The prevention of extra cardiac conduit obstruction: an experimental study

Acquired right ventricular (RV) extracardiac conduit (ECC) obstruction was studied in an animal model. A 16 mm woven Dacron tube graft was inserted between the right ventricle (RV) and main pulmonary artery (PA) in 18 adult mongrel dogs followed by pulmonary artery occlusion with a Dacron tape. In 9 dogs, the RV anastomosis was maintained with a 16 mm Dacron covered polypropylene stent. The remaining 9 animals with direct suture attachment of the graft to the myocardium served as controls. Cardiac output and transconduit resistance were measured at operation, 6 months, and 1 year. The cardiac output remained the same in both groups. Animals with stented ECC showed little change in transconduit resistance and had a widely patent RV anastomosis at 1 year. Unstented conduits had increased transconduit resistance at 6 months and 1 year (P less than 0.002). Postmortem examination showed fibromuscular ingrowth of the ventricular anastomosis to be the site of the acquired obstruction in unstented extracardiac conduits. The inclusion of a rigid stent in RV-ECC may warrant clinical application to prevent fibromuscular ingrowth and late RV anastomotic obstruction.