Method of sampling a heart parameter, in particular an intracardiac impedance, in an active implantable medical device such as pacemaker, cardiac defibrillator, cardioverter and / or multisite device

This method is to execute repeatedly in a plurality of successive cardiac cycles (CYCLE 1 CYCLE 8 ..) the steps of detecting the instant (E) of occurrence of a ventricular event, and operate then a sampling of said signal during the cardiac cycle with a constant sampling step and a predetermined temporal offset (DELTAT1 DELTAT8 ..) between the sensed ventricular event and the first sample, this temporal offset being a progressive offset of a variable cycle to the next.