Homografts: a review.

Since their introduction into clinical practice in 1965 homografts have become established in clinical routine. The storing and sterilization procedures have been improved over time. Long-term results showed that homografts had a superior durability compared to xenogenic biological prostheses. Approximately 40% were still in place 20 years after implantation in aortic position. Their low rate of thromboembolic events made a life-time anticoagulative therapy unnecessary and their hemodynamics were superior to all other heart valve prostheses. There exist two implantation techniques, subcoronary or mini-root, both technically more demanding compared with implantation of stented valve prostheses. When using the subcoronary technique, the valve is suspended into the aortic root leaving the coronary arteries untouched. The success of this technique, however, depends on the relation of the recipients aortic root and the implanted valve. The mini-root technique requires reimplantation of the coronary arteries but left the morphology of the valve and its root unchanged. Especially in patients with endocarditis, the mini-root technique offered the advantage of allowing for excision of all affected tissue with subsequent replacement by the homograft. The Ross-procedure uses the patient's own pulmonary valve as aortic valve substitute with implantation of a homograft in pulmonary position. This proved to be advantageous in children, since in these patients the degeneration of an aortic homograft was faster compared to an older population. This was explained by the recipient's immunologic response to the graft which was more pronounced in younger patients. The advantages of homografts with regards to hemodynamics and thromboembolic risk make them a good alternative to mechanical prostheses in younger, active patients. In very young patients, a Ross-procedure was shown to be superior to aortic homografts due to slower degeneration of the autograft. The decision to use a homograft must be made individually according to the patients demands.