A study of the cells in the explanted viable cryopreserved allograft valve.

From June 1975 to December 1987, 231 patients underwent aortic valve replacement with a viable cryopreserved allograft aortic valve. Throughout this era, a uniform procurement and preservation was used to maintain leaflet fibroblast viability. The allograft valve was obtained from coroner's autopsies within 24 hours of death, and more recently from organ donors, incubated for 24 hours in low dose antibiotic solution followed immediately by cryopreservation (mean time interval 39 hours after donor death). Viability was ensured by monitoring glucose utilization of the aortic and pulmonary valves and by demonstrating fibroblast growth in tissue cultured from the pulmonary valve. A uniform protocol for valve preparation was used during the entire experience. Nine allograft aortic valves have been obtained by eight reoperations (two were for leaflet degeneration) and one autopsy. The time intervals from implantation to explantation were 2 months, 10 months, 20 months, 22 months, 2.2 years, 5 years, 8.3 years, 9.2 years, and 10.8 years. Histologic examination of the leaflet tissue disclosed a variable degree of cellularity, ranging from a highly cellular matrix (9.2 years) to minimal cellularity (20 months). Within the same valve (10 months), one leaflet was completely acellular with a moderate degree of cellularity in the other two leaflets. The competent valve recovered at autopsy (8.2 years) was essentially acellular. Fibroblasts could consistently be cultured from leaflets in which viable cells were seen histologically. Chromosomal analysis of cultured cells from a valve leaflet (9.2 years) that was implanted with a donor and recipient sex mismatch demonstrated persistence of donor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

The viable cryopreserved allograft aortic valve.

One hundred and twenty-four patients underwent aortic valve replacement with a nonviable 4 degrees C refrigerated aortic allograft valve. One hundred and eighty-four patients underwent aortic valve replacement with a viable cryopreserved aortic allograft valve in a later era. The longest follow-up was 16 years for the group with the nonviable valve and 11 years for the group with the viable valves. Within this time frame, reoperation was required in 23 patients with nonviable valves for leaflet perforation or rupture whereas no patients in the group with viable valves developed this complication (p less than 0.0001). The prevalence of endocarditis and thromboembolism was very low in both groups. Viability of leaflet tissue is associated with an important improvement in durability over nonviable allograft valves. Consequently, long-term follow-up results of allograft valves might be best expressed in terms of viability. The current evidence suggests that the viable cells are donor in origin. The viable cryopreserved aortic allograft valve offers significant advantages over current nonviable allograft valves, mechanical valves, and bioprostheses.