[Left syncopal bundle-branch block during tachycardia. A new, syndrome?].

The authors report four observations: three are essentially clinical cases where sustained rate dependent left bundle branch block can induce syncope, where as there is no syncope when the same supraventricular tachycardia at the same frequency has narrow QRS complexes. The fourth case demonstrates the dramatic decrease of arterial electrophysiological slowly accelerated atrial pacing in a patient investigated for a loss of consciousness of unknown origin. The hemodynamic impairment due to intermittent left bundle branch block has been demonstrated even in patients with normal ventricular function.

[Evaluation of electrophysiological properties of asymptomatic Wolff-Parkinson-White syndromes. Comparison with symptomatic Wolff-Parkinson-White syndromes].

The aim of this study was to compare the electrophysiologic properties of asymptomatic Wolff-Parkinson-White (WPW) syndromes with those of symptomatic WPW, and in particular the anterograde refractory period of the accessory tract and atrial vulnerability. This retrospective study involved 171 patients with WPW seen in their surface electrocardiogram, untreated, having undergone standard invasive electrophysiologic investigation. These patients were divided into two groups: group I consisting of 42 asymptomatic patients and group II consisting of 129 asymptomatic patients.