Patent ID: 8639324

Claim:
An implantable or other ambulatory medical apparatus comprising: a cardiac signal sensing circuit configured to provide a sensed cardiac depolarization signal of a heart of a subject; a respiration sensing circuit configured to provide a signal representative of respiration of the subject; and a control circuit communicatively coupled to the cardiac signal sensing circuit and the respiration circuit, wherein the control circuit includes a tachyarrhythmia detection circuit configured to: determine heart rate using the depolarization signal; determine a respiration parameter of the subject using the respiration signal; calculate a ratio of the determined heart rate and the determined respiration parameter and determine a normal baseline value of the ratio; generate an indication of tachyarrhythmia when the calculated ratio satisfies a ventricular tachycardia ratio detection zone, wherein a value of the calculated ratio of the ventricular tachycardia detection zone is a substantial increase over the normal baseline value of the ratio; and provide the indication of tachyarrhythmia to a user or process.