Patent ID: 7513874

Claim:
An active implantable medical device, in particular a cardiac pacemaker, defibrillator, cardiovertor and/or multisite device, having at least one electrode terminal placed in each of at least two distinct respective sites including at least one ventricular site and one atrial site, comprising: means for measuring an intracardiac impedance signal correlated to an instantaneous blood flow, said means comprising a pulse generator providing a current injection and circuit for collecting a differential potential across said respective electrode terminals in response to said current injection; and means for determining periodically, in response to said measured impedance signal, an average hemodynamic index evaluated over a number of successive cardiac cycles satisfying a plurality of preset measurement conditions, said means including: control means for checking a state of the patient and criteria corresponding to a set of predetermined measurement conditions and for inhibiting the determination of said average hemodynamic index if said criteria set are not satisfied; measuring means for determining a plurality of the measured impedance signal samples over a first duration corresponding to a systole of one cardiac cycle, further comprising means for determining a beginning of a systole by detection of a predetermined ventricular cardiac event, and determining an end of said same systole in response to said impedance signal reaching a maximum during said same cardiac cycle; integrating means for determining, in response to said determined samples, a value representative of a blood volume ejected throughout said systole; calculating means for establishing said average hemodynamic index in response to a plurality of said values successively determined by the integrating means over a plurality of cardiac cycles.