Abstract 5843: Porcine Bioprosthetic Calcification Originates from Myocardium Shelves of the Right Coronary Cusps
Background: The right coronary cusps of commonly used porcine bioprostheses contain myocardium shelves (MS). MS occasionally extend to the left coronary cusps. The role of MS in porcine bioprosthetic longevity is poorly understood though the manufacturers of newer generation of porcine bioprostheses advocate removal of the cusps containing MS. HeartMate XVE left ventricular assist device (LVAD) is used to support end-stage congestive heart failure patients. LVAD has a pair of porcine bioprostheses, functioning as inflow and outflow valves. Early calcification was frequently seen in porcine bioprosthese used in LVAD, partly due to their exposure to extremely high pressure generated by LVAD. LVAD bioprostheses thus offer an ideal model to study the pathogenesis of porcine bioprosethetic calcification in humans, especially the role MS play.
Methods: One hundred twenty-eight bioprostheses removed from 64 explanted LVAD were studied histologically. The mean duration of LVAD implantation in patients was 265 ± 151 days (3 to 630). The mean age of patients was 55 ± 12 years (17 to 77). A 3mm-wide section of cusp was cut from the central part of the left and right coronary cusps of each valve, perpendicular to the base. A total of 256 samples were obtained and studied under microscope for the location of calcification.
Results: MS were present in 149 out of 256 valve cusps (58%). Calcium deposits were found in 58 out of 256 valve cusps (23%). Among 58 cusps with calcification, calcium deposits were found in MS only (n = 45, 78%), in both MS and valve collagen (n = 6, 10%), in valve collagen only (n = 4, 7%) and in others (suture and thrombi, n = 3, 5%).
Conclusions: In porcine bioprostheses explanted from LVAD, early calcium deposits located predominately in the MS of valve cusps while sparing valve collagen. Removing valve cusps containing MS during porcine bioprosthetic manufacture might help prevent its calcification.