Objective : To compare the calcification characteristics of four different types of porcine stentless biological valves : 1. Photofix® (photo-oxidation), 2. Freestyle® (gluteraldehyde-fixed, AOA treated), 3. Edwards Prima Plus® (gluteraldehyde-fixed, Tween-80 treated), 4. A tissue-engineered (TE) valve (endothelialized acellular porcine valve).
Materials and methods : All valves were implanted in pulmonary position in juvenile sheep : Photofix® (n=6), Freestyle® (n=6), Prima Plus® (n=6), TE-valve (n=8). Valves were explanted after 3 or 6 months and examined macroscopically, by X-ray, light microscopy and transmission electron microscopy. Calcium content was determined by atomic absorption spectrometry (µg/mg).
Results : The cusps of all implanted valves remained free of calcification, they were nicely pliable and competent. The tissue-enigineered cusps were histologically intact, despite incomplete coverage by an endothelial monolayer. The calcium content was 0,65 ± 0,18 ; 0,87 ± 0,43 ; 0,54 ± 9,09 and 1,26 ± 1,33 for the Photofix®, Freestyle®, Prima Plus® and the TE-valve respectively (p>0,05). The Freestyle®, the Prima Plus® and the TE-valve all showed extensive calcification in the outflow part of the wall, while the wall of all Photofix® valves remained flexible and free from mineralization. Calcium content of the outflow wall portion : 1,87 ± 1,20 in the Photofix® ; 43,88 ± 33,13 in the Freestyle® ; 69,23 ± 20,52 in the Prima Plus® and 45,67 ± 29,58 in the TE-valve (p<0,05 for Photofix® versus all other valves).
Conclusion : Photo-oxidation of a porcine stentless valve can prevent calcification in the cusps as well as in the aortic wall portion. The TE-valves showed good biomechanical results, but further research is necessary to prove the value of endothelialization of heart valves
Conclusion : Mitral valve reconstructive surgery is feasible in the majority of the cases of active infective endocarditis of the mitral valve. These techniques will provide the best resistance to early and late infection while preserving ventricular function.