This study is undertaken to evaluate the hemodynamic effects and pharmacokinetic properties of oral levodopa in pediatric patients with severe congestive heart failure refractory to standard anti-congestive medications. Patients are enrolled in a three-day dose escalation trial to determine the appropriate dose for each individual patient during which multiple non-invasive cardiac studies are performed and catecholamine levels are drawn. Cardiac catheterization and a hemodynamic study is then performed after a 24-hour drug washout.