QRS and cycle length alternans in a patient with idiopathic left ventricular tachycardia: Postulated mechanism and clinical implications.

Idiopathic left ventricular tachycardia is macro-reentrant tachycardia involving the fascicles in the left ventricle as a part of its reentrant circuit. The detailed circuit mechanisms somewhat remain unclear. We reported QRS and cycle length alternans confirmed after the first application of radiofrequency delivery for the distal site of left posterior fascicle potential (P2) in a patient with idiopathic left ventricular tachycardia.