[Clinical aspects of polymorphic ventricular tachycardia]

Polymorphic ventricular tachycardia is defined as constant change of the QRS morphology. The diagnosis has important etiological, therapeutic and prognostic implications. This term covers several different entities which may be artificially distinguished by the electrocardiographic appearances during tachycardia, by changes of the resting electrocardiogramme, the mode of onset, the presence or absence of underlying cardiac disease and of intercurrent drug therapy. However, as the resting ECG may not be available in an emergency situation, or difficult to interpret, the clinical context is the key to diagnosis and treatment. Polymorphic ventricular tachycardia is classified according to the absence or presence of underlying cardiac disease respectively as torsades de pointe with long QT, torsades de pointe with a short coupling interval and catecholamine-induced ventricular tachycardia of childhood on the one hand, and, iatrogenic torsades de pointe, ventricular tachycardia in acute or chronic infarction and other cardiac diseases, on the other hand. Finally, the authors discuss the problem of polymorphic ventricular tachycardia induced by programmed ventricular stimulation.