Patent ID: 7072716

Claim:
An active implantable medical device, including: stimulation means for delivering in at least one cardiac cavity stimulation pulses having a predetermined voltage level and a predetermined pulse width, and means for sensing cardiac activity including an evoked potential corresponding to a myocardial depolarization, said sensing means comprising at least one amplifier of signals sensed by an intracardiac electrode, said sensing means having an output and delivering at its output a measured potential value consecutive to a delivered stimulation pulse, wherein the improvement comprises: means for determining a specific response potential of the sensing means amplifier independently of a presence or absence of a myocardial depolarization, in which the determining means further comprises: means for applying at least two stimulation pulses in two different cycles able to cause a myocardial depolarization, the stimulation voltage level or pulse width of one of said two stimulation pulses being different from the stimulation pulse voltage level or pulse width of the other of said two stimulation pulses, and means for determining, in response to the respective measured potentials sensed in responds to said at least two stimulation pulses in two different cardiac cycles, a constant and a proportionality factor of a linear relation relating the measured potential to the product of the stimulation pulse width by the stimulation pulse voltage level.