Abstract: An implantable atrial defibrillator provides cardioverting electrical energy to the atria of a human heart in need of cardioversion. The atrial defibrillator includes a first detector for detecting ventricular activations of the heart, a second detector for detecting atrial activity of the heart, and an atrial fibrillation detector responsive to the second detector for determining when the atria of the heart are in need of cardioversion. The atrial defibrillator further includes a cardioverter for applying the cardioverting electrical energy to the atria of the heart when the atria of the heart are in need of cardioversion, and a timer delay stage responsive to the first detector for causing the cardioverter to apply the cardioverting electrical energy to the atria of the heart a predetermined delay time after the first detector detects one of the ventricular activations and before the T wave of the heart immediately following the one of the ventricular activations.

Abstract: An implantable atrial defibrillator applies cardioverting electrical energy to the atria of a human heart in need of cardioversion. The atrial defibrillator includes a first detector for sensing atrial activity of the heart, an atrial fibrillation detector responsive to the first detector for determining when the atria of the heart are in need of cardioversion and a second detector for detecting ventricular activations of the heart. The atrial defibrillator further includes a cardioverter for applying cardioverting electrical energy to the atria of the heart when the atria of the heart are in need of cardioversion and is responsive to the second detector for applying the cardioverting electrical energy to the atria of the heart in predetermined time relation to a detected ventricular activation. The detection of atrial activity of the heart is interrupted when a ventricular activation of the heart is detected by the second detector.