What is 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 and are usually discovered in infancy; however, some coarctations develop over time. The narrowing may be discrete or may extend over a long segment of the aorta. Most coarctations are located in chest, but rarely they can occur in the abdomen. The terms "simple" and "complex" are used to describe coarctations that are either isolated or associated with other congenital heart disease. Some of the types of congenital heart disease associated with coarctation include ventricular septal defect, atrioventricular canal, and double outlet right ventricle, to name just a few.
Coarctation of the aorta is the seventh or eighth most common form of congenital heart disease. It is twice as common in boys as in girls. Coarctation rarely runs in families. The only syndrome that has a strong association with coarctation is Turner's syndrome (a condition where a girl has only one instead of two X-chromosomes).
What are the effects of this defect on my child's health?
Infants with coarctation frequently come to medical attention because of congestive heart failure. A narrowing of the aorta results in a selective elevation in blood pressure in the upper extremity blood vessels and ultimately in an increased workload for the heart. 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 major ways that it uses to respond to the increased work caused by coarctation of the aorta. The first way the body uses to compensate for the increased cardiac workload associated with coarctation of the aorta is the development of extra heart muscle (myocardial hypertrophy). The second way is the development of collateral vessels to bypass the aortic obstruction. As the child develops these alternative blood channels the blood pressure and cardiac work are reduced and there is an improvement in blood supply to the abdominal organs such as the liver, gastrointestinal tract and kidneys.
If the child has coarctation in combination with other heart defects, the extra workload for the heart may additive. For example, the presence of a coarctation will increase the amount of blood flowing across a ventricular septal defect; thus, making a small hole act, as far as the heart is concerned, as if it were a large hole.
How is this problem diagnosed?
Clinical features: In contrast to infants, most children with coarctation have no symptoms. If symptoms are present they are usually nonspecific and relate either to the result of 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 (exercise induced leg pain, claudication).
In infancy, coarctation can be associated with congestive heart failure. Although heart failure can develop any time during the first six months of life, it typically develops during the first 6 weeks of life. The major features associated with heart failure are a rapid heart and respiratory rate and poor weight gain. The infant in uncontrolled heart failure needs immediate diagnosis and treatment, since shock and death can rapidly develop.
Physical findings: The hallmarks of coarctation of the aorta are absent leg pulses and a difference in blood pressure between the arms and legs (high blood pressure in the arms and low to normal blood pressure in the legs). The typical heart murmur that is 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 arms and legs a coarctation located in the abdomen should be considered.
Medical tests: The chest x-ray can be very helpful in suggesting the presence of coarctation of the aorta. However, the diagnosis is usually confirmed by an echocardiogram. Heart catheterization is now only performed either because the coarctation cannot be adequately documented by the echocardiogram or to treat the coarctation with the use of balloon angioplasty.
Why treat children with coarctation of the aorta?
Untreated coarctation of the aorta significantly reduces life expectancy, with death frequently occurring within the fourth to fifth decade. Causes of death in individuals with unoperated coarctation of the aorta include congestive heart failure, aortic rupture, bacterial endocarditis, and stroke.
How is the problem treated?
Management of the individual with coarctation of the aorta must be individualized. In the children without symptoms, in who a coarctation is diagnosed on routine examination, repair of the coarctation, either surgically or using balloon angioplasty at a cardiac catheterization is usually recommended by 18-24 months of age.
In the newborn or infant with coarctation who presents with 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 medicines that help the body remove excess fluids, diuretics. If the infant is less than 2 weeks of age the baby will receive a medicine to open the ductus arteriosus, prostaglandin E1, and the most critically ill babies will require the use of a ventilator to help the baby breathe. After a brief period of stabilization, infants with coarctation and congestive heart failure require surgical repair.
Surgical repair involves removing the narrowed segment of aorta and reconnecting the ends directly. Although rare, in some children it is necessary to place a piece of artificial material (Dacron or Gore-Tex) to enlarge or bypass the area of narrowing.
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 and thereby stretching open the aorta.
Care and services for patients with this problem are provided in the Congenital Heart and Cardiovascular Surgery clinics at the University of Michigan Medical Center in Ann Arbor.
What is the outlook for children with coarctation of the aorta?
The long-term outlook for children who have had their coarctation repaired, whether it be surgery or angioplasty, is excellent. Children who have successful repair of coarctation can usually live full and productive lives and women can usually safely become pregnant. However, there are a number of medical problems that can also occur late after repair.
1. Recoarctation Recoarctation is the redevelopment of a narrowing in the aorta. This problem occurs more commonly in children who have had their coarctation repaired very early in life. Recoarctation occurs in around 5-10 % of the time in children who have had their repair in infancy and less than 3% of the time if the repair was performed after 3 years of age. Treatment of recoarctation of the aorta usually involves balloon angioplasty.
2. High Blood Pressure One of the most common medical problems seen in people after successful repair of coarctation is high blood pressure. Approximately 60% of people who have had their coarctation repaired will require, as adults, medicines to treat high blood pressure.
3. Other medical problems Other medical problems that are rarely seen in people after successful repair of coarctation are: 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.
Sandhu N, Beekman RH, Mosca RS, Bove EL: Single-stage repair of aortic arch obstruction and associated intracardiac defects in the neonate. Am J Cardiol 1995;75:370-373.
Minich L, Beekman RH, Rocchini AP, Bove EL: Surgical repair is safe and effective after unsuccessful angioplasty of native coarctation. J Am Coll Cardiol 1992;19:389-93
Shanley CJ, Mosca RS, Bove EL, Greenfield LJ: Thoracic aortic narrowing: Isthmic coarctation. In Surgery of The Aorta and its Branches. Edited by B. L. Gewertz. Published by W. B. Saunders, Philadelphia, PA, in press.
Written: A. Rocchini, MD
Reviewed September, 2012