Atrioventricular re-entrant and ventricular tachycardias of left origin: a rare combination.

The simultaneous occurrence of atrial and ventricular tachycardias, or junctional and ventricular tachycardias, has been reported previously. We report on a patient presenting with syncope and demonstrating, simultaneously, atrioventricular re-entrant tachycardia and ventricular tachycardia of left origin. A left lateral concealed pathway was responsible for the former arrhythmia, while the latter arrhythmia was located in the anterolateral wall of the left ventricle. This is a rare type of double tachycardia and stresses the need for a thorough investigation of patients who have concealed accessory pathways and a previous history of atrioventricular re-entrant tachycardia, when they present with syncope.