Left ventricular outflow tract obstruction secondary to right atrial dilatation and accessory mitral valve tissue in a patient with Ebstein\u2019s anomaly- Case report

Abstract

BackgroundEbsteins anomaly accounts for less than 1% of all congenital cardiac defects. Whilst typically characterised by dysfunction and anatomical defects of the right ventricle and tricuspid valve, it often co-exists with other congenital defects. Less frequently outflow tract obstruction may arise with associated haemodynamic effects and symptoms. In particular there are few reports in the literature of left ventricular outflow tract obstruction. We believe this is because symptomatic outflow tract obstruction as the presenting complaint of this condition is exceptionally rare.Case presentationWe report on a 17 year old male who was referred to the general cardiology clinic with symptoms of exertional fatigue and breathlessness. Transthoracic echocardiogram performed as part of the workup led to the diagnosis of Ebstein’s anomaly. In addition to the characteristic features of this congenital abnormality there was significant dilatation of the right atrium with resultant leftward bulging of the intraventricular septum. The anterior mitral valve leaflet was noted to be elongated with accessory chordal apparatus and demonstrated systolic anterior motion. Turbulence was noted in the left ventricular outflow tract leading to a degree of obstruction. Here we discuss the aetiology and mechanisms behind this unusual presentation.DiscussionEbstein’s anomaly arises due to chromosomal rearrangements affecting early morphogenesis of the right ventricle and tricuspid valve. Associations with other congenital defects such as interatrial communications are well documented. Less commonly the structural abnormalities of this condition lead to functional outflow tract obstruction. Whilst cases have previously described right ventricular outflow tract obstruction there are fewer reports of left ventricular outflow tract obstruction in this patient group. The structural defects that result in dilatation of the right atrium and the atrialised portion of the right ventricle can lead to leftward bulging of the interatrial septum. Turbulence can occur in the left ventricular outflow tract with resultant systolic anterior motion of the mitral valve in a mechanism similar to that encountered in hypertrophic cardiomyopathy. This may only become haemodynamically relevant during exertion.ConclusionIn the absence of ventricular dysfunction, arrhythmias or syncope we suggest that it is reasonable to adopt an observational strategy to the management of these patients.