http://repub.eur.nl/res/aut/23889/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/20060/ 1999-11-17T00:00:00Z The application of human tissue valves for aortic valve or root replacement was introduced during the 19608. The first successful clinical orthotopic implantation of an aortic allograft was performed by Ross and Barrat-Boyes independently in 19621,2, In 1967 Ross first reported the use of the pulmonary autograft in the subCOrOllai), position to replace a diseased aortic valvc3. The initial results of implantation of a freshly harvested allograft valve in the orthotopic position were generally good4, However, limited donor availability led to the development of preservation methods, like freeze-drying and fresh wet stotage at 4 oc. Concern about the transmission of infection initiated aggressive sterilization techniques: irradiation, highly concentrated antibiotic incubation and glutaraldehyde prctreatment2,S,6. Although these methods increased storage time and tissue availability, the clinical durability of dle allograft was dramatically infel10r to fresh untreated allografts4• During this period, reliable artificial heart valves were developed. They were available from the shelf and implantation was less demanding compared to the allograft and autograft implantation. The problems related to preservation and storage. and the development of aortic valve prostheses have delayed a widespread acceptance of human tissue valves. Improved sterilization methods and adequate hatvesting have improved the allograft durability since d,e carll' 1970s7-9, TIle development of cryoprcservation techniques by Angell and O'Brien has extended the duration of allograft storage in liquid nitrogen 10-12 The foundation of hcatt valve banks and the reported good longtetm clinical results in the late "19808 have initiated a renewed interest of cardiac surgeons in the usc of human tissue valves for aortic valve replacemenfS,10-12. Aortic allografts and autografts have advantages over mechanical and bioprothetic aortic valve prostheses due to their low incidence of endocarditis, thtombo-embolism, anticoagulation-related complications and improved durability compared with bioprostheses. However, their durability is still limited, compared with mechanical prostheses. The limited durability of human tissue valves is the main topic of clus thesis.