Mineralization of glutaraldehyde-fixed porcine aortic valve cusps in the subcutaneous rat model: analysis of variations in implant site and cuspal quadrants.

Abstract

When evaluating the efficacy of new antimineralization treatments for bioprosthetic heart valves, subcutaneous implantation in a rat model often is used as an initial test. Although this model is widely used, there still are many aspects of its implementation that have not been investigated. To further investigate several parameters that may affect mineralization in the subcutaneous rat model, portions of glutaraldehyde-treated porcine aortic valve cusps were implanted both ventrally and dorsally into 21-day-old male Sprague-Dawley rats. Cusp quadrants were explanted at 1,2, and 3 weeks postimplantation and the calcium levels determined by atomic absorption spectroscopy. The objective of this study was to determine whether or not different implant locations and/or regions of the cusps affect the degree to which tissue mineralizes in the subcutaneous rat model. A total of 270 tissue specimens were examined. While the specific portion of the cusp implanted did not significantly affect the degree of mineralization, dorsal implantation resulted in significantly more mineralization than abdominal implantation (p = 0.007). As expected, longer implantation time was associated with greater calcification (p = 0.0001). The results of this study indicate that inconsistent placement of tissues in the rat subcutaneous implant model can result in significant differences in the degree of mineralization.