Shape and flow characterization of the pulmonary arteries after the LeCompte maneuver

Integrate statistical shape modeling (SSM) and 4D flow analysis to evaluate the impact of pulmonary artery (PA) geometry in patients with transposition of the great arteries (TGA) after the arterial switch operation (ASO).

Retrospective single-center cohort study.

Congenital cardiac center performing clinically indicated cardiac magnetic resonance imaging, including 4D flow.

Seventy TGA patients post-ASO and 49 age/size-matched controls with structurally normal hearts. Exclusion criteria included PA stents, significant right ventricular (RV) outflow obstruction, reintervention, or inadequate image quality.

Primary measures were PA shape modes (derived via SSM) and 4D flow-based kinetic energy (KE), viscous energy loss (VEL), and vorticity. Secondary measures included RV pressure and RV-to-systemic pressure ratio.

Compared with controls, TGA patients demonstrated higher peak systolic VEL rate (0.106 ± 0.109 mW/mL vs. 0.0125 ± 0.0599 mW/mL), systolic VEL (20.2 ± 18.2 mJ/mL vs. 1.91 ± 8.63 mJ/mL), peak KE (0.300 ± 0.126 mJ/mL vs. 0.0316 ± 0.0897 mJ/mL), and vorticity (194 ± 46.6 1/s vs. 105 ± 30.5 1/s; all p < 0.0001). Statistical shape modeling identified major geometric deviations, including shorter, flatter main PA segments, and increased branch curvature. Shape modes p4, p5, and p8 were significantly associated with increased curvature, reduced vessel caliber, elevated vorticity, and higher RV pressures. Right ventricular-to-systemic ratio also correlated with these shape modes, in addition to PA size, RPA curvature, and peak vorticity.

Abnormal PA geometry after ASO is strongly linked to adverse flow energetics and increased RV afterload. These findings suggest that curvature-driven flow inefficiency, beyond stenosis alone, contributes to long-term hemodynamic burden in TGA, highlighting potential targets for surveillance and intervention.