Patent ID: 7930024

Claim:
A method of determining a status of a ventricular rhythm of a heart using an implantable medical device comprising a sensing electrode, a therapy electrode and a processor, comprising the steps of: measuring a ventricular cycle length of a ventricular rhythm of a heart detected by said sensing electrode; comparing with the processor a number of times the ventricular cycle length exceeds a ventricular cycle length threshold against a predetermined number of intervals to detect threshold (NID threshold) to obtain a comparison; then determining, with the processor and based on the comparison, if the ventricular rhythm is a lethal arrhythmia or a non-lethal arrhythmia; and then if the ventricular rhythm is a lethal arrhythmia, delivering a therapy to the heart using the therapy electrode; if the ventricular rhythm is a non-lethal arrhythmia, withholding the therapy to the heart and increasing the NID threshold; then measuring a subsequent ventricular cycle length of the ventricular rhythm of the heart detected by said sensing electrode; comparing with the processor an updated number of times the ventricular cycle length and the subsequent ventricular cycle length exceed the ventricular cycle length threshold against the NID threshold, as updated, to obtain an update of the comparison, the updated number of times additively incorporating an instance of the subsequent ventricular cycle length exceeding the ventricular cycle length threshold; then returning to the determining step; and wherein the NID threshold is reset to the predetermined NID threshold by the processor upon a first predetermined condition and the number of times the ventricular cycle length exceeds a ventricular cycle length threshold is reset upon a second predetermined condition.