 The study population will be prospective cohort of patients who have undergone Fontan surgery and are currenty followed within the University of Michigan Congenital Heart Center. The target populations are patients with protein losing enteropathy PLE that are having increased disease symptoms requiring additional treatment. Those that have PLE refractory to other treatments and require the addition of continuous dopamine infusion to their treatment regimen will be recruited to the dopamine group. Those that have PLE worsening that require the addition of other treatments except the initiation of continuous dopamine infusion will be recruited to the control group. 