Cardiac resynchronization implantable cardioverter defibrillator: normal or abnormal behaviour?

Cardiac resynchronization permits atrial-synchronized simultaneous pacing of both left and right ventricles in order to optimize mechanical contraction. In case of an atrial tachycardia, a VVI-'ventricular sense'-tracking modus can be programmed to maintain biventricular pacing. In this case report, we describe the use of this modus.