Patients with single ventricle anatomy undergo staged surgical palliation. The result is an
"in series" circulation with pulmonary blood flow and cardiac output directly related to
pulmonary vascular resistance. While surgical outcomes have improved, the physiology of the
single ventricle palliation results in continued long term attrition. Elevated pulmonary
vascular resistance and impaired systemic ventricular function are important risk factors for
failure of single ventricle palliation.
Sildenafil is a pulmonary vasodilator and has been shown to improve cardiac contractility in
the pressure overloaded right ventricle.
The investigators will assess the safety, pharmacokinetics and hemodynamic efficacy of
sildenafil in single ventricle patients following stage II and III surgical palliation.