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My Child Has:
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D-Transposition of the Great Arteries
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Normal heart
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Transposition of the great arteries (TGA) is a congenital (present at birth) heart defect that occurs when the large vessels that take blood away from the heart to the lungs, or to the body, are improperly connected.
Normally:
- oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped through the pulmonary artery 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 through the aorta out to the body.
In transposition of the great arteries, the aorta is connected to the right ventricle, and the pulmonary artery is connected to the left ventricle -- the exact opposite of a normal heart's anatomy:
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- Oxygen-poor (blue) blood returns to the right atrium from the body, passes through the right atrium and ventricle, then goes into the misconnected aorta back to the body.
- Oxygen-rich (red) blood returns to the left atrium from the lungs, passes through the left atrium and ventricle, then goes into the pulmonary artery and back to the lungs.
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d-Transposition of the Great Arteries
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Two separate circuits are formed -- one that circulates oxygen-poor (blue) blood from the body back to the body, and another that recirculates oxygen-rich (red) blood from the lungs back to the lungs.
Other heart defects are often associated with TGA, and actually may be necessary in order for an infant with transposition of the great arteries to live. Openings in the wall separating the left and right sides of the heart, called atrial septal defect or ventricular septal defect, will allow blood from one side to mix with blood from another, creating "purple" blood with an oxygen level somewhere between that of the oxygen-poor (blue) and the oxygen-rich (red) blood.
A patent ductus arteriosus (another type of congenital heart defect) will allow mixing of oxygen-poor (blue) and oxygen-rich (red) blood through the connection between the aorta and pulmonary artery. The "purple" blood that results from this mixing is beneficial, providing small, if not normal, amounts of oxygen to the body.
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The heart is forming during the first eight weeks of fetal development. The problem occurs in the middle of these weeks, allowing the aorta and pulmonary artery to be attached to the incorrect chamber.
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 of the time this heart defect occurs sporadically (by chance), with no clear reason for its development.
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Babies with TGA have two separate circuits -- one that circulates oxygen-poor (blue) blood from the body back to the body, and another that recirculates oxygen-rich (red) blood from the lungs back to the lungs. Without an additional heart defect that allows mixing of oxygen-poor (blue) and oxygen-rich (red) blood, such as an atrial or ventricular septal defect, infants with TGA will have oxygen-poor (blue) blood circulating through the body, a situation that is critical. Even with an additional defect present that allows mixing, babies with transposition of the great arteries may not have enough oxygen in the bloodstream to meet the body's demands.
Even when a significant amount of mixing of oxygen-poor (blue) and oxygen-rich (red) blood occurs, other problems may be present. The left ventricle, which in TGA is connected to the pulmonary artery, is usually the stronger of the two ventricles since it normally has to generate a lot of force to pump blood to the body. The right ventricle, connected to the aorta in TGA, is considered the weaker of the two ventricles and may not be able to pump blood efficiently to the body. As a result, it will enlarge under the strain.
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The obvious indication of TGA is a newborn who becomes cyanotic (blue) in the transitional first day of life, when the maternal source of oxygen (from the placenta) is removed. Cyanosis is noted in the first hours of life in about half the infants with TGA, and within the first days of life in 90 percent of them. The degree of cyanosis is related to the presence of other defects that allow blood to mix, including a patent ductus arteriosus -- a fetal connection between the aorta and the pulmonary artery present in the newborn, which usually closes in the first few days after birth.
The following are the other most common symptoms of TGA. Each child may experience symptoms differently. Symptoms may include:
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The following are the other most common symptoms of TGA. However, each child may experience symptoms differently. Symptoms may include:
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- rapid breathing
- labored breathing
- rapid heart rate
- cool, clammy skin
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The symptoms of TGA may resemble other medical conditions or heart problems. Always consult your child's physician for a diagnosis.
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A pediatric cardiologist and/or a neonatologist may be involved in your child's care. 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. A neonatologist specializes in illnesses affecting newborns, both premature and full-term.
Cyanosis is the major indication that there is a problem with your newborn. Your child's physician may also have heard a heart murmur during a physical examination. A heart murmur is simply a noise caused by the turbulence of blood flowing through the openings that allow the blood to mix.
Other diagnostic 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.
- 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.
- 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 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 transposition of the great arteries 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 to progress
- your opinion or preference
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Your child most likely will be admitted to the intensive care unit (ICU) or special care nursery once symptoms are noted. Initially, your child may be placed on oxygen or a ventilator to assist his/her breathing. Intravenous (IV) medications may be given to help the heart and lungs function more efficiently.
Other important aspects of initial treatment include the following:
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- A cardiac catheterization procedure can be used as a diagnostic procedure, as well as an initial treatment procedure for some heart defects. A cardiac catheterization procedure will usually be performed to evaluate the defect(s) and the amount of blood that is mixing.
- As part of the cardiac catheterization, a procedure called a balloon atrial septostomy may be performed to improve mixing of oxygen-rich (red) and oxygen-poor (blue) blood.
- A special catheter with a balloon in the tip is used to create an opening in the atrial septum (wall between the left and right atria).
- The catheter is guided through the foramen ovale (a small opening present in the atrial septum that closes shortly after birth) and into the left atrium.
- The catheter is quickly pulled back through the hole, into the right atrium, enlarging the hole, allowing blood to mix between the atria.
- An intravenous medication called prostaglandin E1 is given to keep the ductus arteriosus from closing.
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Within the first 1 to 2 weeks of age, transposition of the great arteries is surgically repaired. The procedure that accomplishes this is called a "switch," which roughly describes the surgical process.
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The surgical correction of TGA 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. The aorta and pulmonary arteries are disconnected and reconnected to their proper ventricles. The coronary arteries must be transferred to the newly positioned aorta as well, or "blue" blood will supply the muscle of the heart. Associated holes between the chambers of the heart are closed. The heart is then restarted as the heart-lung machine is withdrawn.
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Many infants who undergo TGA surgical repair will grow and develop normally. After TGA repair, however, your infant will need to be followed periodically by a pediatric cardiologist who will make assessments to check for any heart-related problems, which can include the following:
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- fast, slow or irregular heart rhythms
- leaky heart valves
- narrowing of one or both of the great arteries at the switch connection site(s)
- narrowing of the coronary arteries at their switch connection site
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Consult your child's physician regarding the specific outlook for your child.
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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 initial repair of TGA.
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Contact Children's Hospital Boston Cardiovascular Program physicians for a second opinion.
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