Pacemaker with improved detection of atrial fibrillation

An implantable pacemaker comprising:

• an atrial sensor for sensing atrial signals, said atrial signals having peak amplitudes and including sinus rhythm atrial signals and non-sinus rhythm atrial signals;
• a ventricular sensor for sensing ventricular signals;
• a first analyzer for determining a short term variability and deviation of said non-sinus rhythm signals from said sinus rhythm atrial signals and for generating a first indicia, said first indicia being dependent on said short term peak amplitude variability and deviation;
• a second analyzer for determining a long term variability of said atrial signals and for generating a second indicia, said second indicia being dependent on said long term variability;
• a categorizer for categorizing a new state of the atrium as a pathological state by combining said first and second indicia;
• a pulse generator for generating atrial and ventricular pulses in response to a command signals;
• and
• a controller for generating said command signals in response to said atrial and ventricular signals and said new state of the atrium.

In an implantable pacemaker of the kind having atrial and ventricular sensors for sensing atrial and ventricular events and a pulse generator for generating atrial and ventricular events and a pulse generator for generating atrial and ventricular pulses on demand, a method of classifying cardiac arrhythmia from said atrial events comprising the steps of:

• sensing a predetermined number of atrial events and generating corresponding atrial signals;
• measuring an amplitude of each of said atrial signals;
• determining a short term variability and deviation of said amplitudes;
• determining a long term variability and deviation of said amplitudes;
• generating a first indicative of said short term variability and deviation of said amplitudes;
• generating a second indicia indicative of said long term variation and deviation of said amplitudes;
• combining said first and second indicia into a third indicia;
• and
• categorizing said cardiac arrhythmia in accordance with said third indicia.