The fate of small-diameter homografts in the pulmonary position

Background. Limited durability is expected for small homograft valves that are used to correct congenital cardiac disease. Methods. All 76 homograft valves with an internal annulus diameter ranging from 8 to 13 mm that were implanted from 1987 through 2000 in the pulmonary position were retrospectively analyzed. In each case, homograft size was normalized to the patient’s body surface area: z-value. For 93% (14 of 15) of the 8 to 9 mm grafts, z was less than 2. For 56% (5 of 9) of the 10 mm grafts and 98% (51 of 52) of the 11 to 13 mm allografts, z was greater than 2. Survival and freedom from complications were estimated by the Kaplan-Meier method. Homograft failure was defined as homograft replacement or late death; significant dysfunction, as homograft obstruction with an echo-Doppler gradient greater than 50 mm Hg or grade III or IV valvular insufficiency. The log-rank test was used to compare outcomes. Results. Seven patients died early after operation; three, late. Survival was 86.5% ± 3.8% at 1 year and remained stable during the succeeding years. Freedom from failure for all homografts was 90.6% ± 3.7%, 71.8% ± 6.9%, and 61.8% ± 9.0% at 1, 5, and 10 years, respectively. Corresponding freedom from significant dysfunction was 87.6% ± 4.1%, 51.2% ± 7.4%, and 10.1% ± 8.3%. The smaller homografts (z less than 2) failed and deteriorated faster ( p < 0.0001): only 32.1% ± 13.0% were still functioning at 24 months. The larger grafts (z at least 2) retained function for the first 4 years, and 73.7% ± 10.4% had not yet failed at 10 years. Conclusions. Smaller (z less than 2) homografts (the great majority of 8 to 9 mm grafts) have to be replaced early, usually within 2 years of implantation. Larger (z at least 2) grafts (nearly all 11 to 13 mm grafts) show remarkable durability and are suitable valved conduits for establishing right ventricle to pulmonary artery continuity in neonates and young infants.