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My Child Has:
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Truncus Arteriosus
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Truncus arteriosus
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Truncus arteriosus is a congenital (present at birth) heart defect that first appears as the heart begins to develop. The heart begins as a hollow tube, and the chambers, valves and great arteries develop during pregnancy. The aorta and pulmonary artery start as a single blood vessel, which eventually divides and becomes two separate arteries.
Truncus arteriosus occurs when the single great vessel fails to separate completely, leaving a connection between the aorta and pulmonary artery.
Another congenital heart defect that occurs with truncus arteriosus is a ventricular septal defect (ventricular septum, or dividing wall between the two lower chambers of the heart known as the right and left ventricles).
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Normal heart
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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 truncus arteriosus oxygen-poor (blue) and oxygen-rich (red) blood mix back and forth through the ventricular septal defect. This mixed blood then flows through the common truncal vessel. Some of it will flow through the branch that becomes the pulmonary artery and on to the lungs, and some of the mixed blood will go into the aortic branch and continue to the body.
The mixed blood that goes to the body does not have as much oxygen as normal, and will cause varying degrees of cyanosis (blue color of the skin, lips and nailbeds).
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Truncus arteriosus occurs in less than one out of every 10,000 live births. It makes up 1 percent of all cases of congenital heart disease.
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Truncus arteriosus occurs due to the improper development of the heart in the first eight weeks of fetal growth. 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. Other times this heart defect occurs sporadically (by chance), with no clear reason for its development.
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The blood that passes through the common truncal vessel has a lower oxygen content than normal. Oxygen-poor (blue) blood from the right ventricle and oxygen-rich (red) blood from the left ventricle mix together before entering the common vessel. Some of this mixed blood will go into the aorta and on to the body, producing cyanosis (blue color of the skin, lips and nailbeds).
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The pulmonary artery section of the common vessel gets more blood flow than the aorta does, because the resistance is lower in the lungs than the body and it is easier for blood to travel in that direction. If not repaired, the blood vessels in the lungs become damaged by the extra blood flow. As the pressure in the blood vessels in the lungs becomes higher, less blood goes to the lungs and more goes to the body. Cyanosis becomes worse as blood with lower amounts of oxygen travels to the body.
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The following are the most common symptoms of truncus arteriosus. Each child may experience symptoms differently. Symptoms may include:
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- cyanosis (blue color of the skin, lips and nail beds)
- fatigue
- sweating
- pale skin
- cool skin
- rapid breathing
- heavy breathing
- rapid heart rate
- congested breathing
- disinterest in feeding, or tiring while feeding
- poor weight gain
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The symptoms of truncus arteriosus 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 heart defects. Symptoms your child exhibits will also help with the diagnosis.
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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 that 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 which 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 truncus arteriosus 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 condition
- your child's tolerance for specific medications, procedures or therapies
- how your child's doctor expects the condition may progress
- your opinion or preference
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Truncus arteriosus must be treated by surgical repair of the defects. Medical support may be necessary until the best time for the operation to take place. Treatment may include:
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- Medical Management — Many children will eventually need to take medications to help the heart and lungs work better. Medication that may be prescribed includes 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.
- ACE (angiotensin-converting enzyme) inhibitors -- Dilates the blood vessels, making it easier for the heart to pump blood forward into the body.
- Infants may become tired when feeding, and may not be able to eat enough calories to gain weight. Options that can be used to ensure your baby will have adequate nutrition include:
- 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.
- 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.
- Surgical Repair — Surgery is usually performed after the infant is two weeks old, but before the blood vessels in the lungs are overwhelmed by extra blood flow and become diseased. The operation is performed under general anesthesia, and involves the following:
- The pulmonary arteries are detached from the common artery (truncus arteriosus) and connected to the right ventricle using a homograft (a section of pulmonary artery with its valves intact from a tissue donor). Occasionally, a conduit (a small tube containing a valve) is used instead of a homograft (human tissue valve).
- The ventricular septal defect is closed with a patch.
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Many children who have had truncus arteriosus surgical repair can live healthy lives. Activity levels, appetite and growth will eventually return to normal in most children.
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Future intervention may be necessary if the pulmonary artery branches are small and do not grow well after surgery. The homograft connecting the right ventricle to the pulmonary artery also may need to be replaced as your child grows.
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Your child's cardiologist may recommend that antibiotics be given to prevent bacterial endocarditis after discharge from the hospital.
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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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Contact Children's Hospital Boston Cardiovascular Program physicians for a second opinion.
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