CN115887923A - Implantable medical device and system capable of effectively avoiding ventricular vulnerable period pacing - Google Patents

Abstract

The invention discloses an implantable medical device and system capable of effectively avoiding ventricular vulnerable period pacing.A ventricular pacing adjusting window interval VTVPA is defined, when a ventricular sensed event in a refractory period is detected, the VTVPA is started, the issuing time of the expected ventricular paced event is adjusted according to the time sequence relation between the issuing time of the expected ventricular paced event and the VTVPA, and the VTVPA is dynamically updated by combining individual rhythm change and clinical evaluation information, so that ventricular vulnerable period pacing can be effectively avoided, the occurrence probability of tachyarrhythmia caused by ventricular vulnerable period pacing is reduced, and the adverse consequence of possible life threatening caused by the tachyarrhythmia is reduced; moreover, implantable medical devices and systems can be used in a variety of operating modes, with a wide range of actions and flexibility.

Description

Implantable medical device and system capable of effectively avoiding ventricular vulnerable period pacing

Technical Field

The invention belongs to the technical field of medical instruments, and particularly relates to implantable medical equipment and a system for avoiding pacing in a vulnerable period of a ventricle.

Background

The implanted medical equipment is an electronic therapeutic equipment implanted in the body, and can be used for curing the cardiac dysfunction due to some arrhythmia by using pulse generator to deliver electric pulse powered by battery, and utilizing the conduction of wire electrode to stimulate cardiac muscle contacted with electrode to make heart excite and contract.

The vulnerable period of the ventricles refers to a specific period in the cardiac cycle, and the stimulation given to the ventricles in the period is very easy to cause a series of ventricular tachycardia and even ventricular fibrillation. This period is approximately near the T wave on the electrocardiogram of the body surface, and is located about 30ms before the T wave rises to the peak. During repolarization of the ventricles, there is a difference in repolarization procedure between adjacent myocardial tissues. The ventricular vulnerable period is mainly caused by repolarization and discretization of inner-layer, middle-layer and outer-layer ventricular myocytes, the three-layer cells have sequential differences relative to the starting time of a refractory period after the effective refractory period is finished, the myocardial cell excitability is not uniform and is in a scattered state, and when stronger suprathreshold stimulation (such as premature beat or pacing) is given, micro-reentry caused by one-way block is possibly formed, so that ventricular fibrillation is induced.

An implantable cardiac rhythm management device, such as a cardiac pacemaker, may improperly deliver ventricular pacing stimuli during a ventricular vulnerable period during operation due to either imperceptible ventricular self-signals or improper identification of ventricular action potentials (including ventricular premature beats and ventricular fast beats) as interfering signals during the refractory period, which may easily cause ventricular fibrillation.

Disclosure of Invention

In view of the foregoing, it is an object of the present invention to provide an implantable medical device and system for avoiding pacing during a ventricular vulnerable period by defining and updating a ventricular pacing adjustment window interval in real-time, and adjusting a pacing time according to a relationship of an expected pacing time for a ventricular pacing event to the ventricular pacing adjustment window interval to effectively avoid pacing during the ventricular vulnerable period.

In a first aspect, an implantable medical device capable of effectively avoiding pacing during a ventricular vulnerable period provided by an embodiment includes a ventricular sensing module, a ventricular pacing module, a pacing control module, a therapy control module, and a storage module;

the ventricle sensing module is used for detecting the activity of the ventricle;

the pacing control module is used for judging whether the self activity of the ventricle is a ventricular sensing event in a ventricular refractory period;

the treatment control module is used for controlling to start a ventricular pacing adjustment window interval VTVPA which prevents ventricular tachycardia and is expected to cover a ventricular vulnerable period when a ventricular sensing event occurs in a ventricular refractory period, wherein the VTVPA is set according to individual heart rate change, a clinical evaluation result of T waves and a clinical evaluation result of a heart state;

the treatment control module is used for controlling and adjusting the release time of the expected ventricular pacing event to the starting time of the VTVPA when judging that the condition group I is met; when the condition group II is met, the release time of the expected ventricular pacing event is controlled and adjusted to the termination time of the VTVPA, and the new release time of the ventricular pacing event is updated to the storage module as an operation parameter;

wherein the condition group I comprises: the expected ventricular pacing event is in the first half of the VTVPA, the current time is prior to the starting time of the VTVPA, when the ventricular pacing is in the double-chamber mode, the starting time of the VTVPA is greater than the allowable fastest ventricular pacing frequency point, and the difference between the atrial pacing event and the starting time T1 is greater than an atrioventricular interval threshold value beta; condition set II includes: the expected ventricular pacing event is during VTVPA and does not satisfy condition set I;

the pacing control module is used for acquiring the operating parameters from the storage module to control the ventricular pacing module to perform ventricular pacing.

In one embodiment, the subject's heart rate changes include changes in RR intervals, RP intervals, and PP intervals, wherein an RR interval is an interval between two adjacent R-waves, an RP interval is an interval between an adjacent R-wave and a ventricular pacing event VP, and a PP interval is an interval between two adjacent ventricular pacing events VP; the clinical evaluation result of the T wave comprises a set T wave duration and a set T wave starting time sequence;

the VTVPA is defined as a window interval formed by a starting time T1 to a terminating time T2 after a ventricular sense event in a refractory period, wherein the terminating time T2 is defined as the sum of a corresponding time of the ventricular sense event in the refractory period and a previous RR interval, RP interval or PP interval and an adjustment threshold, wherein the adjustment threshold is set according to a clinical evaluation result of the heart state; the start time T1 is defined as the difference between the end time T2 and the set T-wave duration and as the maximum of the sum of the corresponding time of the ventricular sensed event within the refractory period and the set T-wave start time sequence.

In one embodiment, the therapy control module maintains the starting time T1 of the VTVPA unchanged and extends the ending time T2 of the VTVPA backwards in time sequence when a ventricular sense event within a new refractory period is detected before the expiration of the ending time T2 of the VTVPA, while updating the intermediate time Tm that divides the VTVPA into a first half and a second half to form a new VTVPA; wherein the extended termination time T2 is defined as the sum of the corresponding time of the ventricular sensed event within the new refractory period and half of the previous RR interval, RP interval or PP interval, and an adjustment threshold, wherein the adjustment threshold is set according to the clinical assessment result of the cardiac state;

the therapy control module makes a determination of condition group I and condition group II based on the new VTVPA to adjust the timing of delivery of the expected ventricular pacing event.

In one embodiment, in the therapy control module, the intermediate time Tm of the VTVPA is updated in the following manner:

when the ventricular sensed event in the new refractory period occurs between the corresponding time of the ventricular sensed event in the original refractory period and the starting time T1 of the original VTVPA, updating the middle time Tm to be the middle time of the new VTVPA;

when the ventricular sense event in the new refractory period occurs between the starting time T1 and the ending time T2 of the original VTVPA, the intermediate time Tm is updated to be the corresponding time of the ventricular sense event in the new refractory period.

In one embodiment, the pacing control module determines whether the ventricular intrinsic activity is a refractory ventricular sensed event, including: identifying a ventricular sense event within the refractory period if ventricular self-activity occurs within the ventricular refractory period; if the ventricular self-activity does not affect the pacing timing, all ventricular self-activity is also identified as a ventricular sense event within the refractory period;

the pacing control module sends a notification signal to the treatment control module when detecting a ventricular sensed event in a refractory period;

in one embodiment, the timing module is controlled by the pacing control module, and is used for timing the corresponding time of the ventricular sensed event in the refractory period to the starting time of the VTVPA, the starting time of the VTVPA to the intermediate time Tm of the VTVPA and the intermediate time Tm of the VTVPA to the termination time of the VTVPA respectively according to the VTVPA, and informing the pacing control module after the timing expires.

In one embodiment, the system further comprises a wireless program control module, which is used for being in communication connection with the extracorporeal device to realize interaction between the operating parameters in the storage module and the extracorporeal device.

In a second aspect, embodiments provide a pulse stimulation system capable of effectively avoiding ventricular vulnerable period pacing, including the implantable medical device of the first aspect, an extracorporeal device;

the implantable medical device establishes communication with the extracorporeal device and performs interaction of the operating parameters in the memory module.

In one embodiment, the adjustment threshold, T-wave duration, T-wave start time sequence, atrioventricular interval threshold are updated to the memory module and synchronized to the therapy control module by the extracorporeal device.

In one embodiment, the external device controls the VTVPA function to be turned on or off according to the working mode of the implanted medical device, and when the VTVPA function is turned off, the implanted medical device does not turn on the VTVPA and does not perform delivery time adjustment of ventricular pacing events expected according to the VTVPA.

The technical scheme provided by the embodiment has the beneficial effects that at least:

by defining a ventricular pacing adjustment window interval VTVPA, starting the VTVPA when a ventricular sensed event in a refractory period is detected, adjusting the issuing time of the expected ventricular pacing event according to the time sequence relation between the issuing time of the expected ventricular pacing event and the VTVPA, and dynamically updating the VTVPA by combining individual rhythm variation and clinical evaluation information, the ventricular vulnerable period pacing can be effectively avoided, the occurrence probability of the tachyventricular arrhythmia caused by the ventricular vulnerable period pacing is reduced, and the possibly life-threatening adverse effect caused by the tachyventricular arrhythmia is reduced; in this way, the ventricular vulnerable periods in different heart rhythm states can be defined more accurately, so that the probability of avoiding pacing in the ventricular vulnerable periods is improved; therefore, the necessary ventricular pacing support and the maintenance of a relatively stable ventricular rate can be effectively avoided during the ventricular vulnerable period pacing; moreover, implantable medical devices and systems can be used in a variety of operating modes, with a wide range of actions and flexibility.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic diagram of a pulse pacing system according to an embodiment capable of effectively avoiding ventricular vulnerable period pacing;

FIG. 2 is a VTVPA window interval with ventricular sensing during a refractory period provided by an embodiment;

3 (a) -3 (c) illustrate VTVPA window intervals with ventricular sensing during successive refractory periods, according to one embodiment;

fig. 4 (a) and 4 (b) are schematic diagrams illustrating ventricular pacing adjustments within a VTVPA window according to an embodiment;

FIG. 5 is a workflow of a pulsed pacing system with respect to VTVPA window intervals as provided by an embodiment;

fig. 6 is a flow diagram of an embodiment of a pulsed pacing system with respect to ventricular pacing adjustments within a VTVPA window.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the detailed description and specific examples, while indicating the scope of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

The ventricular pacing method aims to solve the problem that ventricular pacing possibly occurs in a vulnerable period of ventricular activity when the ventricular activity is identified as a ventricular sensing event in a refractory period by equipment due to interference, improper parameter setting, premature ventricular contraction, fast heartbeat and the like, so that ventricular arrhythmia such as ventricular fibrillation is easily caused; the method also aims to solve the problem that the ventricular vulnerable period is easy to change along with the rhythm and is difficult to define accurately, and also aims to solve the problems that the pacing treatment of the ventricular vulnerable period is avoided, and simultaneously necessary ventricular pacing support is ensured and a relatively stable ventricular rate is maintained; the method also aims to solve the problem of adaptive use of multiple working modes. Embodiments provide a pulsed stimulation system for avoiding ventricular vulnerable period pacing.

Fig. 1 is a schematic diagram of a pulse pacing system capable of effectively avoiding ventricular vulnerable period pacing according to an embodiment. As shown in fig. 1, the pulse pacing system according to the embodiment includes an implantable medical device 1 and an external device 10, where the implantable medical device 1 includes a ventricular sense module 2, a ventricular pacing module 3, a wireless program control module 4, a clock/timing module 5, a pacing control module 6, a storage module, and a therapy control module 9. The ventricular sensing module 2 senses the heart self-activity signal and transmits the sensed heart self-activity signal to the pacing control module 6, the pacing control module 6 controls the clock/timing module 5 to time according to the current running state, the clock/timing module 5 informs the pacing control module 6 after expiration, and the pacing control module 6 controls the ventricular pacing module 3 to deliver ventricular pacing pulses according to the current running parameters. The treatment control module 9 can modify the operation parameters in the storage module 7 according to the current treatment function operation or the estimated patient state, the operation parameters in the storage module 7 are updated and transmitted to the pacing control module 6, and the pacing control module 6 controls the pacing time sequence and pacing delivery according to the new operation parameters. The external device 10 is connected with the wireless program control module 4 of the implantable medical device 1 in a wireless communication manner, the external device 10 can modify the operation parameters of the implantable medical device through wireless communication, and the implantable medical device 1 can transmit internal data to the external device 10 through the wireless program control module 4.

In order to effectively avoid pacing in a ventricular vulnerable period, the therapy control module 9 of the implantable medical device 1 provided in the embodiment has a function of controlling the VTVPA to be turned on and adjusted when a ventricular sense event occurs in a ventricular refractory period, and also has a function of adjusting the delivery time of the ventricular pacing event according to the VTVPA, and the pacing control module 6 delivers the ventricular pacing event according to the adjusted delivery time, so as to effectively avoid ensuring necessary ventricular pacing support and maintaining a relatively stable ventricular rate during pacing in the ventricular vulnerable period. The function of the implantable medical device 1 to effectively avoid ventricular vulnerable period pacing is described in detail below.

In an embodiment, the ventricular sense module 2 detects ventricular self-activity in real time, wherein the ventricular self-activity includes ventricular premature beats, ventricular fast beats and the like. After detecting the ventricular self-activity, the pacing control module 6 determines whether the detected ventricular self-activity is a ventricular sensed event in a refractory period, and specifically includes: identifying a ventricular sense event within the refractory period if ventricular self-activity occurs within the ventricular refractory period; all ventricular self-activity is also identified as a ventricular sense event within the refractory period if it does not affect pacing timing.

In the single-chamber, dual-chamber mode of the implantable medical device, ventricular refractory period generally refers to the Ventricular Refractory Period (VRP) following a Ventricular event. In modes where ventricular sensing can affect pacing timing, such as DDD, VVI, a ventricular sense event within a refractory period is identified if ventricular self-activity occurs within the ventricular refractory period; in modes where ventricular sense does not affect pacing timing, such as VOOs, all ventricular self-activity is identified as a ventricular sense event within the refractory period.

The pacing control module 6 sends a notification signal to the therapy control module 9 when detecting a Ventricular sense event in a refractory period, and the therapy control module 9 immediately controls to open a Ventricular pacing adjustment window interval (VTVPA) according to the notification of the occurrence of the Ventricular sense event in the refractory period, wherein the VTVPA can cover a Ventricular vulnerable period and can prevent Ventricular Tachycardia, and the VTVPA is set according to individual heart rate change, a clinical evaluation result of T-wave and a clinical evaluation result of heart state.

In an embodiment, the change in the heart rhythm of the individual comprises a change in an RR interval, an RP interval, and a PP interval, wherein the RR interval is an interval between two adjacent R-waves, the RP interval is an interval between an adjacent R-wave and a ventricular pacing event VP, and the PP interval is an interval between two adjacent ventricular pacing events VP; the results of the clinical assessment of the T-wave include a set T-wave duration, a set sequence of T-wave start times, which may be set by the physician via the extracorporeal device 10. The results of clinical assessment of cardiac status primarily determine the adjustment threshold defining the VTVPA.

Based on this, as shown in fig. 2, VTVPA is defined as a window interval formed from a starting time T1 to a terminating time T2 after a ventricular sense event (VR) in a refractory period, wherein the terminating time T2 is defined as a sum of a corresponding time T0 of the ventricular sense event VR in the refractory period and a previous RR interval, an RP interval or half of a PP interval, and an adjustment threshold delta, i.e., T2= T0+1/2 a + delta, where the adjustment threshold delta is set according to a clinical evaluation result of a heart state, and a is RR, RP or PP; the start time T1 is defined as a difference between the termination time T2 and the set T-wave duration B, i.e. T1= T2-B, if B =250ms, then T1= T2-250ms, and the start time T1 may also be defined as a sum of the corresponding time T0 of the refractory ventricular sensed event VR and the set T-wave start time sequence C, i.e. T1= T0+ C, if C =100ms, then T1= T0+100ms, and finally a maximum of T1= T2-B and T1= T0+ C is taken as a final start time T1. On the basis, the VTVPA is further defined to be divided into a first half and a second half, namely, the middle time of T1 and T2 is Tm, and the middle time Tm is dynamically updated in the application process.

Based on the VTVPA definition, which makes it possible to determine the specific ventricular vulnerable period, the T-wave is crucial for determining the specific ventricular vulnerable period, and the location and duration of the T-wave generally vary with the heart rate or the individual difference, and based on this, the present embodiment combines the individual heart rate variation (variation of RR, RP, PP), the clinical assessment of the patient's cardiac status (the adjustable threshold delta that can be set and adjusted according to the cardiac health status), and the clinical assessment of the T-wave (the settable T-wave duration and the T-wave start time) to define a specific VTVPA window interval, which is used to define the ventricular vulnerable period. Physiologically, the vulnerable period is a specific period in the electrocardiographic period, the period is approximately near the T wave on the body surface electrocardiogram, the definition of the VTVPA window interval is matched with the physiological definition, the VTVPA window can be dynamically adjusted along with the change of the rhythm, the range of the ventricular vulnerable period can be more accurately defined, the transient response of the implanted medical device caused by the overlarge definition of the range of the ventricular vulnerable period is reduced, and the specificity of the algorithm can be improved.

The therapy control module 9 performs judgment according to the started VTVPA to adjust the delivery time of the expected ventricular pacing event, so as to effectively avoid the ventricular vulnerable period pacing. When the judgment is made, whether the condition group I and the condition group II are met or not is judged, and when the condition group I is met, the release time of the expected ventricular pacing event VP is adjusted to the starting time T1 of the VTVPA; when the condition group II is met, the release time of the expected ventricular pacing event VP is adjusted to the termination time T2 of the VTVPA, and the new release time of the ventricular pacing event is used as an operation parameter to be updated to the storage module; pacing control module 6 extracts the operating parameters from memory module 7 for the pacing event.

In an embodiment, condition set I includes: the expected ventricular pacing event occurs during the first half of the VTVPA, i.e., the expected ventricular pacing event VP occurs during T1 to Tm, the current time Tt precedes the start time T1 of the VTVPA, i.e., tt < T1, and when the ventricular pacing is in the biventricular mode, the start time of the VTVPA is greater than the fastest allowable ventricular pacing frequency point (i.e., the upper tracking frequency point), and the atrial pacing event differs from the start time T1 by more than an atrioventricular interval threshold β, i.e., (AP-T1) > β, where the atrioventricular interval threshold β is the smallest Atrioventricular (AV) interval, and (AP-T1) > 30ms, assuming β is 30ms. Upon satisfaction of the set of conditions I, the delivery time of the expected ventricular pacing event VP is adjusted to the starting time T1 of the VTVPA, as shown in fig. 4 (a).

In an embodiment, condition group II includes: the expected ventricular pacing event does not satisfy condition set I during VTVPA. When condition set II is satisfied, the delivery time of the expected ventricular pacing event is adjusted to the termination time T2 of the VTVPA, as shown in fig. 4 (b).

After the ventricular pacing event VP is delivered to the time T1 in advance or delivered to the time T2 after being pushed back, a new pacing timing is delivered according to the delivery time point of the new VP, as shown in fig. 4 (a) and 4 (b); if the expected VP occurs outside of the T1-T2 interval, ventricular pacing is delivered normally and a new pacing timing is set according to the current ventricular pacing time. Updating the pacing timing according to the adjusted ventricular pacing facilitates maintaining a relatively stable ventricular rate.

Ventricular depolarization is crucial to cardiac output, and if ventricular pacing in a ventricular vulnerable period is directly inhibited without supplementing extra ventricular pacing, insufficient cardiac output can be caused, and the activity requirement of a patient is influenced; meanwhile, the relatively stable ventricular rate is more consistent with the physiological needs of the heart. Adjusting the delivery of ventricular pacing in close proximity is therefore beneficial to cardiac output and to maintain a relatively stable ventricular rate. An excessively fast ventricular pacing rate is detrimental to cardiac output, so that the adjusted ventricular pacing rate cannot exceed the allowable fastest ventricular pacing rate; to ensure hemodynamic synchronization of the AV, the adjusted AV interval should not fall below a settable minimum (e.g., 30 ms). In summary, adjusting the delivery of ventricular pacing in close proximity is beneficial for cardiac output and maintaining a relatively stable ventricular rate.

In an embodiment, after the therapy control module 9 turns on the VTVPA, when a ventricular fast beat occurs, the therapy control module 9 is notified of the detection of a new refractory ventricular sense event, and the therapy control module 9 detects that the new refractory ventricular sense event VR ' occurs before T2 of the currently turned on VTVPA, as shown in fig. 3 (a) -3 (c), and whether the new VR ' occurs between T0-T1, between T1-Tm, or between Tm-T2, it is necessary to keep T1 of the VTVPA unchanged and to extend T2-T2 ' of the VTVPA backwards in time sequence while updating Tm of the VTVPA to form a new VTVPA. Wherein, expanded T2 is defined as the sum of the corresponding time T0' of a ventricular sensed event in the new refractory period and half of the previous RR interval, RP interval or PP interval, and the adjustment threshold delta, i.e., T2= T0+1/2 a + delta, wherein the adjustment threshold delta is set according to the clinical assessment result of the heart status, and a is RR, RP or PP.

In the embodiment, the updating method of the intermediate time Tm of the VTVPA is as follows: as shown in fig. 3 (a), when a ventricular sensing event VR ' in a new refractory period occurs between a corresponding time T0 of the ventricular sensing event in the original refractory period and a starting time T1 of the original VTVPA, updating an intermediate time Tm to be an intermediate time of the new VTVPA, that is, tm ' =1/2 (T1-T2 '); as shown in fig. 3 (b) and 3 (c), when a ventricular sensed event VR ' in a new refractory period occurs between the start time T1 and the end time T2 of the original VTVPA, the update intermediate time Tm is the corresponding time of the ventricular sensed event in the new refractory period, i.e., tm ' = T0'.

When the heart rhythm is fast or more interferences occur, the influence of each ventricular sensing event on the ventricular vulnerable period cannot be distinguished, and in this case, the VTVPA is updated by using VTVPA window expansion to adapt to the change of the ventricular vulnerable period in this state, so that the ventricular vulnerable period can be defined more reasonably; after updating the VTVPA, the therapy control module 9 determines the condition group I and the condition group II according to the new VTVPA to adjust the delivery time of the expected ventricular pacing event and update the delivery time to the storage module 7, and the pacing control module 6 performs the pacing event according to the adjusted delivery time of the ventricular pacing event.

In an embodiment, the clock/timing module 5 is controlled by the pacing control module 6, and respectively times the corresponding time T0 of the ventricular sense event in the refractory period to the starting time T1 of the VTVPA, the starting time T1 of the VTVPA to the middle time Tm of the VTVPA, and the middle time Tm of the VTVPA to the termination time T2 of the VTVPA according to the VTVPA, that is, respectively times T0 to T1, T1 to Tm, and Tm to T2, and notifies the pacing control module 6 after the expiration of the timing, and the pacing control module 6 extracts the operating parameters from the storage module 7 to control the ventricular pacing module 3 to perform ventricular pacing event control.

In an embodiment, the external device controls the VTVPA function to be turned on or off according to the operating mode of the implantable medical device, and when the VTVPA function is turned off, the implantable medical device does not expand the VTVPA and does not adjust the delivery time of the ventricular pacing event according to the VTVPA, so as to increase the flexibility of the VTVPA function. Parameters of VTVPA function can also be updated by the extracorporeal device, specifically including updating the adjustment threshold delta, the T-wave duration, the T-wave start time sequence, the atrioventricular interval threshold β to the storage module 7 and synchronizing to the therapy control module 9.

As shown in fig. 1, a medical staff may use the extracorporeal device 10 to interact with the wireless programming module 4 of the implantable medical device 1 according to the specific situation of different patients, and modify the VTVPA-related operating parameters stored in the storage module 7, such as on or off. The therapy control module 9 may also flexibly adjust VTVPA-related operating parameters stored in the memory module 7, such as on, off, or delta values.

The VTVPA function provided by the embodiment can be suitable for all single-chamber and double-chamber modes with ventricular pacing, can be used in a plurality of working modes, and has a wide range of functions.

Fig. 5 is a workflow of a pulsed pacing system with respect to VTVPA window intervals, according to an embodiment. As shown in fig. 5, based on the pulse pacing system provided in the above embodiment, the workflow of the VTVPA window interval is as follows:

after ventricular sense module 2 of implantable medical device 1 detects a ventricular sense event (11), pacing control module 6 determines whether the current ventricular sense event is within the refractory period (12), and if the current ventricular sense event is outside the refractory period, pacing control module 6 performs ventricular sense processing outside the refractory period (13). If the current value is within the refractory period, the treatment control module 9 is informed, and the treatment control module 9 judges the current VTVPA _ flag value (15, 16 and 18);

from the VTVPA window interval as shown in fig. 2, if VTVPA _ flag =0 (15), the therapy control module 9 calculates T1, tm and T2 of VTVPA and updates into the storage module 7, while calculating the delivery time Tp at which the expected ventricular pacing is an event; the treatment control module 9 judges whether the ventricular pacing advanced delivery condition group I is currently satisfied, and if so, controls the clock/timing module 5 to reset the ventricular pacing time Tp = T1; otherwise, the pacing control module 6 directly starts the first timing interval T0 to T1 and sets VTVPA _ flag =1 according to the updated T1, tm, and T2 (22); after the first time period T0-T1 expires (23), the pacing control module 6 turns on the second time period T1-Tm and sets VTVPA _ flag =2 (24); after the second timing interval T1-Tm expires (25), the pacing control module 6 turns on a third timing interval Tm-T2 and sets VTVPA _ flag =3 (26); after expiration of the third timing interval Tm-T2 (27), the pacing control module 6 sets VTVPA _ flag =0 (28);

for the VTVPA window interval shown in fig. 3 (a), if VTVPA _ flag =1 (16), the therapy control module 9 recalculates Tm and T2 time points (17) and updates to the storage module 7, and the pacing control module 6 waits for the expiration of the first time period T0 to T1 during which the ventricular sensed event was turned on during the previous refractory period; after the first time period T0-T1 expires (23), the pacing control module 6 starts a second time period T1-Tm and sets VTVPA _ flag =2 (24) according to the updated Tm and T2; after the second timing interval T1-Tm expires (25), the pacing control module 6 turns on a third timing interval Tm-T2 and sets VTVPA _ flag =3 (26) according to the updated Tm and T2; upon expiration of the third timing interval Tm-T2 (27), the pacing control module 6 sets VTVPA _ flag =0 (28);

for the VTVPA window interval shown in fig. 3 (b), if VTVPA _ flag =2 (18), the therapy control module 9 recalculates the T2 time point, sets Tm to the current time T0' (19) and updates it to the storage module 7, while clearing the second timing interval that has currently been turned on (the ventricular sensing event was turned on during the previous refractory period); the pacing control module 6 turns on a third timing interval Tm-T2 and sets VTVPA _ flag =3 according to the updated Tm and T2 (26); upon expiration of the third timing interval Tm-T2 (27), the pacing control module 6 sets VTVPA _ flag =0 (28);

for the VTVPA window interval shown in fig. 3 (c), if VTVPA _ flag >2 (18), the therapy control module 9 recalculates the T2 time point, sets Tm to the current time T0' (19) and updates to the storage module 7, while clearing the third timing interval that has been currently turned on (the ventricular sensed event was turned on during the previous refractory period); the pacing control module 6 turns on a third timing interval Tm-T2 and sets VTVPA _ flag =3 according to the updated Tm and T2 (26); upon expiration of the third timing interval Tm-T2 (27), the pacing control module 6 sets VTVPA _ flag =0 (28).

Fig. 6 is a flow diagram of an embodiment of a pulsed pacing system with respect to ventricular pacing adjustments within a VTVPA window. As shown in fig. 6, the flow of ventricular pacing adjustments within the VTVPA window is:

ventricular pacing with an expected VP delivery time point outside the VTVPA window interval is implemented as: the pacing control module 6 detects the expiration of the ventricular pacing interval of the clock/timing module 5 (30), and then determines whether the current VTVPA _ flag is 3 (31), and at this time, the VTVPA _ flag should be 0 or 1 outside the interval T1 to T2, so that the pacing control module 6 normally delivers ventricular pacing and sets the pacing timing (33), sets VTVPA _ flag =0, and clears the first, second, and third timers (34).

For the embodiment of adjusting the ventricular pacing delivery in advance as shown in fig. 4 (a), the pacing control module 6 detects that the ventricular pacing interval of the clock/timing module 5 expires (30), determines whether the current VTVPA _ flag is 3 (31), and the ventricular pacing delivery time at this time is adjusted in advance and set at time T1 according to the embodiment shown in fig. 5, so that the VTVPA _ flag is not 3, so that the pacing control module 6 delivers ventricular pacing normally (adjusted ventricular pacing) and sets the pacing timing (33), and sets VTVPA _ flag =0, and clears the first, second, and third timers (34).

For the embodiment of adjusting the delivery of ventricular pacing delay shown in fig. 4 (b), the pacing control module 6 detects expiration of the ventricular pacing interval of the clock/timing module 5 (30), determines whether the current VTVPA _ flag is 3 (31), which is at the Tm-T2 interval and where VTVPA _ flag should be 3, so resetting the ventricular pacing timing to Tp = (T2 +1 ms) (32), where 1ms is added to preferentially expire the third timer, so that VTVPA _ flag is not 3 when the new ventricular pacing interval expires, continues to wait for the pacing control module 6 to detect expiration of the ventricular pacing interval of the clock/timing module 5 (30) and determines whether the current VTVPA _ flag is 3 (31), which is already timed out and VTVPA _ flag is not 3, so the control module 6 delivers ventricular pacing normally (adjusted ventricular pacing) and sets the pacing timing (33), sets vta _ flag =0, and clears the first, second, and third pacers (34).

The pulse stimulation system provided by the embodiment can effectively avoid ventricular vulnerable period pacing, so that the occurrence probability of ventricular tachyarrhythmia caused by ventricular vulnerable period pacing is reduced, and the adverse consequence of possible life threatening caused by ventricular tachyarrhythmia is reduced; the ventricular vulnerable periods in different heart rhythm states can be defined more accurately, so that the probability of avoiding pacing in the ventricular vulnerable periods is improved; the necessary ventricular pacing support can be ensured and the relatively stable ventricular rate can be maintained when the ventricular vulnerable period pacing is effectively avoided; the device can be used in a plurality of working modes, and has a wide and flexible action range.

The above-mentioned embodiments are intended to illustrate the technical solutions and advantages of the present invention, and it should be understood that the above-mentioned embodiments are only the most preferred embodiments of the present invention, and are not intended to limit the present invention, and any modifications, additions, equivalents, etc. made within the scope of the principles of the present invention should be included in the scope of the present invention.

Claims (10)

1. An implantable medical device capable of effectively avoiding pacing in a ventricular vulnerable period is characterized by comprising a ventricular sensing module, a ventricular pacing module, a pacing control module, a treatment control module and a storage module;

the ventricle sensing module is used for detecting the activity of the ventricle;

the pacing control module is used for judging whether the self activity of the ventricle is a ventricular sensing event in a ventricular refractory period;

the treatment control module is used for controlling to start a ventricular pacing adjustment window interval VTVPA which prevents ventricular tachycardia and is expected to cover a ventricular vulnerable period when a ventricular sensing event occurs in a ventricular refractory period, wherein the VTVPA is set according to individual heart rate change, a clinical evaluation result of T waves and a clinical evaluation result of a heart state;

the treatment control module is used for controlling and adjusting the delivery time of the expected ventricular pacing event to the starting time of the VTVPA when judging that the condition group I is met; when the condition group II is met, the release time of the expected ventricular pacing event is controlled and adjusted to the termination time of the VTVPA, and the new release time of the ventricular pacing event is updated to the storage module as an operation parameter;

wherein condition group I comprises: the expected ventricular pacing event is in the first half of the VTVPA, the current time is prior to the starting time of the VTVPA, when the ventricular pacing is in a double-chamber mode, the starting time of the VTVPA is greater than the allowable fastest ventricular pacing frequency point, and the difference between the atrial pacing event and the starting time T1 is greater than an atrioventricular interval threshold beta; condition set II includes: the expected ventricular pacing event is during VTVPA and does not satisfy condition set I;

the pacing control module is used for acquiring the operating parameters from the storage module to control the ventricular pacing module to perform ventricular pacing.

2. The implantable medical device of claim 1, wherein the individual heart rate change comprises a change in an RR interval, an RP interval, and a PP interval, wherein the RR interval is an interval between two adjacent R-waves, the RP interval is an interval between an adjacent R-wave and a ventricular pacing event VP, and the PP interval is an interval between two adjacent ventricular pacing events VP; the clinical evaluation result of the T wave comprises a set T wave duration and a set T wave starting time sequence;

the VTVPA is defined as a window interval formed by a starting time T1 to a terminating time T2 after a ventricular sense event in a refractory period, wherein the terminating time T2 is defined as the sum of a corresponding time of the ventricular sense event in the refractory period and a previous RR interval, RP interval or PP interval and an adjustment threshold, wherein the adjustment threshold is set according to a clinical evaluation result of the heart state; the start time T1 is defined as the difference between the end time T2 and the set T-wave duration, and the maximum of the sum of the corresponding time of the ventricular sense event within the refractory period and the set T-wave start time sequence.

3. The implantable medical device of claim 1 or 2, wherein the therapy control module maintains the start time T1 of the VTVPA unchanged and extends the end time T2 of the VTVPA backwards in time sequence when a ventricular sense event within a new refractory period is detected before the end time T2 of the VTVPA expires, while updating the intermediate time Tm that divides the VTVPA into a first half and a second half, forming a new VTVPA; wherein the extended termination time T2 is defined as the sum of the corresponding time of the ventricular sensed event within the new refractory period and half of the previous RR interval, RP interval or PP interval, and an adjustment threshold, wherein the adjustment threshold is set according to the clinical assessment result of the cardiac state;

the therapy control module makes a determination of condition group I and condition group II based on the new VTVPA to adjust the timing of delivery of the expected ventricular pacing event.

4. The implantable medical device according to claim 3, wherein the therapy control module updates the Tm at the VTVPA intermediate time by:

when the ventricular sensed event in the new refractory period occurs between the corresponding time of the ventricular sensed event in the original refractory period and the starting time T1 of the original VTVPA, updating the middle time Tm to be the middle time of the new VTVPA;

when the ventricular sense event in the new refractory period occurs between the starting time T1 and the ending time T2 of the original VTVPA, the intermediate time Tm is updated to be the corresponding time of the ventricular sense event in the new refractory period.

5. The implantable medical device of claim 1, wherein the pacing control module determines whether ventricular intrinsic activity is a refractory intra-ventricular sensed event, comprising: identifying a ventricular sense event within the refractory period if ventricular self-activity occurs within the ventricular refractory period; if the ventricular self-activity does not affect the pacing timing, all ventricular self-activity is also identified as a ventricular sense event within the refractory period;

the pacing control module sends a notification signal to the therapy control module upon detecting a ventricular sensed event within a refractory period.

6. The implantable medical device of claim 1, further comprising a clock/timing module, controlled by the pacing control module, for timing, according to the VTVPA, a time from a corresponding time of a ventricular sensed event in a refractory period to a start time of the VTVPA, a time from the start time of the VTVPA to an intermediate time Tm of the VTVPA, and a time from the intermediate time Tm of the VTVPA to an end time of the VTVPA, respectively, and notifying the pacing control module after the timing expires.

7. The implantable medical device according to claim 1, further comprising a wireless programming module for communicatively coupling to the extracorporeal device to enable interaction between the operating parameters stored in the storage module and the extracorporeal device.

8. A pulse stimulation system capable of effectively avoiding ventricular vulnerable period pacing, comprising an implantable medical device, an extracorporeal device according to any one of claims 1 to 8;

the implantable medical device establishes communication with the extracorporeal device and performs interaction of the operating parameters in the memory module.

9. A pulse stimulation system capable of effectively avoiding ventricular vulnerable period pacing according to claim 8, characterized in that the adjustment threshold, T-wave duration, T-wave start time sequence, atrioventricular interval threshold are updated to the storage module and synchronized to the therapy control module by the extracorporeal device.

10. A pulse stimulation system according to claim 8, wherein the VTVPA functionality is controlled by the external device to be turned on or off according to an operating mode of the implantable medical device, and wherein the VTVPA functionality is turned off without turning on the VTVPA and without adjusting a timing of delivery of a ventricular pacing event expected according to the VTVPA.

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