Abstract: A cardiac rhythm management system is capable of treating irregular ventricular heart contractions, such as during atrial tachyarrhythmias such as atrial fibrillation. A first indicated pacing interval is computed based at least partially on a most recent V-V interval duration between ventricular beats and a previous value of the first indicated pacing interval. Pacing therapy is provided based on either the first indicated pacing interval or also based on a second indicated pacing interval, such as a sensor-indicated pacing interval. A weighted averager such as an infinite impulse response (IIR) filter adjusts the first indicated pacing interval for sensed beats and differently adjusts the first indicated pacing interval for paced beats. The system regularizes ventricular rhythms by pacing the ventricle, but inhibits pacing when the ventricular rhythms are stable.

Abstract: A system and method for selectively treating a ventricular tachycardia based on sensed atrial and ventricular intervals from the patient's heart. A detection window of the ten most recent atrial and ventricular intervals are analyzed for the occurrence of either tachycardia or fibrillation. When a majority of the sensed intervals are satisfied, the apparatus starts a duration time interval. Ventricular intervals and atrial intervals are compare, ventricular interval greater than the atrial interval by a bias factor the system delivers tachycardia therapy to the heart. Alternatively, the method withholds tachycardia therapy to the heart when the atrial rate is classified as atrial fibrillation and the ventricular response is unstable.

Abstract: This document discusses, among other things, a system and method of monitoring or reporting battery status of an implantable medical device. The battery terminal voltage and charge delivered are measured. Before the battery terminal voltage falls below an Elective Replacement Indicator (ERI) threshold voltage, a charge-delivered indication of battery status is provided. Thereafter, a battery terminal voltage indication of battery status is provided. The Elective Replacement Indicator (ERI) and End of Life (EOL) threshold voltages are each functions of delivered battery current. A fault current detection is also provided. A device temperature sensor discounts the battery voltage reading when the device is too cold.