Rhythm discrimination enhancement - av drive

A system comprising:

• an implantable device including:
• an implantable cardiac signal sensing circuit, configured to provide a sensed depolarization signal from a ventricle and a sensed depolarization signal from an atrium;
• and
• a controller circuit communicatively coupled to the implantable cardiac signal sensing circuit, wherein the controller circuit includes:
• a one-to-one detector circuit configured to:
• measure cardiac depolarization intervals of the atrium and the ventricle;
• and
• determine whether a relationship of atrial (A-A) depolarizations to ventricular (V-V) depolarizations is substantially one-to-one;
• a tachyarrhythmia discrimination circuit configured to:
• detect an episode of tachyarrhythmia when the relationship atrial depolarizations to ventricular depolarizations is substantially one-to-one;
• generate an indication of VT when detecting one of a shortening or prolonging of an A-A interval during the episode that is immediately preceded by the same one of a shortening or prolonging of a V-V interval during the episode;
• generate an indication of a supra-ventricular tachycardia (SVT) event when detecting one of a shortening or prolonging of an A-A interval that immediately precedes the same one of a shortening or prolonging of the V-V interval during the episode;
• and
• classify the tachyarrhythmia episode as one of VT or SVT according to the generated indications of VT and SVT.