Failure and hydrodynamic function testing of explanted pericardial and porcine bioprosthetic valves

The long-term durability and function of cardiac bioprostheses can be affected by both calcification and mechanical failure of the tissue. The mechanisms of failure and hydrodynamic function of 66 explanted bioprostheses have been studied. The majority of porcine valves were heavily calcified with leaflet tears adjacent to the calcification at the commissures. These tears caused prolapsed leaflets and regurgitation of between 30 and 70 per cent. Only three porcine valves had tissue failure in the absence of calcification. The majority of pericardial valves failed due to leaflet tears at the edge of the frame in the absence of macroscopic calcification. These tears also produced prolapsed leaflets and large regurgitation in hydrodynamic tests. Three pericardial valves were heavily calcified and stenotic without leaflet tears. Leaflet dynamics in the pericardial valves were affected by host tissue ingrowth which produced increased pressure drops across the valves, an asymmetrical open position and leaflet flutter. In the absence of calcification and leaflet tears, there was little change in the function of explanted porcine valves.