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Atrial Septal Defect

Atrial Septal Defect: Symptoms, Causes and Risk Factors, Diagnosis, Treatments  | National Heart Centre Singapore

Atrial Septal Defect - What it is

Atrial septal defect (ASD) is a defect between the two upper heart chambers (the atria). This defect allows mixing of oxygenated and deoxygenated blood, eventually causing right heart enlargement and high pressure in the lungs (pulmonary hypertension).

Moderate- to large-sized ASD causing right heart dilatation and raised pressure in the lungs should be closed. Closure can be performed either via percutaneous method using devices (through the femoral vein) or through open-heart surgery.

Small ASD with no chamber enlargement, raised lung pressure or other complications needs only to be followed up at the clinic.

atrial septal defect illustration

Percutaneous Closure of Atrial Septal Defect (ASD)

This procedure is performed to close the ASD by inserting a device through the blood vessels in the groin (percutaneous transcatheter approach) which will close the ASD.

Atrial Septal Defect - Symptoms

Many babies born with atrial septal defects do not exhibit signs and symptoms. In adults, signs or symptoms usually begin by age 30. However, for some cases, the signs and symptoms may not occur until years later.

Signs and symptoms may include:

  • Heart palpitations or skipped beats
  • Frequent lung infections
  • Shortness of breath, especially when exercising
  • Fatigue
  • Swelling of legs, feet or abdomen
  • Stroke
  • Heart murmur, a whooshing sound that can be heard through a stethoscope

Atrial Septal Defect - How to prevent?

Atrial Septal Defect - Causes and Risk Factors

​Doctors know that heart defects present at birth (congenital) arise from errors early in the heart's development, but there's often no clear cause. Genetics and environmental factors may play a role.

Atrial Septal Defect - Diagnosis

If your doctor suspects you have a heart defect, your doctor may request one or more of the following tests:

  • Echocardiogram is the most commonly used test to diagnose an atrial septal defect. 
  • Chest X-ray helps your doctor to see the condition of your heart and lungs and it may identify conditions other than a heart defect that may explain your signs or symptoms.
  • Electrocardiogram (ECG) is a test that records the electrical activity of your heart and helps identify heart rhythm problems.
  • Magnetic resonance imaging (MRI) is ordered to assess for right heart dilatation 

Atrial Septal Defect - Treatments

The defect can be closed percutaneously by inserting a device through the blood vessels in the groin (percutaneous transcatheter approach) or via surgical repair. The choice of treatment depends on the size of the defect and the presence of pulmonary hypertension. After the defect is closed, the patient will need regular follow up with a cardiologist.

Device Closure for Atrial Septal Defect (ASD) 

The procedure usually takes between 1 and 2 hours and the success rate is about 95%. However, there are known risks involved. The risks and their estimated incidence of occurrence are:

  • Device dislodgement (embolisation) and the need for emergency heart surgery: 1%
  • Device erosion (device eroding through the heart walls): 0.3%
  • Death: less than 1% (usually from perforation of the heart chamber)
  • Dislodgement of clot or air bubbles to the brain (causing stroke) and other organs:  less than 1%
  • Rhythm disturbance (arrhythmia) (usually transient): 1 to 2%
  • Other potential risks: Allergic dye reaction, anaesthetic reaction, bleeding and bruising around the sheaths in the groin, injury to the artery/vein/nerves in the groin, perforation of the oesophagus (from the TEE probe), headache or migraine, infection, allergic reaction to the nickel component of the device


Patients with small ASD seldom develop any complications. However patients with moderate- to large-sized defects may develop irregular heart rhythm, heart pump failure and high pressure in the lung. These patients may need additional medications to treat these complications.

Some of these complications, if they do occur, are of a serious nature and may require further treatment including surgery and prolonged hospitalisation. In the event of device dislodgement, you may require surgery for removal of the device and closure of the hole at the same time. 

Not all types of ASD are suitable for device closure. You will need to have a detailed echocardiogram scan including both transthoracic echocardiogram as well as a transoesophageal echocardiogram to assess if your defect is suitable for closure. Defects which do not have sufficient rims for the device to sit safely, are too near to other heart structures such as veins, valves and very large (more than 3.6cm) may not be suitable for device closure and may be better treated with surgery.

Atrial Septal Defect - Preparing for surgery

Atrial Septal Defect - Post-surgery care

The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth

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