Definition

Atrioventricular septal defects are heart defects present at birth.

The heart is divided into four chambers that help circulate blood through the body. The top two chambers are called atria and the bottom two are ventricles. Two valves exist between the upper and lower chambers; the tricuspid valve on the right side of the heart, and the mitral valve on the left side. Tissue, called the septum, divides the chambers and grows as the fetus develops in the womb.

An atrioventricular septal defect is the failure of any of the tissues that help divide the chambers to grow completely, leaving one or more “holes,” and possibly one leaky valve instead of two separate valves. It is possible for this defect to show up as only one small hole, or as multiple holes, and tissue development problems.

Depending on the severity of the defect, the heart may have to work much harder to circulate blood correctly through the body. Open-heart surgery is often required to correct the defect in babies before there is damage to the pulmonary circulation.

The simplest form of the defect is atrial septal defect , which is a hole between the top two chambers (atria) of the heart that causes blood to flow from left to right instead of correctly through the heart.

Causes

During development in the womb, the septal tissue fails to grow correctly, resulting in an atrioventricular septal defect.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

The following factors may increase the chance that a baby will be born with a ventricular septal defect:

• A family history of heart defects
• Down syndrome]]> —Nearly one in five babies with Down syndrome will have some degree of this heart defect
• ]]>Alcohol consumption]]> or ]]>drug abuse]]> by the mother during pregnancy
• A mother with ]]>diabetes]]>
• ]]>Rubella infection]]> during the first three months of pregnancy
• Exposure to thalidomide, anticonvulsant medications, or lithium salts while in the womb
• Exposure to certain industrial chemicals during pregnancy

Symptoms

Symptoms include:

• Difficulty feeding, such as sweating or shortness of breath while eating
• Failing to gain weight
• High blood pressure]]> in the artery leading from the heart to the lungs
• Lung congestion
• A bluish tint to lips and fingernails, called cyanosis
• ]]>Heart murmur]]>
• Enlarged heart (visible on ]]>chest x-ray]]> )

Diagnosis

The best way to diagnose an atrioventricular septal defect is an echocardiogram]]> , a test that uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart.

Many times the diagnosis can be made before the baby is born. A doctor will also listen for a heart murmur, although a murmur is not always predictive of the size of the defect. The doctor will analyze the level of oxygen in the blood, conduct an ]]>electrocardiogram]]> (a test that records the heart’s activity by measuring electrical currents through the heart muscle), and take a 2-D echocardiogram of the heart.

The doctor may use a catheter to test the blood pressure of the artery leading from the heart to the lungs to find out if the blood is flowing at a normal or faster than normal pace, indicating that the heart has to work harder than usual. A ]]>chest x-ray]]> can by used to check the size of the heart.

Treatment

A doctor may recommend any of the following treatments for your baby:

• Medicines to strengthen the heart, keep the heartbeat regular, or decrease the amount of fluid in circulation
• Pacemaker]]> to regulate the heart
• Higher calorie diet and/or breastfeeding to manage poor weight gain
• Ongoing observation of the symptoms and the defect
• Depending on the severity of the defect, limited physical activity
• Counseling to help you adjust to your baby's diagnosis and treatment
• Surgery in early childhood to close the hole (recommended when the defect is severe)
• Diuretics and digoxin to treat heart failure
• Due to the increased risk of bacterial infections, antibiotics before and after surgery

Prevention

Although it may not be possible to prevent the condition because the exact cause is unknown, 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.
• If you have diabetes, control blood sugar levels.
• If you are pregnant, 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.