Patent ID: 8500650

Claim:
An implantable cardiac rhythm management system, comprising: a cardiac sensing circuit configured to sense at least one electrogram; a cardiac event detector coupled to the cardiac sensing circuit and configured to produce a cardiac signal indicative of heart beats using the at least one electrogram; an acoustic sensor configured to sense an acoustic signal indicative of third heart sounds (S3); a sensor processing circuit coupled to the acoustic sensor and configured to precondition the sensed acoustic signal; a heart sound processor coupled to the cardiac event detector and the sensor processing circuit, the heart sound processor including: a beat counter configured to count the heart beats using the cardiac signal; a heart sound detector configured to detect S3 using the preconditioned acoustic signal; a heart sound counter configured to count S3 beats each being a heart beat during which one of S3 is detected; and a heart sound analyzer including a ratio calculator to calculate an S3 index being a ratio of a number of the S3 beats counted during a predetermined time period to the number of the heart beats counted during the predetermined time period; and a hermetically sealed can housing at least the cardiac sensing circuit, the cardiac event detector, the sensor processing circuit, and the heart sound processor.