FATIGUE-INDUCED FAILURE OF THE IONESCU-SHILEY PERICARDIAL XENOGRAFT IN THE MITRAL POSITION - INVIVO AND INVITRO CORRELATION AND A PROPOSED CLASSIFICATION

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  • 1 January 1984
    • journal article
    • research article
    • Vol. 87  (6) , 836-844
Abstract
Four patients had signs of primary bioprosthetic dysfunction within the 4th postoperative yr after mitral valve replacement with an Ionescu-Shiley pericardial xenograft; they represent .apprx. 9% of patients with Ionescu-Shiley pericardial xenograft mitral valves followed up for > 3 yr. Pathological investigation showed severe incompetence of all explanted valves due to cusp tears and lacerations. Histologic study of the pericardial tissue disclosed mild to moderate collagen degeneration, without infection or calcification. Neoendothelial formation on the Dacron cloth of the sewing ring was either absent or minimal. The high incidence of valvular incompetence prompted us to try to establish a correlation between the in vivo and in vitro modes of failure of the Ionescu-Shiley pericardial xenograft. For this purpose, 10 unimplanted Ionescu-Shiley pericardial xenograft valves were tested in a fatigue test system. Severe fatigue-induced lesions occurred in this group after an average of 29.09 .+-. 17.26 .times. 106 cycles; initial failure could be recognized in 6 of them after an average of 16.94 .+-. 20.12 .times. 106 cycles. Valves tested in the fatigue test system showed tears and lacerations similar to those noted in the Ionescu-Shiley pericardial xenografts obtained from the 4 patients (which were assumed to have functioned for > 100 .times. 106 cycles in each case). Correlation between results of the fatigue testing and our clinical experience enabled us to recognize 4 types of tears which may occur in the Ionescu-Shiley pericardial xenograft. The results of this investigation showed the following: Primary tissue failure of the Ionescu-Shiley pericardial xenograft may occur suddenly. A classification of tears occurring in Ionescu-Shiley pericardial xenograft valves is useful since the clinical presentation of patients may differ according to type and location of the lesion. In the manufacture of pericardial valves, particular care must be observed in selection of the tissue and in the frame design. Improvement of the quality control is one of the clues to enhance durability of the Ionescu-Shiley pericardial xenograft.

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