Fate of subpulmonary homograft conduits: determinants of late homograft failure

Abstract

Patients and methods: Between 1971 and 1993, 656 conduits were placed in the subpulmonary position. Patients receiving heterografts or valveless conduits and patients dying within 90 days of insertion were excluded; thus 405 homograft conduits were studied. There were 293 aortic homografts, 94 pulmonary, and 18 of unknown type. The end point of conduit failure was defined by conduit replacement for whatever reason, balloon dilation of the conduit, or death of the patient with the conduit in place. The following factors were analyzed: aortic versus pulmonary homograft, antibiotic preservation versus cryopreservation, ABO and Rh compatibility, type of material used for conduit extension, age at operation, size of the conduit, diagnosis, and reoperations. Conduit number (1 to 405) in the series was included in the multivariable model.

Results: First conduits and conduits inserted earlier in the series appeared to last longer than second and subsequent conduits and those inserted later in the series (p = 0.001 and 0.003, respectively). Overall survival of conduits at 5, 10, and 15 years was 84% (95% CL, 80% to 88%), 58% (95% CL, 50% to 66%), and 31% (95% CL, 19% to 43%). Corresponding figures for the first conduits were 88% (95% CL, 84% to 92%), 65% (95% CL, 56% to 73%), and 34% (95% CL, 20% to 47%). The longest surviving homograft conduit in our series lasted 22.7 years. Regarded univariately, reoperation (redo worse), order number (recent worse), type of conduit (pulmonary worse than aortic), preservation (cryopreserved worse than antibiotic preserved), and age at operation (older patients worse) were statistically significant. However, in multivariable analysis, including all the above in the model, only reoperation and order number had significant predictive power. When patient survival was considered, patients operated on more recently survived longer despite the fact that their conduits were being replaced earlier. Overall, survival of patients at 5 and 15 years was 95% (95% CL, 93% to 98%) and 85% (95% CL, 77% to 92%), respectively.

Conclusions: Pulmonary and aortic homografts, both cryopreserved and preserved in nutrient antibiotic solution, give similar results. All conduits will probably have to be replaced during the lifetime of the patient. In view of the worse performance of replacement conduits, techniques of repair that avoid the use of conduits should be further explored. Despite gradual deterioration of homograft conduits, they remain an important tool in the correction of many complex lesions with excellent 15-year patient survival.