[Polymorphic familial incessant ventricular rhythm disorders with ventricular repolarization abnormalities: borderline form of the congenital long QT syndrome?].

Two cases of polymorphic ventricular tachycardia (VT) are reported in siblings: the elder sister (18 years) was admitted to hospital because of syncope and ECG showed incessant attacks of VT. There was no obvious cardiac disease on echocardiography or cardiac catheterisation. A second syncopal attack occurred during Holter monitoring: this showed prolonged torsades de pointe which terminated spontaneously after a few minutes. Both syncopal attacks occurred at moments of intense emotional stress. Concomitantly, the duration of ventricular repolarisation was also observed to be increased. The attacks of polymorphic VT disappeared when the atrial rhythm accelerated, for example during exercise of isoprenaline infusion. It was not possible to induce VT by ventricular extrastimulation. The arrhythmia was controlled by nadolol and propafenone or flecainide. A familial investigation revealed that a younger brother had attacks of incessant VT with a long QT interval. The mother had frequent polymorphic ventricular extrasystoles and abnormal ST-T wave changes. The association of familial ventricular arrhythmias and long QT interval is suggestive of the Romano-Ward syndrome, but in this condition the intercritical ECG is normal except for the long QT. Conversely, in benign VT, the arrhythmia disappears during atrial pacing and exercise but there have been a few reports of sudden death. Our two cases could represent an intermediary form between these two pathological entities.