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

When evaluating the efficacy of new antimineralization treatments for biopr osthetic heart valves, subcutaneous implantation in a rat model often is us ed as an initial test. Although this model is widely used, there still are many aspects of its implementation that have not been investigated. To furt her investigate several parameters that may affect mineralization in the su bcutaneous rat model, portions of glutaraldehyde-treated porcine aortic val ve cusps were implanted both ventrally and dorsally into 21-day-old male Sp rague-Dawley rats. Cusp quadrants were explanted at 1,2, and 3 weeks postim plantation and the calcium levels determined by atomic absorption spectrosc opy. 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 ti ssue mineralizes in the subcutaneous rat model. A total of 270 tissue speci mens were examined. While the specific portion of the cusp implanted did no t significantly affect the degree of mineralization, dorsal implantation re sulted 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 incons istent placement of tissues in the rat subcutaneous implant model can resul t in significant differences in the degree of mineralization. (C) 1999 John Wiley & Sons, Inc.