Structural valve deterioration does not alter tissue valves' radiopaque landmarks: Implications for valve-in-valve therapy.

Background: Valve-in-valve is established as a safe and efficient alternative to redo surgery in the treatment of structural valve deterioration (SVD). In vitro models rely on the radiopaque landmarks of undeteriorated tissue valves to establish the optimal implantation level of the transcatheter heart valves inside the deteriorated valves. In computed assisted procedures, the radiopaque landmarks of the deteriorated valves may be used to guide valve implantation through image fusion. The purpose of this study is to determine whether SVD alters the radiopaque landmarks of stented tissue valves.
Methods: Our approach was based on the computation of relevant anatomical measurements from CT images. Radiopaque landmarks of degenerated bioprostheses and the corresponding undeteriorated valves were extracted to create surface meshes and cloud points using grey-level thresholding. 3D registration using an iterative closest point algorithm was used to align the corresponding cloud points, while the modified Hausdorff Distance was applied to determine the differences between them.
Results: The proposed evaluation was performed on 19 degenerated tissue valves. 15 valves were scanned from patients evaluated for valve-in-valve procedures, and 4 bioprostheses were scanned after surgical extraction during redo aortic valve replacement. All the degenerated valves were compared to the corresponding undeteriorated models. Overall, the mean difference between degenerated and undeteriorated valves was 0.33 ± 0.12 mm. The maximum observed registration error was 0.66 mm.
Conclusions: Our study demonstrates no significant difference between the radiopaque landmarks of deteriorated and undeteriorated bioprostheses after the occurrence of SVD. Our findings suggest therefore that SVD does not alter radiopaque landmarks of stented tissue valves. These results validate in-vitro studies of optimal transcatheter heart valves implantation inside deteriorated tissue valves based on their radiopaque landmarks, and allow the use of non-deteriorated valves' imaging features in computer assisted valve-in-valve procedures.
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