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Atrial Septal Defect

An atrial septal defect (ASD) is a hole in the septum, which is the muscular wall that separates the heart’s two upper chambers. An ASD is a congenital heart defect that happens when the septum does not form properly.

If an ASD is larger than 2cm, patients have a greater risk of problems such as:

  • Right heart enlargement, which leads to heart failure
  • Abnormal heart rhythms, including atrial fibrillation or atrial flutter
  • Stroke
  • Pulmonary hypertension
  • Leaking tricuspid and mitral valves caused by an enlarged heart

Signs & Symptoms

Many people have no idea they have an ASD because they do not have symptoms. Some patients find out about the defect when a chest X-ray for another problem shows that the right side of the heart is bigger than normal.

By age 50, an ASD can cause symptoms like:

  • Shortness of breath
  • Fainting
  • Irregular heart rhythms
  • Fatigue after mild activity or exercise


Tests to check for an ASD include:

  • Electrocardiogram (ECG/EKG)
  • Transthoracic echocardiography
  • Transesophageal echocardiography (TEE)
  • Intracardiac echocardiography (ICE)
  • Right heart catheterization
  • Left heart catheterization