Patent foramen ovale and implantable cardioverter defibrillator.

A case of patent foramen ovale opening was observed concomitantly to a defibrillation threshold determination in the setting of an internal cardioverter defibrillator implantation. The subsequent transient right-to-left shunt was confirmed by a peroperative transoesophageal echocontrast study. The underlying mechanism of this incident may be related to a transient reversal of the interatrial gradient, due to the pre-existence of pulmonary hypertension and tricuspid regurgitation, associated with ongoing mechanical ventilation and modifications of intracardiac pressures regimen secondary to the succeeding ventricular tachyarrhythmia and defibrillation. Paradoxical embolism can be an aetiology for neurologic injury during internal cardioverter defibrillator implantation.