CHARACTERIZATION OF ABNORMALITIES RESPONSIBLE FOR IMMEDIATE REJECTIONOF PORCINE AORTIC VALVES FOR THE MANUFACTURE OF BIOPROSTHESES

Gross observation at the slaughterhouse determines the primary selecti on of porcine aortic valves for the manufacture of bioprostheses. This step is critical because only valves with significant abnormalities a re rejected. The present study validated this selection process by inv estigating the pathological characteristics of one series of accepted valves and one series of rejected valves. Macroscopy, x-ray examinatio n, light microscopy, and scanning electron microscopy (SEM) were perfo rmed on 5 initially rejected valves, 3 leaflets from 3 other initially rejected valves, and 6 valves that successfully passed this first ste p in the selection process. Abnormalities were macroscopically visible only on the rejected valves and were described as thick white areas, heavy white striations, thin spots, white plaques, and nodules. Indivi dual variability in the structure of each leaflet was more significant in the rejected valves than in the valves that had passed the first i nspection. The leaflets of the rejected valves were also irregularly t hick with a lack of consistency in the position and prominence of the different layers. The formation of nodules and the presence of white p laques in the inner fibrosa layer were among the pathological features . The initially accepted valves considered defect free under gross obs ervation continued to display some weaknesses, and not all of the valv es selected during the first step of the process were suitable to beco me bioprostheses. Because the manufacturer carries out further quality control inspections at every step of preparation resulting in additio nal rejections, it is therefore anticipated that all valves with defec ts will be rejected. None of the rejected valves were defect free, and rejection was fully justified.