Congenital
Heart Defects
When
the heart or blood vessels near the heart do not
develop normally before birth, a condition called
congenital heart defect occurs (congenital means
"inborn" or "existing at birth").
Congenital
heart defects occur in about 8 percent to 10 percent
of every 1,000 infants. About 500,000 adults in
the US have congenital heart disease. Many young
people with congenital heart defects are living
in adulthood now.
In most
cases, the cause is unknown. Sometimes a viral
infection or hereditary causes the condition.
Some congenital heart defects are the result of
too much alcohol or drug use during pregnancy.
Most
heart defects either cause an abnormal blood flow
through the heart, or obstruct blood flow in the
heart or vessels (obstructions are called stenoses
and can occur in heart valves, arteries, or veins).
Rarely,
defects include those in which:
- the right or left side
of the heart is incompletely formed - called
hypoplastic heart.
- only one ventricle
is present.
- both the pulmonary
artery and aorta arise from the same ventricle.
There
are many disorders of the heart that require clinical
care by a physician or other healthcare professional.
Listed below are some of the conditions, for which
we have provided a brief overview.
Obstructive defects:
-
aortic stenosis (AS)
In this condition, the aortic valve between
the left ventricle and the aorta did not form
properly and is narrowed, making it difficult
for the heart to pump blood to the body. A
normal valve has three leaflets or cusps,
but a stenotic valve may have only one cusp
(unicuspid) or two cusps (bicuspid).
In some children, chest pain, unusual tiring,
dizziness or fainting may occur. Otherwise,
most children with aortic stenosis have no
symptoms. But, even mild stenosis may worsen
over time, and surgery may be needed to correct
the blockage - or the valve may need to be
replaced with an artificial one.
-
pulmonary stenosis
(PS)
The pulmonary, or pulmonic, valve, located
between the right ventricle and the pulmonary
artery, opens to allow blood to flow from
the right ventricle to the lungs. When a defective
pulmonary valve does not open properly, it
causes the heart to pump harder than normal
to overcome the obstruction. Usually, the
obstruction can be corrected by balloon valvuloplasty,
although in some patients, open heart surgery
may be needed.
-
bicuspid aortic valve
In this condition, an infant is born with
a bicuspid valve which has only two flaps.
(A normal aortic valve has three flaps that
open and close). If the valve becomes narrowed,
it is more difficult for the blood to flow
through, and often the blood leaks backward.
Symptoms usually do not develop during childhood,
but are often detected during the adult years.
-
subaortic stenosis
This condition refers to a narrowing of the
left ventricle just below the aortic valve.
Normally, blood passes through it to go into
the aorta. However, subaortic stenosis limits
the blood flow out of the left ventricle,
often resulting in an increased workload for
the left ventricle. Subaortic stenosis may
be congenital or caused by a form of cardiomyopathy.
-
coarctation of the
aorta (coarct)
In this condition, the aorta is narrowed or
constricted, obstructing blood flow to the
lower part of the body and increasing blood
pressure above the constriction. Usually there
are no symptoms at birth, but they can develop
as early as the first week after birth. If
severe symptoms of high blood pressure and
congestive heart failure develop, surgery
may be considered.
Some
congenital heart defects allow blood to flow between
the right and left chambers of the heart because
an infant is born with an opening in the septum
wall that separates the right and left sides of
the heart.
- atrial septal defect
(ASD)
In this condition, there is an abnormal opening
between the two upper chambers of the heart
- the right and left atria - causing an abnormal
blood flow through the heart. Children with
ASD have few symptoms. Closing the atrial defect
by open heart surgery in childhood can often
prevent serious problems later in life.
- Ebstein's anomaly
In this defect, there is a downward displacement
of the tricuspid valve (located between the
upper and lower chambers on the right side of
the heart) into the right bottom chamber of
the heart (or right ventricle). It is usually
associated with an atrial septal defect.
- ventricular septal
defect (VSD)
In this condition, a hole occurs between the
two lower chambers of the heart. Because of
this hole, blood from the left ventricle flows
back into the right ventricle, due to higher
pressure in the left ventricle. This causes
an extra volume of blood to be pumped into the
lungs by the right ventricle, which can create
congestion in the lungs.
Cyanotic
defects are defects in which blood pumped to the
body contains less-than-normal amounts of oxygen,
resulting in a condition called cyanosis. It causes
a blue discoloration of the skin. Infants with
cyanosis are often called "blue babies."
- tetralogy of Fallot
This condition is characterized by four defects,
including the following:
- an abnormal opening,
or ventricular septal defect, that allows
blood to pass from the right ventricle to
the left ventricle without going through
the lungs
- a narrowing (stenosis)
at or just beneath the pulmonary valve that
partially blocks the flow of blood from
the right side of the heart to the lungs
- the right ventricle
is more muscular than normal
- the aorta lies
directly over the ventricular septal defect
Tetralogy of Fallot is the most common defect
causing cyanosis in persons beyond 2 years of
age. Most children with tetralogy of Fallot
have open-heart surgery before school age to
close the ventricular septal defect and remove
the obstructing muscle. Lifelong medical follow-up
is needed.
- tricuspid atresia
In this condition, there is no tricuspid valve,
therefore, no blood flows from the right atrium
to the right ventricle. Tricuspid atresia defect
is characterized by the following:
- a small right ventricle
- a large left ventricle
- diminished pulmonary
circulation
- cyanosis
A surgical shunting procedure is often necessary
to increase the blood flow to the lungs.
- transposition of
the great arteries
In this embryologic defect, the positions of
the pulmonary artery and the aorta are reversed,
thus:
- the aorta originates
from the right ventricle, so most of the
blood returning to the heart from the body
is pumped back out without first going to
the lungs.
- the pulmonary artery
originates from the left ventricle, so that
most of the blood returning from the lungs
goes back to the lungs again.
Immediate medical intervention is necessary
to correct this condition.
- left heart syndrome
In this condition, the left side of the heart
is underdeveloped, including the aorta, aortic
valve, left ventricle, and mitral valve. Blood
reaches the aorta through a patent ductus arteriosus,
and if this ductus closes, as is normal, the
baby will die. The baby often seems normal at
birth, but the condition will become noticeable
within a few days of birth, as the ductus closes.
Babies with this syndrome become pale, have
difficulty breathing, and are unable to feed.
Treatment may include complex surgery or a heart
transplant.
- patent ductus arteriosus
(PDA)
This defect, which normally occurs during the
fetal life, short circuits the normal pulmonary
vascular system and allows blood to mix between
the pulmonary artery and the aorta. Prior to
birth, there is an open passageway between the
two blood vessels, which closes soon after birth.
When it does not close, some blood returns to
the lungs. Patent ductus arteriosus is often
seen in premature infants.
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