Comparative study of calcification in the T6-treated and standard Hancock-I porcine xenografts: experimental study in weanling sheep.

We compared the morphological findings in 15 young sheep in which standard Hancock-I cardiac bioprostheses (7 animals) and T6-processed Hancock-I (8 animals) were implanted in the tricuspid position. The animals were sacrificed at intervals from 8 to 47 weeks after valve replacement. No valvular infection was detected. Six of the 7 untreated valves and 5 of the 8 T6-processed valves in the tricuspid position showed calcific deposits in the radiographic examination. Roentgenograms from all specimens showed a fairly uneven distribution of the mineralization sites with the commissures being the structure most frequently involved. Calcium in the aortic wall was more frequent in the T6-processed group while right coronary leaflet involvement more frequent in the control group. Histologic evaluation confirmed the above data and showed a fibrotic reaction with granulomatous degeneration of the muscular shelf in all valves. Comparison of linear regression lines of the evolution of tissue calcium content with time showed no statistically significant difference between the 2 groups. Under the conditions of this study, the T6-treatment does not reduce the extent of calcification in the Hancock-I porcine xenograft after implantation in the tricuspid position in young sheep.