[Ventricular tachycardia by branch to branch re-entry. Familial case with Steinert's disease].

Ventricular tachycardia by branch to branch reentry is a rare arrhythmia. It occurs in cardiomyopathies associated with conduction defects. During tachycardia a His potential precedes each QRS complex which usually has a left bundle branch block appearance. The authors report two familial cases of ventricular branch to branch tachycardia (son and mother) without cardiomyopathy. 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 myotonic dystrophy should be excluded. Conversely, endocavitary electrophysiological investigation with ventricular stimulation should be proposed for symptomatic patients (dizzy spells, syncope) to diagnose branch to branch ventricular tachycardia, even in cases with conduction defects which could also explain the symptoms.