Abstract: An implantable cardiac stimulation device promotes intrinsic activity of a heart during demand pacing. The device increases the time and probability of an AV delay interval extension. The device may further increase the AV delay interval from a first extended AV delay interval to a longer second extended AV delay interval. The device may further encourage intrinsic AV conduction in patients with intact AV conduction by allowing multiple cycles during a search interval and multiple search times to further encourage intrinsic conduction from the atrium to the ventricle.

Abstract: A system for automatically evaluating the sensing and detection of physiological processes by an implantable medical device, such as an implantable cardiac stimulation device. The system includes an automatic testing algorithm which iteratively adjusts at least one of the threshold and gain settings of the device and evaluates the accuracy of the detection for refining the programming of the device. The algorithm can include sampling the physiological process beginning at a relatively low rate to avoid excessive burden on the processing and battery capacity available and progressively increasing the rate to obtain higher resolution data. The algorithm can also evaluate the observed physiological process for periodicity and can determine repetition of an irregular pattern, such as bigeminy, and use the determined pattern for predictive purposes to refine the programming of the device. The algorithm employs observation of a change in observed pattern as indicia for loss of proper detection.

Abstract: An implantable cardiac stimulation device provides bipolar pacing and bipolar autocapture. If a measured bipolar electrode configuration capture threshold is too high, an impedance measuring circuit measures the impedance of the bipolar electrode configuration to determine a possible lead failure. If the bipolar electrode configuration impedance is within a normal range, bipolar pacing is continued in a manner which assures continued capture of the heart. If the bipolar electrode configuration impedance is outside of the given range of impedances, the device is switched to unipolar pacing in a manner which insures capture of the heart and notification of the need for a physician consultation.