There is a hole (shunt) in the wall of tissue that divides the right and left sides of the heart's main pumping chambers (ventricles).
This is the most common cause of Eisenmenger syndrome. Heart problems present at birth (congenital heart defects) that can cause Eisenmenger syndrome include:
These valves open to allow blood to move to the next chamber or to one of the arteries, and then close to keep blood from flowing backward. Heart valves control the flow of blood into and out of the chambers of the heart.