Effect of graft sizing in valve-sparing aortic root replacement for bicuspid aortic valve: The Goldilocks ratio

Abstract

ObjectiveTo investigate the effect of graft sizing on valve performance in valve-sparing aortic root replacement for bicuspid aortic valve. MethodsIn addition to a diseased control model, 3 representative groups—free-edge length to aortic/graft diameter (FELAD) ratio <1.3, 1.5 to 1.64, and >1.7—were replicated in explanted porcine aortic roots (n = 3) using straight grafts sized respective to the native free-edge length. They were run on a validated ex vivo univentricular system under physiological parameters for 20 cycles. All groups were tested within the same aortic root to minimize inter-root differences. Outcomes included transvalvular gradient, regurgitation fraction, and orifice area. Linear mixed effects model and pairwise comparisons were employed to compare outcomes across groups. ResultsThe diseased control had mean transvalvular gradient 10.9 ± 6.30 mm Hg, regurgitation fraction 32.5 ± 4.91%, and orifice area 1.52 ± 0.12 cm2. In ex vivo analysis, all repair groups had improved regurgitation compared with control (P < .001). FELAD <1.3 had the greatest amount of regurgitation among the repair groups (P < .001) and 1.5-1.64 the least (P < .001). FELAD <1.3 and >1.7 exhibited greater mean gradient compared with both control and 1.5 to 1.64 (P < .001). Among the repair groups, 1.5 to 1.64 had the largest orifice area, and >1.7 the smallest (P < .001). ConclusionsFor a symmetric bicuspid aortic valve, performance after valve-sparing aortic root replacement shows a bimodal distribution across graft size. As the FELAD ratio departs from 1.5 to 1.64 in either direction, significant increases in transvalvular gradient are observed. FELAD <1.3 may also result in suboptimal improvement of baseline regurgitation.