Early failures of Ionescu-Shiley bioprosthesis after mitral valve replacement in children.

Two infants, 101/2 and 11 1/2 months of age, underwent mitral valve replacement with Ionescu-Shiley bovine bioprosthesis for congenital cardiac defects. Both patients had early valve failure, 19 months and 4 months after implantation, due to the growth of excessive collagen on the ventricular surface of the bioprosthesis with adherence of the collagen primarily to the sewing rings and struts of the valves. The cause of this excessive collagen reaction is unknown. Further study is needed to document the true incidence of this problem.