Nitrate’s Effect on Hemodynamic Profile and Exercise Capacitance in Fontan Patients (NEET STUDY)

Principal Investigators: Amee Bigelow, MD, MS & Tarek Alsaied, MD, MSC

Co-Investigators: David Morales, MD & Kyle Riggs, MD

Each year over 1,000 Fontan operations are performed on children in the United States with a congenital heart defect resulting in single ventricle physiology. Fontan physiology describes a circulation where the only ventricle pumps blood to the body and blood flow to the lungs is passive, down a pressure gradient, without a sub-pulmonary ventricle. The current approach to managing patients born with one functional ventricle is a series of interventions that lead up to the Fontan operation. As the surgical techniques have improved, the immediate post-operative mortality is extremely low, and now there has been more focus on the medical management and optimization of patients with Fontan physiology. The morbidity associated with Fontan physiology is largely related to chronic venous congestion and difficulty traversing the pulmonary vasculature without a ventricular pump. Nitrate based medications such as isosorbide dinitrate (ISDN) have been used in adults with heart failure demonstrating improved survival, ejection fraction, and exercise tolerance in select populations. In single ventricle patients, nitrates have recently been shown to increase venous capacitance, thereby decreasing central venous pressure within the Fontan circulation. At the Heart Institute at CCHMC, we have a large population of pediatric and adult patients with Fontan physiology. We are investigating the safety, feasibility and preliminary effects of a nitrate medication in this patient population. This study is innovative because it will be the first to systematically evaluate the effects of this medication in healthy Fontan patients with regards to changes in exercise capacitance, and liver stiffness, while also assessing changes to the quality of life in an effort to optimize Fontan hemodynamics for long-term health.