Non-Destructive Method for Assessing the Degree of Calcification in Bioprosthetic Heart Valves

Highlights Micro-computed tomography allows specialists to qualitatively and quantitatively assess the structure of calcified areas of explanted bioprosthetic heart valves. This method enables the evaluation of changes in the structure of the bioprosthesis that have occurred during its prolonged operation. Aim of the study . To evaluate the potential of high-resolution tomography for the study of mitral valve bioprostheses of different designs explanted due to dysfunction and various calcification patterns (microcalcification and macrocalcification). Methods . Single samples of the «UniLine» and «PeriCor» bioprostheses were the objects of study, they were explanted due to dysfunction developed after 76 and 87 months of operation in recipients. The peculiarities of calcification localization in the structure of bioprostheses were studied using high-resolution tomography followed by reconstruction of volumetric images and quantitative analysis of radiodense areas. Moreover, we used light microscopy with Alizarin Red S staining to detect calcifications. Results . The study results showed that the nature of the distribution and volume of calcinates significantly differ between the studied samples: for the «UniLine» bioprosthesis, the affected areas were located in the leaflet material and constituted 21.1% of the total biological tissue volume; for the «PeriCor» bioprosthesis, calcifications were diffusely distributed in small structural formations, accounting for a total of 5.1% of the biological material, primary localized on the «auxiliary» structures of the prosthesis – the covering made of porcine or calf xenopericardium. In addition, high-resolution tomography allowed us to determine the degree of deformation of the «UniLine» bioprosthesis frame, with the posts deviating inward by 1.1–1.4 mm. Conclusion . The possibility of using computed microtomography for qualitative and quantitative assessment of calcified xeno-pericardial and xeno-aortal bioprostheses has been demonstrated. However, this method is limited in its ability to detect macrocalcification within the leaflet thickness.