Protein losing enteropathy after Fontan operation

David Driscoll
Professor of Pediatrics, Mayo Clinic
Rochester, USA

Protein losing enteropathy is a well recognized complication of the Fontan operation. It has been reported to occur in 3-10% of patients after a non-fenestrated Fontan operation. In one study, the 5 year survival was 50% after development of PLE.
　The cause of PLE in this setting is multifactorial. In 2 studies, PLE after the Fontan operation has been associated with longer cardiopulmonary bypass time, right ventricular forms of single ventricle, longer postoperative hospital stay and postoperative renal failure.
　PLE is associated with several cardiac abnormalities including constrictive pericarditis, restrictive cardiomyopathy, and SVC obstruction. All of these conditions are associated with increased venous pressure in the tributaries of the SVC and drainage of the thoracic duct is into a vein with higher than normal pressure. Several of these conditions also are associated with increased venous pressure in the tributaries of the IVC. In addition, low cardiac output and increased mesenteric resistance may be contributing factors. In a variety of animal models, PLE has been associated with thoracic duct ligation, increased venous pressure in the tributaries of the SVC, and elevated ANF. In humans, PLE occurs with portal hypertension if there is concomitant obstruction to the thoracic duct.
　The following treatment strategies have been employed in the management of PLE: albumin infusion, heparin, steroids, somatostatin, fenestration, cardiac pacing, sildenafil, revision of the Fontan pathways, and cardiac transplantation. Each of these strategies may work in some but not in all patients and, infrequently, do they result in permanent resolution of the PLE.
　A more provocative question than “Why do some patients develop PLE after Fontan operation?” is the question “Why do MOST patients NOT develop PLE after Fontan operation?” Indeed there seems to be no significant difference in the level of systemic venous pressure between patients who develop and those who do not develop PLE. We speculate that the patients who develop PLE have a concomitant congenital abnormality of the lymphatic system that predisposes them to developing PLE.