[Multiform ventricular tachycardias and Torsades de Pointe].

The term Torsade de Pointe (T.d.P.) was first introduced by Dessertenne (1966) to designate an unusual ventricular tachyarrhythmia characterized by paroxysms of V.T. at rates typically greater than 200 beats/m, in which the QRS morphology shows alternating polarity in a modulating pattern, so that the complexes appear to be twisting around the baseline. This arrhythmia, triggered by E.V.B. falling in the vulnerable period of a previous beat, occurs in the setting of a prolonged Q-T interval, is generally self-limiting and, occasionally, degenerates into V.F. Similar morphologic features may be observed in patients with a normal Q-T interval. The duration of Q-T interval has important therapeutic implications. The arrhythmia occurring in the setting of a prolonged Q-T requires strict avoidance of all drugs that may potentially further delay repolarization (including class I antiarrhythmic agents), whereas that occurring with a normal Q-T interval usually responds to conventional therapy (including administration of class I antiarrhythmic agents). Thus, it seems reasonable to reserve the term T.d.P. exclusively to the forms with prolonged Q-T interval and to define those with normal Q-T interval with the name of multiform (or polimorphous) ventricular tachycardia (M.V.T.). In this paper the Authors discuss the most important electrocardiographic, clinical, aetiological, electrogenetic features of both the T.d.P. and M.V.T., on the basis of their own experience.