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.