6 Clinical Trials for Various Conditions
The purpose of this study is to find out more about the effectiveness of Tadalafil in improving hemodynamic capabilities, endothelial function, and end-organ function in patients who have previously undergone a Fontan Palliation.
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.
Fontan-palliated patients comprise an interesting group of single-ventricle patients who are dependent upon passive return of blood from the body to the lungs. Systemic venous pressures are therefore quite elevated, and one study demonstrated that venous capacitance was diminished. In addition, these patients have markedly diminished aerobic capacity (Max VO2). Although one recent study demonstrated that Fontan patients can increase their Max VO2 through diligent cardiac rehabilitation, their ultimate results were still well below average. It has previously been described that normal, healthy subjects have decreased exercise performance in a supine vs upright position. However, due to high venous pressures and the need for systemic venous return to overcome gravity in order to perfuse the lungs, one might hypothesize that Fontan patients would have increased exercise performance in a supine vs upright position. The investigators are interested in studying this hypothesis.
Hypothesis: By blocking aldosterone signaling in patients with Tetralogy of Fallot, Transposition of the great vessels with a prior atrial switch, and single ventricle "Fontan" patients, incident heart failure will be delayed, symptoms of heart failure ameliorated, and risk of arrhythmias decreased through decreases in myocardial fibrosis. Half of enrolled patients will complete an SF-36 quality of life questionnaire, perform a 6 minute walk, and have blood drawn for biomarker analysis at enrollment, again after 3 months without therapy, after 6 months on therapy, then finally after 12 months of eplerenone therapy. Half of enrolled patients will have the 3 month drug free period at the end of 12 months on therapy. Patients will be randomly assigned to drug free period up front versus at the conclusion of the trial period. Eplerenone will be started at a dose of 25mg and titrated up to 50mg at 4 weeks if tolerated. Blood will be drawn for basic metabolic panel analysis at enrollment, 3 months, 4 months to allow for dose titration, and at 6 and 12 months for monitoring.
Survival of children with single ventricles ("half a heart") beyond the neonatal period has increased dramatically with the staged Fontan palliation. Yet, long-term morbidity remains high. By the age of 40, 50% of Fontan patients will have died or undergone heart transplantation. With \>1,000 Fontan palliations performed in the US annually, there is a burgeoning population of Fontan patients at risk for progressive heart failure and death. Factors that contribute to onset and progression of heart failure in Fontan patients remain incompletely understood. However, it is established that Fontan patients have poor exercise capacity, associated with a greater risk of morbidity and mortality, in addition to decreased muscle mass, abnormal muscle function, and endothelial dysfunction contributing to disease progression. In adult patients with two ventricles and heart failure, reduced exercise capacity, muscle mass, and muscle strength are powerful predictors of poor outcomes, and exercise interventions can not only improve exercise capacity and muscle mass, but also reverse endothelial dysfunction. Limited exercise interventions in children with congenital heart disease have demonstrated that exercise is safe and effective; however, these studies have been conducted in small, heterogeneous groups, and most had few Fontan patients. Furthermore, none of these interventions have studied the impact of exercise on muscle mass or mitochondrial function, or endothelial function. The investigators propose a milestone-driven, randomized controlled trial in pediatric Fontan patients to test the hypothesis that a live-video-supervised exercise (aerobic + resistance) intervention will improve cardiac and physical capacity; muscle mass, strength and function; and endothelial function. The investigators' ultimate goal is the translation of this model to clinical application as an "exercise prescription" to intervene early in pediatric Fontan patients and decrease long-term morbidity and mortality.
This is an investigator initiated, prospective, single-center, double-blinded, randomized, placebo-controlled trial of post-operative low dose vasopressin infusions as an early treatment of low systemic perfusion in pediatric patients following Fontan palliation.