Source: https://patents.google.com/patent/US9757567B2/en
Timestamp: 2018-05-20 16:31:14
Document Index: 599073745

Matched Legal Cases: ['art.\n8', 'art.\n9', 'art.\n10', 'art.\n18', 'art.\n19', 'art.\n20']

US9757567B2 - Modifying atrioventricular delay based on activation times - Google Patents
Modifying atrioventricular delay based on activation times Download PDF
US9757567B2
US9757567B2 US15176958 US201615176958A US9757567B2 US 9757567 B2 US9757567 B2 US 9757567B2 US 15176958 US15176958 US 15176958 US 201615176958 A US201615176958 A US 201615176958A US 9757567 B2 US9757567 B2 US 9757567B2
US15176958
US20160339247A1 (en )
This application is a continuation of U.S. patent application Ser. No. 13/744,038 (now allowed), filed Jan. 17, 2013 entitled “MODIFYING ATRIOVENTRICULAR DELAY BASED ON ACTIVATION TIMES” and also claims the benefit of U.S. Provisional Patent Application Ser. No. 61/588,924 filed 20 Jan. 2012, entitled “MODIFYING ATRIOVENTRICULAR DELAY BASED ON ACTIVATION TIMES,” which is incorporated herein by reference in its entirety.
For some patients suffering from heart failure and intraventricular conduction delays due to, e.g., left bundle branch block, right bundle branch block, the delivery of CRT can occur due to a single ventricular pacing stimulus by pre-exciting the ventricle with conduction delay. Such a stimulus must be properly timed relative to intrinsic depolarization of the other, non-delayed ventricle. This phenomenon may be referred to herein as “fusion pacing” since ventricular activation from a pacing stimulus fuses or merges with ventricular activation from intrinsic conduction. When the ventricular pacing stimulus is properly timed a desired ventricular resynchronization results with a minimum of pacing energy, thereby extending the operating life of an implantable pulse generator (e.g., an implantable cardioverter-defibrillator, pacemaker, and the like). Moreover, in some cases a more effective or physiologic form of CRT delivery can be achieved since the system and methods herein utilize a portion of intrinsic activation, which can be superior to an entirely evoked (e.g., paced) form of CRT. Fusion pacing may also be referred to herein as left ventricle-only pacing or right ventricle-only pacing.
To optimize or adjust the AV delay, a cardiac therapy device such as an IMD may measure a patient's intrinsic AV conduction time. A patient's intrinsic AV conduction time is the time between an intrinsic atrial event (e.g., depolarization of the right atrium) and an intrinsic ventricular event (e.g., depolarization of the right ventricle). As used herein, an “intrinsic” event or conduction is one that occurs or is conducted naturally (e.g., an intrinsic ventricular event is an event triggered by electrical activity transmitted across the AV node of the heart from the atria to the ventricles, etc.). A cardiac therapy device may periodically measure a patient's intrinsic AV conduction time, or interval, and adjust the AV delay in response to the measured intrinsic AV conduction time, e.g., to optimize cardiac functionality.
For each paced heartbeat 152, a measured activation time, or ΔT, may be measured and calculated continuously or periodically for a selected number of, or N, heartbeats 154 (e.g., 10 successive heartbeats). The measured activation time, or ΔT, is equal to the time between an atrial sense or atrial pace and the right ventricular activation (e.g., as determined by analysis of an electrogram of the right ventricle) minus the AV delay (e.g., the time between either an atrial sense or atrial pace and the left ventricular pace).
The measured activation times may then be evaluated 156. For example, if the measured activation time, or ΔT, is less than (e.g., less than or equal to) a predetermined reference activation time, or ΔTref, by a selected threshold value or is greater than (e.g., greater than or equal to) the predetermined reference activation time, or ΔTref, by the selected threshold, then it may be determined 156 that the AV delay should be adjusted 158.
As shown, the determination process 156 may also evaluate any statistical metric of the measured activation times such as, e.g., the standard deviation of the measured activation times from the predetermined reference activation times. For example, if a standard deviation of the difference between the measured activation time, or ΔT, and the predetermined reference activation time, or ΔTref, is less than a variability limit (e.g., 15 ms) for a first selected number of, or M, beats (e.g., 5 heartbeats) out a second selected number of, or N, beats (e.g., 10 heartbeats), then it may be determined 156 that the AV delay should be adjusted 158. If it is not determined that AV delay should be adjusted in process 156, the exemplary method 150 may continue delivering LV pacing 152 without adjusting the AV delay.
If it is determined that the AV delay should be adjusted, then the AV delay (e.g., the time period between the atrial sense or atrial pace and the ventricular pace) may be adjusted for the next beat 158. For example, the AV delay may be set to the median or modal value of the AV delay of a selected number of, or M, heartbeats (e.g., 5 heartbeats) plus a median or modal value of the difference between the measured activation times, or ΔT, and the predetermined reference activation time, or ΔTref, of the selected number of, or M, heartbeats 158.
Three exemplary calculations of measured activation times, or ΔT, are shown in FIG. 7. In these examples, the predetermined reference activation time, or ΔTref, for optimal fusion pacing is 50 ms and the threshold value is 10 ms.
In the first example 300, the time period between an atrial sense (As) and a ventricular pace (VP) is 140 ms (which is the AV delay) and the time period between the atrial sense and a right ventricular activation is 190 ms. Thus, the measured activation time, or ΔT, equals 50 ms, which is within the threshold value, 10 ms, of the predetermined reference activation time of 50 ms. Therefore, no adjustment to the AV delay may be triggered or initiated.
In the second example 310, the time period between an atrial sense (As) and a ventricular pace (VP) is 140 ms (which is the AV delay) and the time period between the atrial sense (As) and right ventricular activation is 220 ms. Thus, the measured activation time, or ΔT, equals 80 ms, which is not within the threshold value, 10 ms, of the predetermined reference activation time of 50 ms. Therefore, adjustment of the AV delay may be initiated.
In the third example 320, the time period between an atrial sense (As) and a ventricular pace (VP) is 140 ms (which is the AV delay) and the time period between the atrial sense (As) and right ventricular activation is 130 ms. In this example, the right ventricular activation occurred before the ventricular pace (VP), and therefore, the right ventricular activation may have occurred naturally (e.g., intrinsic conduction). The measured activation time, or ΔT, equals −10 ms, which is not within the threshold value, 10 ms, of the predetermined reference activation time of 50 ms. Therefore, adjustment of the AV delay may be initiated.
As shown, the difference between the measured activation time and the predetermined reference activation time may be calculated, which is −60 ms. The AV delay, or As-VP (next beat), may be set to the last AV delay (As-VP), which was 140 ms, plus the difference between the measured activation time and the predetermined reference activation time. As such, the new AV delay may be set to 80 ms. The dotted line in example 320 depicts where the next ventricular pace (VP) should occur using the newly adjusted AV delay.
1. An implantable medical device operable for delivery of cardiac therapy to a patient, the device comprising:
a therapy delivery module configured to deliver pacing therapy to either the left ventricle or the right ventricle of a patient's heart using at least one electrode;
a sensing module configured to sense electrical activity of the patient's heart using at least one other electrode; and
determine an AV delay,
control the delivery of the pacing therapy to either the left ventricle or the right ventricle of a patient's heart based on the AV delay, wherein the pacing therapy is delivered over a plurality of heartbeats,
sense the electrical activity of the patient's heart using the sensing module during the delivery of the pacing therapy,
measure a ventricular activation time for each of the plurality of heartbeats between the delivery of pacing stimulus of the pacing therapy and at least one selected fiducial point of the sensed electrical activity resulting from at least one of the delivered pacing stimulus of the pacing therapy and an intrinsic conduction of the patient's heart,
determine between whether or not to modify the AV delay for use in delivering pacing therapy based on one or more of the measured ventricular activation times resulting from the delivered pacing stimulus of the pacing therapy being greater than or less than a predetermined reference activation time by a selected threshold value,
modify the AV delay for use in delivering pacing therapy based on the measured ventricular activation times when determining that the AV delay is to be modified based on the one or more of the measured ventricular activation times resulting from the delivered pacing stimulus of the pacing therapy being greater than or less than a predetermined reference activation time by a selected threshold value, otherwise not modifying the AV delay based on the determination,
determine between whether or not to modify the AV delay for use in delivering pacing therapy based on one or more of the measured ventricular activation times resulting from the intrinsic conduction of the patient's heart being greater than or less than a predetermined reference activation time by a selected threshold value, and
modify the AV delay for use in delivering pacing therapy based on the measured ventricular activation times when determining that the AV delay is to be modified based on the one or more of the measured ventricular activation times resulting from the intrinsic conduction of the patient's heart being greater than or less than a predetermined reference activation time by a selected threshold value, otherwise not modifying the AV delay based on the determination.
2. The device of claim 1, wherein, to modify the AV delay for use in delivering pacing therapy based on the measured ventricular activation times, the control module is further configured to set the AV delay to the last AV delay plus the last measured activation time minus the predetermined reference activation time.
3. The device of claim 1, wherein, to modify the AV delay for use in delivering pacing therapy based on the measured ventricular activation times, the control module is further configured to set the AV delay to either a mode or a median of a selected number of previous AV delays plus either a mode or median of a selected number of activation time differences, wherein the activation time differences are the measured ventricular activation times minus the predetermined reference activation time.
4. The device of claim 1, wherein the control module is configured to modify the AV delay for use in delivering pacing therapy based on the measured ventricular activation times if a first selected number of the measured ventricular activation times are greater than or less than the predetermined reference activation time by the selected threshold value over a second selected number of heartbeats.
5. The device of claim 1, wherein, to modify the AV delay for use in delivering pacing therapy based on the measured ventricular activation times, the control module is configured to modify the AV delay for use in delivering pacing therapy if a standard deviation of a first selected number of activation time differences are less than a selected variability threshold value over a second selected number of heartbeats, wherein the activation time differences are the measured ventricular activation times minus the predetermined reference activation time.
6. The device of claim 1, wherein the sensing module is configured to sense electrical activity of the right ventricle of the patient's heart using the at least one electrode, and wherein the control module is configured to sense electrical activity of the right ventricle of the patient's heart using the sensing module during the delivery of the pacing therapy.
7. The device of claim 1, wherein sensing module is further configured to sense near-field electrical activity of the right ventricle of the patient's heart using the at least one electrode, wherein the control module is configured to sense near-field electrical activity of the right ventricle of the patient's heart using the sensing module during the delivery of the pacing therapy, and wherein the at least one selected fiducial point of the sensed electrical activity comprises a maximum value of the near-field electrical activity of the right ventricle of the patient's heart.
8. The device of claim 1, wherein sensing module is further configured to sense far-field electrical activity of the right ventricle of the patient's heart using the at least one electrode, wherein the control module is configured to sense far-field electrical activity of the right ventricle of the patient's heart using the sensing module during the delivery of the pacing therapy, and wherein the at least one selected fiducial point of the sensed electrical activity comprises a maximum negative slope of the far-field electrical activity of the right ventricle of the patient's heart.
9. The device of claim 1, wherein the at least one electrode is configured to deliver pacing therapy to the left ventricle of the patient's heart.
10. The device of claim 1, wherein the therapy delivery module is further configured to deliver bi-ventricular pacing therapy to the patient's heart, and wherein the control module is further configured to initiate the delivery of bi-ventricular pacing therapy to the patient's heart using the therapy delivery module if the modified AV delay is greater than a selected limit value.
11. A method for use in an implantable medical device operable for delivery of cardiac therapy to a patient, the method comprising:
delivering pacing therapy to either the left ventricle or the right ventricle of a patient's heart using at least one electrode based on an AV delay using an implantable medical device, wherein the pacing therapy is delivered over a plurality of heartbeats;
sensing electrical activity of the patient's heart using at least one other electrode of the implantable medical device during the delivery of the pacing therapy;
measuring a ventricular activation time for each of the plurality of heartbeats between the delivery of pacing stimulus of the pacing therapy and at least one selected fiducial point of the sensed electrical activity resulting from at least one of the delivered pacing stimulus of the pacing therapy and an intrinsic conduction of the patient's heart;
determining between whether or not to modify the AV delay for use in delivering pacing therapy based on one or more of the measured ventricular activation times resulting from the delivered pacing stimulus of the pacing therapy being greater than or less than a predetermined reference activation time by a selected threshold value;
modifying the AV delay for use in delivering pacing therapy based on the measured ventricular activation times when determining that the AV delay is to be modified based on the one or more of the measured ventricular activation times resulting from the delivered pacing stimulus of the pacing therapy being greater than or less than a predetermined reference activation time by a selected threshold value, otherwise not modifying the AV delay based on the determination;
determining between whether or not to modify the AV delay for use in delivering pacing therapy based on one or more of the measured ventricular activation times resulting from the intrinsic conduction of the patient's heart being greater than or less than a predetermined reference activation time by a selected threshold value; and
modifying the AV delay for use in delivering pacing therapy based on the measured ventricular activation times when determining that the AV delay is to be modified based on the one or more of the measured ventricular activation times resulting from the intrinsic conduction of the patient's heart being greater than or less than a predetermined reference activation time by a selected threshold value, otherwise not modifying the AV delay based on the determination.
12. The method of claim 11, wherein modifying the AV delay for use in delivering pacing therapy based on the measured ventricular activation times comprises setting the AV delay to the last AV delay plus the last measured ventricular activation time minus the predetermined reference activation time.
13. The method of claim 11, wherein modifying the AV delay for use in delivering pacing therapy based on the measured ventricular activation times comprises setting the AV delay to either a mode or a median of a selected number of previous AV delays plus either a mode or median of the selected number of ventricular activation time differences, wherein the ventricular activation time differences are the measured ventricular activation times minus the predetermined reference activation time.
14. The method of claim 11, wherein modifying the AV delay for use in delivering pacing therapy based on the measured ventricular activation times if a first selected number of the measured ventricular activation times are greater than or less than the predetermined reference activation time by the selected threshold value over a second selected number of heartbeats.
15. The method of claim 11, wherein modifying the AV delay for use in delivering pacing therapy based on the measured ventricular activation times comprises modifying the AV delay for use in delivering pacing therapy if a standard deviation of a first selected number of activation time differences are less than a selected variability threshold value over a second selected number of heartbeats, wherein the activation time differences are the measured ventricular activation times minus the predetermined reference activation time.
16. The method of claim 11, wherein sensing electrical activity of the patient's heart using at least one electrode of the implantable medical device during the delivery of the pacing therapy comprises sensing electrical activity of the right ventricle of the patient's heart using the at least one electrode.
17. The method of claim 11, wherein sensing electrical activity of the patient's heart using at least one electrode of the implantable medical device during the delivery of the pacing therapy comprises sensing near-field electrical activity of the right ventricle of the patient's heart using the at least one electrode during the delivery of the pacing therapy, and wherein the at least one selected fiducial point of the sensed electrical activity comprises a maximum value of the near-field electrical activity of the right ventricle of the patient's heart.
18. The method of claim 11, wherein sensing electrical activity of the patient's heart using at least one electrode of the implantable medical device during the delivery of the pacing therapy comprises sensing far-field electrical activity of the right ventricle of the patient's heart using the at least one electrode during the delivery of the pacing therapy, and wherein the at least one selected fiducial point of the sensed electrical activity comprises a maximum negative slope of the far-field electrical activity of the right ventricle of the patient's heart.
19. The method of claim 11, wherein delivering pacing therapy to either the left ventricle or the right ventricle of a patient's heart using at least one electrode based on an AV delay using an implantable medical device comprises delivering pacing therapy to the left ventricle of the patient's heart.
20. The method of claim 11, wherein the method further comprises delivering bi-ventricular pacing therapy to the patient's heart using the implantable medical device if the modified AV delay is greater than a selected limit value.
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US15668945 Continuation US9950176B2 (en) 2012-01-20 2017-08-04 Modifying atrioventricular delay based on activation times
US20160339247A1 true US20160339247A1 (en) 2016-11-24
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