Characterization of a polyepoxy compound fixed porcine heart valve bioprosthesis

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Abstract
Concerns with the currently available bioprostheses are calcification, long‐term durability, and suboptimal hemodynamic performance. It is well known that these concerns are all more or less related to the cross‐linking reagent, glutaraldehyde or formaldehyde, used in fixing bioprostheses. To address these concerns, we undertook the development of a porcine bioprosthesis fixed with a polyepoxy compound. In the development of this polyepoxy compound valve, it was found that the porcine leaflets fixed with polyepoxy compound were softer and more pliable than those fixed with glutaraldehyde. In this study, a special microtoming technique was developed to section the biological tissue so that the fixation uniformity in distinct layers of porcine aortic wall could be characterized. The fixation index and the denaturation temperature measurements in distinct layers of aortic walls showed that the cross‐linking density was uniform throughout the entire aortic wall for the polyepoxy compound fixed porcine valve. It was also noticed that the fixation index of the polyepoxy compound fixed aortic wall (91.5 ± 0.5, n =3) was not significantly different from that of its valvular leaflet (90.6 ± 0.8, n = 3). Similarly, the denaturation temperature of the polyepoxy compound fixed aortic wall (80.4 ± 0.9°C, n = 5) was statistically comparable to that of its valvular leaflet (79.0 ± 0.5°C, n = 5). The results of this study indicated that polyepoxy compound can adequately fix the entire porcine aortic wall as well as its valvular leaflets. In a preliminary study, three polyepoxy compound fixed valves were evaluated in the mitral position in a juvenile sheep model. At 5‐month retrieval, no calcification could be visually observed in any of the explanted valves. © 1994 John Wiley & Sons, Inc.