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Atrioventricular Septal Defects

(Atrioventricular Canal Defect; Endocardial Cushion Defect)


Lee B. Beerman

, MD, Childrens Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine

Last full review/revision Mar 2021| Content last modified Mar 2021
  • Children who have no defect in the ventricle or only a small defect may have no symptoms.

  • If the ventricular septal defect is large, infants may have difficulty breathing while they are eating, poor growth, a rapid heart rate, and sweating.

  • The diagnosis is suspected based on a typical heart murmur that a doctor can hear through a stethoscope and is confirmed by echocardiography.

  • Defects are repaired with surgery.

Atrioventricular septal defects account for about 5% of birth defects of the heart.

Types of atrioventricular septal defect

An AV septal defect may be

  • Complete, with a large septal defect that includes both the atria and the ventricles, and a single atrioventricular valve

  • Transitional, with a small or moderate-sized ventricular septal defect in addition to the atrial septal defect

  • Partial, with an atrial septal defect but no ventricular septal defect, and the common AV valve separated into a right- and a left-sided AV valve

Most infants with the complete form have Down syndrome Down Syndrome (Trisomy 21) Down syndrome is a chromosome disorder caused by an extra chromosome 21 that results in intellectual disability and physical abnormalities. Down syndrome is caused by an extra chromosome 21... read more Down Syndrome (Trisomy 21) . Atrioventricular septal defect is also common among infants who have other organ system abnormalities including being born without a spleen or with multiple small spleens.

Symptoms of Atrioventricular Septal Defects

Complete atrioventricular septal defect often causes a large left-to-right shunt Shunting of blood flow About one in 100 babies is born with a heart defect. Some are severe, but many are not. Defects may involve abnormal formation of the heart's walls or valves or of the blood vessels that enter... read more , which means some blood that has already picked up oxygen from the lungs goes through the hole and back to the lungs. These infants may develop heart failure (see figure Heart Failure: Pumping and Filling Problems Heart Failure: Pumping and Filling Problems Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or... read more Heart Failure: Pumping and Filling Problems ), which causes symptoms such as rapid breathing, shortness of breath while eating, poor weight gain, and sweating) by age 4 to 6 weeks. Eventually, the blood vessels between the lungs and the heart may develop high blood pressure (pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension is a condition in which blood pressure in the arteries of the lungs (the pulmonary arteries) is abnormally high. Many disorders can cause pulmonary hypertension. People... read more ) and lead to heart failure (Eisenmenger syndrome Eisenmenger syndrome About one in 100 babies is born with a heart defect. Some are severe, but many are not. Defects may involve abnormal formation of the heart's walls or valves or of the blood vessels that enter... read more ).

Children with transitional AV septal defects may have no symptoms if the ventricular defect is small. Children with larger defects may have signs of heart failure.

Partial AV septal defects do not usually cause symptoms during childhood unless valve leakage (regurgitation) is severe. However, symptoms (eg, exercise intolerance, fatigue, palpitations) may develop during adolescence or early adulthood. Infants with moderate or severe valve regurgitation often have signs of heart failure.

Diagnosis of Atrioventricular Septal Defects

  • Echocardiography

Diagnosis is suggested by a doctor's findings during an examination of the infant. ECG may give an important clue to help make this diagnosis. Chest x-ray X-Rays of the Chest Anyone thought to have a heart disorder has chest x-rays taken from the front and the side. Typically, the person is standing upright, but chest x-rays can be done with people lying in bed if... read more X-Rays of the Chest may be done to look at the size of the heart and the blood flow to the lungs.

Treatment of Atrioventricular Septal Defects

  • Surgical repair

Because most infants with complete atrioventricular septal defect have heart failure and failure to thrive, these defects are usually repaired with surgery when the child is 2 to 4 months of age. Even if infants are growing well and do not have symptoms, surgical repair is usually done before the infant is 6 months old to prevent development of complications.

For children with a partial defect and no symptoms, surgery is done when the child is older, usually between age 1 year and age 3 years.

If the infant develops heart failure before surgery is done, doctors give drugs such as diuretics, digoxin, and angiotensin-converting enzyme inhibitors to help manage symptoms before surgery.

Children usually need to take antibiotics before visits to the dentist and before certain surgeries (such as on the respiratory tract) during the 6-month period after surgical repair. If there is a residual defect after surgery, antibiotics are needed before these procedures indefinitely. These antibiotics are used to prevent serious heart infections called endocarditis Infective Endocarditis Infective endocarditis is an infection of the lining of the heart (endocardium) and usually also of the heart valves. Infective endocarditis occurs when bacteria enter the bloodstream and travel... read more Infective Endocarditis .

More Information

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