Impact of Valve Model and Orientation on Valve-in-Valve Clotting Formation: An In Vitro Study

Background: The mechanism underlying valve thrombosis after transcatheter aortic valve-in-valve (ViV) is poorly understood. Previous reports suggest that the type of surgical and transcatheter heart valve may be related to valve thrombosis. Furthermore, it has not been investigated whether the orientation of the THV inside the surgical valve is related to valve thrombosis. The aim of this study was to investigate the impact of valve model and the orientation of the THV with respect to the surgical valve on clotting formation in an in-vitro study.

Method: Two transcatheter heart valves (THV) (self-expanding CoreValve 26-mm and balloon-expanding SAPIEN XT 23 mm) were implanted as ViV in three surgical aortic valve (SAV) models (Perimount Magna Ease 23 mm, Hancock II 25 mm, Trifecta 23 mm) in A-orientation (commissure–commissure) and B-orientation (commissure–cusp). Clotting formation (CF) was simulated with milk, the clotting microbial rennet (enzyme chymosin and pepsin), and calcium chloride in a cardiac circulatory simulator with 2 L/min flow at 37°C till the onset of milk-clotting for every combination (n = 60). The nadir, commissure, leaflet, and wall of the THV within the SAV were scored (1 point = low, 2 points = middle, and 3 points = strong CF). The summary of this TF score was compared within the different ViV combinations and positions amongst each other.

Results: CF was compared in the following groups: (1) the combination of surgical valve and THV and (2) the orientation of THV inside the surgical valve (A vs. B). The commissure and leaflet of the THV as ViV showed predisposition for CF in comparison to the nadir and wall. The orientation A versus B had no significant effect on ViV clotting for both THVs. We found significant lower CF in THV-in-Magna Ease versus THV-in-Hancock (CoreValve + Sapien: 119 vs. 133 points; p = 0.016), Sapien-in-Magna Ease versus CoreValve-in-Magna Ease (52 vs. 67 points; p = 0.008) and Sapien-in-Hancock versus CoreValve-in-Hancock (63 vs. 70 points; p = 0.035). There was no significant difference between Sapien-in-Trifecta and CoreValve-in-Trifecta (62 vs. 61 points; p > 0.05) regarding CF.

Conclusion: The implantation orientation commissure-commissure versus commissure-cusp had no significant effect on ViV clotting for both THVs. ViV combination seems to have an impact on the incidence of CF regarding valve model. These findings may be very useful during a ViV procedure to prevent valve thrombosis.

Publication History

Article published online:
28 January 2023