FACTORS IN THE EARLY FAILURE OF CRYOPRESERVED HOMOGRAFT PULMONARY VALVES IN CHILDREN - PRESERVED IMMUNOGENICITY

Methods: Between 1990 and 1995, 48 homograft valves (15 aortic and 33 pulmonary), cryopreserved on-site, were implanted to reconstruct the r ight ventricular outflow tracts in 44 children (mean age 6.2 +/- 6.0 y ears; range 3 days to 20.2 years), Blinded serial echocardiographic fo llow-up evaluation was performed for ail 45 valves in the 41 survivors , Results: Four homograft valves were replaced because of pulmonary in sufficiency (3) or stenosis and insufficiency (1). freedom from reoper ation was 90% (70% interval, 84% to 97%) at 50 months, During the foll ow-up period 15 valves developed progressive pulmonary insufficiency o f at least two grades, Three valves developed transvalvular gradients of greater than or equal to 50 mm Hg, and one of these valves was also insufficient, The freedom from echocardiographic failure (two or more grades of pulmonary regurgitation or greater than or equal to 50 mm H g gradient) was 44% at 50 months (70% confidence interval, 32% to 55%) , Young age (p = 0.03), low operative weight (p = 0.04), small graft s ize (p = 0.04), and homograft retrieval-to-cryopreservation time of le ss than 24 hours (p = 0.02) were significantly associated with failure , The type of donor valve (pulmonic or aortic), donor age, and blood g roup mismatch were not associated with failure, although blood group m ismatch approached significance (p = 0.05), Conclusions: Homografts fu nction well as conduits between the pulmonary ventricle and pulmonary arteries if long-term valve competency is not crucial, However, many r apidly become insufficient. This has important implications for the ch oice of a valve if the indication for valve replacement is to protect a ventricle failing due to pulmonary insufficiency. Short periods betw een homograft retrieval and cryopreservation enhance viability and ant igenicity. This may suggest an immunologic basis for the failure.