[Structural changes in xenografts used for heart valve replacement]

Macroscopic, lights-and electron microscopic examination of 14 xenograft valve prostheses was carried out over a follow-up period of 1-49 months. 8 out of the 14 were acidic formaldehyde pretreated porcine aortic valves, 4 glutaraldehyde pretreated ones (Carpentier-Edwards) and 2 of them were glutaraldehyde calf's pericardium valves (Ionescu-Shiley). Formaldehyde pretreated grafts had to be surgically removed for valve failure. Glutaraldehyde grafts were obtained at autopsy. Until death, their function was excellent. The main pathological finding in both type of grafts was disintegration of collagen, which in glutaraldehyde grafts appeared to be of milder degree. In formaldehyde pretreated grafts cellular reaction indicating chronic rejection has also been observed. It is concluded that formaldehyde pretreated xenografts are not suitable for clinical use. On the other hand glutaraldehyde pretreated ones inspite of structural alterations may be functioning for years.