Gamma Radiation and its Role in Bioprosthetic Aortic Valves Implanted in Rat Hearts

pp 263-269

Abstract

Porcine heart valves glutaraldehyde fixed are implanted in patients whith valvular deterioration.Mineralization may be the major factor in the long-term failure of tissue bioprosthesis. Gamma radiation randomly breaks some glutaral-dehyde cross-links. As a consequence of irradiation, the polymeric fibers belonging to the valvular tissue are broken too, leading to sites of collagen fiber disorganization. It is well known that the collagen fibers may act as a passive nucleator of salts where the calcium phosphate salts precipitate.These salt concentration has been described in association with desintegrated sites of protein fiber, which may favour new sites where the calcium salts would be deposit. The irradiation process is a technique used for sterilization of porcine heart valve. The main objective of this work was to study the effect of different doses of gamma radiation on the calcification process of subcutaneously implanted valves in rats.

Small pieces from glutaraldehyde fixed valves, irradiated to different doses with a60Co source were implanted subcutaneously in rats. The calcium was measured by X-ray and atomic absorption spectrophotometry. In our experimental conditions and at the radiation doses used in these tests, the calcium measurements on control and irradiated material were not significantly different. We conclude that, at the employed doses, the gamma radiation does not alter the process.