Patent ID: 8133187

Claim:
An implantable medical device for detecting a condition of a heart of a patient, said device comprising: a pulse generator that emits cardiac stimulating pacing pulses; a lead comprising at least one electrode, said lead being connected to said pulse generator and being configured for implantation in the patient to deliver said cardiac stimulating pacing pulses to cardiac tissue in the patient; an acoustic sensor configured to sense acoustic energy in the patient, said acoustic sensor emitting an acoustic sensor signal indicative of heart sounds produced by the heart of the patient; a signal processor connected to said acoustic sensor configured to extract signal components from said acoustic sensor signal respectively corresponding to a first heart sound, known as the first heart sound S 1 , and a second heart sound, known as the second heart sound S 2 , over predetermined periods of a cardiac cycle during successive cardiac cycles, and to calculate a first energy value E 1 corresponding to said first heart sound S 1 and a second energy value E 2 corresponding to said second heart sound S 2 ; a storage unit in communication with said signal processor that stores said first and second energy values E 1 and E 2 corresponding to said first and second heart sounds S 1 and S 2 ; and a controller connected to said pulse generator, and configured to calculate a quotient E 1 /E 2 for successive cardiac cycles, and to use said quotient E 1 /E 2 to identify a condition of the heart of the patient or a change of said condition of the heart of the patient, and to control emission of said cardiac stimulating pacing pulses from said pulse generator dependent on said condition or said change of said condition.