Surgical treatment of Ebstein anomaly: combined correction of morphologic alterations and arrhythmias

Abstract

Ebstein’s anomaly corresponds to less than 1% of all cardiac congenital malformations. In this anomaly, there is a fail in delamination of the posterior and septal cusps of the tricuspid valve during embryogenesis, resulting in adherence of these cusps to the subjacent myocardium, rotation and apical displacement of the functional valvar annulus. This anatomical changes lead to valve dysfunction, atrialization of part of the right ventricle and dilatation of the right atrioventricular junction, with consequent impairment in the ventricular function. The apical displacement of the cusps leads to discontinuity between the fibrous valvar skeleton and the functional valvar annulus, creating an anatomic substrate for accessory conduction pathways and ventricular pre-excitation. This is reflected in the high prevalence of pre-excitation and Wolf-Parkinson-White (WPW) syndrome in these patients, with consequent increase in risk of supraventricular and ventricular tachiarrhytmias, syncope and sudden cardiac death. Elimination of the arrytmogenic substrate by means of surgery or catheter results in significant reduction in mortality and morbidity in the medium and long-term. Nevertheless, ablation, especially by means of catheter, still faces important challenges when performed both prior and subsequent to surgical correction. Before the surgical repair, the ablation is dificulted by the anatomic particularities of this malformation, such as right ventricular dilatation changing the usual landmarks, presence of tricuspid regurgitation, greater catheter instability and often presence of multiple and broad accessory pathways. After the surgical correction, there are also marked technical challenges involving catheter ablation due to the inaccessibility of the accessory pathway to the intravenous catheter, as it becomes “buried” by the surgical approach involving the tricuspid ring. These factors together reduce the success rate of catheter ablation in patients with Ebstein’s anomaly compared with other patient groups without this malformation. In an attempt to reduce risks and increase success rate in eliminating the arrytmogenic substrate, some groups have performed a combined procedure in patients with surgical indication, where the electrophysiological study and eventual ablation are performed during the surgical correction. The aim of the present study is to report our experience with the combined treatment, with emphasis on the prevalence of arrhythmias during the in-hospital period in this group of patients.