ACID HYDROLYZABLE ALDEHYDES IN LONG-TERM STORED COMMERCIAL BIOPROSTHETIC HEART-VALVES - IMPLICATIONS FOR CALCIFICATION

There is evidence that glutaraldehyde used routinely in the fixation p rocess of bioprosthetic heart valves may be a major factor in their su bsequent calcification. A further complication is introduced by the us e of a formaldehyde treatment step, whether for sterilization or stora ge. The effects of this second aldehyde on calcification is also unkno wn, The aim of the present work is to determine the degree of glutaral dehyde and formaldehyde incorporation into commercial valve leaflets a nd to establish whether there is a relationship between the aldehyde t reatment and tissue calcification. Both pre- and post-implantation con centrations of aldehydes were estimated by high performance liquid chr omatography of acid hydrolyzates of commercial valve tissue. Control s amples were taken from freshly prepared porcine aortic valves and bovi ne pericardium fixed in glutaraldehyde. The degree of calcification wa s investigated using the rat subcutaneous implant model. Samples were retrieved after 56 days and calcium estimated by atomic absorption spe ctroscopy. The results indicated that storage of both porcine and peri cardial valves for periods of 5 years or longer reduced calcification, A greater reduction in calcification was noted when tissue was treate d sequentially with glutaraldehyde and formaldehyde rather than glutar aldehyde alone. From this work it can be concluded that bioprosthetic valves calcify less in the rat model when they are stored for extended periods of time in glutaraldehyde solution. This effect is enhanced w hen formaldehyde storage is employed. (C) 1998 by Elsevier Science Inc .