Nitric oxide synthase expression by pulmonary arteries: a predictive marker of Fontan procedure outcome?

Abstract

We retrospectively analyzed lung biopsy specimens from patients who underwent the Fontan procedure to identify predictive markers of outcome. We studied the intra-acinar pulmonary arteries present in lung biopsy specimens from 17 patients undergoing the Fontan procedure. We evaluated both their morphology and their expression of endothelial nitric oxide synthase and endothelin 1. We compared these data with those of 6 patients who died of no pulmonary cause (control group). Eight patients had a good surgical outcome (group 1). Their distal arteries were thin and weakly expressed endothelin 1 and endothelial nitric oxide synthase. The procedure failed in 9 patients (group 2). Their distal arteries displayed muscle extension with an increased wall thickness (P <.01 vs group 1). Their endothelin 1 expression remained low (not significant vs group 1). By contrast, endothelial nitric oxide synthase was markedly overexpressed (P <.001 vs group 1). Distal pulmonary arteries of patients in whom the Fontan procedure failed exhibited a markedly increased wall thickness and a clear endothelial nitric oxide synthase overexpression. In addition to giving clues to the pathogenesis of the procedure's failure, our study might help to define reliable predictive markers of its outcome.