Automatic adjustment of detection rate threshold in an implantable antitachycardia therapy device

摘要

An antitachycardia stimulation device that automatically adjusts its detection rate threshold as a function of a sensed physiological parameter indicative of cardiac rate. The implantable antitachycardia stimulation device includes heart rate detection circuitry and antitachycardia therapy circuitry for applying a specific antitachycardia therapy in the event that the detected heart rate falls within at least one tachycardia rate zone. The tachycardia rate zone is defined by a lower threshold limit, and may also be defined by an upper threshold limit if more than one rate zone is used. The lower threshold limit is automatically adjusted as a function of an independently sensed physiological parameter that predicts a normal or natural change in the heart rate. If more then one rate zone is used, other threshold limits may also be adjusted automatically as a separate function of the same sensed physiological parameter. In one embodiment of the invention, the implantable stimulation device comprises a rate-responsive pacemaker, and the sensed physiological parameter used to adjust the rate threshold limit(s) is also used to define a sensor indicated rate signal to control the pacing rate of the pacemaker.