Changes in transvalvular flow patterns after aortic valve repair: comparison of symmetric versus asymmetric aortic valve geometry

OBJECTIVES: The aim of this study was to compare the effect of asymmetric versus symmetric bicuspid aortic valve (BAV) repair on transvalvular flow patterns and aortic wall shear stress (WSS). METHODS: Four-dimensional flow magnetic resonance imaging was prospectively and consecutively performed in patients with congenital aortic valve (AV) disease before and after AV repair. The following MRI-based parameters were assessed: (i) flow eccentricity index, (ii) backward flow across the AV, (iii) grading of vortical and helical flow, and (iv) WSS (N/m2) in the proximal aorta. MRI-derived flow parameters were compared between patients who underwent 'asymmetric BAV repair' (n = 13) and 'symmetric BAV repair' (n = 7). RESULTS: A total of 20 patients (39 ± 12 years, 80% male), who underwent BAV repair, were included. In the asymmetric BAV repair group, circumferential WSS reduction was found at the level of the aortic arch (P = 0.015). In the symmetric BAV repair group, postoperative circumferential WSS was significantly reduced compared to baseline at all levels of the proximal aorta (all P < 0.05). Postoperative circumferential WSS was significantly higher in the asymmetric versus symmetric BAV repair group at the level of the sinotubular junction (0.45 ± 0.15 vs 0.30 ± 0.09 N/m2; P = 0.028), ascending aorta (0.59 ± 0.19 vs 0.44 ± 0.08 N/m2; P = 0.021) and aortic arch (0.59 ± 0.25 vs 0.40 ± 0.08 N/m2; P = 0.017). Segmental WSS analysis showed significantly higher postoperative WSS after asymmetric versus symmetric BAV repair, especially in the anterior aortic segment (P = 0.004). CONCLUSIONS: Symmetric BAV repair results in more physiological flow patterns and significantly reduces WSS, as compared to asymmetric BAV repair. From a haemodynamic point of view, symmetric AV geometry should be attempted in every congenital AV repair.