The Effects of Ambrisentan on Exercise Capacity in Fontan Patients
Status:
Completed
Trial end date:
2015-05-01
Target enrollment:
Participant gender:
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.