Key result
Ex vivo straight grafts best match native aortic root biomechanics among hemodynamically comparable valve-sparing conduits.
Why the study?
The specific impact of graft neosinuses on valvular and root biomechanics and their potential influence on long-term durability remain unknown.
Do different conduit configurations for valve-sparing aortic root replacement differ in biomechanical performance compared to native aortic roots in an ex vivo model?
Do different conduit configurations for valve-sparing aortic root replacement differ in biomechanical performance compared to native aortic roots in an ex vivo model?
In an ex vivo porcine model, the straight graft configuration for valve-sparing aortic root replacement most closely recapitulated native aortic root biomechanics compared to other clinically used graft configurations.
May influence conduit selection in valve-sparing root replacement; leaves open clinical relevance of ex vivo biomechanical differences.
Background: Many graft configurations are clinically used for valve-sparing aortic root replacement, some specifically focused on recapitulating neosinus geometry. However, the specific impact of such neosinuses on valvular and root biomechanics and the potential influence on long-term durability are unknown. Methods: Using a custom 3-dimenstional–printed heart simulator with porcine aortic roots (n=5), the anticommissural plication, Stanford modification, straight graft (SG), Uni-Graft, and Valsalva graft configurations were tested in series using an incomplete counterbalanced measures design, with the native root as a control, to mitigate ordering effects. Hemodynamic and videometric data were analyzed using linear models with conduit as the fixed effect of interest and valve as a fixed nuisance effect with post hoc pairwise testing using Tukey’s correction. Results: Hemodynamics were clinically similar between grafts and control aortic roots. Regurgitant fraction varied between grafts, with SG and Uni-Graft groups having the lowest regurgitant fractions and anticommissural plication having the highest. Root distensibility was significantly lower in SG versus both control roots and all other grafts aside from the Stanford modification ( P ≤0.01 for each). All grafts except SG had significantly higher cusp opening velocities versus native roots ( P <0.01 for each). Relative cusp opening forces were similar between SG, Uni-Graft, and control groups, whereas anticommissural plication, Stanford modification, and Valsalva grafts had significantly higher opening forces versus controls ( P <0.01). Cusp closing velocities were similar between native roots and the SG group, and were significantly lower than observed in the other conduits ( P ≤0.01 for each). Only SG and Uni-Graft groups experienced relative cusp closing forces approaching that of the native root, whereas relative forces were >5-fold higher in the anticommissural plication, Stanford modification, and Valsalva graft groups. Conclusions: In this ex vivo modeling system, clinically used valve-sparing aortic root replacement conduit configurations have comparable hemodynamics but differ in biomechanical performance, with the straight graft most closely recapitulating native aortic root biomechanics.
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Paulsen et al. (2020) studied Valve-sparing aortic root replacement (n=5). Conduit configurations (anticommissural plication, Stanford modification, straight graft, Uni-Graft, and Valsalva graft) vs. Native root was evaluated on Hemodynamic and videometric data (regurgitant fraction, root distensibility, cusp velocities and forces). In an ex vivo model, clinically used valve-sparing aortic root replacement conduits had comparable hemodynamics but differed biomechanically, with the straight graft most closely matching native roots.
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