Experimental Evaluation of the Mitroflow Pericardial Heart Valve Prosthesis. Part I. In Vivo Hemodynamic Evaluation

Evaluation of possible enhanced durability of the Mitroflow pericardial heart valve prosthesis was undertaken in an experimental animal model using the Chacma baboon. For comparison purposes a small series of 4 Ionescu-Shiley pericardial valves were also implanted.

The 33 Mitroflow prostheses implanted were all manufacturer's size 21mm and belonged to 4 different groups according to the process used for the prepa ration of the pericardium (Process I to IV). The Ionescu-Shiley prostheses were all manufacturer's size 19mm and were commercially available valves. The valves were implanted in the mitral position, except one each Mitroflow and Ionescu-Shiley prosthesis that was implanted in the tricuspid position.

Four animals died in the early postoperative period, between 2 and 14 days. Two died from a probable viral infection, one from a low cardiac output state and the fourth one from bacterial endocarditis. The clinical evaluation of the animals for an implantation time of up to twelve months was unremarkable. Hemodynamic studies were performed immediately after implantation (n = 29), at an intermediate cardiac catheterization at 9 months after implantation (n = 4) and at the time of terminal elective sacrifice of the animals (n=33). From the data obtained the resultant prosthetic valve area at the time of elective sacrifice of the animals was also calculated. The data obtained for each of the 5 groups of valves tested are presented in the text. Transvalvular gradients measured at the time of sacrifice of the animals were elevated. Statistically however the rate of change of pressure gradient per month did not differ significantly from the controls (Ionescu-Shiley valves) for each of the processes I to IV.

As far as it could be ascertained in this study the Mitroflow size 21mm bo vine pericardial heart valve prosthesis, although it went through multiple modi fications during the study period, did not prove to have any significant long-term hemodynamic advantage over the Ionescu-Shiley size 19 mm bovine pericardial heart valve prosthesis.