Homograft valve preparation and predicting viability at implantation

An experimental study was performed using C14 proline uptake in order to: (1) assess the effects of current sterilization and storage methods on fibroblast viability, and (2) establish a control tissue that could be used to determine viability of each homograft valve at the time of implantation in the clinical setting. The results were expressed as disintegrations per minute per milligram of tissue (DPM/mg). Swine aortic (AV), pulmonary (PV), and tricuspid leaflets (TV), and adjacent AV and PV arterial wall were procured sterile and subjected to routine sterilization and storage. Thirty samples of AV were analyzed for incorporation of labeled proline at procurement (208 +/- 7 DPM/mg), following 48-hour antibiotic exposure (87 +/- 6 DPM/mg, P less than .0001), and following controlled rate cryopreservation and storage for 12 days at -80 degrees C (78 +/- 8 DPM/mg, P = .42). Proline uptake of the other tissues at the same intervals disclosed that only the TV resulted in the same degree of viability at implantation (AV 78 +/- 8, PV 68 +/- 3, TV 75 +/- 2, P = NS). The homograft valves were obtained under sterile conditions from brain dead, multiorgan donors (homovital). It has been postulated that these valves are sterile and ready for implantation. Of 17 homovital valves cultured at procurement, 9 had positive cultures within 48 hours (53%). We conclude that: (1) the TV can be processed as a control tissue with each homograft and then utilized to predict viability at the time of implantation in the clinical setting; (2) antibiotic exposure is an essential step in the preparation of all homografts, however, modification of the antibiotic solution is necessary.