Electrical dyssynchrony and endocardial fibroelastosis resection in the rehabilitation of hypoplastic left cardiac syndrome

Abstract

Staged left ventricular rehabilitation is a novel surgical approach in patients undergoing single ventricle palliation for borderline hypoplastic left cardiac disease, in an attempt to salvage the left ventricle. The procedure includes resection of endocardial fibroelastosis from the left ventricular free wall and apex. We hypothesised that endocardial fibroelastosis removal may significantly affect ventricular conduction and myocardial electrical characteristics. This study included 27 patients with borderline hypoplastic left cardiac syndrome who underwent staged left ventricle rehabilitation with endocardial fibroelastosis resection following single ventricle palliation. The effect on electrical synchrony was measured by ventricular depolarisation timing (QRS duration) on electrocardiogram. Patients were evaluated for a change in QRS duration before and after fibroelastosis removal and at most recent follow-up. The QRS change in the immediate period after endocardial fibroelastosis resection ranged from -16 to 36 milliseconds with a median of 0 (p = 0.09). However, long-term conduction delay was common in 44% (12/27) of patients having a QRS duration greater than 98th percentile for the age at the most recent electrocardiogram. Only one patient had QRS duration greater than 98th percentile before any surgical procedure. Two patients developed left bundle branch block and one developed right bundle branch block with left, but anterior-fascicular block. Overall, the QRS duration correlated with left ventricular size (R = 0.54, p = 0.006) at the most recent electrocardiogram. Electrical dyssynchrony is a common finding in patients undergoing staged left ventricular rehabilitation after single ventricle palliation; however, it is not acutely related to surgical endocardial resection. Left ventricular size is correlated with QRS duration. Diligent follow-up is required to evaluate the effects of left ventricular growth and consideration of resynchronisation in this population.