A Fontan circulation is a surgically created circulation performed to improve the survival of children born with a functionally single ventricle circulation. It is used as a treatment for severe forms of congenital heart disease where a biventricular repair is not possible. A Fontan circulation allows venous return from the body to flow passively into the pulmonary circulation. The heart then acts as a pump purely for blood flow around the arterial system of the body. However, as these patients are reaching adulthood and middle age they are developing problems such as reduced exercise capacity, frequent hospital admissions and heart failure. Due to limited research in this field there is currently little evidence.