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Truncus arteriosus is a rare type of heart disease that is present at birth (congenital) in which there is a single main blood vessel, rather than the normal two, carrying blood away from the heart. Instead of having a separate pulmonary artery, to carry blood to the lungs, and aorta, to carry blood to the rest of the body, a baby with truncus arteriosus has just one blood vessel leaving the heart which then branches into other blood vessels. Blood from both ventricles of the heart is mixed, resulting in a situation in which some oxygen-rich blood travels needlessly back to the lungs and some oxygen-poor blood travels to the rest of the body. Babies with this condition may have a bluish tint (cyanosis) to their skin, lips, and fingernails. In most cases, truncus arteriosus occurs in conjunction with a missing upper portion of the wall between the ventricles of the heart (ventricular septal defect).
Symptoms of truncus arteriosus include rapid breathing (tachypnea), lethargy, a bluish tint to the skin (cyanosis), poor feeding, difficulty breathing (dyspnea), and broadening of the fingertips (clubbing).
Other symptoms may include abnormal accumulations of fluid in the face, arms, and/or legs (edema), an abnormally rapid heartbeat, slow weight gain, failure to thrive, recurrent respiratory infections, poor physical development, and/or growth delays.
Congestive heart failure usually develops during the first few weeks of life because of the excessive amount of blood flow to the lungs. There may be abnormal enlargement of the heart (cardiomegaly), and/or the gradual development of obstructive lung disease.
When the blood pressure in the lungs is raised (pulmonary hypertension), the amount of work that the heart must perform is increased and blood vessels leading to and from the lungs become vulnerable to permanent damage.
The symptoms of truncus arteriosus are similar to those of a severe ventricular septal defect (VSD), a relatively common form of congenital heart disease. In VSD, the wall (septum) separating the two ventricles is incompletely formed before birth. This can result in inefficient distribution of oxygen to the various tissues of the body (hypoxia) and various degrees of congestive heart failure. Some infants with truncus arteriosus may also have narrowing or constriction (stenosis) of the valve that connects the heart and the major arteries. This may result in the backward flow of blood into the heart (regurgitation).
The exact cause of truncus arteriosus is not known. It has been suggested that some cases may develop due to the interaction of many genetic and environmental factors (multifactorial inheritance). The malformation is the result of an error in embryonic development. Approximately 35 percent of children with this disorder also have DiGeorge syndrome, which is a severe congenital immune deficiency disorder involving the thymus and parathyroid glands. (For more information on DiGeorge Syndrome, see the Related Disorders Section of this report.)
Truncus arteriosus is a rare, congenital heart defect that affects males and females in equal numbers. This disorder occurs in approximately 1 in 33,000 births in the United States. It is estimated that truncus arteriosus accounts for about 1 in 200 congenital heart defects.
Most commonly known risk factors are:
A mother who has had rubella (German measles) or other viral illnesses during early pregnancy.
A parent who had a congenital hearth defect
Excessive alcohol consumption during pregnancy
A mother who has diabetes
Taking medicines during pregnancy
Symptoms of the following disorders can be similar to those of Persistent Truncus Arteriosus. Comparisons may be useful for a differential diagnosis:
Ventricular Septal Defects (Cor Triloculare Biventricularis) are a group common congenital heart defects characterized by the absence of one atrium. Infants with this defect have 2 ventricles and 1 large atrium. Symptoms of Ventricular Septal Defects are similar to Atrioventricular Septal Defect and may include an abnormally rapid rate of breathing (tachypnea), wheezing, rapid heartbeat (tachycardia), and/or an abnormally enlarged liver (hepatomegaly). Ventricular Septal Defects can also cause the excessive accumulation of fluid around the heart, leading to congestive heart failure. (For more information on this disorder, choose "Ventricular Septal Defects" as your search term in the Rare Disease Database.)
Tetralogy of Fallot (Pseudotruncus Arteriosus) is a congenital heart disease. It consists of 4 defects: ventricular septal defect, subpulmonary stenosis, overriding aorta, and right ventricular hypertrophy. The most common symptom is a bluish discoloration to the skin due to the lack of sufficient oxygen to the tissues (cyanosis). This occurs during periods of rest and while crying. Other symptoms may include excessive fatigue, poor feeding, slow weight gain, and/or developmental delays. Exertion may produce potentially life-threatening complications including low levels of oxygen in the blood (hypoxia). (For more information on this disorder, choose "Tetralogy of Fallot" as your search term in the Rare Disease Database.)
Atrial Septal Defects are congenital heart defects characterized by the presence of a small opening between the two atria of the heart. This defect leads to an increase in the workload on the right side of the heart, and excessive blood flow to the lungs. The symptoms, which may become apparent during infancy, childhood, or adulthood, can vary greatly and depend on the severity of the defect. The symptoms tend to be mild at first and may include difficulty breathing (dyspnea), increased susceptibility to respiratory infections, and/or abnormal bluish discoloration of the skin and mucous membranes (cyanosis). Some people with Atrial Septal Defects may be at increased risk for the formation of blood clots that can travel to the major arteries (embolism), blocking blood circulation. (For more information on this disorder, choose "Atrial Septal Defects" as your search term in the Rare Disease Database.)
Cor Triatriatum is an extremely rare congenital heart defect characterized by the presence of an extra chamber above the left atrium of the heart. The pulmonary veins, returning blood from the lungs, drain into this extra "third atrium". The symptoms of Cor Triatriatum vary greatly and depend on the size of the opening between the chambers. Symptoms may include abnormally rapid breathing (tachypnea), wheezing, coughing, and/or abnormal accumulation of fluid in the lungs (pulmonary congestion). (For more information on this disorder, choose "Cor Triatriatum" as your search term in the Rare Disease Database.)
Cor Triloculare Biatriatum is an extremely rare congenital heart defect characterized by the absence of one ventricle. Infants with this defect have two atria and one large ventricle. The symptoms are similar to those of Atrioventricular Septal Defect and include breathing difficulties (dyspnea), excessive accumulation of fluid in the lungs and around the heart (pulmonary edema), and/or a bluish discoloration of the skin and mucous membranes (cyanosis). Other symptoms may include poor feeding habits, abnormally rapid breathing (tachypnea), and/or an abnormally rapid heartbeat (tachycardia).
Mitral Valve Stenosis is a rare heart defect that may be present at birth (congenital) or acquired. In the congenital form, the symptoms vary greatly and may include coughing, difficulty breathing, heart palpitations, and/or frequent respiratory infections. In acquired Mitral Valve Stenosis, the symptoms may also include weakness, abdominal discomfort, chest pain (angina), and/or periodic loss of consciousness.
The following disorder may be associated with Persistent Truncus Arteriosus. It is not necessary for a differential diagnosis:
DiGeorge Syndrome is a very rare group of congenital abnormalities that are the result of defects during early fetal development. These defects occur in areas known as the 3rd or 4th pharyngeal pouches which later develop into the thymus and parathyroid glands. Children with DiGeorge Syndrome who have a severely underdeveloped thymus gland have a dysfunctional immune system. They typically develop frequent infections from viruses, fungi, and certain bacteria. Common symptoms of this disorder include chronic nasal infections, diarrhea, thrush (oral candidiasis), and pneumonia. Unusual physical characteristics of DiGeorge Syndrome may include Persistent Truncus Arteriosus, wide-set eyes (hypertelorism), a downward slant to the eyes, notched and/or low-set ears, and/or an abnormally small mouth. (For more information on this disorder, choose "DiGeorge" as your search term in the Rare Disease Database.)
The diagnosis of truncus arteriosus is confirmed by clinical evaluation, electrocardiogram (EKG), and specialized imaging techniques that allow the physician to view the structure of the heart. These may include an echocardiogram, angiocardiogram, and/or cardiac catheterization.
Babies with truncus arteriosus require corrective surgery if they are to thrive. In some cases, a preliminary surgical procedure may be performed (pulmonary artery banding) that is designed to ease the condition by reducing the pulmonary hypertension, but not to cure it.
Corrective surgery (open-heart surgery) will separate the pulmonary and aortic arteries, close the hole in the ventricle wall, and attach the pulmonary artery to the reinforced right ventricle wall.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.
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Report last updated: 2007/07/23 00:00:00 GMT+0