Infrared spectroscopy in the evaluation of the process of calcification ofvalvular bioprostheses

Background. The methods currently used to analyze the process of calcificat ion of bioprostheses give only global information on calcium deposition. We investigated the potential advantage of infrared spectroscopy, which makes it possible to analyze the various components of the calcification process , ie, lipids, proteins, and calcium deposits. Methods. Sixty porcine aortic leaflets were fixed in 0.6% glutaraldehyde an d then subsequently implanted in 10-day-old Wistar rats. The valve leaflets were removed 2, 7, 14, 21, 35, and 56 days after implantation. Results. Before implantation infrared spectroscopic analysis revealed the p resence of proteins only. On day 2 after implantation, all valves showed mi nor lipid deposits. On day 7, amorphous calcium phosphate was detected. Bet ween days 7 and 14, crystalline forms of calcium phosphate appeared and amo rphous calcium phosphate progressively changed into carbapatite over the 56 -day period. Conclusions. Infrared spectroscopy yields valuable additional information o n the nature and kinetics of the various components of glutaraldehyde-treat ed tissues after implantation. It may prove to be important in the evaluati on of new techniques of calcium mitigation. (C) 1998 by The Society of Thor acic Surgeons.