Aortic root rotational position associates with aortic valvar incompetence and aortic dilation after arterial switch operation for transposition of the great arteries.

Purpose: Aortic dilation and valvar regurgitation can develop in transposition of the great arteries (TGA) after the arterial switch operation (ASO). Variation in aortic root rotational position affects flow dynamics in patients without congenital heart disease. The aim of this study was to assess neo-aortic root (neo-AoR) rotational position and its association with neo-AoR dilation, ascending aorta (AAo) dilation, and neo-aortic valvar regurgitation in TGA following ASO.

Methods: Patients with TGA repaired by ASO who underwent cardiac magnetic resonance (CMR) were reviewed. Neo-AoR rotational angle, neo-AoR and AAo dimensions indexed (to height), indexed left ventricular end diastolic volume (LVEDVI), and neo-aortic valvar regurgitant fraction (RF) were obtained from CMR.

Results: Among 36 patients, the median age at CMR was 17.1 years (12.3, 21.9). Neo-AoR rotational angle (range - 52 to + 78°) was clockwise ( ≥ + 15°) in 50%, counterclockwise (<-9°) in 25%, and central (-9 to + 14°) in 25% of patients. A quadratic term for neo-AoR rotational angle, indicating increasing extremes of counterclockwise and clockwise angles, was associated with neo-AoR dilation (R = 0.132, p = 0.03), AAo dilation (R = 0.160, p = 0.016), and LVEDVI (R = 0.20, p = 0.007). These associations remained statistically significant on multivariable analyses. Rotational angle was negatively associated with neo-aortic valvar RF on univariable (p < 0.05) and multivariable analyses (p < 0.02). Rotational angle was associated with smaller bilateral branch pulmonary arteries (p = 0.02).

Conclusion: In patients with TGA after ASO, neo-AoR rotational position likely affects valvar function and hemodynamics, leading to a risk of neo-AoR and AAo dilation, aortic valvar incompetence, increasing left ventricular size, and smaller branch pulmonary arteries.