VENTRICULAR-TACHYCARDIA WITHOUT APPARENT CARDIAC DISEASE

Idiopathic ventricular tachycardia is not a single clinical entity. Se veral electrophysiological mechanisms are responsible for at least two typical electrocardiographical pictures. The tachycardia with right b undle branch block morphology and inferior axis is the most common typ e and originates in the right ventricular outflow tract. It has to be differentiated from right ventricular dysplasia, and also from tachyca rdia in association with mitral valve prolapse. It is responsive to ca lcium antagonists, and can be treated with radiofrequency ablation. Th e other tachycardia (left bundle branch block morphology and right axi s) originates in the posterior left ventricular septum and has typical ly sharp potentials preceding the ventricular electrogram in the site where ablation is successful. Both types car? be associated with diffe rent types of cardiomyopathy, and therefore further investigation migh t be useful.