Idiopathic sustained left ventricular tachycardia: clinical and electrophysiologic characteristics.

TLDR

Electrophysiologic studies in 16 patients (ages 11–45) with idiopathic sustained left‑ventricular VT revealed that the arrhythmia originates from the left ventricle. Endocardial mapping showed earliest activation at the apical inferior LV in 14 patients and at the apical anterosuperior LV in 2 patients; VT was inducible by programmed stimulation or rapid pacing, terminated by pacing in all cases, and was effectively suppressed acutely and long‑term with verapamil, supporting a reentrant mechanism.

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 initiation of VT by constant pacing depended on the number of pacing beats but not the duration of pacing in all four patients tested. Intravenous verapamil terminated the VT in 13 of 14 patients. Long-term oral verapamil was also effective in all five patients who required long-term oral therapy for their symptoms associated with VT. In conclusion (1) idiopathic left ventricular tachycardia has unique electrocardiographic, electrophysiologic, and electropharmacological properties, (2) the electrophysiologic characteristics suggest that the mechanism is reentry, and (3) verapamil is effective in both the short- and long-term treatment of VT.