ABSTRACT
BACKGROUND: Valve replacement using cryopreserved valved homograft is increasing because of resistance of infection and excellent hemodynamics. The viability of fibroblast which is related with warm ischemic time affects the durability of implanted cryopreserved valved homograft. We evaluated how long the warm schemic time is acceptable by examining the viability of cells depending upon warm ischemic time. MATERIAL AND METHOD: 1. Retrieval of tissues; Thirty-two slaughted porcine heart and lung enblocs were stored at refrigerator(4~8 degreesC) for various time period(Warm Ischemic Time), and the heart was dissected and stored in Hartman solution at 4 degreesCfor 24 hours(Cold Ischemic Time) as the simulation of retrieval and dissection of human heart. The hearts were assigned to groups A(2 hours), B(12 hours), C(24 hours), D(36 hours) depending on warm ischemic time. 2. Sterilization; The valved homografts were sterilized in the RPMI 1640 solution with antibiotics. 3. Freezing and Storage; The homografts were freezed by computerized freezer, stored 7 days at liquid nitrogen tank, and thawed. 4. Evaluation of the viability; The viability was evaluated by Triphan blue test after warm ischemic time, after cold ischemic time and after thawing. 5. Analysis; The viability of fibroblast was analysed by pearson correlation test of SAS program. RESULT: 1. The viability between after cold ischemic time and after thawing was not different(p=0.619) for the adequacy of sterilization, freezing and thawing. 2. The viability which was evaluated after warm ischemic time, cold ischemic time and thawing, and the various warm ischemic times are strongly correlated as R is -0.857, -0.673 and -0.549 respectively. The viability of tricuspid valve is well related with the viability of aortic valve. CONCLUSION: 1. The longer the warm ischemic time, the lesser the viability of fibroblast. The viability of fibroblast after cryopreservation was decreased less 60% if the warm ischemic time was over 12 hours. 2. The method of cryopreservation is acceptable for maintaining the viability of fibroblast, and the viability of tricuspid valve may be the indicator of the viability of aortic valve. 3. However, the study for the optimal viability which is necessary to the durabiltiy of implanted valved homograft is needed.