08/10/2019
Information for you (4)
Atrioventricular Septal Defect (AVSD)
What is Atrioventricular Septal Defect?
Atrioventricular septal defect (AVSD) is a large hole in center of the heart affecting all four chambers where they would normally be divided. It's located where the wall (septum) between the upper chambers (atria) joins the wall between the lower chambers (ventricles).
This septal defect involves both upper and lower chambers and the valves that control the flow of blood between these chambers may not be formed correctly.
This condition is also called atrioventricular canal (AV canal) defect or endocardial cushion defect.
In AVSD, blood flows where it normally should not go. The blood can travel across the holes from the left heart chambers to the right heart chambers and out into the lungs. This extra blood being pumped into the lungs forces the heart and lungs to work hard and may lead to congestive heart failure.
There are two general types of AVSD that can occur, depending on which structures are not formed correctly:
1. Complete AVSD
A complete AVSD occurs when there is a large hole in the center of the heart where the septa (walls) separating the two top chambers (atria) and two bottom chambers (ventricles) normally meet. There is also one common atrioventricular valve in the center of the heart instead of two separate valves – the tricuspid valve on the right side of the heart and the mitral valve on the left side of the heart. This common valve often has leaflets (flaps) that may not be formed correctly or do not close tightly.
2. Partial or Incomplete AVSD
A partial or incomplete AVSD occurs when the heart has some, but not all the defects of complete AVSD. There is usually a hole in the atrial wall or in the ventricular wall near the center of the heart. A partial AVSD usually has both mitral and tricuspid valves, but one of the valves (usually mitral) may not close completely, allowing blood to leak backward from the left ventricle into the left atrium.
What are the causes or the risk factors for the occurrence of such disease?
The etiology for AVSD is unknown. However, there are some risk factors that may increase the incidence of its occurrence:
• It’s a very common type of heart defect in children with a chromosome problem, Trisomy 21 (Down syndrome).
• Rubella or another viral disease during the early pregnancy
• Use of alcohol during pregnancy
• Poor control of diabetes during pregnancy
• Smoking during pregnancy
• Take certain medications during pregnancy - Talk to your doctor before taking any medications during pregnancy
• One parent has a congenital heart defect
How does the AVSD affect your child?
High pressure may occur in the blood vessels in the lungs because more blood than normal is being pumped there. Over time this causes permanent damage to the lung blood vessels. Consequently, the lungs become prone to be infected resulting in recurrent chest infections.
In some infants, the common valve between the upper and lower chambers doesn't close properly. This lets blood leak backward from the heart's lower chambers to the upper ones. This leak, called regurgitation or insufficiency, can make the heart work harder, too.
Eventually, this stressed suffering heart fails to do a proper function resulting in a heart failure.
How can be diagnosed?
AVSD may be diagnosed during pregnancy or soon after the baby is born.
1) During Pregnancy
During pregnancy, there are screening tests to check for birth defects and other conditions. AVSD may be diagnosed during pregnancy with an ultrasound test (fetal echocardiogram), but whether or not the defect can be seen with the ultrasound test depends on the size or type (partial or complete) of the AVSD. The fetal echocardiogram can show problems with the structure of the heart and how well the heart is working.
2) After the Baby is born
During a physical exam of an infant, a complete AVSD may be suspected. Using a stethoscope, a doctor will often hear a heart murmur (an abnormal “whooshing” sound caused by blood flowing through the abnormal hole). However, not all heart murmurs are present at birth. Babies with a complete AVSD usually do show signs of problems within the first few weeks after birth. When symptoms do occur, they may include
• Breathing problems
• Pounding heart
• Weak pulse
• bluish skin color
• Poor feeding, slow weight gain
• Tiring easily
• Swelling of the legs or belly
For partial AVSDs, if the holes between the chambers of the heart are not large, the signs and symptoms may not occur in the newborn or infancy periods. In these cases, people with a partial AVSD might not be diagnosed for years.
Symptoms which might indicate that a child’s complete AVSD or partial AVSD is getting worse include
• Arrhythmia, an abnormal heart rhythm. An arrhythmia can cause the heart to beat too fast, too slow, or erratically. When the heart does not beat properly, it can’t pump blood effectively.
• Congestive heart failure, when the heart cannot pump enough blood and oxygen to meet the needs of the body.
• Pulmonary hypertension, a type of high blood pressure that affects the arteries in the lungs and the right side of the heart.
The healthcare provider can request one or more tests to confirm the diagnosis of AVSD. The most common test is an echocardiogram. This is an ultrasound of the heart that can show problems with the structure of the heart, like holes between the chambers of the right and left side of the heart, and any irregular blood flow. An electrocardiogram (ECG), which measures the electrical activity of the heart, chest x-rays and other medical tests may also be used to make the diagnosis.
Because many babies with Down syndrome have an AVSD, all infants with Down syndrome should have an echocardiogram to look for an AVSD or other heart defects.
What can be done to treat your child?
Unlike some other types of septal defects, the AVSD can't close on its own.
All AVSDs, both partial and complete types, usually require surgery. During surgery, any holes in the chambers are closed using patches. If the mitral valve does not close completely, it is repaired or replaced. For a complete AVSD, the common valve is separated into two distinct valves – one on the right side and one on the left side.
The age at which surgery is done depends on the child’s health and the specific structure of the AVSD. If possible, surgery should be done before there is permanent damage to the lungs from too much blood being pumped to the lungs.
Medication may be used to treat congestive heart failure, but it is only a short term measure until the infant is strong enough for surgery.
What will your child need after surgery?
Infants who have surgical repairs for AVSD are not cured; some of them might have lifelong complications. The most common of these complications is a leaky mitral valve. This is when the mitral valve does not close all the way so that it allows blood to flow backwards through the valve. A leaky mitral valve can cause the heart to work harder to get enough blood to the rest of the body; a leaky mitral valve might have to be surgically repaired. But, for many children, the long-term outlook is good, and usually no medicines or additional surgery are needed.
A child or adult with an AVSD will need regular follow-up visits with your doctor to monitor his or her progress, avoid complications, and check for other health conditions that might develop as the child gets older. The frequency of the visits depends on the extent of problems with the repair, the presence of abnormal heart rhythms and pulmonary hypertension. In general, you should visit the cardiologist at least once a year.
With proper treatment, most babies with AVSD grow up to lead healthy, productive lives.
What activities can your child do?
If the AVSD has been closed with surgery, your child may not need any special precautions regarding physical activities and may be able to participate in normal activities without increased risk.
What about preventing endocarditis?
Children with AVSD may risk endocarditis both before and after repair. Ask about your child's risk of endocarditis and about your child's need to take antibiotics before certain dental, minor or major other surgical procedures.
What if the AV canal defect is still present? Should it be repaired in adulthood?
High pressure may occur in the blood vessels in the lungs that can lead to permanent damage with pulmonary hypertension that persists into adulthood.
Many adults who have not had previous repair have pulmonary hypertension. They’re more likely to have heart failure and Eisenmenger's syndrome. This complication is more common than in patients with an ASD or a VSD. Even in adults without Eisenmenger's syndrome, symptoms including shortness of breath, intolerance to exercise and palpitations are common. On physical examinations, murmurs due to the blood flow across the defects and due to the valve leak are common.
The decision to repair an AVSD in adulthood is complicated. It depends on the pressures in the lung and the heart's pumping function. However, when the pressures aren't too high and the pump function is good, these defects can be repaired and adult patients are likely to improve. A heart catheterization is almost always required to know whether the defect should be closed.
If my AVSD was closed in childhood, can I expect Pregnancy?
If after surgery you have no significant residual (leftover) problems, the risk from pregnancy is low.
If there are problems like a leaking valve or irregular heart rhythms, you may be at increased risk for complications of pregnancy.
If you have heart failure or pulmonary hypertension, pregnancy isn't recommended.
Women with unrepaired AV canal defects or who have leftover problems should talk to their cardiologist before deciding to get pregnant.
Pregnant women with repaired AV canal defects who are free of significant problems may not require high risk obstetrical care. In contrast those unrepaired AV canal defects, significant valve leaks or pulmonary hypertension.
