Most children with ASD are generally asymptomatic and do not affect their activities; most patients do not develop symptoms until after adolescence. Congestive heart failure and pulmonary hypertension will occur in large and medium-sized ASD around the age of 20 to 30 years, especially after the age of 35 years when the disease progresses rapidly and complications can occur if no intervention is taken: for example, pulmonary hypertension, if it reaches an irreversible stage, leads to right-to-left shunt causing heart failure cyanosis; atrial enlargement fibrosis causing atrial arrhythmias such as atrial flutter atrial fibrillation and paradoxical embolism leading to stroke.