Patent ID: 7254442

Claim:
A method of LV-only fusion pacing therapy delivery to a non-synchronous pair of ventricles, comprising: a) measuring an intrinsic P-R cardiac interval for a right ventricular (RV) chamber for at least one prior cardiac cycle; b) decrementing the P-R interval to derive a nominal A-LVp interval; c) delivering an LV-only pacing therapy using the nominal A-LVp interval and d) determining whether ventricular fusion resulted, and in the event that adequate ventricular fusion resulted, then: i) measuring a left ventricular pacing, right ventricular sensing (LEPARS) interval by the amount of time elapsed between the delivery of the LV-only pacing therapy and a subsequent sensed depolarization of the RV; and ii) delivering during a subsequent cardiac cycle at least one LV-only pacing therapy pulse to a left ventricular (LV) chamber, wherein said at least one LV-only pacing therapy pulse is delivered at the expiration of an A-LVp interval that preserves heart rate response requirements and substantially preserves the LEPARS interval; and in the event that ventricular fusion failed to result, then: modifying the A-LVp interval and repeating step c) through step d) above wherein the modified A-LVp interval is implemented in lieu of the nominal A-LVp interval.