Ventricular Tachycardia in Ebstein’s Anomaly
A 79-year-old man with chronic atrial fibrillation and dilated cardiomyopathy presented with incessant ventricular tachycardia (VT). On physical examination, the heart rate was at 150 bpm along with a blood pressure of 110/70 mm Hg and jugular venous distension to the angle of the jaw. Additional findings included tricuspid regurgitation with multiple systolic sounds and diastolic flow murmur, a pulsatile, tender, enlarged liver, and peripheral edema. Echocardiogram showed findings suggestive of Ebstein’s anomaly: markedly enlarged right atrium, moderately depressed right ventricular function, and apically displaced tricuspid valve leaflets with regurgitation (Figure 1). ECG showed a wide complex rhythm at 130 bpm, axis of 80°, and left bundle-branch morphology with broad R wave in V2: all features that supported VT as the rhythm (Figure 2). The patient underwent an electrophysiology study with catheters placed in the high right atrium, coronary sinus, and right ventricle and one was used for mapping and ablation. The initial rhythm was ventricular tachycardia at cycle-length 430 ms and atrial fibrillation. Using a 3D mapping system (CARTO Biosense, Webster) (Figure 3) and electrograms, an early site was identified in a portion of the atrialized ventricle just distal to the His bundle recording. This site was noted to have fractionated electrograms, which occurred 100 ms earlier than the QRS (Figure 4). Pacing could not terminate the VT; neither could it be entrained, suggesting a likely automatic mechanism. A single radiofrequency lesion at this site terminated the ventricular tachycardia with resumption of underlying atrial fibrillation (Figure 5). Pressure recording from this site confirmed that this part of the heart had atrial pressures (22 mm Hg) with ventricular electrograms. Further testing showed that no more VT was inducible.