What is a potential complication of untreated atrial septal defect in adulthood?

Untreated atrial septal defect (ASD) can lead to multiple complications as the patient ages. One significant complication is pulmonary hypertension. In an ASD, there is an abnormal communication between the left and right atria, allowing oxygen-rich blood to flow from the left atrium to the right atrium. This extra volume of blood increases the flow to the right side of the heart and into the pulmonary circulation.

Over time, this higher blood flow to the lungs can cause the blood vessels in the lungs to thicken and stiffen, resulting in increased pressure within the pulmonary arteries, a condition known as pulmonary hypertension. This complication can occur relatively insidiously and might not present symptoms until it has progressed significantly, leading to further cardiac complications and reduced exercise tolerance.

Understanding that pulmonary hypertension develops from the volume overload situation created by an ASD underscores the importance of monitoring and potentially treating this defect early in life to prevent long-term sequelae in adulthood. Other potential complications such as heart failure can arise from chronic volume overload, but the primary and distinct concern in relation to untreated ASD is the progression to pulmonary hypertension.