Patent ID: 7580746

Claim:
A method of generating a pressure-volume loop for a heart using an implantable medical device including a pulse generator having control circuitry, a first cardiac lead including a proximal end and a distal end, the cardiac lead coupled to the pulse generator at the proximal end, a first electrode located at the distal end of the cardiac lead and operatively coupled to the control circuitry, a sound sensor, and a pressure sensor, wherein the medical device is adapted to measure an intracardiac impedance using the first electrode, wherein the sounds sensor is coupled to the housing, and wherein the control circuitry is adapted to receive data from the sounds sensor, the pressure sensor and the first electrode and generate a pressure-volume loop using the sound, pressure and impedance data, the method comprising: creating a first corner of the pressure-volume loop by recording a first cardiac pressure and a first cardiac volume at a first time associated with an S1 heart sound; creating a second corner of the pressure-volume loop by recording a second cardiac pressure and a second cardiac volume at a second time at which cardiac volume starts decreasing; creating a third corner of the pressure-volume loop by recording a third cardiac pressure and a third cardiac volume at a third time associated with an S2 heart sound; and creating a fourth corner of the pressure-volume loop by recording a fourth cardiac pressure and a fourth cardiac volume at a fourth time at which the cardiac volume increases rapidly.