Ventricular tachycardia by branch to branch reentry: a familial case with Steinert's disease.

Ventricular tachycardia by branch to branch reentry is a rare arrhythmia. I t occurs in cardiomyopathies associated with conduction defects. During tac hycardia a His potential precedes each QRS complex which usually has a left bundle branch block appearance. The authors report two familial cases of v entricular branch to branch tachycardia (son and mother) without cardiomyop athy. The diagnosis of Steinert's disease was made post-mortem in these two patients. In cases of branch to branch ventricular tachycardia, the diagnosis of myot onic dystrophy should be excluded. Conversely, endocavitary electrophysiolo gical investigation with ventricular stimulation should be proposed for sym ptomatic patients (dizzy spells, syncope) to diagnose branch to branch vent ricular tachycardia, even in cases with conduction defects which could also explain the symptoms.