Explanted porcine aortic bioprosthetic heart valves (n=14, 42 cusps) all showed substantial noncalcific structural damage spatially distinct from calcification deposits after 5-20 years of function.
Observational (n=14)
Collagen fiber disruption occurs independently of calcification in explanted bioprosthetic heart valves, highlighting mechanical stress as a key driver of structural valve deterioration.
The durability of bioprosthetic heart valves (BHV) is severely limited by tissue deterioration, manifested as calcification and mechanical damage to the extracellular matrix. Extensive research on mineralization mechanisms has led to prevention strategies, but little work has been done on understanding the mechanisms of noncalcific matrix damage. The present study tested the hypothesis that calcification-independent damage to the valvular structural matrix mediated by mechanical factors occurs in clinical implants and could contribute to porcine aortic BHV structural failure. We correlated quantitative assessment of collagen fiber orientation and structural integrity by small angle light scattering (SALS) with morphologic analysis in 14 porcine aortic valve bioprostheses removed from patients for structural deterioration following 5-20 years of function. Calcification of the explants varied from 0 (none) to 1+ (minimal) to 4+ (extensive), as assessed radiographically. SALS tests were performed over entire excised cusps using a 0.254-mm spaced grid, and the resultant structural information used to generate maps of the local collagen fiber damage that were compared with sites of calcific deposits. All 42 cusps showed clear evidence of substantial noncalcific structural damage. In 29 cusps that were calcified, structural damage was consistently spatially distinct from the calcification deposits, generally in a distribution similar to that noted in porcine BHV subjected to in vitro durability testing. Our results suggest a mechanism of noncalcific degradation dependent on cuspal mechanics that could contribute to porcine aortic BHV failure.
Sacks et al. (Tue,) conducted a observational in Bioprosthetic heart valve structural deterioration (n=14). Explanted porcine aortic bioprosthetic heart valves was evaluated on Collagen fiber orientation and structural integrity assessed by small angle light scattering (SALS). Explanted porcine aortic bioprosthetic heart valves (n=14, 42 cusps) all showed substantial noncalcific structural damage spatially distinct from calcification deposits after 5-20 years of function.