Ventricular Tachycardia in a Grossly Enlarged Ebstein's Right Ventricle: Challenges in Immediate and Long-Term Management

Abstract

Case: A 27-year-old male with known Ebstein's anomaly and prior sternotomies presented with palpitations and presyncope. He had ventricular tachycardia (VT) and was cardioverted in the Emergency Department. The electrocardiogram was consistent with scar VT. He had undergone prior tricuspid valve (TV) repair with subsequent tissue valve replacement and right ventricular (RV) excisional reduction. Transthoracic echocardiogram revealed a massively dilated RV and severely stenosed TV bioprosthesis. Cardiac magnetic resonance imaging quantified the scarred, thin-walled RV volume at 1,157 mL. A three-dimensional model was printed, highlighting the grossly enlarged RV. Further surgical valvular intervention was deemed inappropriate after multidisciplinary discussion. Ventricular tachycardia catheter ablation was not considered viable, given the limited endocardial and epicardial access and high perforation risk. Subsequently, secondary prevention implantable cardiac defibrillator (ICD) options were considered. A transvenous ICD was thought to likely compromise the stenosed TV and carry significant perforation risk. Surgically placed epicardial ICD systems pose extreme risks due to redo sternotomy. Given the marked repolarisation abnormalities, subcutaneous ICD (S-ICD) would carry a high risk of inappropriate shock due to T-wave oversensing. However, after 2 of 3 vectors screened in, an S-ICD was implanted. Increasing dyspnoea was noted and cardiopulmonary exercise test showed declining VO2 max. Sinus tachycardia resulted in T-wave oversensing and inappropriate shocks. With limited sudden death prevention options and declining functional status, the patient was listed for transplant. A wearable cardioverter-defibrillator was prescribed whilst waiting.