THE VALUE OF THE STENTLESS BIOVALVE PROSTHESIS - AN EXPERIMENTAL-STUDY

Clinical use of the stentless bioprosthesis has not yet been accepted world-wide. Experimental studies are scarce. In a study in growing pig s, 23 aortic valve replacements were performed (7 stented bioprosthese s (STB), 10 stentless bioprostheses (SLB) and 6 cryopreserved homograf ts (CAH)). Valves were studied macroscopically and microscopically aft er explantation. Five animals died between 1.5 and 4 months after impl antation. Two STBs showed extreme calcific degeneration. A third STB a nimal died suddenly: this STB showed only minimal leaflet calcificatio n. One SLB was stenosed with a large fibrin deposit in one cusp, a sec ond SLB showed slight cusp calcification and there were paracommissura l tears in one cusp. In all other animals the valves were explanted af ter 5 to 6.5 months. All STBs showed severe calcific degeneration. Fiv e SLBs showed mild calcific degeneration, while three others were unal tered after 6 months. All CAHs were free of calcific degeneration, thr ee were perfect, two had a tear in a commisure and another was prolaps ed with a fibrin nodule in one cusp. Fibroblast proliferation was seen in all CAHs. This study shows that SLBs also suffer from calcific deg eneration. The speed and extent of valve degeneration were less than i n the STB group. The stentless design is an important contribution whi ch may result in a higher durability of bioprosthetic valves.