Coarctation of the aorta (COA) is a congenital heart defect that develops in the fetus. It involves a constricture of the aorta, the main artery that delivers blood from the
left ventricle of the heart to the rest of the body. In a constricture or coarctation, the sides (walls) of the aorta press together abnormally, impeding the flow of blood. COA can produce symptoms of congestive heart failure or high blood pressure (hypertension) as early as the first week of life or may produce no symptoms until later in life.
Description
In the fetus, blood from the heart to the lungs is delivered into the aorta through a short blood vessel called the ductus arteriosis. This duct or shunt normally closes at birth or shortly after. In symptomatic children with COA, the descending aorta receives blood from the right side of the heart through the ductus arteriosus, an abnormal condition often accompanying other heart abnormalities such as a duct that does not close normally (patent ductus arteriosus or PDA), mitral valve defects, and other types of congenital heart disease. In asymptomatic children with COA, the descending aorta receives left ventricle blood through the ascending aorta; these children have fewer, if any, associated cardiac abnormalities. Approximately 10 percent of newborns with congenital heart disease have symptomatic coarctation of the aorta. About 85 percent of all children and adults with COA have a double aortic valve (bicuspid aortic valve) in the heart.
Blood normally leaves the heart by way of the left ventricle and is distributed to the body through the arteries. The aortic arch is the first artery to carry blood as it leaves the heart. Other arteries to the head and arms branch off the aortic arch. Constriction of the aorta, as in COA, produces resistance to the flow of blood, resulting in raising the blood pressure above the narrowing and reducing blood pressure below or downstream from the narrowing. High blood pressure (hypertension) affects parts of the body supplied by arteries that branch off the aortic arch above the narrowing. By contrast, most of the lower body does not receive enough blood supply. To compensate for this, the heart works harder, and blood pressure rises.
About half of all infants with COA are diagnosed within the first three months of life. Frequently, other congenital cardiac complications are also present. Thirty percent of infants with Turner syndrome, for example, also have coarctation. Evidence exists that at least some cases of coarctation may be inherited.
COA is congenital, that is it develops while the baby is in the womb and may appear in newborns along with other signs of congenital heart disease. Among the consequences of COA is an enlargement of the left ventricle (ventricular hypertrophy) in response to increased back-pressure of the blood and the demand for more blood by the lower body. Symptoms in infants may include shortness of breath (dyspnea), difficulty in feeding, and poor weight gain. Children can also have no symptoms at all at birth (asymptomatic) and develop mild symptoms as older children. The older child with COA may display fatigue, shortness of breath, or a feeling of weakness or lameness in the legs.
When to call the doctor
COA is typically diagnosed within the first three months of life because of circulatory problems that produce symptoms. Some children have surgery, and some children are managed with drug therapy alone. Parents learn to recognize symptoms of high blood pressure or insufficient blood supply to the lower extremities. Medical attention is needed at the first sign of shortness of breath. Even when a child has had surgery or is on medication, the doctor should be contacted when any abnormal symptoms arise, such as shortness of breath, difficulty in feeding (with infants), and poor weight gain. Older children generally have fewer symptoms but may appear to be easily fatigued or to experience shortness of breath or weakness or lameness in their legs.
Diagnosis
Physical examination may reveal a pale child with some degree of dyspnea. On examination of the heart rhythm using a stethoscope, infants with coarctation of the aorta usually have an abnormal "gallop" heart rhythm, and 50 percent of children also have heart murmurs. Sometimes excessive arterial pulses can be seen in the arteries of the neck (carotid and suprasternal notch arteries), indicating increased pressure in these arteries, while the major artery of the legs (femoral artery) may have a weak pulse or none can be detected. The systolic pressure is higher in the arms than in the legs. Enlargement of the heart can be seen in x rays and congestion of the blood vessels in the lungs. Similar symptoms may be seen in older children and adults. A 10 mm Hg (mercury) pressure difference between the upper and lower extremities is diagnostic for coarctation of the aorta. For some individuals, the systolic pressure difference is observed only during exercise. Infants frequently have an abnormal electrocardiogram (ECG) that indicates that the right or both ventricles are enlarged, while in older children
the ECG may be normal or show that the left ventricle is enlarged. The site and the extent of coarctation may also be detected using color-flow Doppler ultrasonography (echocardiology).
Asymptomatic children may have a normal heart size or only slight enlargement. Differences in blood pressure between the arms and legs may be noted. Hypertension is less likely and, if noted, may be less marked than in symptomatic children with other heart defects. The bicuspid aortic valve is usually present. Color-flow Doppler studies may show a reduced blood flow below the coarctation.
Treatment
The goal of treatment in children is to reopen the ductus arteriosus and restore blood flow to the descending aorta. Congestive heart failure may be treated simultaneously with anticongestive medications. Drug therapy is used first to treat hypertension and heart failure in children and adults who have coarctation of the aorta. Surgery may be required for infants who have severe coarctation of the aorta and is usually recommended for those who have associated cardiac defects or those infants who do not respond to drug therapy. Surgery may also be indicated for infants whose early symptoms do not indicate immediate surgery but who develop severe hypertension during the first several months of life. Older children and adults are advised to avoid vigorous exercise prior to surgical correction of the coarctation. Surgery may involve resection of the coarctation segment or opening and patching the aorta where the coarctation occurred. Balloon angioplasty is sometimes performed on infants who are not ideal candidates for repair surgery because of higher risk; this procedure involves passing a catheter with an attached deflated balloon through the femoral artery in the groin and inflating the balloon to open the coarctation segment of the aorta. Recoarctation can occur in some individuals, even after corrective surgery. Recurrence is higher with balloon angioplasty than with repair surgery.
Prognosis
Approximately half of all infants diagnosed with coarctation of the aorta have no other cardiac defects and respond well to medical management, growing and developing normally. These infants are generally asymptomatic and will eventually outgrow the condition after several years of life. Although hypertension may increase for several months early in life, it eventually decreases as the circulatory system develops and vessels become larger.
Symptomatic children who have other heart defects generally respond well to repair surgery, and COA symptoms are reduced. The mortality rate for COA infants is about 5 percent. The average life span of children who have coarctation of the aorta is 34 years of age, reduced primarily due to complications and to the presence of other heart problems. The most common complications following repair surgery are postoperative renal failure and recoarctation. Complications in children who have not had surgery are hypertension, aortic rupture, intracranial bleeding, and congestive heart failure. Undetected or untreated COA can also lead to early adulthood death due to congestive heart failure, systemic hypertension, coronary artery disease, and aortic aneurysm. Women who have an uncorrected coarctation of the aorta have a mortality rate of 10 percent during pregnancy and a 90 percent rate of complications.
Parental concerns
Because congenital coarctation of the aorta is unpredicted, parents may be unprepared for the diagnosis and need careful, sensitive medical explanation by the pediatrician or surgeon. The birth of a child with this condition may raise parents' concerns about their child's ability to lead a normal life. If COA is detected, with or without the child's presenting symptoms, medical and surgical treatment usually corrects the condition and reduces symptoms. Over half of children overcome the condition and grow and develop normally without severe restrictions. Children who have other heart problems may have the repair surgery and other procedures to reduce symptoms and improve blood flow and with continued drug therapy and some restrictions on activity can lead relatively normal lives into adulthood.
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ORGANIZATIONS
American Heart Association. 7320 Greenville Ave., Dallas, TX 75231. Web site: <www.americanheart.org>.
WEB SITES
"Children: Heart Disease and Health." American Heart Association, 2004. Available online at <www.americanheart.org> (accessed January 5, 2005).
L. Lee Culvert
John T. Lohr, PhD
KEY TERMS
Aneurysm—A weakened area in the wall of a blood vessel which causes an outpouching or bulge. Aneurysms may be fatal if these weak areas burst, resulting in uncontrollable bleeding.
Angioplasty—A medical procedure in which a catheter, or thin tube, is threaded through blood vessels. The catheter is used to place a balloon or stent (a small metal rod) at a narrowed or blocked area and expand it mechanically.
Aorta—The main artery located above the heart that pumps oxygenated blood out into the body. The aorta is the largest artery in the body.
Electrocardiagram (ECG, EKG)—A record of the electrical activity of the heart, with each wave being labeled as P, Q, R, S, and T waves. It is often used in the diagnosis of cases of abnormal cardiac rhythm and myocardial damage.
Hypertension—Abnormally high arterial blood pressure, which if left untreated can lead to heart disease and stroke.
Patent ductus arteriosus—A congenital defect in which the temporary blood vessel connecting the left pulmonary artery to the aorta in the fetus doesn't close after birth.
Turner syndrome—A chromosome abnormality characterized by short stature and ovarian failure caused by an absent X chromosome. It occurs only in females.
