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

Abstract

The present invention discloses an implantable medical device and system that can effectively avoid ventricular vulnerable period pacing. The device defines a ventricular pacing adjustment window interval (VTVPA) and activates the VTVPA when a ventricular sensing event is detected during the refractory period. The expected ventricular pacing event timing is adjusted based on the timing relationship between the expected ventricular pacing event timing and the VTVPA. The VTVPA is dynamically updated by combining individual heart rhythm changes and clinical evaluation information. This can effectively avoid ventricular vulnerable period pacing, thereby reducing the probability of rapid ventricular arrhythmias caused by ventricular vulnerable period pacing, thereby reducing the potential life-threatening adverse consequences caused by rapid ventricular arrhythmias. Furthermore, the implantable medical device and system can be used in multiple working modes, with a wide and flexible range of action.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical devices, and in particular relates to an implantable medical device and system for avoiding ventricular vulnerable period pacing. Background Art

[0002] An implantable medical device is an electronic therapeutic instrument implanted in the body. It emits electrical pulses powered by a battery through a pulse generator. These pulses are conducted through wire electrodes to stimulate the myocardium that the electrodes contact, causing the heart to become excited and contract, thereby achieving the purpose of treating heart dysfunction caused by certain arrhythmias.

[0003] The ventricular vulnerable period refers to a specific period in the cardiac cycle during which stimulation of the ventricles can easily induce a series of ventricular tachycardias or even ventricular fibrillation. This period occurs roughly near the T wave on the surface electrocardiogram, approximately 30 milliseconds before the ascending limb of the T wave reaches its peak. During ventricular repolarization, adjacent myocardial tissues experience differences in repolarization schedules. The ventricular vulnerable period is primarily caused by the discrete repolarization of the inner, middle, and outer ventricular myocytes. The three layers of cells differ in the timing of the end of their effective refractory period relative to the onset of their refractory period. During this period, the excitability of myocardial cells is most uneven and disorganized. If strong suprathreshold stimulation (such as premature beats or pacing) is applied at this time, microreentry caused by unidirectional block is very likely to occur, thereby inducing ventricular fibrillation.

[0004] During operation, implantable cardiac rhythm management devices (such as pacemakers) may not sense the ventricular signals themselves, or may inappropriately identify ventricular action potentials (including ventricular premature beats and ventricular tachycardia) as interference signals within the refractory period, and may inappropriately deliver ventricular pacing stimulation during the ventricular vulnerable period, which can easily induce ventricular fibrillation. Summary of the Invention

[0005] In view of the above, an object of the present invention is to provide an implantable medical device and system for avoiding ventricular vulnerable period pacing, by defining and updating the ventricular pacing adjustment window interval in real time, and adjusting the pacing time according to the relationship between the expected pacing time of the ventricular pacing event and the ventricular pacing adjustment window interval, so as to effectively avoid pacing during the ventricular vulnerable period.

[0006] In a first aspect, an embodiment provides an implantable medical device capable of effectively avoiding ventricular vulnerable period pacing, comprising a ventricular sensing module, a ventricular pacing module, a pacing control module, a treatment control module, and a storage module;

[0007] The ventricular sensing module is used to detect the ventricular activity itself;

[0008] The pacing control module is used to determine whether the ventricular activity itself is a ventricular sensing event during the ventricular refractory period;

[0009] The treatment control module is configured to control the start of a ventricular pacing adjustment window interval (VTVPA) to prevent ventricular tachycardia and to cover the ventricular vulnerability period when a ventricular sensing event occurs during the ventricular refractory period, wherein the VTVPA is set based on individual heart rhythm changes, clinical assessment results of T waves, and clinical assessment results of cardiac status;

[0010] The treatment control module is configured to control the adjustment of the expected ventricular pacing event delivery time to the start time of the VTVPA when it is determined that condition group I is satisfied; and control the adjustment of the expected ventricular pacing event delivery time to the end time of the VTVPA when condition group II is satisfied, and update the new ventricular pacing event delivery time as an operating parameter to the storage module;

[0011] Condition Group I includes: the expected ventricular pacing event is in the first half of VTVPA, the current time is prior to the start time of VTVPA, when ventricular pacing is in dual-chamber mode, the start time of VTVPA is greater than the fastest allowed ventricular pacing frequency point, and the difference between the atrial pacing event and the start time T1 is greater than the atrioventricular interval threshold β; Condition Group II includes: the expected ventricular pacing event is during VTVPA, and Condition Group I is not met;

[0012] The pacing control module is used to obtain operating parameters from the storage module to control the ventricular pacing module to perform ventricular pacing.

[0013] In one embodiment, the individual heart rhythm changes include changes in the RR interval, RP interval, and PP interval, wherein the RR interval is the interval between two adjacent R waves, the RP interval is the interval between adjacent R waves and a ventricular pacing event VP, and the PP interval is the interval between two adjacent ventricular pacing events VP; the clinical assessment results of the T wave include a set T wave duration and a set T wave start time sequence;

[0014] The VTVPA is defined as the window interval formed from the starting time T1 to the ending time T2 after the ventricular sensing event in the refractory period, wherein the ending time T2 is defined as the sum of the corresponding time of the ventricular sensing event in the 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 results of the cardiac state; the starting time T1 is defined as the difference between the ending time T2 and the set T wave duration, and the sum is the maximum value of the sum of the corresponding time of the ventricular sensing event in the refractory period and the set T wave starting time sequence.

[0015] In one embodiment, when the treatment control module detects a new ventricular sensing event in the refractory period before the expiration of the end time T2 of the VTVPA, the treatment control module maintains the start time T1 of the VTVPA unchanged, extends the end time T2 of the VTVPA backward along the time sequence, and updates the middle time Tm that divides the VTVPA into the first half and the second half to form a new VTVPA; wherein the extended end time T2 is defined as the sum of the corresponding time of the ventricular sensing event in 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 a clinical assessment result of the cardiac status;

[0016] The treatment control module makes judgments on condition group I and condition group II based on the new VTVPA to adjust the expected delivery time of the ventricular pacing event.

[0017] In one embodiment, in the treatment control module, the intermediate time Tm of VTVPA is updated as follows:

[0018] When the ventricular sensing event in the new refractory period occurs between the corresponding time of the ventricular sensing event in the original refractory period and the starting time T1 of the original VTVPA, the intermediate time Tm is updated to the intermediate time of the new VTVPA;

[0019] When the ventricular sensing event in the new refractory period occurs between the start time T1 and the end time T2 of the original VTVPA, the intermediate time Tm is updated to the corresponding time of the ventricular sensing event in the new refractory period.

[0020] In one embodiment, the pacing control module determines whether the ventricular self-activity is a ventricular sensed event within the refractory period, including: if the ventricular self-activity occurs within the ventricular refractory period, identifying it as a ventricular sensed event within the refractory period; if the ventricular self-activity does not affect the pacing timing, all ventricular self-activity is also identified as a ventricular sensed event within the refractory period;

[0021] The pacing control module sends a notification signal to the treatment control module when detecting a ventricular sensing event during the refractory period;

[0022] In one embodiment, a clock / timing module is further included, which is controlled by the pacing control module and, based on the VTVPA, times the corresponding moment of the ventricular sensing event in the refractory period to the start moment of the VTVPA, the start moment of the VTVPA to the middle moment Tm of the VTVPA, and the middle moment Tm of the VTVPA to the end moment of the VTVPA, and notifies the pacing control module after the timing expires.

[0023] In one embodiment, a wireless thread control module is further included, which is used to communicate with the external device to realize the interaction between the operating parameters in the storage module and the external device.

[0024] In a second aspect, an embodiment provides a pulse stimulation system capable of effectively avoiding ventricular vulnerable period pacing, comprising the implantable medical device and the external device described in the first aspect;

[0025] The implantable medical device establishes communication with the external device and interacts with the operating parameters in the storage module.

[0026] In one embodiment, the threshold, T wave duration, T wave start time sequence, and atrioventricular interval threshold are updated and adjusted to the storage module through an external device, and synchronized to the treatment control module.

[0027] In one embodiment, an external device is used to control the turning on or off of the VTVPA function according to the working mode of the implantable medical device. When the VTVPA function is turned off, the implantable medical device does not turn on the VTVPA and does not adjust the delivery time of the ventricular pacing event expected by the VTVPA.

[0028] The technical solutions provided in the above embodiments have at least the following beneficial effects:

[0029] By defining the ventricular pacing adjustment window interval VTVPA and turning on the VTVPA when a ventricular sensing event is detected during the refractory period, the expected ventricular pacing event timing is adjusted based on the timing relationship between the expected ventricular pacing event timing and the VTVPA. By combining individual rhythm changes and clinical assessment information, the VTVPA is dynamically updated. This can effectively avoid ventricular vulnerable period pacing, thereby reducing the probability of rapid ventricular arrhythmias caused by ventricular vulnerable period pacing, thereby reducing the potential life-threatening adverse consequences caused by rapid ventricular arrhythmias; this can also more accurately define the ventricular vulnerable period under different rhythm states, thereby increasing the probability of avoiding ventricular vulnerable period pacing; this can also effectively ensure necessary ventricular pacing support and maintain a relatively stable ventricular rate when avoiding ventricular vulnerable period pacing; furthermore, implantable medical devices and systems can be used in multiple working modes, with a wide and flexible range of effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a schematic structural diagram of a pulse pacing system capable of effectively avoiding ventricular vulnerable period pacing provided by an embodiment;

[0032] Figure 2is the VTVPA window interval under ventricular sensing during the refractory period provided by an embodiment;

[0033] Figure 3(a) to Figure 3(c) is the VTVPA window interval under the condition of ventricular sensing during the continuous refractory period provided by an embodiment;

[0034] FIG4(a) and FIG4(b) are schematic diagrams of ventricular pacing adjustment within a VTVPA window provided by an embodiment;

[0035] Figure 5 This is a workflow regarding the VTVPA window interval of a pulse pacing system provided by an embodiment;

[0036] Figure 6 This is a flow chart of a pulse pacing system provided by an embodiment regarding ventricular pacing adjustment within the VTVPA window. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0038] To address the risk of ventricular arrhythmias, such as ventricular fibrillation, when ventricular activity is identified by the device as a refractory ventricular sensing event due to interference, inappropriate parameter settings, premature ventricular beats, or rapid heartbeats; to address the difficulty of accurately defining the vulnerable period of ventricular activity, which easily varies with heart rhythm; to address the difficulty of avoiding pacing during the vulnerable period while ensuring necessary ventricular pacing support and maintaining a relatively stable ventricular rate; and to address the problem of adapting to multiple working modes. Embodiments provide a pulse stimulation system for avoiding pacing during the vulnerable period of ventricular activity.

[0039] Figure 1 FIG. 1 is a schematic diagram of a pulse pacing system that can effectively avoid ventricular vulnerable period pacing provided by an embodiment. Figure 1As shown, the pulse pacing system provided in the embodiment includes an implantable medical device 1 and an external device 10. The implantable medical device 1 includes a ventricular sensing module 2, a ventricular pacing module 3, a wireless threaded 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's own activity signals and transmits them to the pacing control module 6. The pacing control module 6 controls the clock / timing module 5 to set a timer based on the current operating status. Upon expiration of the timer, the clock / timing module 5 notifies the pacing control module 6. The pacing control module 6 controls the ventricular pacing module 3 to deliver ventricular pacing pulses based on the current operating parameters. The therapy control module 9 can modify the operating parameters in the storage module 7 based on the current treatment function operation or the assessed patient status. The updated operating parameters in the storage module 7 are then transmitted to the pacing control module 6. The pacing control module 6 controls the pacing sequence and delivery of pacing pulses based on the new operating parameters. The external device 10 is connected to the wireless control module 4 of the implantable medical device 1 via wireless communication. The external device 10 can modify the operating parameters in the implantable medical device via wireless communication, and the implantable medical device 1 can send internal data to the external device 10 via the wireless control module 4.

[0040] To effectively prevent ventricular vulnerable period pacing, the treatment control module 9 of the implantable medical device 1 provided in this embodiment has the function of controlling the activation and adjustment of the VTVPA when a ventricular sensing event occurs during the ventricular refractory period. It also has the function of adjusting the delivery timing of ventricular pacing events based on the VTVPA. The pacing control module 6 delivers ventricular pacing events according to the adjusted delivery timing, effectively preventing ventricular vulnerable period pacing while ensuring necessary ventricular pacing support and maintaining a relatively stable ventricular rate. The following details the function of the implantable medical device 1 that effectively prevents ventricular vulnerable period pacing.

[0041] In this embodiment, the ventricular sensing module 2 detects ventricular intrinsic activity in real time, where ventricular intrinsic activity includes ventricular premature beats and ventricular tachycardia. After detecting ventricular intrinsic activity, the pacing control module 6 determines whether the detected ventricular intrinsic activity is a refractory period ventricular sensing event. Specifically, if the ventricular intrinsic activity occurs within the ventricular refractory period, it is identified as a refractory period ventricular sensing event; if the ventricular intrinsic activity does not affect the pacing sequence, all ventricular intrinsic activity is also identified as a refractory period ventricular sensing event.

[0042] In single-chamber and dual-chamber modes of implantable medical devices, the 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 and VVI, if ventricular intrinsic activity occurs within the ventricular refractory period, it is identified as a ventricular refractory event. In modes where ventricular sensing does not affect pacing timing, such as VOO, all ventricular intrinsic activity is identified as a ventricular refractory event.

[0043] When the pacing control module 6 detects a ventricular sensing event during the refractory period, it sends a notification signal to the treatment control module 9. The treatment control module 9 immediately controls the start of a ventricular tachycardia ventricular pace adjustment window interval (VTVPA) based on the notification of the occurrence of the ventricular sensing event during the refractory period. The VTVPA can cover the ventricular vulnerable period and prevent ventricular tachycardia. The VTVPA is set based on the clinical evaluation results of individual heart rhythm changes, T waves, and cardiac status.

[0044] In this embodiment, individual heart rhythm changes include changes in the RR interval, RP interval, and PP interval. The RR interval is the interval between two adjacent R waves, the RP interval is the interval between adjacent R waves and a ventricular pacing event VP, and the PP interval is the interval between two adjacent ventricular pacing events VP. Clinical assessment results of T waves include a set T wave duration and a set T wave start time sequence, which can be set by a physician via the external device 10. Clinical assessment results of cardiac status primarily determine the definition of the adjustment threshold for VTVPA.

[0045] Based on this, Figure 2As shown in FIG, VTVPA is defined as the window interval formed from the start time T1 to the end time T2 after the ventricular sensing event (VR) in the refractory period, wherein the end time T2 is defined as the sum of the corresponding time T0 of the ventricular sensing event VR in the refractory period and half of the previous RR interval, RP interval or PP interval, and the adjustment threshold delta, that is, T2 = T0 + 1 / 2 * A + delta, wherein the adjustment threshold delta is set according to the clinical assessment results of the cardiac status, A is RR, RP or PP; The start time T1 is defined as the difference between the end time T2 and the set T-wave duration B, that is, T1 = T2 - B. Assuming B = 250 ms, then T1 = T2 - 250 ms. The start time T1 can also be defined as the sum of the corresponding time T0 of the ventricular sensory event VR during the refractory period and the set T-wave start time sequence C, that is, T1 = T0 + C. Assuming C = 100 ms, then T1 = T0 + 100 ms. The maximum of T1 = T2 - B and T1 = T0 + C is ultimately taken as the final start time T1. Based on this, the VTVPA is divided into the first half and the second half, that is, the middle time between T1 and T2 is Tm, which is dynamically updated during the application process.

[0046] Based on the definition of VTVPA, the T wave is crucial for determining the specific ventricular vulnerable period. However, the T wave's position and duration typically vary with heart rhythm and individual differences. Therefore, this embodiment combines individual heart rhythm variations (RR, RP, and PP), clinical assessment of the patient's cardiac status (a configurable threshold delta that can be adjusted based on cardiac health), and clinical assessment of the T wave (configurable T wave duration and T wave onset) to define a specific VTVPA window interval, which is used to define the ventricular vulnerable period. Physiologically, the vulnerable period refers to a specific period in the cardiac cycle, roughly adjacent to the T wave on the surface electrocardiogram (ECG). This VTVPA window interval definition aligns with this physiological definition. By dynamically adjusting the VTVPA window with changes in heart rhythm, the range of the ventricular vulnerable period can be more precisely defined, reducing transient reactions of implantable medical devices caused by overly broad definitions of the ventricular vulnerable period, and improving the algorithm's specificity.

[0047] Therapy control module 9 determines, based on the activated VTVPA, the expected ventricular pacing event delivery time to effectively avoid ventricular vulnerable period pacing. During the determination, it determines whether condition group I and condition group II are met. If condition group I is met, the expected ventricular pacing event VP delivery time is adjusted to the VTVPA start time T1. If condition group II is met, the expected ventricular pacing event VP delivery time is adjusted to the VTVPA end time T2. The new ventricular pacing event delivery time is updated as an operating parameter in the storage module. The pacing control module 6 retrieves the operating parameter from the storage module 7 to perform the pacing event.

[0048] In this embodiment, condition group I includes the following: the expected ventricular pacing event occurs in the first half of the VTVPA, i.e., the expected ventricular pacing event VP occurs between T1 and Tm; the current time Tt precedes the VTVPA start time T1, i.e., Tt < T1; when ventricular pacing is in dual-chamber mode, the VTVPA start time is greater than the fastest allowable ventricular pacing frequency point (i.e., the upper tracking frequency limit); and the difference between the atrial pacing event and the start time T1 is greater than the atrioventricular interval threshold β, i.e., (AP - T1) > β. The atrioventricular interval threshold β is the minimum atrioventricular (AV) interval. Assuming β is 30 ms, (AP - T1) > 30 ms. When condition group I is met, the delivery time of the expected ventricular pacing event VP is adjusted to the VTVPA start time T1, as shown in FIG4(a).

[0049] In an embodiment, condition group II includes: the expected ventricular pacing event occurs during VTVPA, and condition group I is not satisfied. When condition group II is satisfied, the delivery time of the expected ventricular pacing event is adjusted to the termination time T2 of VTVPA, as shown in FIG4(b).

[0050] When a ventricular pacing event (VP) is delivered early to T1 or delayed to T2, a new pacing sequence is delivered based on the new VP delivery time, as shown in Figures 4(a) and 4(b). If the expected VP occurs outside the T1-T2 interval, ventricular pacing is delivered normally, and a new pacing sequence is set based on the current ventricular pacing time. Updating the pacing sequence based on the adjusted ventricular pacing helps maintain a relatively stable ventricular rate.

[0051] Ventricular depolarization is crucial for cardiac output. Directly inhibiting ventricular pacing during the vulnerable period without supplemental ventricular pacing may result in insufficient cardiac output, affecting the patient's activity needs. At the same time, a relatively stable ventricular rate is more in line with the physiological needs of the heart. Therefore, adjusting the delivery of ventricular pacing locally is beneficial to cardiac output and maintaining a relatively stable ventricular rate. An excessively fast ventricular pacing rate is detrimental to cardiac output, so the adjusted ventricular pacing rate should not exceed the maximum allowable ventricular pacing rate. To ensure AV hemodynamic synchronization, the adjusted AV interval should not be lower than a configurable minimum value (e.g., 30ms). In short, adjusting the delivery of ventricular pacing locally is beneficial to cardiac output and maintaining a relatively stable ventricular rate.

[0052] In the embodiment, after the VTVPA is turned on, when ventricular tachycardia occurs, the treatment control module 9 is notified that a ventricular sensing event in a new refractory period is detected, and the treatment control module 9 detects that the ventricular sensing event VR' in the new refractory period occurs before T2 of the currently turned-on VTVPA, such as Figure 3(a) to Figure 3(c) As shown, regardless of whether the new VR' occurs between T0 and T1, T1 and Tm, or Tm and T2, the T1 of the VTVPA must remain unchanged, and the T2 of the VTVPA must be extended backward along the time sequence to T2'. Simultaneously, the Tm of the VTVPA is updated to form a new VTVPA. The extended T2 is defined as the sum of T0', the time corresponding to the ventricular sensing event within the new refractory period, half of the previous RR interval, RP interval, or PP interval, and the adjustment threshold delta: T2 = T0 + 1 / 2 * A + delta. The adjustment threshold delta is set based on clinical assessment of cardiac status, with A representing RR, RP, or PP.

[0053] In this embodiment, the middle time Tm of the VTVPA is updated as follows: as shown in FIG3(a), when the new ventricular sensing event VR' in the refractory period occurs between the corresponding time T0 of the ventricular sensing event in the original refractory period and the starting time T1 of the original VTVPA, the middle time Tm is updated to the middle time of the new VTVPA, that is, Tm'=1 / 2*(T1-T2'); Figure 3(b) and 3(c) As shown, when the new ventricular sensing event VR' occurs between the start time T1 and the end time T2 of the original VTVPA, the intermediate time Tm is updated to the corresponding time of the ventricular sensing event in the new refractory period, that is, Tm'=T0'.

[0054] When a fast heart rhythm or more interference occurs, it is impossible to distinguish the impact of each ventricular sensing event on the ventricular vulnerable period. In this case, using the VTVPA window expansion to update the VTVPA can adapt to the changes in the ventricular vulnerable period in this state, thereby more reasonably defining the ventricular vulnerable period; after updating the VTVPA, the treatment control module 9 judges condition group I and condition group II based on the new VTVPA to adjust the expected ventricular pacing event delivery time and updates it to the storage module 7, and the pacing control module 6 performs the pacing event according to the adjusted ventricular pacing event delivery time.

[0055] In the embodiment, the clock / timing module 5 is controlled by the pacing control module 6. According to the VTVPA, the clock / timing module 5 performs timing from the corresponding moment T0 of the ventricular sensing event in the refractory period to the starting moment T1 of the VTVPA, from the starting moment T1 of the VTVPA to the middle moment Tm of the VTVPA, and from the middle moment Tm of the VTVPA to the ending moment T2 of the VTVPA, that is, the clock / timing module 5 performs timing from T0 to T1, from T1 to Tm, and from Tm to T2, respectively. After the timing expires, the pacing control module 6 is notified. 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.

[0056] In this embodiment, an external device controls the activation or deactivation of the VTVPA function based on the operating mode of the implantable medical device. When the VTVPA function is deactivated, the implantable medical device does not expand the VTVPA and does not adjust the timing of ventricular pacing events anticipated by the VTVPA, thereby increasing the flexibility of the VTVPA function. The external device can also update VTVPA function parameters, specifically adjusting the threshold delta, T wave duration, T wave onset sequence, and atrioventricular interval threshold β, to storage module 7 and synchronize them to treatment control module 9.

[0057] Specific implementation examples Figure 1 As shown, medical personnel can use the external device 10 to interact with the wireless control module 4 in the implantable medical device 1 to modify VTVPA-related operating parameters stored in the storage module 7, such as on or off, based on the specific conditions of different patients. The treatment control module 9 can also flexibly adjust the VTVPA-related operating parameters stored in the storage module 7, such as on, off, or delta value.

[0058] The VTVPA function provided in the above embodiment is applicable to all single-chamber and dual-chamber modes with ventricular pacing, can be used in multiple working modes, and has a wide range of effects.

[0059] Figure 5 This is a working process of the pulse pacing system regarding the VTVPA window interval provided by an embodiment. Figure 5As shown, based on the pulse pacing system provided in the above embodiment, the workflow of the VTVPA window interval is as follows:

[0060] After the ventricular sensing module 2 of the implantable medical device 1 detects a ventricular sensing event (11), the pacing control module 6 determines whether the current ventricular sensing event is within the refractory period (12). If it is outside the refractory period, the pacing control module 6 performs ventricular sensing outside the refractory period (13). If it is within the refractory period, the treatment control module 9 is notified, and the treatment control module 9 determines the current VTVPA_flag value (15, 16, 18).

[0061] According to Figure 2 If VTVPA_flag=0(15), the treatment control module 9 calculates T1, Tm and T2 of VTVPA and updates them to the storage module 7, and calculates the expected ventricular pacing event release time Tp; the treatment control module 9 determines whether the ventricular pacing early release condition group I is currently satisfied. If so, the clock / timing module 5 is controlled to reset the ventricular pacing time Tp=T1; otherwise, the pacing control module 6 directly starts the first fixed time period T0 according to the updated T1, Tm and T2. ~T1 and sets VTVPA_flag=1 (22); after the first fixed time period T0~T1 expires (23), the pacing control module 6 starts the second fixed time period T1~Tm and sets VTVPA_flag=2 (24); after the second fixed time period T1~Tm expires (25), the pacing control module 6 starts the third fixed time period Tm~T2 and sets VTVPA_flag=3 (26); after the third fixed time period Tm~T2 expires (27), the pacing control module 6 sets VTVPA_flag=0 (28);

[0062] For the VTVPA window interval shown in FIG3(a), if VTVPA_flag=1 (16), the treatment control module 9 recalculates the Tm and T2 time points (17) and updates them to the storage module 7, and the pacing control module 6 waits for the expiration of the first fixed time period T0-T1, which is the time period for the ventricular sensing event to be activated in the previous refractory period; after the expiration of the first fixed time period T0-T1 (23), the pacing control module 6 activates the second fixed time period T1-Tm according to the updated Tm and T2 and sets VTVPA_flag=2 (24); after the expiration of the second fixed time period T1-Tm (25), the pacing control module 6 activates the third fixed time period Tm-T2 according to the updated Tm and T2 and sets VTVPA_flag=3 (26); after the expiration of the third fixed time period Tm-T2 (27), the pacing control module 6 sets VTVPA_flag=0 (28);

[0063] For the VTVPA window interval shown in FIG3( b ), if VTVPA_flag=2 (18), the treatment 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 fixed time period that is currently turned on (the ventricular sensing event is turned on in the previous refractory period); the pacing control module 6 turns on the third fixed time period Tm~T2 according to the updated Tm and T2 and sets VTVPA_flag=3 (26); after the third fixed time period Tm~T2 expires (27), the pacing control module 6 sets VTVPA_flag=0 (28);

[0064] For the VTVPA window interval shown in FIG3(c), if VTVPA_flag>2(18), the treatment control module 9 recalculates the T2 time point, sets Tm to the current time T0'(19) and updates it to the storage module 7, and clears the third fixed time period that is currently turned on (the ventricular sensing event is turned on in the previous refractory period); the pacing control module 6 turns on the third fixed time period Tm~T2 according to the updated Tm and T2 and sets VTVPA_flag=3(26); after the third fixed time period Tm~T2 expires (27), the pacing control module 6 sets VTVPA_flag=0(28.

[0065] Figure 6 FIG1 is a flow chart of a pulse pacing system for adjusting ventricular pacing within a VTVPA window according to an embodiment. Figure 6 As shown in Figure 2, the process of adjusting ventricular pacing in the VTVPA window is as follows:

[0066] The ventricular pacing when the expected VP delivery time point is outside the VTVPA window interval is implemented as follows: the pacing control module 6 detects that the ventricular pacing interval of the clock / timing module 5 has expired (30), and then determines whether the current VTVPA_flag is 3 (31). At this time, it is outside the T1-T2 interval, and the VTVPA_flag should be 0 or 1. Therefore, the pacing control module 6 delivers ventricular pacing normally and sets the pacing timing (33). At the same time, it sets VTVPA_flag=0 and clears the first, second, and third timers (34).

[0067] For the embodiment of adjusting the early release of ventricular pacing as shown in FIG4(a), the pacing control module 6 detects that the ventricular pacing interval of the clock / timing module 5 has expired (30), and then determines whether the current VTVPA_flag is 3 (31). Figure 5In the embodiment shown, the ventricular pacing delivery time has been adjusted in advance and set at time T1, so VTVPA_flag is not 3 at this time. Therefore, the pacing control module 6 delivers ventricular pacing normally (adjusted ventricular pacing) and sets the pacing timing (33). At the same time, it sets VTVPA_flag=0 and clears the first, second, and third timers (34).

[0068] For the embodiment of adjusting the delayed release of ventricular pacing as shown in FIG4( b ), the pacing control module 6 detects that the ventricular pacing interval of the clock / timing module 5 has expired (30), and then determines whether the current VTVPA_flag is 3 (31). At this time, it is in the interval Tm to T2, and VTVPA_flag should be 3, so the ventricular pacing timing is reset to Tp = (T2 + 1ms) (32), where 1ms is added to make the third timer expire first, so that V can be detected when the new ventricular pacing interval expires. If TVPA_flag is not 3, the module continues to wait for the pacing control module 6 to detect the expiration of the ventricular pacing interval of the clock / timing module 5 (30) and to determine whether the current VTVPA_flag is 3 (31). At this time, the Tm-T2 interval has timed out and VTVPA_flag is not 3. Therefore, the pacing control module 6 normally delivers ventricular pacing (adjusted ventricular pacing) and sets the pacing timing (33). At the same time, it sets VTVPA_flag = 0 and clears the first, second, and third timers (34).

[0069] The pulse stimulation system provided in the above embodiment can effectively avoid ventricular vulnerable period pacing, thereby reducing the probability of rapid ventricular arrhythmias caused by ventricular vulnerable period pacing, thereby reducing the adverse consequences of rapid ventricular arrhythmias that may be life-threatening; it can also more accurately define the ventricular vulnerable period under different heart rhythm states, thereby increasing the probability of avoiding ventricular vulnerable period pacing; it can also ensure necessary ventricular pacing support and maintain a relatively stable ventricular rate while effectively avoiding ventricular vulnerable period pacing; it can also be used in multiple working modes, with a wide and flexible range of action.

[0070] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An implantable medical device capable of effectively avoiding ventricular vulnerable period pacing, characterized in that: It includes a ventricular sensing module, a ventricular pacing module, a pacing control module, a treatment control module, and a storage module; The ventricular sensing module is used to detect the ventricular activity itself; The pacing control module is used to determine whether the ventricular activity itself is a ventricular sensing event during the ventricular refractory period; The treatment control module is configured to control the start of a ventricular pacing adjustment window interval (VTVPA) to prevent ventricular tachycardia and to cover the ventricular vulnerability period when a ventricular sensing event occurs during the ventricular refractory period, wherein the VTVPA is set based on individual heart rhythm changes, clinical assessment results of T waves, and clinical assessment results of cardiac status; The treatment control module is configured to control the adjustment of the expected ventricular pacing event delivery time to the start time of the VTVPA when it is determined that condition group I is satisfied; and control the adjustment of the expected ventricular pacing event delivery time to the end time of the VTVPA when condition group II is satisfied, and update the new ventricular pacing event delivery time as an operating parameter to the storage module; Condition Group I includes: the expected ventricular pacing event is in the first half of VTVPA, the current time is prior to the start time of VTVPA, when ventricular pacing is in dual-chamber mode, the start time of VTVPA is greater than the fastest allowed ventricular pacing frequency point, and the difference between the atrial pacing event and the start time T1 is greater than the atrioventricular interval threshold β; Condition Group II includes: the expected ventricular pacing event is during VTVPA, and Condition Group I is not met; The pacing control module is configured to obtain operating parameters from the storage module to control the ventricular pacing module to perform ventricular pacing; the individual heart rhythm changes include changes in the RR interval, the RP interval, and the PP interval, wherein the RR interval is the interval between two adjacent R waves, the RP interval is the interval between adjacent R waves and a ventricular pacing event VP, and the PP interval is the interval between two adjacent ventricular pacing events VP; the clinical assessment results of the T wave include a set T wave duration and a set T wave start time sequence; The VTVPA is defined as the window interval formed from the starting time T1 to the ending time T2 after the ventricular sensing event in the refractory period, wherein the ending time T2 is defined as the sum of the corresponding time of the ventricular sensing event in the 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 results of the cardiac state; the starting time T1 is defined as the maximum value of the sum of the corresponding time of the ventricular sensing event in the refractory period and the set T wave starting time sequence.

2. The implantable medical device capable of effectively avoiding ventricular vulnerable period pacing according to claim 1, characterized in that: When the treatment control module detects a new ventricular sensing event in the refractory period before the expiration of the end time T2 of the VTVPA, the treatment control module maintains the start time T1 of the VTVPA unchanged, extends the end time T2 of the VTVPA backward along the time sequence, and updates the middle time Tm that divides the VTVPA into the first half and the second half to form a new VTVPA; wherein the extended end time T2 is defined as the sum of the corresponding time of the ventricular sensing event in 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 a clinical assessment result of the cardiac state; The treatment control module makes judgments on condition group I and condition group II based on the new VTVPA to adjust the expected delivery time of the ventricular pacing event.

3. The implantable medical device capable of effectively avoiding ventricular vulnerable period pacing according to claim 2, characterized in that: In the treatment control module, the update method of the intermediate time Tm of VTVPA is: When the ventricular sensing event in the new refractory period occurs between the corresponding time of the ventricular sensing event in the original refractory period and the starting time T1 of the original VTVPA, the intermediate time Tm is updated to the intermediate time of the new VTVPA; When the ventricular sensing event in the new refractory period occurs between the start time T1 and the end time T2 of the original VTVPA, the intermediate time Tm is updated to the corresponding time of the ventricular sensing event in the new refractory period.

4. The implantable medical device capable of effectively avoiding ventricular vulnerable period pacing according to claim 1, characterized in that: The pacing control module determines whether the ventricular self-activity is a ventricular sensing event within the refractory period, including: if the ventricular self-activity occurs within the ventricular refractory period, it is identified as a ventricular sensing event within the refractory period; if the ventricular self-activity does not affect the pacing timing, all ventricular self-activity is also identified as a ventricular sensing event within the refractory period; The pacing control module sends a notification signal to the treatment control module when detecting a ventricular sensing event during the refractory period.

5. The implantable medical device capable of effectively avoiding ventricular vulnerable period pacing according to claim 1, characterized in that: It also includes a clock / timing module, which is controlled by the pacing control module and, based on VTVPA, times the corresponding moment of the ventricular sensing event in the refractory period to the start moment of VTVPA, the start moment of VTVPA to the middle moment Tm of VTVPA, and the middle moment Tm of VTVPA to the end moment of VTVPA, and notifies the pacing control module after the timing expires.

6. The implantable medical device capable of effectively avoiding ventricular vulnerable period pacing according to claim 1, characterized in that: It also includes a wireless thread control module for communicating with the in vitro device to achieve interaction between the operating parameters in the storage module and the in vitro device.

7. A pulse stimulation system capable of effectively avoiding ventricular vulnerable period pacing, characterized in that: An implantable medical device or an in vitro device according to any one of claims 1 to 6; The implantable medical device establishes communication with the external device and interacts with the operating parameters in the storage module.

8. The pulse stimulation system capable of effectively avoiding ventricular vulnerable period pacing according to claim 7, characterized in that: The threshold, T wave duration, T wave starting time sequence, and atrioventricular interval threshold are updated and adjusted to the storage module through the extracorporeal device and synchronized to the treatment control module.

9. The pulse stimulation system capable of effectively avoiding ventricular vulnerable period pacing according to claim 7, characterized in that: The VTVPA function is controlled to be turned on or off by an external device according to the working mode of the implantable medical device. When the VTVPA function is turned off, the implantable medical device does not turn on the VTVPA and does not adjust the delivery time of the ventricular pacing event expected by the VTVPA.

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