Durability of Hancock Xenograft Valve

행콕 판막의 내구성

The Hancock porcine xenograft valves had been used in Seoul National University Hospital, mainly because of their antithrombogenicity despite of the predicted failure, from March 1976 to April 1984, and a total and consecutive 163 patients were retrospectively studied for late results with the special stress on the structural failure. The hospital mortality rate [within 30 days] was 6.1 %, and the 153 early survivors were followed up for a total of 822.9 patient-years [p-y][Mean * SD 5.38 * 3.02 years]. The linealized late mortality was 1.823%/p-y. Four major complications related to the Hancock valve were: 1.822% thromboembolism/p-y; 0.729 % bleeding/p-y; 0.972% endocarditis/p-y; 3.646% overall valve failure/p-y and 2.187 % primary tissue failure [PTF]/p-y. The actuarial survival rates at 5 and 10 years were 94.90 * 1.89% and 80.58 * 5.21 %; and the probabilities of freedom from thromboembolism at 5 and 10 years were 90.93 * 2.63% and 83.35 * 7.64 9o respectively. The probabilities from PTF at 5, 10 and 12 years were 98.02 * 1.39%, 60.62 * 8.89% and 49.60 * 12.34 %. One hundred-eighteen patients [72.4%] had single MVR [age, 34.0 * 10.9 years] with the operative mortality rate of 4.2%; and 113 early survivors were followed up for a total 616.4 patient-years[5.46 * 2.96 years]. The late mortality rate was 1.460 %/p-y. The major complications were: 1.622 % thromboembolism /p-y; 0.487% bleeding/p-y; 0.649 % endocarditis/p-y; 2.920% primary valve failure/p y and 1.785% PTF/p-y. The actuarial survival rates were 97.08 * 1.67%[at 5 years] and 81.27 * 6.64%[at 10 years], and the probabilities of freedom from thromboembolism 92.44 * 2.76 %[at 5 years] and 80.89 * 11.08%[at 10 years]. The probabilities of freedom from PTF at 5 and 10 years were 98 70 * 1.29% and 65.59 * 9.78% respectively. The mean age of 11 patients of PTF was 25.7 * 8.8 years and the valve extraction period 7.16 * 1.45 years. Failure of bioprosthetic xenograft valves are reportedly known to occur earlier in young patients in an accelerated fashion. The study with two groups divided into the cumulative younger and the cumulative older patients according to the age limits of 5-year interval strongly suggested these tendency. Although PTF began to occur past postoperative 5 years and the probabilities of freedom from PTF increased as the age limits raised and the number of patients increased in the cumulative younger patients while they decreased as the age limits lowered and the number of patients increased in the cumulative older patients, the definite age limits from which the Hancock valve can be safely recommended could not be obtained. From the results, the Hancock valves are contraindicated in patients younger than 20 to 25 years and may be safely recommended in patients older than 45 years as a tentative conclusion. Further longitudinal study may define these age factors.