[Malignant ventricular hyperkinetic arrhythmias: diagnostic aspects]

Diagnosis of ventricular arrhythmias is generally easy. The differentiation between ventricular tachycardia (VT) and supraventricular tachycardia (ST) with aberrant intraventricular conduction deserves some comments. Frequently the distinction can be made on the electrocardiogram alone. VT is characterized by: a) QRS wider than 0.14 sec., b) left axis deviation (a and b criteria are no longer reliable when a preexisting bundle branch block is present), c) mono or biphasic V1 configuration (biphasic rSR' in ST), d) multiformity, e) A-V ratio different from 1:1 in spontaneous conditions or during vagal or pharmacological (ATP, verapamil) stimulation, f) presence of fusion or capture beats. None of these criteria has an absolute diagnostic value. His bundle potential (H) recording confirms the diagnosis when bundle of His is activated during or after QRS complex or when H-V interval is shorter than during sinus rhythm. Special cases are discussed, particularly the diagnosis of rapid supraventricular arrhythmias with anterograde conduction through an anomalous pathway. Characteristics of "slow", "bidirectional" and "iterative" VT are reported. "iterative" VT are reported. Electrocardiographic aspects of "torsades de pointe" are obtained in relation to the presence or the absence of a QT interval prolongation (multiform VT). The torsade is the result of rapid variations in depolarizing wavefront direction due to a high degree of electrical heterogeneity of ventricular myocardium; it has a severe prognostic significance regardless of the QT interval duration. However a long QT interval, when present, is the mark of the pathophysiological mechanism of the arrhythmia and a major indicator for therapeutical decisions. Finally the malignant aspects of unsustained ventricular arrhythmias in different cardiac diseases (mitral prolapse, obstructive cardiomyopathy, ischemic cardiac disease) and in apparently normal subjects are taken into consideration. The concept that the prognostic significance of the arrhythmias is in a large part dependent upon the type and severity of the underlying cardiac disease is stressed. The risk related to R/T premature ventricular beats is confirmed.