Abstract: Techniques are provided for coordinating the delivery of cardioversion therapy and overdrive pacing therapy to the heart of a patient, primarily to prevent the re-occurrence of atrial fibrillation (AF) following a cardioversion shock. Included are techniques for modulating the aggressiveness of overdrive pacing by adjusting the magnitude of overdrive pulses or by changing the electrodes with which overdrive pacing pulses are generated. In one example, three phases or “tiers” of AF suppression therapy are provided: cardioversion therapy; far-field dynamic atrial overdrive (DAO) pacing; and near-field DAO pacing. Briefly, a cardioversion shock is delivered to the heart of the patient in response to the detection of AF, then smoothed, far-field overdrive pacing pulses are delivered using widely-spaced electrodes for a period of two minutes while the magnitude of the pulses is gradually reduced.

Abstract: An implantable cardiac stimulation device provides capture of a chamber of a heart with pacing pulses while minimizing parasitic muscle tissue stimulation. A parasitic muscle stimulation detector detects if the application of pacing pulses result in parasitic muscle stimulation. If there is parasitic muscle stimulation resulting from the application of pacing pulses, a pulse generator control adjusts the pacing pulse amplitudes and durations until the pacing pulses capture the chamber of the heart without causing parasitic muscle stimulation.

Abstract: An implantable cardioverter/defibrillator applies a quantity of electrical energy to a heart to terminate an arrhythmia of the heart. The cardioverter/defibrillator employs therapy delivery timing to avoid delivery of the therapy during vulnerable periods of the heart. The cardioverter/defibrillator includes an arrhythmia detector that detects an arrhythmia of the heart, a ventricular activation detector that detects ventricular activations of the heart, and an atrial activation detector that detects atrial activations of the heart. A ventricular timer, resettable by detected ventricular activations, and an atrial timer, resettable by detected atrial activations, keep time responsive to the arrhythmia detector detecting the arrhythmia. A generator applies the quantity of electrical energy to the heart responsive to the arrhythmia detector detecting the arrhythmia, when neither chamber is in its vulnerable period.