Ventricular septal defect (VSD) is a hole (defect) in the
wall that separates the lower chambers of the heart. The lower chambers of the
heart are called the ventricles. The wall between them is
called the ventricular septum. In the normal heart, the septum prevents blood
from flowing directly from one ventricle to the other. In a heart with a VSD,
blood can flow directly between the two ventricles.
VSD is a congenital
heart defect, which means that it is present at birth. In children with a
VSD, blood usually flows through the defect from the left ventricle to the
right ventricle. This causes extra blood (called volume overload) in the
pulmonary arteries and lungs, and in the left atrium and left
ventricle.
VSD is the most common type of congenital heart defect. Infants born with a
VSD may have a single hole or more than one hole in the wall that separates
the two ventricles. The defect may also occur by itself or with other
congenital heart defects.
Most VSDs close on their own or are so small that they don't need
treatment. Some children and adults need surgery or other procedures to close
the VSD, especially if it is large. Most children and adults live long and
productive lives after their VSD closes or is repaired.
Figure A shows the normal anatomy and blood flow of the
interior of the heart. Figure B shows two common locations of ventricular
septal defects. The defect allows oxygen-rich blood from the left ventricle to
mix with oxygen-poor blood in the right ventricle.
Effects of VSD
Over time, a VSD that does not close—especially a large VSD—can cause:
- Congestive
heart failure. Infants with large VSDs may develop congestive heart
failure. Extra blood flows from the left ventricle through the right
ventricle to the lungs and back to the left atrium and on to the left
ventricle. This causes the left atrium and left ventricle to handle an
increased amount of blood, and the workload on the heart increases. The
increased workload on the heart also increases the heart rate and the
body's demand for energy. The extra blood flow in the lungs may cause
rapid breathing, while also increasing the body's demand for energy.
- Growth failure, especially in infancy. Your baby may not be able to eat
enough to keep up with his or her body's increased energy demands. Your
baby may lose weight or fail to grow and develop as he or she should.
- Bacterial
endocarditis is an infection of the lining of the heart, valves, or
arteries. Endocarditis often occurs following dental and medical
procedures.
- Irregular
heartbeat or rhythm (arrhythmia). The extra blood flowing into the
left atrium can cause the atrium to stretch and enlarge. When this occurs,
your child can develop a fast heartbeat with symptoms such as dizziness or
fainting.
- Pulmonary
artery hypertension (high blood pressure in the pulmonary arteries).
If a moderate or large VSD is not closed, sustained blood flow under
higher pressure into the pulmonary arteries causes the arteries to become
thickened and stiff. The amount of blood flow to the lungs decreases over
time as the resistance to blood flow into the pulmonary arteries
increases. However, this causes the right ventricle to work harder. Today,
pulmonary artery hypertension rarely develops because most large or
moderate VSDs are closed in infancy or early childhood.
Types of VSD
Doctors classify VSDs based on the:
- Size of the defect.
- Location of the defect.
- Number of defects.
- Presence or absence of a ventricular septal aneurysm—a thin flap of
tissue on the septum. It is harmless and can help a VSD close on its own.
VSDs range in size from small to large.
- Small VSDs usually allow only a small amount of blood flow between the
ventricles. Because of this, they are sometimes called restrictive. Most
small VSDs:
- Do not cause symptoms in infants and children
- Close on their own, often by school age
- Rarely need surgery or other procedures to close the defect
- Moderate (or medium-sized) VSDs are less likely than small defects to
close on their own. They may require surgery to close and may cause
symptoms during infancy and childhood.
- Large VSDs allow a large amount of blood to flow from the left ventricle
to the right ventricle and are sometimes called nonrestrictive. A large
VSD is less likely to close completely on its own, but it may get smaller.
A large VSD can cause more symptoms in infants and children, and surgery
is usually needed to close it.
VSDs are found in different parts of the septum.
- Membranous VSDs are located near the heart valves. They can close at any
time if a ventricular septal aneurysm is present.
- Muscular VSDs are found in the lower part of the septum. They are
surrounded by muscle, and most close on their own during early childhood.
- Inlet VSDs are located close to where blood enters the heart. They are
less common than membranous and muscular VSDs.
- Outlet VSDs are found in the part of the ventricle where the blood
leaves the heart. This is the rarest type of VSD.
Symptoms
The major signs and symptoms of ventricular septal defect (VSD) are:
Most newborns with VSD do not have heart-related symptoms.
Heart Murmur
A heart murmur is an extra or unusual sound heard during your heartbeat. It
is usually present in VSD and may be the first and only sign found by your
doctor. The heart murmur is often present right after birth in many infants,
but it may not appear until the baby is 6 to 8 weeks old. Sometimes the heart
murmur is not found until the child is older or much later in life as an
adult.
Congestive Heart Failure
A baby with a moderate or large VSD can develop congestive heart failure.
These symptoms usually appear during the baby's first 2 months of life. Some
older children and adults with VSD also may develop symptoms of congestive
heart failure, which include:
- Fatigue or tiring easily
- Shortness of breath
- Fast breathing
- Slow growth and poor weight gain
Diagnosis
Ventricular septal defect (VSD) is diagnosed using a medical history, a
physical exam, and tests. Your baby's doctor may see symptoms of VSD during a
routine checkup. Some parents also notice signs, such as poor feeding, and
bring the baby to the doctor.
Most cases are diagnosed in infancy and childhood. Babies born with a large
VSD may have symptoms of congestive heart failure by the time they are 1 - 2
months old. They are usually diagnosed at that time. Some cases are not
diagnosed until adulthood.
Medical and Family History
Your child's doctor will ask you about:
Physical Exam
During the physical exam, the doctor:
- Listens to your baby's heart with a stethoscope to hear and evaluate a
heart murmur
- Looks for signs of congestive heart failure
Tests
- Echocardiogram. This test is harmless and painless. It uses sound waves to create a moving picture of
your baby's heart. During an echocardiogram, reflected sound waves outline the
heart's structure completely. The test allows the doctor to clearly see any
problem with the way the heart is formed or the way it's working. An
echocardiogram is the most important test available to your baby's
cardiologist to both diagnose a heart problem and follow the problem over
time. With VSD, the echocardiogram shows exactly where the hole is located in
the wall between the two lower heart chambers, how big the hole is, and
whether the heart is overworking because of the defect. An echocardiogram also
is used for a baby with VSD to make sure there are no other problems with the
heart's structure.
- Chest
x ray. This test takes a picture of the heart and lungs. It can show
if the heart is enlarged or if there is fluid in the lungs.
- EKG
(electrocardiogram). This test measures the rate and regularity of your
child's heartbeat. It provides an estimate of enlargement of the heart
chambers and shows abnormal heart rhythms (arrhythmia).
- Cardiac
catheterization. A thin, flexible tube (catheter) is passed through a
blood vessel (artery or vein) to the heart. With the assistance of x rays,
the doctor can see the child's blood vessels and heart. During the
procedure, the doctor can measure blood pressure in the heart and arteries
connected to the heart, and see how much blood is mixing between the two
sides of the heart. Cardiac catheterization is rarely used for diagnosis
unless the echocardiogram does not provide enough information or if other
defects or problems are suspected.
Causes
Doctors do not know what causes ventricular septal defect (VSD).
Heredity may play a role. Parents who have congenital
heart defects are more likely to have a child with VSD than parents who do
not have congenital heart defects. In some cases, VSD may be due to a defect
in one or more genes or to chromosomal abnormalities.
Reference:
National Heart, Lung, and Blood Institute, USA.
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