Atrioventricular canal defect

Definition

What is atrioventricular canal defect?

Atrioventricular canal defect is a combination of heart problems resulting in a defect in the center of the heart. The condition occurs when there’s a hole between the heart’s chambers and problems with the valves that regulate blood flow in the heart.

Sometimes called endocardial cushion defect or atrioventricular septal defect, atrioventricular canal defect is present at birth (congenital). The condition is often associated with Down syndrome.

Atrioventricular canal defect allows extra blood to flow to the lungs. The extra blood forces the heart to overwork, causing the heart muscle to enlarge.

Untreated, atrioventricular canal defect can cause heart failure and high blood pressure in the lungs. Doctors generally recommend surgery during the first year of life to close the hole in the heart and to reconstruct the valves.

How common is atrioventricular canal defect?

Please discuss with your doctor for further information.

Symptoms

What are the symptoms of atrioventricular canal defect?

Atrioventricular canal defect can involve only the two upper chambers of the heart (partial) or all four chambers (complete). In either type, extra blood circulates in the lungs.

Complete atrioventricular canal defect

Signs and symptoms usually develop in the first several weeks of life. These signs and symptoms are generally similar to those associated with heart failure and might include:

• Difficulty breathing or rapid breathing
• Wheezing
• Fatigue
• Lack of appetite
• Poor weight gain
• Pale skin color
• Bluish discoloration of the lips and skin
• Excessive sweating
• Irregular or rapid heartbeat
• Swelling in the legs, ankles and feet (edema)

Partial atrioventricular canal defect

Signs and symptoms might not appear until early adulthood and might be related to complications that develop as a result of the defect. These signs and symptoms can include:

• Abnormal heartbeat (arrhythmia)
• Shortness of breath
• High blood pressure in the lungs (pulmonary hypertension)
• Heart valve problems
• Heart failure

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

If you have any signs or symptoms listed above or have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.

Causes

What causes atrioventricular canal defect?

Atrioventricular canal defect occurs before birth when a baby’s heart is developing. Some factors, such as Down syndrome, might increase the risk of atrioventricular canal defect. But the cause is generally unknown.

The normal-functioning heart

The heart is divided into four chambers, two on the right and two on the left.

The right side of your heart moves blood into vessels that lead to the lungs. There, oxygen enriches the blood. The oxygen-rich blood flows back to your heart’s left side and is pumped into a large vessel (aorta) that circulates blood to the rest of your body.

Valves control the flow of blood into and out of the chambers of your heart. These valves open to allow blood to move to the next chamber or to one of the arteries, and close to keep blood from flowing backward.

What happens in atrioventricular canal defect

In partial atrioventricular canal defect:

There’s a hole in the wall (septum) that separates the upper chambers (atria) of the heart.

Often the valve between the upper and lower left chambers (mitral valve) also has a defect that causes it to leak (mitral valve regurgitation).

In complete atrioventricular canal defect:

There’s a large hole in the center of the heart where the walls between the atria and the lower chambers (ventricles) meet. Oxygen-rich and oxygen-poor blood mix through that hole.

Instead of separate valves on the right and left, there’s one large valve between the upper and lower chambers.

The abnormal valve leaks blood into the ventricles.

The heart is forced to work harder and enlarges.

Risk factors

What increases my risk for atrioventricular canal defect?

There are many risk factors for atrioventricular canal defect, such as:

• Down syndrome
• German measles (rubella) or another viral illness during a mother’s early pregnancy
• Alcohol consumption during pregnancy
• Poorly controlled diabetes during pregnancy
• Smoking during pregnancy
• Certain medications taken during pregnancy — talk to your doctor before taking any drugs while you’re pregnant or trying to become pregnant
• Having a parent who had a congenital heart defect

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is atrioventricular canal defect diagnosed?

When a child’s pediatrician hears a heart murmur during a physical examination, the pediatrician may refer the child to a pediatric cardiologist, who specializes in the diagnosis and treatment of congenital heart defects and heart problems that may develop later in childhood. To make a diagnosis, the cardiologist performs a physical examination, listens to the heart and lungs and makes other observations. Heart murmurs are evaluated on the basis of pitch, loudness and duration, which give the cardiologist an initial idea of which heart problem a child may have. Diagnostic testing for congenital heart disease varies by the child’s age and clinical condition, and may include:

• Chest X-ray. This diagnostic test uses X-ray beams to produce images onto film of internal tissues, bones and organs.
• Electrocardiogram (ECG or EKG). The test records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias) and detects heart muscle stress.
• Echocardiogram (or “echo”). This procedure uses sound waves recorded on an electronic sensor to produce a moving picture of the heart and its valves. An echo can show the pattern of blood flowing through septal openings and determine the openings’ size and how much blood is passing through them. The vast majority of AV canal defects are diagnosed by echocardiography alone.
• Cardiac catheterization. This invasive procedure gives very detailed information about the structures inside the heart. Under sedation, a small, thin, flexible tube (catheter) is inserted into a blood vessel in the groin, and gently guided to the inside of the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, pulmonary artery and aorta. In addition, contrast dye is injected to more clearly visualize the structures inside the heart. Cardiac catheterization is recommended prior to AV canal repair if pulmonary hypertension (high blood pressure in the vessels of the lungs) is suspected or if other information is desired. Cardiac catheterization is typically not necessary if surgical repair of AV canal defects occurs before age 6 months (in Down syndrome children) or before age 1 (in children without Down syndrome).

How is atrioventricular canal defect treated?

A physician determines the best course of treatment for atrioventricular canal, based on:

• A child’s age, overall health and medical history
• Severity of the disease
• A child’s tolerance for specific medications, procedures or therapies
• Expectations for the course of the disease
• Parents’ opinions or preferences

AV canal is treated by surgical repair of the defects. Until the surgery can be performed, the condition may be managed by:

• Many children with an AV canal eventually need to take medications to help their heart and lungs work better. Medications that may be prescribed include:
• It helps strengthen the heart muscle, enabling it to pump more efficiently.
• The body’s water balance can be affected when the heart is not working as well as it could. Diuretics help the kidneys remove excess fluid from the body.
• ACE (angiotensin-converting enzyme) inhibitors. This medication dilates the blood vessels, making it easier for the heart to pump blood forward into the body.
• Adequate nutrition. Infants may become tired when feeding, and may not be able to eat enough to gain weight. Options to ensure a baby has adequate nutrition include:
  • High-calorie formula or breast milk. Special nutritional supplements may be added to formula or pumped breast milk that increases the number of calories in each ounce, thereby allowing a baby to drink less and still consume enough calories to grow properly.
  • Supplemental tube feedings. Feedings given through a small, flexible tube (that passes through the nose, down the esophagus and into the stomach) can either supplement or take the place of bottle feedings. Infants who can drink part of their bottle, but not all, may be fed the remainder through the feeding tube. Infants who are too tired to bottle feed may receive their formula or breast milk through the feeding tube alone.
• Infection control. Children with certain heart defects are at risk for developing an infection of the valves of the heart known as bacterial endocarditis. It is important that parents inform all medical personnel that their child has an atrioventricular canal defect so it can be determined if antibiotics are necessary before any major procedure.
• To prevent damage to a child’s lungs from too much blood flow and pressure, it is necessary to surgically repair the septal openings and valves. A child’s cardiologist recommends when the repair should be performed, based on echocardiogram and/or cardiac catheterization test results. Surgical techniques to repair atrioventricular canal have improved greatly over the past decade, giving the operation a high likelihood of success. While most children undergo surgery by age 6 months, children with Down syndrome may need the surgical repair at an earlier age to prevent lung problems. During surgery to close a ventricular septal defect, a synthetic patch made from a polyester-like material known as Dacron is often used. For atrial septal defects, the opening is often closed with a pericardial patch made from the membrane that covers the outside surface of the heart. Valves are repaired by converting the abnormal three-leaflet mitral valve into a two-leaflet mitral valve by suturing the cleft (the cut in the valve leaflets) to recreate a two-leaflet (two-cusp) mitral valve. The operation is performed under general anesthesia.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage atrioventricular canal defect?

Atrioventricular canal defect generally can’t be prevented.

Heredity may play a role in some heart defects. If you have a family history of heart defects or if you already have a child with a congenital heart defect, talk with a genetic counselor and a cardiologist before getting pregnant again.

Immunization with rubella vaccine has been one of the most effective preventive strategies against congenital heart defects.

If you have any questions, please consult with your doctor to better understand the best solution for you.