Patent ID: 8571642

Claim:
For use with an implantable system, a method for monitoring a patient's pre-ejection interval (PEI), the method comprising: (a) using one or more electrodes implanted within and/or on the patient's heart to obtain a signal indicative of cardiac electrical activity; (b) using an implanted sensor to obtain a signal indicative of changes in arterial blood volume; (c) detecting a predetermined feature of the signal indicative of cardiac electrical activity; (d) detecting a predetermined feature of the signal indicative of changes in arterial blood volume; (e) determining an interval between the predetermined feature of the signal indicative of cardiac electrical activity and the predetermined feature of the signal indicative of changes in arterial blood volume; (f) determining a transit time representing at least one of i) a delay from an onset of the signal indicative of cardiac electrical activity obtained at the one or more electrodes to when the signal indicative of changes in arterial blood volume arrives at the implanted sensor or ii) a time for a pressure pulse to travel from an aorta to the implanted sensor; and (g) monitoring the patient's PEI based on the interval and the transit time.