Beta Blockers for Treatment of Pulmonary Arterial Hypertension in Children

Inclusion Criteria: * Patients must be ≥ 8 and ≤ 17.5 years of age at the time of study enrollment. * Patients must have a mean pulmonary artery pressure of greater than 25mmHg at rest in a setting of normal pulmonary arterial wedge pressure of 15mmHg or less with a PVR index greater than 3 Woods units•m2 at last hemodynamic study. * Patients must be diagnosed with any of the following:Idiopathic PAH (IPAH), PAH associated with repaired congenital heart disease, PAH associated with minor congenital heart disease (small interventricular communication, small interarterial communication, small ductus arteriosis) * Patients must be clinically stable (i.e. no treatment changes) for the last 3 months * Patients must have no or minimal evidence of fluid overload or volume depletion judged by clinical evaluation (with or without diuretic treatment) * Written informed consent Exclusion Criteria: * Patients who are unable to perform a six minute walk test (6MWT) * Patients with a known history of pulmonary hypertension secondary to venoocclusive disease and/or capillary hemangiomatosis; pulmonary hypertensions owing to left heart disease * Patients who have previously received treatment with an intravenous positive inotropic agent in the last 3 months * Patients who are currently receiving β-blockers * Patients with a known history of reactive airways disease (bronchial asthma or relate bronchospastic conditions) * Patients with chronic obstructive pulmonary disease (COPD) * Patients with a known history of adverse reaction to β-blockers * Patients with a heart block on ECG or resting heart rate \< 60 bpm * Patients with systemic hypotension (below 5th percentile for age) are not eligible as follows: 1-10 years old: systolic blood pressure defined as \< \[70 + (2 x age in years)\] mmHg; Older than 10 years: systolic blood pressure \< 90 mmHg * Patients with coagulopathy (INR \< 1.5 or platelet count \<50,000/mm3) * Patients with a known history of severe hepatic impairment (defined by the presence of ascites, esophageal varices, jaundice or spider angiomata) * Patients with severe renal insufficiency (defined as creatinine clearance \< 30 mL/min/m2) * Patients with a known malignancy or other co-morbidity expected to limit survival or to limit the ability to complete the study * Patients with trisomy 21 * Patients with a known history of sick sinus syndrome * Patients with a known history of moderate or severe primary obstructive valvular heart disease * Patients with a known history of diabetes * Female patients who are pregnant of breast-feeding