Atrial Septal Defect (ASD)

An atrial septal defect (ASD) is a type of congenital heart defect in which there is an abnormal opening in the dividing wall or septum that separates the upper chambers of the heart (the atria). It develops early in pregnancy.

Atrial septal defect occurs in 5 to 10 percent of all children with congenital heart disease. Generally, girls have atrial septal defects more often than boys.

Causes of ASD

Heart formation commences during the first 8 weeks of foetal development. It begins as a hollow tube, followed by partitions in the tube that become the walls or septa dividing the left and right sides of the heart. When the partitioning process does not occur completely, it leaves an opening in the atrial septum, causing atrial septal defects.

If left unrepaired, atrial septal defects can cause lung problems. It leads to a larger volume of blood from the left atrium to the right atrium. The extra blood passes through the pulmonary artery into the lungs, causing higher pressure in the blood vessels in the lungs, or pulmonary hypertension.

Types of ASD

There are several types of atrial septal defects. These include

  • Secundum: This is the most common type of ASD and occurs in the middle of the atrial septum.
  • Primum: This occurs in the lower part of the atrial septum and might occur with other congenital heart problems.
  • Sinus venosus: This is a rare defect that usually occurs in the upper part of the atrial septum. It is often associated with other congenital heart problems.
  • Coronary sinus: This is also a rare defect in which part of the wall between the coronary sinus and the left atrium is missing. The coronary sinus is a part of the vein system of the heart.

Symptoms of ASD

Many children born with atrial septal defects have no signs or symptoms and seem healthy. Many patients may be diagnosed only in their adulthood. However, if the ASD is present, patients may have the following symptoms:

  • Fatigue
  • Sweating
  • Rapid breathing or shortness of breath
  • Heart Palpitations or skipped heartbeat
  • Poor growth
  • Stroke
  • Heart murmur, which is a whooshing sound that can be heard through a stethoscope by a physician during a check-up.

Treatment of ASD

Small ASDs that are discovered in infants often narrow or close on their own. Surgery or other treatment may not be required. Large ASDs can be closed with open-heart surgery, or by cardiac catheterization using a device inserted into the opening to plug it.

A cardiologist may advise some activity changes for a short time after surgery or catheter closure. After successful healing from surgery or catheter closure, no restrictions are generally needed. Medicines may be prescribed for a few months to prevent blood