Idiopathic sustained left ventricular tachycardia: clinical and electrophysiologic characteristics.

Abstract
Electrophysiologic studies were performed in 16 patients 11 to 45 years old (mean 33 years) with idiopathic sustained (lasting more than 5 min) ventricular tachycardia (VT) originating from the left ventricle. Endocardial mapping during VT showed that the earliest site of activation was at the apical inferior portion of the left ventricle in 14 patients whose QRS morphology during VT showed a right bundle branch block pattern and left-axis deviation, but at the apical anterosuperior portion of the left ventricle in two patients whose QRS morphology during VT showed a right bundle branch block and right-axis deviation. Single programmed ventricular stimulation induced VT in 13 patients, and rapid ventricular pacing induced VT in the remaining three patients. Rapid ventricular pacing terminated VT in all patients. The relationship between the coupling interval and the echo interval was inverse in all eight patients with a wide VT inducible zone. Entrainment was recognized in three of six patients. The initi...