Method and apparatus for optimizing 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 depolarization (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;
• and
• an optimization module configured to optimize one or more pacing parameters of the plurality pacing parameters using the measured at least one optimization parameter while keeping the S2-R interval within an acceptable range, the one or more pacing parameters including an electrode configuration parameter specifying one or more first ventricular electrodes selected from the plurality of first ventricular electrodes for delivering first ventricular pacing pulses of the pacing pulses to the first ventricle using the measured at least one optimization parameter and one or more pacing timing parameters specifying timing of the delivery of the first ventricular pacing pulses determined for each electrode of the selected one or more first ventricular electrodes using the measured at least one optimization parameter.