The heart is divided into 4 chambers that help circulate blood through the body. The top 2 chambers are called atria. The bottom 2 chambers are called ventricles. 2 valves are between the upper and lower chambers. Tissue called the septum divides the chambers. The tissue grows as the fetus develops.

An atrioventricular septal defect is present at birth. It occurs when any of the tissues that divide the septum do not grow completely. This leaves 1 or more holes. It may also leave 1 leaky valve instead of 2 separate valves.


This condition is caused when the septal tissue fails to grow correctly as the fetus develops in the womb.

Ventricular Septal Defect

Ventral septal defect
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Risk Factors

Risk factors that increase the chance that a baby will be born with a ventricular septal defect include:


Symptoms include:

  • Difficulty feeding
  • Failing to gain weight
  • Difficulty breathing, especially during feeding
  • Sweating
  • A bluish tint to lips and fingernails
  • Pale skin
  • Lack of appetite
  • Swollen legs or abdomen—rare in children


You will be asked about your baby's symptoms and medical history. A physical exam will be done. Most types of congenital heart disease can be identified by listening for a heart murmur.

Images may be needed of your baby's heart. This can be done with a chest x-ray.

Information may be needed about how your baby's heart functions. This can be done with:


Any of the following treatments may be advised:

  • Ongoing observation of the symptoms and the defect
  • Medication to strengthen the heart, keep the heartbeat regular, or decrease the amount of fluid in circulation
  • Surgery in early childhood to close the hole
  • Antibiotics before and after surgery to reduce the risk of bacterial infections
  • A high calorie diet and/or breastfeeding to manage poor weight gain
  • Limited physical activity depending on the severity of the defect
  • Counseling to help you adjust to your baby's diagnosis and treatment
  • A pacemaker to regulate the heart


It may not be possible to prevent the condition because the exact cause is unknown. A septal defect can be identified, watched, and treated early in pregnancy and childhood:

  • If you are pregnant or planning to become pregnant, seek early and regular prenatal care, get exercise, and eat a well-balanced diet.
  • Control your blood sugar levels if you have diabetes.
  • Avoid drugs, cigarettes, and alcohol.
  • A prenatal ultrasound when the fetus is 10-14 weeks old will identify many babies with heart defects.
  • If you have a child with this defect, consult a genetics counselor to find out if your future children are also at risk.

12 Week Fetus

12 week fetus
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