Tricuspid
Atresia (TA)
Tricuspid
atresia (TA) is a congenital (present at birth)
heart defect that occurs due to abnormal development
of the fetal heart during the first 8 weeks of
pregnancy. The tricuspid valve, normally located
between the right atrium and the right ventricle,
does not develop properly during pregnancy.
Normally,
oxygen-poor (blue) blood returns to the right
atrium from the body, travels to the right ventricle,
then is pumped through the pulmonary artery into
the lungs where it receives oxygen. Oxygen-rich
(red) blood returns to the left atrium from the
lungs, passes into the left ventricle, and then
is pumped through the aorta out to the body.
In tricuspid
atresia, however, the following occurs:
- Improper development
of the tricuspid valve prevents oxygen-poor
(blue) blood from passing from the right atrium
to the right ventricle and on to the lungs as
it should.
- The right ventricle
is also underdeveloped.
- Openings are also present
in the atrial and ventricular walls (atrial
and ventricular septal defects), allowing oxygen-poor
(blue) blood and oxygen-rich (red) blood to
mix with each other.
- A patent ductus arteriosus
also allows blood to pass through from the aorta
to the pulmonary artery and receive oxygen from
the lungs.
Tricuspid
atresia makes up 1 to 2 percent of all cases of
congenital heart disease. TA occurs equally in
boys and girls.
The
heart is forming during the first 8 weeks of fetal
development. In TA, during the middle of this
development period, the tricuspid valve does not
develop properly. Ventricular development is influenced
by blood flowing through it, and since no blood
is able to pass through the tricuspid valve, the
right ventricle remains small.
Some
congenital heart defects may have a genetic link,
either occurring due to a defect in a gene, a
chromosome abnormality, or environmental exposure,
causing heart problems to occur more often in
certain families. Most of the time, this heart
defect occurs sporadically (by chance), with no
clear reason for its development.
This
heart defect causes children to be cyanotic (blue)
since a combination of oxygen-poor (blue) and
oxygen-rich (red) blood leaves the heart and goes
to the body. Just how much oxygen or how little
oxygen will be in the bloodstream depends on a
number of factors. Some children will only be
mildly cyanotic, while others will not have enough
oxygen in the blood to meet the body's needs.
Symptoms
are noted shortly after birth. The following are
the most common symptoms of tricuspid atresia.
However, each child may experience symptoms differently.
Symptoms may include:
- blue color of the skin,
lips, and nail beds
- rapid breathing
- labored breathing
- rapid heart rate
- cool, clammy skin
The
symptoms of TA may resemble other medical conditions
or heart problems. Always consult your child's
physician for a diagnosis.
A pediatric
cardiologist and/or a neonatologist may be involved
in your child's care. A pediatric cardiologist
specializes in the diagnosis and medical management
of congenital heart defects, as well as heart
problems that may develop later in childhood.
A neonatologist specializes in illnesses affecting
newborns, both premature and full-term.
Cyanosis
is the major indication that there is a problem
with your newborn. Your child's physician may
have also heard a heart murmur during a physical
examination. A heart murmur is simply a noise
caused by the turbulence of blood flowing through
the openings that allow the blood to mix.
Other
diagnostic tests are needed to help with the diagnosis,
and may include the following:
- chest x-ray -
a diagnostic test which uses invisible electromagnetic
energy beams to produce images of internal tissues,
bones, and organs onto film.
- electrocardiogram
(ECG or EKG) - a test that records
the electrical activity of the heart, shows
abnormal rhythms (arrhythmias or dysrhythmias),
and detects heart muscle stress.
- echocardiogram (echo)
- a procedure that evaluates the
structure and function of the heart by using
sound waves recorded on an electronic sensor
that produce a moving picture of the heart and
heart valves.
- cardiac catheterization
- a cardiac catheterization is an
invasive procedure that gives very detailed
information about the structures inside the
heart. Under sedation, a small, thin, flexible
tube (catheter) is inserted into a blood vessel
in the groin, and guided to the inside of the
heart. Blood pressure and oxygen measurements
are taken in the four chambers of the heart,
as well as the pulmonary artery and aorta. Contrast
dye is also injected to more clearly visualize
the structures inside the heart.
Specific
treatment for TA will be determined by your child's
physician based on:
- your child's age, overall
health, and medical history
- extent of the disease
- your child's tolerance
for specific medications, procedures, or therapies
- expectations for the
course of the disease
- your opinion or preference
Your
child will most likely be admitted to the intensive
care unit (ICU) or special care nursery once symptoms
are noted. Initially, your child may be placed
on oxygen, and possibly even on a ventilator,
to assist his/her breathing. Intravenous (IV)
medications may be given to help the heart and
lungs function more efficiently.
Other
important aspects of initial treatment include
the following:
- A cardiac catheterization
procedure can be used as a diagnostic procedure,
as well as initial treatment procedure for some
heart defects. A cardiac catheterization procedure
will usually be performed to evaluate the defect(s)
and the amount of blood that is mixing.
- As part of the cardiac
catheterization, a procedure called a balloon
atrial septostomy may be performed to improve
mixing oxygen-rich (red) blood and oxygen-poor
(blue) blood.
- A special catheter
with a balloon in the tip is used to create
or enlarge an opening in the atrial septum
(wall between the left and right atria).
- The catheter is
guided through the foramen ovale (a small
opening present in the atrial septum that
closes shortly after birth) and into the
left atrium.
- The balloon is
inflated.
- The catheter is
quickly pulled back through the hole, into
the right atrium, enlarging the hole, allowing
blood to mix between the atria.
- An intravenous (IV)
medication called prostaglandin E1 is given
to keep the ductus arteriosus from closing.
The
ductus arteriosus (the normal connection between
the aorta and the pulmonary valve) will likely
close if the prostaglandin E1 infusion is stopped.
Another pathway for blood to reach the lungs to
receive oxygen must be surgically created.
A series
of operations are performed in the first two years
of life that will re-route blood so that enough
oxygen is added to the bloodstream to meet the
child's needs.
Each
operation is performed under general anesthesia.
Types of operations include the following:
- Blalock-Taussig shunt
The first operation creates a pathway for blood
to reach the lungs. A connection is made between
the first artery that branches off the aorta
(called the right subclavian artery) and the
right pulmonary artery. Some of the blood traveling
through the aorta towards the body will "shunt"
through this connection and flow into the pulmonary
artery to receive oxygen. However, the child
will still have some degree of cyanosis since
oxygen-poor (blue) blood from the right atrium
and oxygen-rich (red) blood from the left side
of the heart mix and flow through the aorta
to the body.
- Glenn shunt
A second operation, often performed at about
4 to 12 months of age, replaces the Blalock-Taussig
shunt with another connection to the pulmonary
artery. In this operation, the Blalock-Taussig
shunt is removed, and the superior vena cava
(the large vein that brings oxygen-poor blood
from the head and arms back to the heart) is
connected to the right pulmonary artery. Blood
from the head and arms passively flows into
the pulmonary artery and proceeds to the lungs
to receive oxygen. However, oxygen-poor (blue)
blood returning to the heart from the lower
body through the inferior vena cava will still
mix with oxygen-rich (red) blood in the left
heart and travel to the body, so the child will
remain mildly cyanotic. This operation helps
create some of the connections necessary for
the final operation, the Fontan procedure.
- Fontan procedure
This operation is often performed at about 18
to 36 months of age, and allows all the oxygen-poor
(blue) blood returning to the heart to flow
into the pulmonary artery, greatly improving
the oxygenation of the blood. The Glenn shunt,
connecting the superior vena cava to the right
atrium, is left in place. A second connection
is made directing blood from the inferior vena
cava to the right pulmonary artery. This connection
can be created in slightly different variations,
depending on the method your child's surgeon
prefers, and what is best for your child.
After
surgery, infants will return to the intensive
care unit (ICU) to be closely monitored during
recovery period.
While
your child is in the ICU, special equipment will
be used to help him/her recover, and may include
the following:
- ventilator -
a machine that helps your child breathe while
he/she is under anesthesia during the operation.
A small, plastic tube is guided into the windpipe
and attached to the ventilator, which breathes
for your child while he/she is too sleepy to
breathe effectively on his/her own. After a
tricuspid atresia, children will benefit from
remaining on the ventilator overnight or even
longer so they can rest.
- intravenous (IV) catheters
- small, plastic tubes inserted
through the skin into blood vessels to provide
IV fluids and important medicines that help
your child recover from the operation.
- arterial line -
a specialized IV placed in the wrist or other
area of the body where a pulse can be felt,
that measures blood pressure continuously during
surgery and while your child is in the ICU.
- nasogastric (NG) tube
- a small, flexible tube that keeps
the stomach drained of acid and gas bubbles
that may build up during surgery.
- urinary catheter -
a small, flexible tube that allows urine to
drain out of the bladder and accurately measures
how much urine the body makes, which helps determine
how well the heart is functioning. After surgery,
the heart will be a little weaker than it was
before, and, therefore, the body may start to
hold onto fluid, causing swelling and puffiness.
Diuretics may be given to help the kidneys to
remove excess fluid from the body.
- chest tube -
a drainage tube may be inserted to keep the
chest free of blood that would otherwise accumulate
after the incision is closed. Bleeding may occur
for several hours, or even a few days after
surgery.
- heart monitor -
a machine that constantly displays a picture
of your child's heart rhythm, and monitors heart
rate, arterial blood pressure, and other values.
Your
child may need other equipment not mentioned here
to provide support while in the ICU, or afterwards.
The hospital staff will explain all of the necessary
equipment to you.
Your
child will be kept as comfortable as possible
with several different medications; some which
relieve pain, and some which relieve anxiety.
The staff will also be asking for your input as
to how best to soothe and comfort your child.
After
discharged from the ICU, your child will recuperate
on another hospital unit for several days before
going home. You will learn how to care for your
child at home before your child is discharged.
Your child may need to take medications for a
while, and these will be explained to you. The
staff will give you written instructions regarding
medications, activity limitations, and follow-up
appointments before your child is discharged.
Infants
who spent a lot of time on a ventilator, or who
were fairly ill while in the ICU, may have trouble
feeding initially. These babies may have an oral
aversion; they might equate something placed in
the mouth, such as a pacifier or bottle, with
a less pleasant sensation such as being on the
ventilator. Some infants are just tired, and need
to build their strength up before they will be
able to learn to bottle-feed. Strategies used
to help infants with nutrition include the following:
- high-calorie formula
or breast milk
Special nutritional supplements may be added
to formula or pumped breast milk that increase
the number of calories in each ounce, thereby
allowing your baby to drink less and still consume
enough calories to grow.
- supplemental tube
feedings
Feedings given through a small, flexible tube
that passes through the nose, down the esophagus,
and into the stomach, that can either supplement
or take the place of bottle feedings. Infants
who can drink part of their bottle, but not
all, may be fed the remainder through the feeding
tube. Infants who are too tired to bottle feed
at all may receive their formula or breast milk
through the feeding tube alone.
Pain
medications, such as acetaminophen or ibuprofen,
may be recommended to keep your child comfortable.
Your child's physician will discuss pain control
before your child is discharged from the hospital.
If any
special treatments are to be given at home, the
nursing staff will ensure that you are able to
provide them, or a home health agency may assist
you.
You
may receive additional instructions from your
child's physicians and the hospital staff.
Infants
will remain cyanotic after the first two operations
until the final operation (Fontan procedure) is
performed. Your child will likely grow and develop
more slowly than the average baby because of the
lower amounts of oxygen available for the body's
needs. Following the Fontan procedure, when oxygen
levels improve, many children will see major improvements
in growth and development, and can eventually
catch up to normal children.
After
each operation, your infant will need to be followed
by a pediatric cardiologist who will make adjustments
to medications, assist you with feeding problems,
measure oxygen levels, and determine when it is
time for the next operation.
There
is significant risk for progressive development
of complications such as heart failure, dysrhythmias,
and protein-losing enteropathy (liver congestion).
Pregnancy
and other non-cardiac surgeries pose major risks
and require careful evaluation and discussion
with a congenital cardiologist.
Regular
follow-up care at a center offering pediatric
or adult congenital cardiac care should continue
throughout the individual’s lifespan.
Consult
with your child's physician regarding the specific
outlook for your child.
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