Single Ventricle Heart Disease

The purpose of this research is to determine whether treatment with the study drug dapagliflozin for 3 months affects peripheral venous pressure at rest and during exercise in adults with failing Fontan circulation.

This study will evaluate the clinical efficacy and safety of udenafil, an orally administered, potent and selective inhibitor of PDE5, versus placebo for the treatment of adolescent who have had the Fontan procedure.