Septal Defects



Septal defects are problems with the structure of the heart. They are present at birth. Septal defects are on the inside of the heart. They are on a wall that is between the chambers of the heart. There are two upper chambers of the heart called atria. There are two lower chambers of the heart called ventricles.

In a healthy heart, the blood flows from the body to the right atrium. The blood then goes into the right ventricle. The right ventricle pumps this blood to the lungs to pick up fresh oxygen. The blood then returns to the left side of the heart. It enters the left atrium first, then down to the left ventricle. The left ventricle pushes the blood out to the rest of the body. The blood from the left side should not mix with blood from the right side.

Septal defects allow the blood to move between the left and right chambers. The blood most often moves from the left side of the heart into the right side. This means that blood that has just returned from the lungs may end up being sent right back to the lungs. As a result, both the heart and lungs have to work harder than they need to work.

There are three main types of septal defects:

  • Atrial septal defect (ASD)—a hole in the wall between the two upper chambers (atria) of the heart
  • Ventricular septal defect (VSD)—a hole in the wall between the two lower chambers (ventricles) of the heart
  • Atrioventricular septal defect (AVSD)—a mix of ASD, VSD, and problems with openings between chambers called valves

The stress of pushing extra blood to the lungs may lead to heart failure. The following information applies to all three of these defects except where noted.

Ventricular Septal Defect
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In most cases the cause is not known.

Risk Factors

Factors that may increase the risk of septal defects include:

  • Family history of congenital heart defects
  • Exposure to a viral infection, drugs, or alcohol during pregnancy
  • Certain medicines, such as those used to treat seizure disorder during pregnancy
  • Genetic disorders, such as Down syndrome



Many people with ASD or VSD do not have symptoms. Large defects and AVSD may cause:

  • Shortness of breath
  • Getting tired easily
  • Poor growth


A septal defect may be found during a regular exam. The doctor may hear a heart murmur .

The heart may be tested. This can be done with:

  • Echocardiogram
  • Electrocardiogram (EKG)
  • Cardiac catheterization

Chest x-rays can evaluate the heart and the structures around it.



Treatment may depend on the type and size of defect. There may be some treatment needed for any problems of the septal defect. This may mean:

  • No treatment.
    • Almost half of all ASDs and many VSDs will close on their own during the first year of life.
    • This is more likely to happen with small defects.
    • Small VSDs that do not close rarely cause problems, but small ASDs may get bigger over time.
  • Medicine
    • May be needed for infants with septal defects with:
      • Congestive heart failure
        • Most likely to happen with medium and large VSDs and AVSD
        • Supportive care may be needed until surgery can be done.
      • Abnormal heart beat
      • Pulmonary Hypertension
    • May include medicines to help the heart beat strongly, keep the heart rate regular, lower the amount of fluid in the blood, or raise blood flow to the lungs.
  • Surgery
    • May be advised in children with:
      • Significant heart failure
      • Pulmonary Hypertension
      • Other significant symptoms related to the septal defect
      • ASDs past two years of age.
        • An ASD that still exists at age two is unlikely to ever close on its own.
        • If it is not closed in childhood, it may cause problems in adulthood.
      • VSDs that do not close after one year
      • AVSD
    • The hole may be closed with stitches or a patch
    • Infants with AVSD will also need repair of abnormal heart valves
    • Usually done as open-heart procedure
  • Some ASDs can be closed without surgery.
    • A device is placed in the hole with cardiac catheterization .
    • This is a process that sends the device to the heart through a large blood vessel.
  • Limiting physical activity may be needed for severe congestive heart failure

Living With Septal Defects

Certain septal defects or surgeries may raise the risk of infections in the heart. You may need to take antibiotics before certain medical and dental procedures to lower the risk of this infection. Check with your doctor to see if you need to do this. If you do need to take antibiotics, ask your doctor to explain when they may be needed.


Follow these steps:

  • If you are a woman, talk to your doctor before becoming pregnant.
  • Go to all prenatal appointments and complete all screening tests.
  • Avoid alcohol and drugs during pregnancy.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.

a (Atrioventricular Canal Defect; Atrioventricular Septal Defect; Endocardial Cushion Defect; Ventricular Septal Defect)


American Heart Association 

National Institute of Child Health and Human Development 


Canadian Cardiovascular Society 

The College of Family Physicians of Canada 


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Atrial septal defects and patent foramen ovale. EBSCO DynaMed Plus website. Available at:  . Updated December 27, 2017. Accessed July 23, 2018.

Congenital heart defects. American Heart Association website. Available at: Accessed July 23, 2018.

Congenital ventricular septal defect (VSD) in children and adults. EBSCO DynaMed Plus website. Available at:  . Updated June 16, 2017. Accessed July 23, 2018.

6/18/2010 DynaMed Plus Systematic Literature Surveillance  : Jentink J, Loane M, Dolk H, et al. Valproic acid monotherapy in pregnancy and major congenital malformations. N Engl J Med. 2010;362(23):2185.