Cardiac resynchronization therapy using accelerometer
An implantable medical device includes a plurality of electrodes to detect electrical activity, a motion detector to detect mechanical activity, and a controller to determine at least one electromechanical interval based on at least one of electrical activity and mechanical activity. The activity detected may be in response to delivering a pacing pulse according to an atrioventricular (AV) pacing interval using the second electrode. The electromechanical interval may be used to adjust the AV pacing interval. The electromechanical interval may be used to determine whether cardiac therapy is acceptable or whether atrial or ventricular remodeling is successful.
1. An implantable medical device comprising:
a plurality of electrodes comprising:
a first electrode configured to be implanted in an atrium of a patient's heart to deliver a cardiac therapy or sense atrial electrical activity of the atrium of the patient's heart; and
a second electrode configured to be implanted in a septal wall of the patient's heart distal to the first electrode and to deliver the cardiac therapy to or sense ventricular electrical activity of a ventricle of the patient's heart;
a motion detector to detect mechanical activity of the patient's heart;
a therapy delivery circuit operably coupled to the plurality of electrodes to deliver the cardiac therapy to the patient's heart;
a sensing circuit operably coupled to the plurality of electrodes to sense the atrial electrical activity and the ventricular electrical activity of the patient's heart, and operably coupled to the motion detector to sense the mechanical activity of the patient's heart; and
a controller comprising processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit, the controller configured to:
deliver at least one pacing pulse of the cardiac therapy according to an atrioventricular (AV) pacing interval using the second electrode;
determine at least one electromechanical interval based on one or more of the atrial electrical activity, the ventricular electrical activity, and the mechanical activity in response to delivering the at least one pacing pulse, wherein the at least one electromechanical interval is based on at least the mechanical activity in response to delivering the at least one pacing pulse, and wherein the at least one electromechanical interval comprises an interval from the ventricular electrical activity indicating ventricular pacing to the mechanical activity indicating mitral valve closure; and
adjust the AV pacing interval based on the at least one electromechanical interval.
2. The device according to claim 1 , wherein, to adjust the AV pacing interval based on the at least one electromechanical interval, the controller is further configured to:
determine whether the at least one electromechanical interval is acceptable for the cardiac therapy; and
adjust the AV pacing interval in response to the at least one electromechanical interval being unacceptable for the cardiac therapy.
3. The device according to claim 1 or 2 , wherein the at least one electromechanical interval comprises an interval from the atrial electrical activity indicating atrial activation to the mechanical activity indicating atrial contraction.
4. The device according to claim 3 , wherein the atrial activation detected is an intrinsic atrial activation detected using the first electrode.
5. The device according to claim 4 , wherein the mechanical activity indicating atrial contraction corresponds to an S4 heart sound.
6. The device according to claim 1 , further comprising a housing including a distal end region, wherein the first electrode is leadlessly coupled to the housing and the second electrode extends leadlessly from the distal end region of the housing, and wherein the motion detector, the therapy delivery circuit, the sensing circuit, and the controller are enclosed within the housing.
7. The device according to claim 1 , wherein the first electrode is a right atrial electrode and the second electrode is a tissue-piercing electrode.
8. The device according to claim 1 , wherein the first electrode is configured to be implanted in the right atrium (RA) of the patient's heart to deliver the cardiac therapy to or sense the atrial electrical activity of the RA of the patient's heart and the second electrode is configured to be implanted in the triangle of Koch region of the RA of the patient's heart to deliver the cardiac therapy to or sense the ventricular electrical activity of the left ventricle (LV) in the basal region, septal region, or basal-septal region of the left ventricular myocardium of the patient's heart.
9. The device according to claim 2 , wherein the interval from ventricular pacing to mitral valve closure is unacceptable in response to being longer than a predetermined percentage of an interval from intrinsic ventricular activation to mitral valve closure.
10. The device according to claim 1 or 9 , wherein the mechanical activity indicating mitral valve closure corresponds to an S1 heart sound.
11. The device according to claim 2 , wherein adjusting the AV pacing interval in response to the at least one electromechanical interval being unacceptable for the cardiac therapy comprises shortening the AV pacing interval in response to the at least one electromechanical interval being unacceptable for the cardiac therapy.
12. The device according to claim 2 , wherein, to determine whether the at least one electromechanical interval is acceptable for the cardiac therapy, the controller is further configured to:
receive electrical activity from an external electrode apparatus comprising a plurality of external electrodes;
determine a particular AV pacing interval based on the received electrical activity;
determine a respective threshold electromechanical interval using the particular AV pacing interval; and
compare the at least one electromechanical interval to the respective threshold electromechanical interval.
13. The device according to claim 1 , wherein to determine the at least one electromechanical interval, the controller is further configured to determine the at least one electromechanical interval based on the mechanical activity in response to delivering the at least one pacing pulse and based on one or more of the atrial electrical activity and the ventricular electrical activity.
14. An implantable medical device comprising:
a plurality of electrodes comprising:
a first electrode configured to be implanted in an atrium of a patient's heart to deliver a cardiac therapy or sense atrial electrical activity of the atrium of the patient's heart; and
a second electrode configured to be implanted in a septal wall of the patient's heart distal to the first electrode and to deliver the cardiac therapy to or sense ventricular electrical activity of a ventricle of the patient's heart;
a motion detector to detect mechanical activity of the patient's heart;
a therapy delivery circuit operably coupled to the plurality of electrodes to deliver the cardiac therapy to the patient's heart;
a sensing circuit operably coupled to the plurality of electrodes to sense the atrial electrical activity and the ventricular electrical activity of the patient's heart, and operably coupled to the motion detector to sense the mechanical activity of the patient's heart; and
a controller comprising processing circuitry operably coupled to the therapy delivery circuit and the sensing circuit, the controller configured to:
deliver at least one pacing pulse of the cardiac therapy according to an atrioventricular (AV) pacing interval using the second electrode;
determine at least one electromechanical interval based on one or more of the atrial electrical activity, the ventricular electrical activity, and the mechanical activity in response to delivering the at least one pacing pulse, wherein the at least one electromechanical interval is based on at least the mechanical activity in response to delivering the at least one pacing pulse; and
adjust the AV pacing interval based on the at least one electromechanical interval,
wherein, to adjust the AV pacing interval based on the at least one electromechanical interval, the controller is further configured to:
determine whether the at least one electromechanical interval is acceptable for the cardiac therapy; and
adjust the AV pacing interval in response to the at least one electromechanical interval being unacceptable for the cardiac therapy,
wherein, to determine whether the at least one electromechanical interval is acceptable for the cardiac therapy, the controller is further configured to:
receive electrical activity from an external electrode apparatus comprising a plurality of external electrodes;
determine a particular AV pacing interval based on the received electrical activity;
determine a respective threshold electromechanical interval using the particular AV pacing interval; and
compare the at least one electromechanical interval to the respective threshold electromechanical interval.
15. The device according to claim 14 , wherein the at least one electromechanical interval comprises an interval from the atrial electrical activity indicating atrial activation to the mechanical activity indicating atrial contraction.
16. The device according to claim 15 , wherein the atrial activation detected is an intrinsic atrial activation detected using the first electrode.
17. The device according to claim 16 , wherein the mechanical activity indicating atrial contraction corresponds to an S4 heart sound.
18. The device according to claim 14 , further comprising a housing including a distal end region, wherein the first electrode is leadlessly coupled to the housing and the second electrode extends leadlessly from the distal end region of the housing, and wherein the motion detector, the therapy delivery circuit, the sensing circuit, and the controller are enclosed within the housing.
19. The device according to claim 14 , wherein the first electrode is a right atrial electrode and the second electrode is a tissue-piercing electrode.
20. The device according to claim 14 , wherein the first electrode is configured to be implanted in the right atrium (RA) of the patient's heart to deliver the cardiac therapy to or sense the atrial electrical activity of the RA of the patient's heart and the second electrode is configured to be implanted in the triangle of Koch region of the RA of the patient's heart to deliver the cardiac therapy to or sense the ventricular electrical activity of the left ventricle (LV) in the basal region, septal region, or basal-septal region of the left ventricular myocardium of the patient's heart.
21. The device according to claim 14 , wherein the at least one electromechanical interval comprises an interval from the ventricular electrical activity indicating ventricular pacing to the mechanical activity indicating mitral valve closure, and wherein the interval from ventricular pacing to mitral valve closure is unacceptable in response to being longer than a predetermined percentage of an interval from intrinsic ventricular activation to mitral valve closure.
22. The device according to claim 21 , wherein the mechanical activity indicating mitral valve closure corresponds to an S1 heart sound.
23. The device according to claim 14 , wherein adjusting the AV pacing interval in response to the at least one electromechanical interval being unacceptable for the cardiac therapy comprises shortening the AV pacing interval in response to the at least one electromechanical interval being unacceptable for the cardiac therapy.
24. The device according to claim 14 , wherein to determine the at least one electromechanical interval, the controller is further configured to determine the at least one electromechanical interval based on the mechanical activity in response to delivering the at least one pacing pulse and based on one or more of the atrial electrical activity and the ventricular electrical activity.