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What Is a Congenital Heart Defect?
A congenital heart defect is a structural problem (or defect)
in the heart that is present at birth. A baby's heart begins
to develop shortly after conception. During development,
structural defects can occur. These defects can involve the
walls of the heart, the valves of the heart, and the arteries
and veins near the heart. Congenital heart defects can disrupt
the normal flow of blood through the heart. The blood flow
can:
- Slow down
- Go in the wrong direction or to the wrong place
- Be blocked completely
Congenital heart defect is the most common type of major
birth defect. Each year, more than 30,000 babies in the United
States are born with congenital heart defects.
Types of Congenital Heart Defects
There are many types of congenital heart defects. They include:
- Abnormal passages in the heart or between blood vessels
- Problems with the heart valves
- Problems with the placement or development of blood vessels
near the heart
- Problems with development of the heart itself
Some of these problems are described below.
Abnormal passages in the heart or between blood
vessels
- Atrial septal
defect (ASD) is a hole in the wall that
separates the upper chambers (atria (AY-tree-uh)) of
the heart. This causes blood to leak from one atrium
to the other.
- Ventricular septal
defect (VSD) is a hole in the wall that
separates the lower chambers (ventricles (VEN-trih-kuls))
of the heart. This causes blood to leak from one ventricle
to the other.
- Atrioventricular septal defect (AVSD) includes
an ASD, VSD, and abnormal development of the atrioventricular
valves (tricuspid (tri-CUSS-pid) and mitral (MI-trul)).
This causes blood to flow abnormally inside the heart.
An AVSD is also known as an atrioventricular canal defect.
- Patent ductus
arteriosus (PDA) is a persistent connection
between the aorta and the pulmonary (PULL-mun-ary)
artery. This connection is called the ductus arteriosus
and is normally present before birth. In most babies,
the vessel closes within a few hours or days after
birth. In some children, the vessel fails to close,
resulting in PDA.
Problems with the heart valves
Congenital heart defects can involve any of the valves and
include the following types of problems:
- Stenosis. The valve opening is narrow
and does not open completely.
- Atresia. The valve does not form, so
there is no opening for blood to pass from one chamber
to another.
- Regurgitation. The valve does not close
completely, so blood can leak back through the valve.
Examples of particular heart valve problems include:
- Aortic valve stenosis is a narrowing
of the aortic (ay-OR-tik) valve in the heart that causes
it to open incompletely. This can reduce blood flow to
the body.
- Pulmonary valve atresia is a defect
in which a solid sheet of tissue forms in place of the
pulmonary valve. This prevents blood in the right side
of the heart from traveling normally to the lungs to pick
up oxygen.
- Pulmonary valve stenosis is a narrowing
of the pulmonary valve. The narrowing slows the flow of
blood from the right side of the heart to the lungs. The
heart must pump harder to push blood through the smaller
opening.
- Tricuspid valve atresia is a defect
in which a solid sheet of tissue forms in place of the
tricuspid valve. Without the tricuspid valve, blood entering
the right atrium cannot travel normally to the right ventricle
and then to the lungs to pick up oxygen.
- Ebstein's anomaly is a defect in which
the tricuspid valve is both displaced and abnormally formed.
The valve leaks and allows blood to flow back into the
right atrium instead of to the lungs to pick up oxygen.
Problems with placement or development of blood
vessels near the heart
- Transposition of the great vessels is
a defect in which the location of the "great vessels" (the
aorta and pulmonary artery) coming off the heart is switched.
The aorta comes off the right ventricle instead of the
left ventricle. The pulmonary artery comes off the left
ventricle instead of the right ventricle. Therefore, blood
without oxygen is continually pumped to the body, instead
of blood with oxygen.
- Tetralogy of Fallot is
a combination of four defects:
- Pulmonary valve stenosis is the narrowing of the
pulmonary valve. The narrowing slows the flow of
blood from the right ventricle to the lungs.
- VSD is a hole in the wall that separates the left
and right ventricles.
- Overriding aorta is a defect in which the aorta
is positioned between the left and right ventricles,
over the VSD.
- Right ventricular hypertrophy is the thickening
of the right ventricle. The thickening is caused
by the heart having to work harder because of the
other defects.
- Truncus arteriosus is a defect of the
great vessels. The aorta and pulmonary artery do not form
as separate arteries. Instead, a large artery, called the
truncus, comes from the heart. As the truncus leaves the
heart, it may branch into arteries that carry blood to
the body and to the lungs.
- Coarctation of the aorta is a narrowing
of the aorta. It slows or blocks the flow of blood from
the heart to the body.
- Anomalous pulmonary venous return is
a defect in which one or more of the four pulmonary veins,
which normally return oxygen-rich blood from the lungs
to the heart, return to the wrong chamber in the heart.
Problems with development of the heart
- Hypoplastic left heart syndrome is a combination of defects
in which the left side of the heart does not develop properly.
Defects usually include mitral atresia, aortic atresia,
and a tiny left ventricle.
- Mitral atresia occurs when a solid sheet of tissue
forms instead of the mitral valve, which separates
the left atrium and the left ventricle.
- Aortic atresia occurs when a solid sheet of tissue
forms instead of the aortic valve, which separates
the left ventricle from the aorta.
- Single ventricle describes a group of heart defects in
which only one ventricle is present instead of two. It
can be a single right or a single left ventricle. The other
ventricle is usually absent or very tiny. Hypoplastic left
heart syndrome is an example of a single ventricle defect.
Today, the outlook for an infant born with a heart defect
is much better than it was 30 years ago. Rapid advances in
infant and childhood surgery, better tests, and new medicines
help most children with congenital heart defects. Many children
born with more complex or severe heart defects now reach
adulthood. Today, there are more than 1 million adults living
with congenital heart defects.
Other Names for Congenital Heart Defects
- Congenital heart disease
- Cyanotic heart disease
- Heart defects
- Congenital cardiovascular malformations
To read the rest of this article, and related
material from the National Heart, Lung and Blood Institute,
please click here: http://www.nhlbi.nih.gov/health/dci/Diseases/chd/chd_what.html
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