Results of aortic valve replacement with pulmonary and aortic homografts

Background and aim of the study: Aortic valve replacement with cryopreserved human pulmonary or aortic valves (homografts) is an attractive alternative to the implantation of mechanical valves or bioprostheses, as anticoagulation can be avoided and a near-normal anatomy restored. However, few reports exist on the long-term follow up of patients with this type of valve. Methods: Between 1990 and 1997, a total of 64 homografts were implanted in 62 adults (mean age 42 +/- 12 years) with non-endocarditic valve lesions (insufficiency, n = 16; stenosis, n = 20; combined lesions, n = 12; redo, n = 16). In total, 23 pulmonary grafts (PG) and 41 aortic grafts (AG) were used. Valves were obtained from the European Homograft Bank in Brussels. Two patients with aortic homografts were lost to follow up; the others were examined clinically and echocardiographically at yearly intervals (mean 3.6 +/- 2.0 years). Children aged less than 16 years (n = 21), and patients receiving a homograft due to endocarditis (n = 28) or during a Ross procedure (n = 16) were excluded from the study. Results: Three patients (5%) died due to early postoperative complications (two with AG, one with PG). Three PG had to be explanted due to primary malfunction, and five (total 35%) during further follow up due to severe aortic insufficiency (at a mean of 3.3 +/- 1.8 years). In contrast, all AG were functioning at the end of the observation period (log rank test, p = 0.0001, chi-square test 13.9). The mean echocardiographic degree of regurgitation for PG was significantly higher than for AG (2.2 +/- 1 vs. 0.75 +/- 0.7, p <0.0001). The peak transvalvular gradient did not differ between groups (FG 12.3 +/- 9 mmHg vs. AG 16.7 +/- 10 mmHg, p = NS). In respect of perioperative parameters, patients with FG showed a significantly higher body temperature during the first seven postoperative days (37.3 +/- 0.6 degrees C vs. 36.8 +/- 0.3 degrees C, p = 0.003). All three patients with acute graft malfunction in long-term follow up had a perioperative febrile response without overt bacterial infection. Conclusion: In contrast to grafts of aortic origin, pulmonary homograft valves should not be used for aortic valve replacement because of their high rate of malfunction, both acutely and chronically. Higher postoperative body temperatures should lead to further investigations of possible enhanced immunoreactions against pulmonary homografts.