Modulate pacing rate to increase the percentage of effective ventricular capture during atrial fibrillation
The present disclosure pertains to cardiac pacing methods and systems, and, more particularly, to cardiac resynchronization therapy (CRT). In particular, the present disclosure pertains to determining whether a patient is experiencing atrial fibrillation (AF). If the patient is experiencing AF, the efficacy of CRT is determined. A signal is sensed in response to a ventricular pacing stimulus. Through signal processing, a number of features are parsed from the signal and a determination is made as to whether the ventricular pacing stimulus evoked a response from the ventricle.
1 . An implantable medical device comprising:
a control module configured to be coupled to at least one electrode and to deliver ventricular pacing therapy to a patient at a pacing rate to increase effective ventricular capture during atrial fibrillation in an active mode and a power conservation mode, wherein the control module is configured to:
determine that the patient is experiencing atrial fibrillation based on cardiac signals sensed by the at least one electrode;
initiate delivery of the ventricular pacing therapy using the at least one electrode in response to determining the patient is in atrial fibrillation;
sense cardiac signals using the at least one electrode in response to the delivery of the ventricular pacing therapy;
enable effective capture analysis during the active mode, wherein the effective capture analysis comprises determining capture of the ventricular pacing therapy based on the sensed cardiac signals and modifying the pacing rate in response to the determined capture of the ventricular pacing therapy; and
disable the effective capture analysis during the power conservation mode to maximize battery life.
2 . The device of claim 1 , further comprising the at least one electrode configured to deliver the ventricular pacing therapy to a patient's heart and to sense cardiac signals from the patient's heart.
3 . The device of claim 1 , wherein the control module is further configured to initiate the active mode in response to determining the patient is in atrial fibrillation.
4 . The device of claim 3 , wherein the control module is further configured to switch to the power conservation mode from the active mode after expiration of an initiation time period.
5 . The device of claim 4 , wherein the initiation time period is greater than or equal to 30 seconds.
6 . The device of claim 1 , wherein the control module is further configured to switch to the active mode from the power conservation mode after expiration of a hold time period.
7 . The device of claim 6 , wherein the hold time period is greater than or equal to 20 seconds.
8 . The device of claim 1 , wherein the control module is further configured to switch to the power conservation mode from the active mode in response to one or more of expiration of an active time period and a number of ventricular events monitored during the active mode exceeding a ventricular event threshold.
9 . The device of claim 8 , wherein the active time period is less than or equal to 10 seconds.
10 . The device of claim 8 , wherein the ventricular event threshold is less than or equal to 10.
11 . The device of claim 1 , wherein the control module is further configured to increase the pacing rate during the power conservation mode in response to a selected number of sensed ventricular events exceeding a sensed ventricular event threshold.
12 . The device of claim 11 , wherein the sensed ventricular event threshold is greater than or equal to 2.
13 . A method comprising:
delivering ventricular pacing therapy to a patient at a pacing rate to increase effective ventricular capture during atrial fibrillation in an active mode and a power conservation mode;
determining that the patient is experiencing atrial fibrillation based on cardiac signals sensed by at least one electrode;
initiating delivery of the ventricular pacing therapy using the at least one electrode in response to determining the patient is in atrial fibrillation;
sensing cardiac signals using the at least one electrode in response to the delivery of ventricular pacing therapy;
enabling effective capture analysis during the active mode, wherein the effective capture analysis comprises determining capture of the ventricular pacing therapy based on the sensed cardiac signals and modifying the pacing rate in response to the determined capture of the ventricular pacing therapy; and
disabling the effective capture analysis during the power conservation mode to maximize battery life.
14 . The method of claim 13 , wherein the method further comprises initiating the active mode in response to determining the patient is in atrial fibrillation.
15 . The method of claim 14 , wherein the method further comprises switching to the power conservation mode from the active mode after expiration of an initiation time period.
16 . The method of claim 15 , wherein the initiation time period is greater than or equal to 30 seconds.
17 . The method of claim 13 , wherein the method further comprises switching to the active mode from the power conservation mode after expiration of a hold time period.
18 . The method of claim 17 , wherein the hold time period is greater than or equal to 20 seconds.
19 . The method of claim 13 , wherein the method further comprises switching to the power conservation mode from the active mode in response to one or more of expiration of an active time period and a number of ventricular events monitored during the active mode exceeding a ventricular event threshold.
20 . The method of claim 19 , wherein the active time period is less than or equal to 10 seconds.
21 . The method of claim 19 , wherein the ventricular event threshold is less than or equal to 10.
22 . The method of claim 13 , wherein the method further comprises increasing the pacing rate during the power conservation mode in response to a selected number of sensed ventricular events exceeding a sensed ventricular event threshold.
23 . The method of claim 22 , wherein the sensed ventricular event threshold is greater than or equal to 2.
24 . An implantable medical device comprising:
a control module configured to be operably coupled to at least one electrode to deliver ventricular pacing therapy at a pacing rate to increase effective ventricular capture and to sense cardiac signals from the patient's heart, wherein the control module is further configured to:
determine that the patient is experiencing atrial fibrillation based on cardiac signals sensed by the at least one electrode;
initiate delivery of the ventricular pacing therapy using the at least one electrode in response to determining the patient is in atrial fibrillation;
sense cardiac signals using the at least one electrode in response to the delivery of the ventricular pacing therapy; and
periodically determine effective capture of the ventricular pacing therapy based on the sensed cardiac signals and modify the pacing rate of the ventricular pacing therapy in response to the determined effective capture of the ventricular pacing therapy.
25 . The device of claim 24 , wherein the periodically determining effective capture of the ventricular pacing therapy based on the sensed cardiac signals and modifying the pacing rate of the ventricular pacing therapy in response to the determined effective capture of the ventricular pacing therapy comprises determining effective capture of the ventricular pacing therapy based on the sensed cardiac signals and modifying the pacing rate of the ventricular pacing therapy in response to the determined effective capture of the ventricular pacing therapy for an active time period upon expiration of a hold time period.
26 . The device of claim 25 , wherein the hold time period is greater than the active time period.