Coarctation
of the Aorta
Health
Effects | Diagnosis | Treatments | References
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).
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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.
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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.
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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 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 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.
Clinics
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.
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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 is with 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.
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References
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
October, 1999
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