- Complications & Prognosis
- Risk Factors
An atrioventricular canal defect is a congenital heart defect that results in a hole in the center of the heart, between the chambers. The defect causes extra blood to flow to the lungs and strains the heart, causing the heart muscle to enlarge. If left untreated, it can lead to heart failure and high blood pressure in the lungs (pulmonary hypertension).
The only definitive treatment for children with atrioventricular canal defect is surgical repair, depending on the child's symptoms, age, overall health, and the severity of the condition. They may require additional treatments as well.
Many children require medication to help their hearts and lungs function better:
- Digoxin: Helps the heart pump better.
- Diuretics: Helps the kidneys remove extra fluid from the body.
- Angiotensin-converting enzyme inhibitors: Make it easier for the heart to pump blood to the body.
Babies with atrioventricular canal defects often become tired as they are being fed. This reduces their milk intake, which can lead to malnutrition and weight loss. An affected child must be provided with:
- High-calorie formula or breast milk
- Nutritional supplements that are added to their formula or pumped breast milk
- Feeding tube that travels from the nose to the esophagus and then to the stomach
- Tube feedings may be used in addition to or instead of formula or breast milk
Infections of the heart lining and heart valves (bacterial endocarditis) are common in children with heart problems. Antibiotics may be required before medical tests or procedures to prevent infection.
Once an atrioventricular canal defect is diagnosed, the child will be closely monitored to determine when surgery is required. This is an open-heart surgery, which means that the heart will have to be stopped and opened to be repaired. The procedure is carried out under general anesthesia.
If the child has other heart defects, the type of surgery required will depend on how the heart can be best modified to deal with problems. The average stay in the hospital is 10-12 days, with a couple of days spent in the intensive care and high dependency units. Of course, this is dependent on how well the child is before and after surgery, as well as whether complications arise. If the surgery is simple and the child does not have any other health issues, they should fully recover within a few days.
- A heart bypass machine will perform the functions that the heart normally performs.
- The goal is to restore normal blood circulation through the heart and lungs. The holes between the atria and ventricles (septal defect) are patched.
- The single atrioventricular valve is then split into two functional valves.
- One or two patches are used to close the septum between the heart chambers.
- The patches are permanent in the heart, becoming part of the septum as the lining of the heart grows over them.
- Surgery for a partial atrioventricular canal defect includes repair of the mitral valve so that it can close properly. If repair is not an option, the valve may need to be replaced.
- Surgery for a complete atrioventricular canal defect includes splitting the large single valve that separates the upper and lower chambers of the heart into two valves on both the left and right sides of the repaired septum.
- If it is not possible to separate the single valve, heart valve replacement of both the tricuspid and mitral valves may be required.
- A scar will run down the center of the chest, and there may be small scars where drain tubes were used.
What are the complications and prognosis of surgery for atrioventricular canal defect?
- It is not uncommon for the valves to leak slightly. If the situation worsens, they may need to be repaired or replaced with artificial valves.
- If an artificial valve is implanted, the child will need to take anticoagulant medication to prevent blood clots from forming.
- During surgery, the electrical system of the heart can be damaged. This can result in a slow heartbeat, called heart block. This may necessitate the placement of a pacemaker in the child.
- Some patients develop sub-aortic stenosis, a blockage beneath the aortic valve that may require open heart surgery to repair.
- Failure to repair the defect may result in irreversible damage to the lungs' blood vessels (pulmonary vascular obstructive disease).
- As the blood vessels deteriorate, less blood flows to the lungs, resulting in bluish discoloration of the skin.
- An untreated defect can eventually lead to death. The goal of surgical repair within the first year of life is to avoid this outcome.
- The prognosis is favorable following a successful surgery. Children who undergo the operation are more likely to live a normal, healthy life. Care, however, is ongoing and necessitates yearly check-ups to track progress and monitor potential complications, such as a leaky heart valve.
- Children will be required to take preventative antibiotics before any dental or surgical procedures. These preventative antibiotics help reduce the risk of complications, such as endocarditis (a bacterial infection that occurs within the lining of the heart and can be fatal).
- Adults may not require any additional surgery. Women who are planning to have children should have an atrioventricular canal defect evaluated by a cardiologist.
- In most cases, more than one surgery is required.
- The mortality rate varies with the defect and age:
- Partial defect: 10-year survival is more than 98%.
- Complete defect: Operative mortality is 3%-5% and 10-year survival is more than 90%.
What are the signs and symptoms of atrioventricular canal defects?
Atrioventricular canal defect can involve only the two upper chambers (atria) of the heart (partial) or all four chambers (complete). In either type, extra blood circulates in the lungs.
Complete atrioventricular canal defect
Typically, signs and symptoms appear within the first few weeks of life. These signs and symptoms are generally similar to those associated with heart failure:
- Difficulty breathing or rapid breathing
- 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 may not appear until early adulthood and may be related to complications caused by the defect:
- Abnormal heartbeat (arrhythmia)
- Shortness of breath
- High blood pressure in the lungs (pulmonary hypertension)
- Heart valve problems
- Heart failure
When to seek medical help
Contact a doctor immediately if the following signs are observed in children:
- Fast breathing
- Poor feeding
- Slow growth
- Bluish skin color
- Lowered alertness
- Swelling of the legs, ankles, and feet
- Excessive sweating
- Fast heartbeat
- Sudden weight gain
What are the risk factors of developing an atrioventricular canal defect?
It is unclear why atrioventricular canal defects occur. Factors that may increase the risk of developing this condition include:
How is an atrioventricular canal defect diagnosed?
During pregnancy, an ultrasound may be used to diagnose the child. When listening to the child’s heart with a stethoscope, the doctor may hear an abnormal sound (heart murmur) that leads them to suspect a heart defect. The doctor will be able to make a diagnosis based on the location and type of the murmur. Tests that may be ordered include:
- Chest X-ray: A chest X-ray may reveal heart and lung changes caused by an atrioventricular canal defect.
- Electrocardiogram: The electrical activity of the heart is recorded during this test. It detects abnormal heart rhythms (arrhythmias) and heart muscle stress. These problems could be caused by an atrioventricular canal defect.
- Echocardiogram: This test employs sound waves to create a moving image of the heart and its valves. The pattern of blood flow through the septal openings can be visualized using an echocardiogram. It can reveal the size of the openings and the amount of blood flowing through them. An echocardiogram is used to diagnose the majority of atrioventricular canal defects.
- Cardiac catheterization: Cardiac catheterization provides extremely detailed information about the structures within the heart. A small, thin, flexible tube (catheter) is inserted into a blood vessel in the child's groin during this test. The doctor then directs it to the child's heart. To see the child's heart more clearly, a contrast dye may be infected. Under sedation, the child's blood pressure and oxygen levels will be monitored.
- Genetic counseling: Because genetic factors may cause an atrioventricular canal defect, a genetic counselor and a cardiologist may help if there is a family history of heart defects or if a person already has had a child with a congenital heart defect. One of the most effective preventive strategies against congenital heart defects has been rubella vaccination.
The Children’s Hospital of Philadelphia. Atrioventricular Canal (AVC) Defects. https://www.chop.edu/conditions-diseases/atrioventricular-canal-defects
American Heart Association. Complete Atrioventricular Canal defect (CAVC). https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/complete-atrioventricular-canal-defect-cavc
Nationwide Children’s Hospital. Atrioventricular (AV) Canal Defect in Children. https://www.nationwidechildrens.org/conditions/health-library/atrioventricular-av-canal-defect-in-children
CHOC. Atrioventricular Canal Defect. https://www.choc.org/heart/congenital-heart-defects/atrioventricular-canal-defect/
Mayo Clinic. Atrioventricular canal defect. https://www.mayoclinic.org/diseases-conditions/atrioventricular-canal-defect/diagnosis-treatment/treatment/txc-20361532#
Medanta The Medicity. Atrioventricular Canal Defect. https://www.medanta.org/heart-hospital/disease/atrioventricular-canal-defect/
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