Patent ID: 8868170

Claim:
An active implantable medical device, comprising means for collecting, amplifying, prefiltering and converting from analog-to-digital an endocardial signal, means for digitally processing and analyzing the digitized endocardial signal, and for delivering an indicator of signal peak detection representative of a presence of a QRS complex in the endocardial signal, wherein the digitized endocardiac signal has an amplitude, the means for digital processing and analyzing comprises a double threshold comparator, having as an input said digitized endocardial signal, a peak amplitude threshold and a peak width threshold and having as an output said indicator of peak detection in response to, cumulatively: the digitized endocardiac signal amplitude exceeding said peak amplitude threshold; and said peak amplitude threshold is exceeded for a period greater than said peak width threshold; wherein said peak amplitude threshold is a variable adaptive threshold, and wherein the means for digitally processing and analyzing further comprises: means for determining said peak amplitude threshold, by combining a predetermined base threshold and a variable value of noise level of the input endocardial signal; and means for determining said variable value of noise level based upon an energy (root mean square (RMS)) of the noise present in the input signal outside of the periods of said digitized endocardial signal amplitude exceeding said peak amplitude threshold.