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Ventricular Septal Defect
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The normal heart has two sides, the left and the right, which are separated by a muscular wall called the septum. Each side of the heart also has two parts - an upper chamber called an atrium and a lower chamber called a ventricle.
Ventricular septal defect (VSD), a congenital (present at birth) defect, is an opening in the ventricular septum, or dividing wall between the two lower chambers of the heart known as the right and left ventricles.
Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, then is pumped out to the body through the aorta. See About the Heart and Blood Vessels and Anatomy and Function of the Heart Valves for more information on how the heart normally works.
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A ventricular septal defect allows oxygen-rich (red) blood to pass from the left ventricle through the opening in the septum, and then mix with oxygen-poor (blue) blood in the right ventricle.
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Two basic types of VSD are:
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- Perimembranous VSD — An opening in the upper section of the ventricular septum, near the valves, occurs in 75 percent of all VSD cases.
- Muscular VSD — An opening in the lower section of the ventricular septum occurs in up to 20 percent of all VSD cases.
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Ventricular septal defects are the most commonly occurring type of congenital heart defect, occurring in one to three out of every 1,000 live births, and four to seven out of every 1,000 premature births.
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Normal heart
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The heart is forming during the first eight weeks of fetal development. It begins as a hollow tube, then partitions develop within the tube that eventually become the septa (or walls) dividing the right side of the heart from the left. Ventricular septal defects occur when the partitioning process does not occur completely, leaving an opening in the ventricular septum.
Some congenital heart defects may have a genetic link, either occurring due to a defect in a gene, a chromosome abnormality or environmental exposure, causing heart problems to occur more often in certain families. Most ventricular septal defects occur sporadically (by chance), with no clear reason for their development.
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If not treated, this heart defect can cause lung disease. When blood passes through the VSD from the left ventricle to the right ventricle, a larger volume of blood than normal must be handled by the right side of the heart, causing the right side to become overworked and enlarged. Extra blood then passes through the pulmonary artery into the lungs, causing higher pressure than normal in the blood vessels in the lungs, a condition known as pulmonary hypertension.
A small opening in the ventricular septum allows a small amount of blood to pass through from the left ventricle to the right ventricle. A large opening allows more blood to pass through and mix with the normal blood flow in the right heart. The larger the volume of blood that goes to the lungs, the higher the pressure.
The lungs are able to cope with this extra pressure for while, depending on exactly how high the pressure is. After a while, however, the blood vessels in the lungs become diseased by the extra pressure. If this combination of lung disease and damage to the right side of the heart is severe, it could lead to an inability of the heart to pump effectively, called congestive heart failure.
As pressure builds up in the lungs, the flow of blood from the left ventricle through the VSD, into the right ventricle, and on to the lungs will diminish. This helps preserve the function of the lungs, but causes another problem. Blood flow within the heart goes from areas where the pressure is high to areas where the pressure is low. If a ventricular septal defect is not repaired and lung disease begins to occur, pressure in the right side of the heart will eventually exceed pressure in the left. In this instance, it will be easier for oxygen-poor (blue) blood to flow from the right ventricle, through the VSD, into the left ventricle and on to the body. When this happens, the body does not receive enough oxygen in the bloodstream to meet its needs.
Because blood is pumped at high pressure by the left ventricle through the VSD, tissue damage may eventually occur in the right ventricle. Bacteria in the bloodstream can easily infect this injured area, causing a serious illness known as bacterial endocarditis.
Some ventricular septal defects are found in combination with other heart defects (such as in transposition of the great arteries).
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The size of the ventricular septal opening will affect the type of symptoms noted, the severity of symptoms and the age at which they first occur. A VSD permits extra blood to pass from the left ventricle through to the right side of the heart, and the right ventricle and lungs become overworked as a result. The larger the opening, the greater the amount of blood that passes through and overloads the right ventricle and lungs.
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Symptoms often occur in infancy. The following are the most common symptoms of VSD. Each child may experience symptoms differently. Symptoms may include:
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- fatigue
- sweating
- rapid breathing
- heavy breathing
- congested breathing
- disinterest in feeding, or tiring while feeding
- poor weight gain
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The symptoms of VSD may resemble other medical conditions or heart problems. Always consult your child's physician for a diagnosis.
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Your child's physician may have heard a heart murmur during a physical examination and referred your child to a pediatric cardiologist for a diagnosis. A heart murmur is simply a noise caused by the turbulence of blood flowing through the opening from the left side of the heart to the right.
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A pediatric cardiologist specializes in the diagnosis and medical management of congenital heart defects, as well as heart problems that may develop later in childhood. The cardiologist will perform a physical examination, listening to the heart and lungs, and make other observations that help in the diagnosis. The location within the chest where the murmur is heard best, as well as the loudness and quality of the murmur (harsh, blowing, etc.), will give the cardiologist an initial idea of which heart problem your child may have. Other tests are needed to help with the diagnosis, and may include the following:
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- Chest X-ray — A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones and organs onto film. With a VSD, the heart may be enlarged because the right ventricle handles larger amounts of blood flow than normal. Also, there may be changes that take place in the lungs due to extra blood flow that can be seen on an X-ray.
- Electrocardiogram (ECG or EKG) — A test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias) and detects heart muscle stress.
- Echocardiogram (echo) — A procedure that evaluates the structure and function of the heart by using sound waves, recorded on an electronic sensor, that produce a moving picture of the heart and heart valves. An echo can show the pattern of blood flow through the septal opening and determine how large the opening is, as well as how much blood is passing through it.
- Cardiac Catheterization — A procedure that 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 guided to the inside of the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as in the pulmonary artery and aorta. Contrast dye also is injected to more clearly visualize the structures inside the heart.
- Cardiac Magnetic Resonance Imaging (MRI) — A non-invasive test that uses three-dimensional imaging technology produced by magnets to accurately determine blood flow and functioning of the heart as it is working.
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Specific treatment for VSD will be determined by your child's physician based on:
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- your child's age, overall health and medical history
- extent of the disease
- your child's tolerance for specific medications, procedures or therapies
- how your child's doctor expects the disease may progress
- your opinion or preference
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Small ventricular septal defects may close spontaneously as your child grows. A larger VSD usually requires surgical repair. Regardless of the type, once a ventricular septal defect is diagnosed, your child's cardiologist will evaluate your child periodically to see whether it is closing on its own. A VSD will be repaired if it has not closed on its own -- to prevent lung problems that will develop from long-time exposure to extra blood flow. Treatment may include:
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- Medical Management — Some children have no symptoms and require no medication. Most children, however, may need to take medications to help the heart work better, since the right side is under strain from the extra blood passing through the VSD. Medications that may be prescribed include the following:
- Digoxin -- A medication that helps strengthen the heart muscle, enabling it to pump more efficiently.
- Diuretics -- The body's water balance can be affected when the heart is not working as well as it could. These medications help the kidneys remove excess fluid from the body.
- Adequate Nutrition — Infants with a larger VSD may become tired when feeding, and are not able to eat enough to gain weight. Options that can be used to ensure your baby will have adequate nutrition include the following:
- High-calorie Formula or Breast milk -- Special nutritional supplements may be added to formula or pumped breast milk that increase the number of calories in each ounce, thereby allowing your 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 inner surfaces of the heart known as bacterial endocarditis. A common procedure that puts your child at risk for this infection is a routine dental check-up and teeth cleaning. Other procedures may also increase the risk of the heart infection occurring. Giving children with heart defects an antibiotic by mouth before these procedures can help prevent bacterial endocarditis. It is important that you inform all medical personnel that your child has a VSD so they may determine if the antibiotics are necessary before a procedure.
- Cardiac Catheterization — Your child's VSD may be repaired surgically in the operating room or by a cardiac catheterization procedure. One method currently being used to close some VSDs is the use of a device called a septal occluder. During this procedure, the child is sedated and a small, thin, flexible tube is inserted into a blood vessel in the groin and guided into the heart. Once the catheter is in the heart, the cardiologist will pass the septal occluder into the VSD. The septal occluder closes the ventricular septal defect providing a permanent seal.
- Surgical Repair — Some types of VSDs will close on their own with time. Many, however, are too large or are positioned such that they cannot close on their own and require surgical closure.
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The surgical closure of a VSD is carried out through an incision in the middle of the chest. The breast bone is split in the middle and spread apart to expose the heart. A heart-lung machine is used to do the work of the heart while the heart is cooled, stopped, emptied and opened, usually through the right atrium. The hole in the wall between the right and left ventricles is closed by sewing to it a patch of Dacron cloth or a patch of thin leather-like material called pericardium. The heart is then closed and restarted as the heart-lung machine is withdrawn. Advancements in cardiovascular surgical repair include minimally invasive cardiac surgery.
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Complementing the Cardiovascular Program of Children's Hospital Boston is the nation's most intensive clinical and basic research program focused on pediatric heart disease. Children's is a world leader in opening new avenues of "translational research," bringing laboratory advances to the bedside and doctor's office as quickly as possible. All senior medical staff members of the Cardiovascular Program participate in clinical research activities.
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Children's Hospital Boston has pioneered interventional catheterization repair of many types of congenital heart defects, including ventricular septal defect. In many cases, this eliminates the need for open-heart surgery, allowing less pain, reduced chance of infection, and shorter recovery time.
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Contact Children's Hospital Boston Cardiovascular Program physicians for a second opinion.
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Ventricular Septal Defect (VSD)
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