It is a disease consists of pulmonary hypertension, RVH, and reversal of left-to-right shunt. It is also associated with large congenital cardiac defects that have been untreated including ASD, VSD, surgically-created extracardiac left-to-right shunts. Patients commonly present with exercise intolerance, shortness of breath, fatigue/lethargy, presyncope/syncope, accompanied by other heart failure symptoms. Diagnosis is by using echocardiogram or Chest X-ray which show signs of shunt and pulmonary hypertension.