Conditions: Single Ventricle Fontan Palliation
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 28
Healthy volunteers: no

Brief summary:
Hypothesis:

Patients with a Fontan type palliation are limited by preload, or the rate at which blood returns to the heart after passively traversing the pulmonary capillary bed. By decreasing pulmonary vascular resistance using an endothelin receptor antagonist, both ventricular filling pressures and volumes will increase with a simultaneous decrease in systemic impedance to flow and decrease in central venous pressures, leading to an improved capacity to increase cardiac output, and thereby an improvement in patient functional status.

Patients who are candidates for the study will be randomized to a double-blind single crossover study. Therapy with either ambrisentan or placebo will be continued for 12 weeks, with a 2 week washout period between treatment periods. Subjects will be subjected to a VO2 max test to evaluate exercise capacity at enrolment, and on the last day of each treatment period. As a component of the VO2 max testing the patient's VE, VCO2, VE/VCO2 slope, ventilatory anaerobic threshold (VAT), peak work, efficiency, and other physiologic parameters as typically obtained from cardiopulmonary testing will be assessed. In addition, each patient will be asked to complete an SF-36 quality of life questionnaire at enrollment, and on the last day of each study period.

Detailed description:

Arms:
arm 1: These patients will be randomized to have ambrisentan during the first study period, and placebo during the second study period. arm 2: These patients will be randomized to have placebo during the first study period, and ambrisentan during the second study period.

Interventions: intervention 1: Ambrisentan
Intervention descriptions: intervention 1: None

Protocol document: