Authors:
Publish Date: 1991/03/01
Volume: 5, Issue: 3, Pages: 144-154
Abstract
Histological scanning and transmission electron microscope studies weremade of normal human dura mater and cardiac valvular bioprostheses made ofglyceroltreated human dura mater recovered after having been implanted inthe aortic position 8 patients or the mitral position 1 patient forperiods up to 4 years Human dura mater has two layers an inner ormeningeal layer and an outer or endosteal layer The surface of the innerlayer is smoother than that of the outer layer Both layers are composedmainly of large wavy collagen fibrils which are thought to correspond totype I collagen and are relatively poor in elastic fibers andproteoglycans Small calcific deposits were found in normal dura from olderpatients Changes occurring in dura mater bioprostheses within 2 days afterimplantation consisted mainly of small surface thrombi Calcific nodulesdegenerated collagen and evidence of penetration of erythrocytes and plasmaproteins into the cusps were observed in bioprostheses that had failedafter being in place for 14 years The calcific deposits and thedegenerated collagen appeared structurally similar to those inglutaraldehydetreated porcine aortic valvular bioprostheses Howevercollagen fibrils in the latter were smaller than those in dura materPlatelet aggregates on the cuspal surfaces were much less numerous in duramater bioprostheses than in porcine aortic valvular bioprostheses It ispostulated that this difference is a function of the size of the collagenfibrils in the bioprostheses and that this accounts for the very lowincidence of clinically evident thromboembolism in patients with implanteddura mater valves
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