Study on Sildenafil for Adults with Single Ventricle Heart Condition Post-Fontan Surgery

This clinical trial is focused on studying the effects of the medication sildenafil in adults who have undergone a specific heart surgery known as the Fontan operation. This surgery is typically performed on individuals with a congenital heart defect called a functionally single ventricle, where one of the heart's ventricles is underdeveloped. The Fontan operation helps improve blood flow in these patients by creating a pathway that bypasses the right side of the heart, which can lead to complications over time, including reduced exercise capacity and increased pressure in the veins.

The purpose of this study is to determine if adding sildenafil to the current treatment regimen of these patients can enhance their physical performance. Sildenafil is a medication that is often used to treat conditions related to blood flow. In this study, participants will receive either sildenafil or a placebo for a period of 24 weeks. Throughout the study, various tests will be conducted to assess improvements in exercise capacity, heart function, and overall quality of life.

Participants will undergo tests such as the ergospirometry test, which measures oxygen uptake during exercise, and the 6-minute walk test, which evaluates the distance they can walk in six minutes. Other assessments will include echocardiography to examine heart function and questionnaires to gauge quality of life. The study aims to provide insights into whether sildenafil can be a beneficial addition to the treatment of patients with a functionally single ventricle after the Fontan operation.