Polymorphic Ventricular Tachycardia Induced by Left Ventricular Pacing
A 67-year-old woman with advanced heart failure accompanying idiopathic dilated cardiomyopathy had a broad QRS complex on the ECG and significant inter- and intraventricular asynchrony as shown by tissue Doppler echocardiography. She had no history of syncope, no documentation of any ventricular arrhythmias, and no metabolic or electrolyte abnormalities. Implantation of a biventricular pacemaker was indicated. When left ventricular stimulation was started, she developed multiple polymorphic ventricular extrasystoles (Figure 1) and polymorphic ventricular tachycardias. During the left ventricular lead threshold testing, the first noncaptured stimulus generated a “long-short”–like sequence that triggered a sustained episode of torsade de pointes that required electrical cardioversion (Figure 2). No ventricular arrhythmias were induced when the right ventricle or both ventricles were paced simultaneously.
Heterogeneity within the ventricular wall is a major mechanism of ventricular arrhythmias in primary electrical disorders such as Brugada syndrome and the long-QT syndrome. But acquired forms also exist, such as drug-induced torsade de pointes, drug-induced Brugada syndrome, and the entity shown here, left ventricular pacing–induced polymorphic ventricular tachycardia.
↵*The first 2 authors contributed equally to this work.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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