Coarctation of the Aorta
Coarctation of the aorta is a narrowing of the aorta that causes a blockage to blood flow. Most coarctations are congenital (meaning they are present at birth) and usually are discovered in infancy; however, some coarctations can develop over time. The narrowing may be discrete or may extend over a long segment. Most coarctations are located in the chest, and rarely they can occur in the abdomen. "Simple" is the term used to describe coarctations that are isolated; "complex" is the term used to describe coarctations that are associated with other congenital heart disease. Types of congenital heart disease associated with coarctation include ventricular septal defect (an abnormal hole between the two ventricles), atrioventricular canal (an abnormal connection between the atrium and the ventricle), and double outlet right ventricle (two exit vessels from the ventricle, rather than one).
Coarctation of the aorta is one of the more common forms of congenital heart disease. It is twice as common in boy as in girls. Coarctation rarely runs in families. The only syndrome that has a strong association with coarctation is Turner's syndrome, a condition in which a girl has only one instead of two X chromosomes.
Infants with coarctation frequently have congestive heart failure (the heart cannot keep up with its workload, so it starts to fail). A narrowing of the aorta results in a selective elevation in blood pressure in the upper extremity blood vessels and, ultimately, in an increase in heart work. In some newborns with coarctation, closure of the ductus arteriosus results in an acute increase in heart work. If the coarctation is severe, the increased heart work results in the development of congestive heart failure. In infants with milder degrees of coarctation, the heart adapts to the increase in work, and heart failure does not occur.
The cardiovascular system has two ways to respond to the increased work produced by coarctation of the aorta. The first way the body compensates for the increased cardiac workload is to develop extra heart muscle (myocardial hypertrophy). The second way is to develop collateral vessels to bypass the aortic obstruction. As the child develops these alternate blood channels, the blood pressure and the cardiac work are reduced, and there is an improvement in blood supply to the abdominal organs, such as the liver, the gastrointestinal tract, and the kidneys.
Cardiovascular lesions can aggravate the heart's burden associated with coarctation. The presence of a coarctation will increase the amount of blood flow across a ventricular septal defect, making a small hole act (as far as the heart is concerned) as if it were a large hole.
Clinical features of coarctation
Most children with coarctation have no symptoms. In older children, if symptoms are present, they are usually nonspecific and relate either to high blood pressure (hypertension) in the upper part of the body, causing headaches or frequent nose bleeds, or to reduced blood supply to the lower extremities (e.g., exercise-induced leg pain, claudication).
In infancy, coarctation can be associated with congestive heart failure. Although heart failure can develop in an infant at any time during the first six months, it typically develops during the first six weeks. The major features associated with heart failure are a rapid heart and respiratory rate and poor weight gain. The infant in heart failure needs to be diagnosed and treated immediately, since the infant rapidly can develop shock that can result in death.
Physical findings in coarctation
The hallmarks of coarctation of the aorta are absent leg pulses and a difference in blood pressure between the arms and the legs (i.e., high blood pressure in the arms and low to normal blood pressure in the legs). The typical heart murmur associated with a coarctation is a systolic murmur that is loudest in the back below the left shoulder blade (scapula). If a prominent back murmur is not heard and the child has a blood pressure difference between the arms and the legs, a coarctation located in the abdomen should be considered.
Laboratory findings in coarctation
The chest x-ray can be very helpful in suggesting the presence of coarctation of the aorta. However, the diagnosis usually is confirmed by an echocardiogram (a specialized ultrasound of the heart). A heart catheterization is performed only if the coarctation cannot be adequately documented by the echocardiogram or to treat the coarctation with the use of a balloon angioplasty.
How is coarctation of the aorta treated?
Management of a patient with coarctation of the aorta must be individualized. In children without symptoms, in whom a coarctation is diagnosed on routine examination, repair of the coarctation-either surgically or using balloon angioplasty at a cardiac catheterization-is not recommended before 18 to 24 months of age.
In the newborn or infant with coarctation who presents in congestive heart failure, initial treatment consists of stabilizing the infant with medications. These medications include agents that increase the strength of the heartbeat, inotropic agents, and agents that help the body remove excess fluids, diuretics. If the infant is less than two weeks of age, a medicine (prostaglandin E1) will be administered to keep open the ductus arteriosus. The most critically ill babies will require the use of a ventilator to assist with breathing. After a brief period of stabilization, all infants with coarctation and congestive heart failure require surgical repair.
Surgical repair involves removal of the narrowed segment of aorta. In some children, it is necessary to place a piece of artifical material (e.g., Dacron, Gore-Tex) to enlarge the area of narrowing or to bypass the area of narrowing. A balloon angioplasty is performed at the time of a heart catheterization. The angioplasty involves the placement of a special balloon catheter across the narrowed area and then inflating the balloon, thereby stretching open the aorta.
Why treat children with coarctation of the aorta?
Untreated coarctation of the aorta significantly reduces life expectancy, with death frequently occurring within a patient's fourth to fifth decade. Causes of death in individuals with unoperated coarctation of the aorta include congestive heart failure, aortic rupture (the aorta bursts), bacterial endocarditis (an infection of the heart), and stroke.
The long-term outlook for children who have had their coarctation repaired, either with surgery or angioplasty, is excellent. Children who have successful repair of coarctation usually can live full and productive lives. Women usually can become pregnant safely. However, medical problems can occur after repair.
Recoarctation is the redevelopment of a narrowing in the aorta. This problem occurs more commonly in children who have had their coarctation repaired during the first year of life. Recoarctation occurs in approximately 10% to 20% of children who have had their repair in infancy, and in less than 3% of children who have had their repair after 3 years of age. Treatment of recoarctation of the aorta usually is with a balloon angioplasty.
High blood pressure
High blood pressure is one of the most common medical problems seen in patients after successful repair of coarctation. Approximately 60% of people who have had their coarctation repaired will require medication to treat high blood pressure in adulthood.
Other medical problems
Other medical problems, which are seen rarely in people after successful repair of coarctation, include the development of aneurysms in the aorta, the early development of coronary artery disease, the development of disease to the aortic valve, and the development of a stroke.
Beekman R, Rocchini A. Coarctation of the aorta and interruption of the aortic arch. In: Moller J, Neal W, eds. Fetal, neonatal, and infant cardiac disease. Norwalk, CT: Appleton and Lange, 1990:497-521.
Keith J. Coarctation of the aorta. In: Keith J, Rowe R, Valad P, eds. Heart disease in infancy and children. New York: MacMillan, 1978.
About the Author
Dr. Rocchini received both his bachelor of science degree in chemical engineering and his medical degree from the University of Pittsburgh. He completed his pediatric residency at the University of Minnesota and his pediatric cardiology fellowship at the Children's Hospital of Boston. Dr. Rocchini is currently a professor of pediatrics and serves as director of pediatric cardiology at the University of Michigan. His research interests include interventional cardiac catheterization and obesity-induced hypertension.
Copyright 2012 Albert P. Rocchini, M.D., All Rights Reserved