Effectiveness of ventricular sense response in CRT

1. A method comprising:

(a) delivering biventricular cardiac resynchronization therapy (CRT) to a heart at an atrio-ventricular (AV) interval;

(b) monitoring atrial contraction events;

(c) monitoring intrinsic ventricular contraction events;

(d) applying a biventricular CRT pacing stimulus on detection of an intrinsic ventricular contraction event to produce a ventricular-sense response (VSR);

(e) recording electrical activity of the heart in a defined time window centered or off centered on a time of delivery of the biventricular CRT pacing stimulus to obtain an electrogram of the VSR;

(f) comparing the electrogram of the VSR, or features thereof, to a template electrogram, or features thereof, of a pure biventricular paced beat to determine a similarity index between the electrogram of the VSR and the template electrogram;

(g) determining whether the similarity index meets or exceeds a predetermined threshold, wherein if the similarity index meets or exceeds the threshold steps (a)-(f) are repeated; and

(h) determining whether an atrial contraction event preceded the VSR if the threshold is not met or exceeded.

2. The method of claim 1 , further comprising:

(i) if the atrial contraction event preceded the VSR and the threshold is not met or exceeded, determining whether a preset number of sequentially preceding VSRs were preceded by an atrial contraction event in which the similarity index did not meet or exceed the threshold,

wherein if the preset number of sequentially preceding VSRs were not preceded by atrial contraction events in which the similarity index did not meet or exceed the threshold, steps (a)-(h) are repeated;

(j) decreasing the AV interval of the CRT by a predetermined amount if the preset number of sequentially preceding VSRs were preceded by atrial contraction events in which the similarity index did not meet or exceed the threshold; and

(k) repeating steps (a)-(j) until the similarity index of a VSR meets or exceeds the predetermined threshold in step (g).

3. The method of claim 2 , wherein the decreasing the AV interval of the CRT by a predetermined amount in step (j) comprises decreasing the AV interval by between 5 milliseconds and 20 milliseconds.

4. The method of any of claims 1 - 3 , further comprising:

collecting data regarding electrical activity of the heart within a predefined time window from a start of the delivery of the CRT in step (a);

verifying no intrinsic ventricular event preceded, or occurred concurrently, with the delivery of the CRT; and

forming the template electrogram, or features thereof, from the collected data if no intrinsic ventricular event preceded, or occurred concurrently, with the delivery of the CRT.

5. The method claim 1 , wherein the monitoring atrial contraction events comprises monitoring atrial sensed events or monitoring atrial paced events.

6. The method of claim 1 , wherein the determining of a similarity index between the electrogram of the VSR and the template electrogram comprises computing a wavelet match percent.

7. A non-transitory computer readable medium for a system configured to deliver cardiac resynchronization therapy, the computer readable medium comprising instructions that, when implemented, cause the system to:

(a) deliver biventricular cardiac resynchronization therapy (CRT) to a heart at an atrio-ventricular (AV) interval;

(b) monitor atrial contraction events;

(c) monitor intrinsic ventricular contraction events;

(d) apply a biventricular CRT pacing stimulus on detection of an intrinsic ventricular contraction event to produce a ventricular-sense response (VSR);

(e) record electrical activity of the heart in a defined time window centered or off centered on a time of delivery of the biventricular CRT pacing stimulus to obtain an electrogram of the VSR;

(f) compare the electrogram of the VSR, or features thereof, and a template electrogram, or features thereof, of a pure biventricular paced beat to determine a similarity index between the electrogram of the VSR and the template electrogram;

(g) determine whether the similarity index meets or exceeds a predetermined threshold, and repeat steps (a)-(f) if the similarity index meets or exceeds the threshold; and

(h) determine whether an atrial contraction event preceded the VSR if the threshold is not met or exceeded.

8. The computer readable medium of claim 7 , further comprising instructions that when implemented, cause the system to:

(i) if the atrial contraction event preceded the VSR and the threshold is not met or exceeded, determine whether a preset number of sequentially preceding VSRs were preceded by an atrial contraction event in which the similarity index did not meet or exceed the threshold, and repeat steps (a)-(h) if the preset number of sequentially preceding VSRs were not preceded by atrial contraction events in which the similarity index did not meet or exceed the threshold;

(j) decrease the AV interval of the CRT by a predetermined amount if the preset number of sequentially preceding VSRs were preceded by atrial contraction events in which the similarity index did not meet or exceed the threshold; and

(k) repeat steps (a)-(j) until the similarity index of a VSR meets or exceeds the predetermined threshold in step (g).

9. A system comprising:

the computer readable medium of claim 7 or 8 ;

electronics capable of executing the instructions of the computer readable medium;

one or more electrodes to deliver the CRT of steps (a) and (d); and

one or more electrodes configured to monitor the atrial contractions events in step (a), monitor the intrinsic ventricular contraction events in step (c), record the electrical activity of the heart in step (e).

10. A device comprising:

the computer readable medium of claim 7 or 8 ;

a processor capable of executing the instructions of the computer readable medium;

one or more pacing circuits configured to deliver the CRT of steps (a) and (d); and

one or more sensing circuits configured to monitor the atrial contractions events in step (a), monitor the intrinsic ventricular contraction events in step (c), record the electrical activity of the heart in step (e).