VARIABLE ATRIAL BLANKING PERIOD IN AN IMPLANTABLE MEDICAL DEVICE

摘要

An implantable medical device (100) for electrically stimulating the heart to beat including a pulse generator (150), a logic and control unit (180), and an atrial sense circuit (160). The atrial sense circuit (160) processes signals from electrodes (110, 120) implanted in an atrial chamber of the heart. The atrial sense circuit provides an atrial sense signal to the logic and control unit (180) when the magnitude of electrical activity in the atria exceeds a threshold. The medical device preferably paces the ventricles in response to detected electrical activity in the atria indicative of atrial contraction. Immediately following ventricular pacing, the medical device initiates an absolute atrial blanking period followed by an atrial sensing period and a programmable blanking period. During both the absolute atrial blanking period and the programmable blanking period, atrial sensing is disabled, while during the atrial sense period, atrial sensing is enabled. The time durations of the atrial sensing period and the programmable blanking period are programmable and may be programmed noninvasively while the medical device is implanted. The time durations of the atrial sense period and the programmable blanking period are adjusted so that paced far field R-waves resulting from a ventricular pace preferably occur during the programmable blanking period when atrial sensing is disabled. Atrial sensing during the atrial sensing period advantageously allows the medical device to monitor the atrial sense signal for normal atrial contractions.