Effect of AOA on glutaraldehyde-fixed bioprosthetic heart valve cusps and walls: binding and calcification studies

Alpha-aminooleic acid (AOA), a potent, non-toxic and biocompatible anticalcification agent, has been shown to be effective for glutaraldehyde-fixed valves in rat and juvenile sheep models, and is used for the treatment of Medtronic heart valve bioprostheses currently in clinical trials. In the pre-clinical sheep study of a stentless aortic root, the treatment with AOA prevented calcification of the cusps, but not of the wall. The experiments described in this manuscript were designed to investigate a possible relationship between the binding of AOA and the differential treatment efficacy in the cusp and the wall, and to improve the anticalcification effect of the AOA treatment in the wall. Glutaraldehyde-fixed porcine roots were treated with [14C]-AOA for binding studies, and with non-radioactive AOA for calcification studies for rat subdermal implants. The results indicate that a) the AOA treatment did reduce wall calcification, but only temporarily, b) the low efficacy of the AOA treatment on the wall was probably due to the limited penetration of AOA, and c) increasing the volume of the AOA solution during treatment significantly increased the content of AOA in the wall, and significantly decreased wall calcification. This study suggests that AOA efficacy in the wall may be hindered because of the physical characteristics of the wall, and that wall calcification may be prevented by developing methods aimed at increasing AOA penetration into the wall.