Method and apparatus for ambulatory optimization of multi-site pacing using heart sounds

A system for delivering pacing pulses through a plurality of electrodes to a heart having first and second ventricles, the plurality of electrodes including a plurality of first ventricular electrodes placed in or on the first ventricle, the system comprising:

• a cardiac sensing circuit configured to sense one or more cardiac signals;
• a pacing output circuit configured to deliver the pacing pulses;
• a heart sound sensor configured to sense a heart sound signal;
• and
• a control circuit configured to control the delivery of the pacing pulses using cardiac electrical events and a plurality of pacing parameters, the control circuit including:
• a heart sound detector configured to detect heart sounds including second heart sounds (S2) using the heart sound signal;
• an electrical event detector configured to detect the cardiac electrical events including ventricular depolarizations (R-waves) using at least one cardiac signal of the sensed one or more cardiac signals;
• a measurement module configured to measure at least one optimization parameter indicative of hemodynamic response to the delivery of the pacing pulses using the detected heart sounds and to measure an S2-R interval between an occurrence of the S2 and a subsequently adjacent R-wave of the R-waves;
• an optimization module configured to perform an optimization procedure including selection of an optimal pacing configuration from a plurality of pacing configurations using the at least one optimization parameter while keeping the S2-R interval within an acceptable range in response to an optimization command, the selection of the optimal pacing configuration including selection between a single-site pacing configuration and a multi-site pacing configuration, the single-site pacing configuration being a configuration of a plurality of single-site configurations each specifying a single first ventricular electrode of the plurality of first ventricular electrodes for delivering first ventricular pacing pulses of the pacing pulses, the multi-site pacing configuration being a configuration of a plurality of multi-site pacing configurations each specifying two or more first ventricular electrodes of the plurality of first ventricular electrodes for delivering the first ventricular pacing pulses of the pacing pulses;
• and
• an optimization initiator configured to generate the optimization command.