Abstract 16754: Novel Characterization of Pulmonary Artery Bending, Rather Than Stenosis, Detects Increased Right Ventricular Afterload and is Associated With Increased Right Ventricular Mass in the Post-Arterial Switch Operation Heart

Abstract

Introduction: Surgical treatment of transposition of great arteries involves the Arterial Switch Operation (ASO) and the LeCompte maneuver, where the pulmonary artery (PA) and its bifurcation are translocated anterior to the neoaortic root, creating relative PA stenosis and exaggerated PA bending. Assessment of branch PA dimensions can identify stenosis, however complex 3-dimensional bending without clear stenosis may contribute to elevated right ventricular (RV) afterload. Initial data suggest elevated RV afterload and RV mass are prevalent in these patients but the etiology and associated risk factors remain unclear. Hypothesis: In post-ASO patients, more extreme PA bending, as described by radius of curvature, will be associated with elevated RV afterload and RV mass independently of relative PA stenosis. Methods: Retrospective single-center analysis of 22 post-ASO patients was performed, representing native anatomy of D-TGA with (15, 68%) and without (7, 32%) intact ventricular septum, excluding those with PA stent, pulmonary hypertension, or other anatomical confounders. RV systolic pressure (RVSP) was recorded from echocardiography (11, 50%) or catheterization (11, 50%) and correlated to cardiac magnetic resonance (CMR) imaging measurements including: radius of curvature (Rcw) weighted to differential pulmonary blood flow and RV mass indexed to body surface area. Results: In ASO patients, receiver operating characteristic curve demonstrated Rcw, but not PA stenosis, moderately detected presence of elevated RVSP (>40 mmHg) (respectively: AUC 0.84, p = 0.03 and AUC 0.49, p =0.60). Patients with elevated RV Mass had more extreme Rcw (when normalized to body surface area), but no difference in PA stenosis via Nakata index (respectively: p = 0.10, p = 0.02). Conclusions: Abnormal PA bending as described by Rcw is associated with increased RV afterload and RV Mass. Rcw may serve as a promising future clinical proxy to RV afterload.