Comparison of porcine xenografts and homografts for pulmonary valve replacement in children

Background. Due to the limited availability of homografts, different alternatives are used for replacement of the pulmonary valve. This study investigates the value of porcine stentless pulmonary xenografts in pediatric cardiac patients. Methods. Twenty-three pediatric xenograft (size 10 to 21 mm) recipients were compared with 23 homograft (size 9 to 21 mm) recipients. Results. Hospital mortality was 2 of 23 patients in the xenograft group and 3 of 23 in the homograft group (NS). Six out of 20 xenografts and 1 of 19 homografts were stenotic after 1 year (p = 0.011). Xenograft stenoses were mainly located at the distal anastomosis, while the leaflets were preserved. Homografts showed valvular stenoses and wall calcification. The 1 year freedom from reoperation was 77% in the xenograft and 93% in homograft recipients (NS), and from transcatheter intervention 84% and 100% (p = 0.004), respectively. Transcatheter intervention in 7 xenograft patients and 1 homograft recipient improved stenosis gradients from 65 to 40 mm Hg (mean) in 6 out of 8 patients. Explanted xenografts showed a loss of elastic membranes and proliferating connective tissue scares coated with activated endothelium. Conclusions. Xenografts demonstrated a higher incidence of supravalvular obstructions, which were possibly due to unfavorable hemodynamics at the distal anastomosis. Histological findings additionally indicated a pronounced immunological response. Interventional angioplasty lowered the rate of reoperation. Thus, the use of xenografts in children can be accepted as a second choice when a homograft is unavailable. (Ann Thorac Surg 2000;70:717-22) (C) 2000 by The Society of Thoracic Surgeons.