Experimental Evaluation of the Mitroflow Pericardial Heart Valve Prosthesis. Part II. Pathologic Examination

The results of the morphologic and histopathologic examination of 37 bovine pericardial heart valve prostheses that were retrieved after experimental implantation in Chacma baboons for periods of one to twelve months are presented in this study. The implanted prostheses consisted of 33 Mitroflow valves, size 21 mm, that belonged to four different groups according to the method of preparation of the pericardium (process I to IV) and 4 commercially available Ionescu-Shiley valves, size 19 mm. All implantations were in the mitral position, except 1 Mitroflow and 1 Ionescu-Shiley prosthesis, which were implanted in the tricuspid position. Moderate or abundant noninfected thrombotic deposits were found on the cusps of 13 of the 33 Mitroflow valves (39%). The Ionescu-Shiley valves shared this tendency, perhaps to a lesser extent, for the formation of thrombus on the valve cusps. Results of transmission electron microscopy, scanning electron microscopy, and calcification analysis are also presented. In this experimental study, the authors did not identify any significant characteristics in the Mitroflow bovine pericardial heart valve prosthesis that would lead to improved or extended durability of this device over the commercially available Ionescu-Shiley bovine pericardial heart valve prosthesis and probably over any other glutaraldehyde-treated bioprosthesis. They would suggest, therefore, that any clinical investigations of the prosthesis be undertaken very cautiously.