees of AVB events of the first to third classes can be detected, which can more accurately determine the occurrence of AVB events and the degree of AVB events than prior art techniques.

Preferably, the cardiac pacing system provided by this embodiment can implement the interconversion between ADD and DDD modes by changing the "VP function flag". Specifically, different working modes may be implemented by using a combination of bit pattern coded, for example, the bit pattern coded may be as shown in table 2 below (the following schemes such as sorting and naming are merely examples and are not limited):

table 2: bit pattern coded

Wherein:

AS: whether the current mode has an atrial sensing function, 0 is absent and 1 is present;

VS: whether the current mode has a ventricular sensing function or not, wherein 0 is absent and 1 is present;

and (2) DS: whether the current mode is a double-cavity mode or not, wherein 0 is a single cavity and 1 is a double cavity;

AP: whether the current mode has an atrial pacing function, 0 is absent, and 1 is present;

VP: whether the current mode has a ventricular pacing function or not, wherein 0 is absent and 1 is present;

I/T: whether the current mode has a trigger function or not, wherein 0 is absent and 1 is present;

for example, the bit pattern for the AAI mode is 00001001, which means that the AAI mode has atrial sensing and atrial pacing, and the bit pattern for the other modes has similar meaning. The mode switching of uninterrupted time sequence can be realized under the unified functional module architecture, the time point of the mode switching can be accurately controlled, and the application range of the modes before and after the switching can be very flexible. For example, when the mode is switched from the AAI mode to the VVI mode, the bit pattern only needs to be switched from 00001001 to 00010010, and the AV conduction interval is started after the next atrial event to trigger the first ventricular pacing after the mode switching, and the pacing timing does not need to be reset in the whole switching process, so that the mode switching with uninterrupted timing is realized; the mode switching time point is controlled after the current time sequence is set, and the mode switching is flexible and physiological through a transitional AV time sequence. Therefore, only the "VP" bit needs to be modified when the ADD and DDD modes are switched, so that seamless fast switching between the two modes can be realized.

As shown in fig. 3, no less than M of the ventricular events (Vs) are absent for N consecutive cardiac cycles, where M is a natural number greater than 2 and N is a natural number greater than M, an AVB event of a third type may be identified as occurring. The values of N and M can be set according to different monitoring standards, for example, N is 16, and M is 4. Upon the absence of 4 ventricular events (Vs) in 16 cardiac cycles, it is assumed that AV interval shedding has occurred, at which point the cardiac pacing system transitions to DDD mode operation, providing ventricular pacing and establishing physiological AV synchrony to enhance the heart's pumping ability. It is to be understood that the 16 cardiac cycles are rolling statistical cycles, i.e. when sensing one cardiac cycle, the statistics are performed for the first 15 cardiac cycles. When the next cardiac cycle is sensed, the sensing result of the first cardiac cycle in the first 15 cardiac cycles is rejected, that is, each time a result of one cardiac cycle is sensed, the sensing result of the 16 th cardiac cycle before the first cardiac cycle is rejected in a rolling manner, which is a rolling statistical cycle. During the rolling statistical period, AV interval shedding is considered to have occurred once a missing 4 ventricular events (Vs) are counted. Of course, the values of N and M are not limited to 16 and 4, for example, N is 12, and M is 3; or N is 20, M is 5, etc., and different settings can be made according to the actual condition of the patient and the experience of the doctor.

Preferably, the first set value is the sum of the average value of PR intervals and the first increment value in R consecutive cardiac cycles before the current cardiac cycle, or the sum of the maximum value of PR intervals and the first increment value, wherein R is a natural number greater than 2. Clinically, too long of the patient's own PR interval is also considered a pathological AV conduction, and can be classified as a range of atrioventricular conduction blocks. A long PR interval event (AVB of a first type) may be identified when the perception module senses that consecutive S PR intervals all exceed a first set value. However, in the prior art, the criterion for determining that the PR interval is too long (i.e. the first setting value) is generally set by a doctor during program control, and cannot be well adapted to the situation that the heart rate changes greatly. In patients with large variations in heart rate, the PR interval criteria may be improperly defined, for example, when the PR interval is physiologically extended, the PR interval criteria may be too small, which may result in incorrect determination of a normal PR interval as too long, resulting in excessive delivery of ventricular pacing. In the present invention, the first set value can be dynamically calculated according to the detected real-time PR propagation time. Therefore, the first setting value can flexibly adapt to different heart rhythm change conditions. For example, when the cardiac pacing system is operating in an ADD mode, the sensing module continuously monitors the real-time PR conduction time, calculates based on an average or maximum of a plurality of PR intervals over R successive cardiac cycles prior to the current cardiac cycle, and increases the first incremental value as a margin to increase the detected threshold. Both the R and the first increment value can be set differently according to the actual condition of the patient and the experience judgment of the doctor, such as R is 16, or R is 8; the first increment value may take, for example, 50ms or the like. Therefore, the proper PR interval standard value can be obtained dynamically according to the change condition of the heart rhythm of the patient, so that the judgment of the too long PR interval is more accurate, and the unnecessary ventricular pacing can be further reduced. In other embodiments, the plurality of PR intervals may also be maximized every Q cardiac cycles, followed by an increase of the first increment value by a margin; if Q can be 16, the first increment value can be 50ms, and every 16 cardiac cycles, the maximum value of the monitored PR interval is taken as the basis, plus 50ms of the first increment value, as the PR interval standard value (i.e., the first set value). The PR interval standard value calculated in real time can adapt to the change of the heart rhythm in various degrees in real time, can accurately detect the AVB (first-class AVB) and adjust the heart rhythm to a normal state.

As shown in fig. 4, the PR interval exceeds the first set value for each of S consecutive cardiac cycles; wherein S is a natural number greater than 1. The value of S here can be set differently according to the actual condition of the patient and the judgment of the experience of the doctor, for example, S is 8, at this time, if the sensing module senses that 8 PR intervals in 8 continuous cardiac cycles all exceed the first set value, that is, long PR intervals in 8 continuous cardiac cycles all occur, at this time, it is very likely that a first-class AVB occurs, at this time, the cardiac pacing system judges that an atrioventricular conduction block occurs and switches to the DDD mode to operate.

Further, when the atrioventricular conduction block occurs and the cardiac pacing system works in the second mode (DDD mode), the control module also controls the sensing module and the pacing module to periodically perform atrioventricular conduction recovery detection, and when the atrioventricular conduction recovers to be normal, the control module controls the cardiac pacing system to switch to work in the first mode (ADD mode). In some patients, atrioventricular block is often a sporadic event because it does not occur continuously, and if the cardiac pacing system detects an atrioventricular block event and switches from ADD mode to DDD mode, an exit mechanism needs to be set to minimize ventricular pacing; that is, when it is detected that atrioventricular conduction is restored to normal, the cardiac pacing system can exit from the DDD mode and resume operation in the ADD mode to reduce delivery of ventricular pacing. Thus, the control module periodically performs atrioventricular conduction recovery tests. The period may be set according to the condition of the patient, such as every minute or every hour.

As shown in fig. 5, the control module preferably performs atrioventricular conduction restoration detection by AV interval extension (Atria ventural delay); the AV interval extension includes: using a sum of a standard atrioventricular interval (such As a normal atrioventricular interval in an ADD mode or a DDD mode) and a second increment value As an extended atrioventricular interval, said control module controlling said sensing module to sense the presence or absence of a ventricular sense event (Vs) during said extended atrioventricular interval following said sensing module sensing said atrial event (As) or said pacing module delivering an electrical stimulus (AP) to said atrium, and delivering an electrical stimulus (VP) to said ventricle if a ventricular sense event (Vs) is absent during said extended atrioventricular interval; if T continuous ventricular sense events (Vs) occur in Q continuous cardiac cycles, judging that the atrioventricular conduction is recovered to be normal, and switching the cardiac pacing system to an ADD mode to work; if there are no T consecutive ventricular sense events (Vs) occurring in Q consecutive cardiac cycles, determining that atrioventricular conduction is not restored, the atrioventricular conduction block continues to exist, the cardiac pacing system continues to operate in the DDD mode, and the control module resumes operation at the standard atrioventricular interval (i.e., the extended atrioventricular interval minus the second increment value returns to the atrioventricular interval prior to the AV interval being extended); wherein T is a natural number greater than 2, and Q is a natural number greater than T. Since the pacing signal is delivered to the ventricle according to the AV timing in the DDD mode, generally, even if an autonomous ventricular event (Vs) occurs in the heart, the occurrence of the autonomous ventricular event is often later than that of the ventricular pacing, that is, the Vs is often later than the VP, so that the detection of a ventricular download event (Vs) is easily masked by the ventricular pacing, and thus, if the heart normally operates in the normal DDD mode, the autonomous ventricular event (Vs) occurs in the heart is difficult to detect. Therefore, the embodiment performs atrioventricular conduction recovery detection through AV interval expansion, and can effectively detect the spontaneous ventricular events (Vs) of the heart on the basis of ensuring safe pacing. When the AV interval expansion is started, the control module prolongs the atrioventricular interval according to the AV timing, specifically, a second increment value may be added to the current atrioventricular interval to serve as an expanded atrioventricular interval, the setting of the second increment value may be set according to the patient's condition, such as 50ms, and the time period of the second increment value is used to wait for searching whether a ventricular download event occurs. If an autonomous ventricular event (Vs) cannot be searched over the extended atrioventricular interval, the control module controls the pacing module to deliver electrical stimulation (VP) to the ventricle to ensure minimally safe ventricular pacing.

After the AV interval is extended, if T ventricular download events (Vs) occur in Q consecutive cardiac cycles, the atrioventricular conduction is considered to be normal, and the cardiac pacing system is immediately switched to the ADD mode. The atrioventricular conduction recovery detection is carried out through AV interval expansion, the atrioventricular interval can be properly prolonged to search autonomous ventricular downloading events of the heart on the basis of ensuring safe pacing, the reliability is high, and the safety can be guaranteed. Meanwhile, as the AV time sequence is maintained, the bad phenomenon of VP loss can not occur. Furthermore, as shown in fig. 6, if there are no T consecutive ventricular download events (Vs) occurring in Q cardiac cycles, it is determined that the atrioventricular block continues to exist, the cardiac pacing system continues to operate in the DDD mode, and the control module resumes operation with the atrioventricular interval, i.e., restores the atrioventricular interval to the normal value before the AV interval is extended. T and Q may be set differently depending on the actual condition of the patient and the experience of the doctor, for example, T is 12 and Q is 16. Since there is a small increase in the atrioventricular interval (i.e., an increase in the second incremental value) during the extension of the AV interval, the extension of the AV interval is preferably performed at a fixed frequency, since the long-term extension of AVD is not beneficial to the patient. The frequency may also be set differently depending on the patient's condition, such as once per minute, once per hour, once per day, etc. Atrioventricular conduction recovery detection through AV interval expansion is active atrioventricular conduction recovery detection, can be effectively performed regularly, and can reduce ventricular pacing by enabling a cardiac pacing system to work in an ADD mode as much as possible according to the condition of a patient.

In addition, when the cardiac pacing system is operating in a second mode (DDD mode), the sensing module senses a ventricular sense event (Vs) occurring during an atrioventricular interval of U consecutive cardiac cycles, the control module determines that atrioventricular conduction is restored to normal and controls the cardiac pacing system to switch to the first mode (ADD mode) of operation. Wherein U is a natural number greater than 2. The control module also senses and counts cardiac autonomous ventricular download events (Vs) via the sensing module when the cardiac pacing system does not perform AV interval expansion for atrioventricular conduction recovery detection. In some cases, a cardiac autonomous ventricular download event (Vs) may occur during an atrioventricular interval, i.e., prior to delivery of ventricular pacing, Vs being prior to VP, when the pacing system is no longer delivering ventricular pacing VP during the cardiac cycle. The control module counts the situations, and if ventricular events (Vs) are sensed in continuous U cardiac cycles, the atrioventricular conduction can be judged to be recovered to be normal, and the cardiac pacing system is switched to an ADD mode to work. The value of U can be selected according to needs, for example, U is 12. The manner in which ventricular events (Vs) are sensed by the sensing module in the DDD mode is a passive atrioventricular conduction recovery detection that supplements the active AV interval extension detection, further enabling the cardiac pacing system to operate in the ADD mode as much as possible to reduce ventricular pacing, making the pacing function of the cardiac pacemaker more physiological.

More preferably, when detecting that the atrioventricular conduction is recovered to be normal through the active or passive atrioventricular conduction recovery detection, and the control module determines that the atrioventricular conduction is recovered to be normal and controls the cardiac pacing system to switch to the first mode to operate, the sum of the maximum PR conduction time (i.e. the current maximum PR conduction time) and the third increment value in the W cardiac cycles before the cardiac pacing system is switched to the first mode to operate is taken as the first set value; wherein, W is a natural number larger than 2, and the value of W can be selected according to requirements, such as W is 12. In general, when atrioventricular conduction is just recovered, the PR conduction time may be relatively long, and if a shorter PR interval standard value is used as a comparison standard, the atrioventricular conduction just recovered is likely to be mistakenly identified as the PR interval being too long, and the cardiac pacing system returns to the DDD mode. To avoid this, the sum of the current maximum PR conduction time and the third increment value may be taken as the first set value, i.e., increased by the first set value as a comparison criterion. The third incremental value may be set according to the patient's condition, such as 50 ms. So configured, the cardiac pacing system can more reliably transition to the ADD mode when atrioventricular conduction returns to normal. Of course, in some embodiments, not only the sum of the current maximum PR conduction time and the third increment value may be selected as the first set value, but also the sum of the average PR conduction time (i.e., the current average PR conduction time) and the third increment value in the W cardiac cycles before the cardiac pacing system switches to the first mode may be selected as the first set value, which also enables the cardiac pacing system to smoothly and reliably perform the mode switching.

Referring to fig. 7, preferably, the hardware of the cardiac pacing system provided in this embodiment includes: acontrol module 08, and a digital/analog module 09 connected to thecontrol module 08. Here, thecontrol module 08 may be a microprocessor or the like. The invention does not limit the selection and implementation of the microprocessor.

Thecontrol module 08 may include amain control unit 01, atime control unit 02, and a data/information interaction interface 03. Themain control unit 01 controls events and events that need to occur, and can record and count events, such as cardiac events. Themain control unit 01 can selectively implement time-related control functions such as timing and timing through thetime control unit 02, for example, thetime control unit 02 can capture and record the time of an event occurrence, and can also control the accurate occurrence time of an event to be occurred. The data/information interaction interface 03 is used for realizing interaction of data or information and the like with other modules in the device, such as interaction with the digital/analog module 09. The data/information interaction interface 03 may be a common I/O interface, or may also be a serial or parallel data transmission module, and the data/information interaction interface 03 may receive sensed event information, issue a pacing event request, perform serial data interaction, clock data interaction, and the like, for example, interactive communication between a pacing signal and a sensing signal is realized through an I/O line.

The digital/analog module 09 may include asensing module 06 and apacing module 05, and may further include a data/information interaction interface 04 and aprogram control unit 07; thepacing module 05 includes a pacing control/generation unit and thesensing module 06 includes a sensing control/amplification unit. The data/information interaction interface 04 can be in signal connection with a corresponding data/information interaction interface (such as the data/information interaction interface 03 located at the control module) for interaction, although the implementation manner may be different from that of the data/information interaction interface 04. The pacing control/generation unit receives a pacing request from the microprocessor and generates a signal of a desired intensity to be applied to the outside, such as the atrium or ventricle. Of course, in some embodiments, the pacing control/generation unit may also assume a small portion of the control functions simultaneously, such as fine-tuning the pacing signal based on differences in the subject, the strength, type, etc. of the signal. The sensing control/amplification unit is able to capture and distinguish external real signals and inform thecontrol module 08 about them, such as cardiac signals, and to amplify them as required. Theprogram control unit 07 can perform information interaction with the outside, such as a user, for example, receive a user mode switching operation request, transmit the request information to themain control unit 01 through the data/information interaction interface 04 and the data/information interaction interface 03, and realize mode switching through the control of themain control unit 01. The user can transmit the information for starting the minimized right ventricular pacing function to the digital/analog module 09 through theprogram control unit 07, and themain control unit 01 acquires the information requested by the user through the data/information interaction interface 03, sets a corresponding function flag bit, and sets the working mode of the cardiac pacing system. In particular, thesensing module 06 is always on regardless of the mode in which the cardiac pacing system is operating.

It should be noted that the above-provided hardware structure of the cardiac pacing system should be regarded as a preferred example of the type of device for implementing the present invention, and the present invention is not limited thereto.

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 present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims (15)

1. A cardiac pacing system, comprising a control module, a sensing module and a pacing module; under the condition of normal atrioventricular conduction, the control module controls the cardiac pacing system to work in a first mode, and under the condition of normal atrioventricular conduction, the control module detects whether atrioventricular block occurs;

the atrioventricular conduction block comprises a first type of atrioventricular conduction block or a second type of atrioventricular conduction block; the first type of atrioventricular block is: the PR interval exceeds a first set value in each of S successive cardiac cycles; the second type of atrioventricular block is: when the sensing module senses that in two consecutive cardiac cycles, a ventricular event is absent in the first cardiac cycle and a ventricular event is absent when the second cardiac cycle reaches the first set value; wherein S is a natural number greater than 2;

when the control module detects an atrioventricular conduction block, the control module controls the cardiac pacing system to switch to a second mode of operation;

when atrioventricular conduction block occurs, the control module periodically detects the atrioventricular conduction recovery, and when the atrioventricular conduction recovers to be normal, the control module controls the cardiac pacing system to switch to the first mode to work; the control module performs atrioventricular conduction restoration detection through AV interval expansion; the AV interval extension is: taking the sum of the atrioventricular interval and the second increment value as an extended atrioventricular interval;

in detecting whether atrioventricular conduction is restored, the control module controls the cardiac pacing system to operate in the second mode at the extended atrioventricular interval; in the process of detecting whether the atrioventricular conduction is recovered, if continuous T ventricular sensing events occur in continuous Q cardiac cycles, the atrioventricular conduction is judged to be recovered to be normal; if continuous T ventricular sense events do not occur in continuous Q cardiac cycles, judging that the atrioventricular block continues to exist, and controlling the cardiac pacing system to recover to work in the second mode at the atrioventricular interval by the control module; wherein T is a natural number greater than 2, and Q is a natural number greater than T.

2. The cardiac pacing system of claim 1, wherein the control module controls the pacing module to deliver electrical stimulation to the ventricle when the second cardiac cycle reaches the first set point in the event the second type of atrioventricular conduction block is detected.

3. The cardiac pacing system according to claim 1, wherein the first set point is a sum of an average value of the PR intervals and a first increment value or a sum of a maximum value of the PR intervals and the first increment value in R consecutive cardiac cycles prior to a current cardiac cycle, where R is a natural number greater than 2.

4. The cardiac pacing system of claim 1, wherein during operation of the cardiac pacing system in the second mode, if the sensing module senses a ventricular sense event occurring during an atrioventricular interval of U successive cardiac cycles, the control module determines that atrioventricular conduction is restored to normal and controls the cardiac pacing system to switch to the first mode of operation; wherein U is a natural number greater than 2.

5. The cardiac pacing system according to claim 1 or 4, wherein when the control module determines that atrioventricular conduction is restored to normal and controls the cardiac pacing system to switch to the first mode of operation, the sum of the maximum value of the PR conduction time and the third increment value in the W cardiac cycles before the cardiac pacing system switches to the first mode of operation is taken as the first set value; wherein W is a natural number greater than 2.

6. The cardiac pacing system of claim 1, wherein the first mode is configured such that the control module controls the pacing module to deliver electrical stimulation to an atrium when the sensing module senses the absence of an atrial event; the pacing module follows the sensing module to sense the atrial event at an atrioventricular interval according to the control of the control module, or the pacing module sends electrical stimulation to the atrium, and if the ventricular event is absent in the atrioventricular interval, the pacing module does not send pacing electrical stimulation to the ventricle and marks the atrial event as a virtual pacing event.

7. The cardiac pacing system of claim 1, wherein the second mode is configured to: and the pacing module follows the sensing module to sense the atrial event or the pacing module to deliver the electrical stimulation to the atrium at an atrioventricular interval according to the control of the control module, and delivers the electrical stimulation to the atrium if the ventricular event is absent in the atrioventricular interval.

8. The cardiac pacing system of claim 1, wherein the atrioventricular conduction block further comprises a third type of atrioventricular conduction block that is: not less than M ventricular events are absent in N consecutive cardiac cycles, where M is a natural number greater than 2 and N is a natural number greater than M.

9. A cardiac pacing system, comprising a control module, a sensing module and a pacing module; under the condition of normal atrioventricular conduction, the control module controls the cardiac pacing system to work in a first mode, and under the condition of normal atrioventricular conduction, the control module detects whether atrioventricular block occurs;

the atrioventricular conduction block comprises a first type of atrioventricular conduction block or a second type of atrioventricular conduction block; the first type of atrioventricular block is: the PR interval exceeds a first set value in each of S successive cardiac cycles; the second type of atrioventricular block is: when the sensing module senses that in two consecutive cardiac cycles, a ventricular event is absent in the first cardiac cycle and a ventricular event is absent when the second cardiac cycle reaches the first set value; wherein S is a natural number greater than 2;

when the control module detects an atrioventricular conduction block, the control module controls the cardiac pacing system to switch to a second mode of operation;

during the operation of the cardiac pacing system in the second mode, if the sensing module senses that ventricular sensed events occur in atrioventricular intervals of consecutive U cardiac cycles, the control module judges that atrioventricular conduction is recovered to be normal, and controls the cardiac pacing system to switch to the first mode; wherein U is a natural number greater than 2;

when the control module judges that the atrioventricular conduction is recovered to be normal and controls the cardiac pacing system to be switched to the first mode to work, the sum of the maximum value of the PR conduction time and the third increment value in the W cardiac cycles before the cardiac pacing system is switched to the first mode to work is taken as the first set value; wherein W is a natural number greater than 2.

10. The cardiac pacing system of claim 9, wherein the control module controls the pacing module to deliver electrical stimulation to the ventricle when the second cardiac cycle reaches the first set point in the event the second type of atrioventricular conduction block is detected.

11. The cardiac pacing system according to claim 9, wherein the first set point is a sum of an average value of PR intervals and a first increment value or a sum of a maximum value of PR intervals and a first increment value in R consecutive cardiac cycles prior to a current cardiac cycle, wherein R is a natural number greater than 2.

12. The cardiac pacing system of claim 9, wherein the control module periodically performs an atrioventricular conduction restoration test when an atrioventricular conduction block has occurred, and controls the cardiac pacing system to switch to the first mode of operation when atrioventricular conduction has restored to normal.

13. The cardiac pacing system of claim 9, wherein the first mode is configured such that the control module controls the pacing module to deliver electrical stimulation to an atrium when the sensing module senses the absence of an atrial event; the pacing module follows the sensing module to sense the atrial event at an atrioventricular interval according to the control of the control module, or the pacing module sends electrical stimulation to the atrium, and if the ventricular event is absent in the atrioventricular interval, the pacing module does not send pacing electrical stimulation to the ventricle and marks the atrial event as a virtual pacing event.

14. The cardiac pacing system of claim 9, wherein the second mode is configured to: and the pacing module follows the sensing module to sense the atrial event or the pacing module to deliver the electrical stimulation to the atrium at an atrioventricular interval according to the control of the control module, and delivers the electrical stimulation to the atrium if the ventricular event is absent in the atrioventricular interval.

15. The cardiac pacing system of claim 9, wherein the atrioventricular conduction block further comprises a third type of atrioventricular conduction block that is: not less than M ventricular events are absent in N consecutive cardiac cycles, where M is a natural number greater than 2 and N is a natural number greater than M.

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