Post-shock recovery monitoring for tachyarrhythmia discrimination

A method for operating a cardiac rhythm management device, composing:

• measuring a ventricular rate from sensed ventricular electrical activity;
• detecting a tachyarrhythmia that may be either a supraventricular tachycardia (SVT) or a ventricular tachycardia (VT) if the measured ventricular rate is within a specified range;
• generating a first electrogram signal from a cardiac sensing channel;
• discriminating between SVT and VT with a test for SVT/VT discrimination that includes a morphology criterion based on an analysis of the first electrogram signal;
• delivering either a cardioversion/defibrillation shock or anti-tachycardia pacing to treat the tachyarrhythmia;
• and,
• if a cardioversion/defibrillation shock is delivered:
• discontinuing use of the morphology criterion in the test for SVT/VT discrimination after delivery of the cardioversion/defibrillation shock for at least one ventricular beat;
• judging whether or not one or more ventricular beats that occur after delivery of the cardioversion/defibrillation shock are normally conducted;
• and,
• resuming use of the morphology criterion in the test for SVT/VT discrimination when a first predetermined minimum number of ventricular beats occurring after delivery of the cardioversion/defibrillation shock has been judged as normally conducted.