What Is Tetralogy of Fallot?
Tetralogy (teh-TRAL-o-je) of Fallot (fah-LO) is a
congenital
heart defect. A congenital heart defect is a problem with the heart's
structure that’s present at birth. This type of heart defect changes the
normal flow of blood through the heart.
Tetralogy of Fallot is a rare, complex heart defect
that occurs in about 5 out of every 10,000 babies. It affects boys and
girls equally.
To understand this defect, it's helpful to know how
a healthy heart works. The Diseases and Conditions Index
How
the Heart Works article describes the structure and function of a healthy
heart. The article also has animations that show how your heart pumps blood and
how your heart's electrical system works.
Overview
Tetralogy of Fallot involves four heart defects:
- A large
ventricular
septal defect (VSD)
- Pulmonary (PULL-mon-ary) stenosis
- Right ventricular hypertrophy (hi-PER-tro-fe)
- An overriding aorta
Ventricular Septal Defect
The heart has a wall that separates the two chambers
on its left side from the two chambers on its right side. This wall is called a
septum. The septum prevents blood from mixing between the two sides of the
heart.
A VSD is a hole in the part of the septum that
separates the ventricles, the lower chambers of the heart. The hole allows
oxygen-rich blood from the left ventricle to mix with oxygen-poor blood from
the right ventricle.
Pulmonary Stenosis
This defect is a narrowing of the pulmonary valve
and the passage through which blood flows from the right ventricle to the
pulmonary artery.
Normally, oxygen-poor blood from the right ventricle
flows through the pulmonary valve, into the pulmonary artery, and out to the
lungs to pick up oxygen. In pulmonary stenosis, the heart has to work harder
than normal to pump blood, and not enough blood reaches the lungs.
Right Ventricular Hypertrophy
This defect occurs if the right ventricle thickens
because the heart has to pump harder than it should to move blood through the
narrowed pulmonary valve.
Overriding Aorta
This is a defect in the aorta, the main artery that
carries oxygen-rich blood to the body. In a healthy heart, the aorta is
attached to the left ventricle. This allows only oxygen-rich blood to flow to
the body.
In tetralogy of Fallot, the aorta is between the
left and right ventricles, directly over the VSD. As a result, oxygen-poor
blood from the right ventricle flows directly into the aorta instead of into
the pulmonary artery to the lungs.
Outlook
Together, these four defects mean that not enough
blood is able to reach the lungs to get oxygen, and oxygen-poor blood flows out
to the body.
Normal Heart and Heart With
Tetralogy of Fallot
Figure A shows the structure and
blood flow in the interior of a normal heart. Figure B shows a heart with the
four defects of tetralogy of Fallot.
Babies and children who have tetralogy of Fallot
have episodes of cyanosis (si-a-NO-sis). This is a bluish tint to the skin,
lips, and fingernails. Cyanosis occurs because the oxygen level in the blood is
below normal.
Tetralogy of Fallot must be repaired with open-heart
surgery, either soon after birth or later in infancy. The timing of the surgery
depends on how severely the pulmonary valve is narrowed.
Over the past few decades, the diagnosis and
treatment of tetralogy of Fallot have greatly improved. As a result, most
children who have this heart defect survive to adulthood. However, they’ll
need lifelong medical care from specialists to help them stay as healthy as
possible.
Other Names for Tetralogy of Fallot
What Causes Tetralogy of Fallot?
Doctors don't know what causes most cases of
tetralogy of Fallot and other
congenital
heart defects.
Certain conditions or factors that occur during
pregnancy may raise your risk for having a child with tetralogy of Fallot.
These conditions and factors include:
- German measles (rubella) and some other viral
illnesses
- Poor nutrition
- Overuse of alcohol
- Age (being older than 40)
- Diabetes
Heredity may play a role in causing tetralogy of
Fallot. An adult who has tetralogy of Fallot may have an increased chance of
having a baby with the condition.
Children who have certain genetic disorders, such as
Down syndrome and
DiGeorge syndrome, often have congenital heart defects,
including tetralogy of Fallot.
Scientists continue to search for the causes of
tetralogy of Fallot and other congenital heart defects.
What Are the Signs and Symptoms of Tetralogy of
Fallot?
An important sign of tetralogy of Fallot is
cyanosis. Cyanosis is a bluish tint to the skin, lips, and fingernails. Low
levels of oxygen in the blood cause cyanosis.
Babies who have unrepaired tetralogy of Fallot
sometimes have “tet spells" in response to an activity like crying or
having a bowel movement. A tet spell occurs when the oxygen level in the blood
suddenly drops. This causes the baby to become very blue. The baby also may:
- Have a hard time breathing
- Become very tired and limp
- Not respond to a parent's voice or touch
- Become very fussy
- Lose consciousness
In years past, when tetralogy of Fallot wasn't
treated in infancy, children would get very tired during exercise and could
faint. This heart defect is now repaired in infancy to prevent symptoms like
this.
Another common sign of tetralogy of Fallot is a
heart
murmur. A heart murmur is an extra or unusual sound that doctors may hear
while listening to the heart.
The sound occurs because the heart defect causes
abnormal blood flow through the heart. However, not all heart murmurs are signs
of congenital
heart defects. Many healthy children have heart murmurs.
Normal growth and development depend on a normal
workload for the heart and normal flow of oxygen-rich blood to all parts of the
body. Babies who have tetralogy of Fallot may not gain weight or grow as
quickly as children who have healthy hearts because they tire easily while
feeding.
Children who have tetralogy of Fallot also may have
clubbing. Clubbing is the widening or rounding of the skin or bone around the
tips of the fingers.
How Is Tetralogy of Fallot Diagnosed?
Doctors diagnose tetralogy of Fallot based on a
baby’s signs and symptoms, a physical exam, and the results from tests and
procedures.
Signs and symptoms of the heart defect usually occur
during the first weeks of life. Your infant's doctor may notice signs or
symptoms during a routine checkup. Some parents also notice cyanosis (a bluish
tint to the skin, lips, and fingernails) or poor feeding and bring the baby to
the doctor.
Specialists Involved
If your child has tetralogy of Fallot, a pediatric
cardiologist and cardiac surgeon may be involved in his or her care.
A pediatric cardiologist is a doctor who specializes
in diagnosing and treating heart problems in children. Cardiac surgeons repair
heart defects using surgery.
Physical Exam
During a physical exam, the doctor may:
- Listen to your baby's heart and lungs with a
stethoscope.
- Look for signs and symptoms, such as a bluish
tint to the skin, lips, or fingernails and rapid breathing.
- Look at your baby’s general appearance.
Some children who have tetralogy of Fallot have characteristic facial traits
because they have
DiGeorge syndrome.
Diagnostic Tests and Procedures
Your child’s doctor may recommend several tests
to diagnose tetralogy of Fallot. These tests can provide information about the
four heart defects that occur in tetralogy of Fallot and how serious they are.
Echocardiography
Echocardiography
(echo) is a painless test that uses sound waves to create a moving picture of
the heart. During the test, the sound waves (called ultrasound) bounce off the
structures of the heart. A computer converts the sound waves into pictures on a
screen.
Echo allows the doctor to clearly see any problem
with the way the heart is formed or the way it's working.
Echo is an important test for diagnosing tetralogy
of Fallot because it shows the four heart defects and how the heart is
responding to them. This test helps the cardiologist decide when to repair
these defects and what type of surgery is needed.
Echo also is used to check a child's condition over
time, after the defects have been repaired.
EKG (Electrocardiogram)
An
EKG
is a simple, painless test that records the heart’s electrical activity.
The test shows how fast the heart is beating and its rhythm (steady or
irregular). It also records the strength and timing of electrical signals as
they pass through each part of the heart.
An EKG also can help the doctor determine whether
the right ventricle is enlarged (ventricular hypertrophy).
Chest X Ray
A
chest
x ray is a painless test that creates pictures of the structures in the
chest, such as the heart and lungs. This test can show whether the heart is
enlarged or whether the lungs have extra blood flow or extra fluid, a sign of
heart
failure.
Pulse Oximetry
For this test, a small sensor is attached to a
finger or toe (like an adhesive bandage). The sensor gives an estimate of how
much oxygen is in the blood.
Cardiac Catheterization
During
cardiac
catheterization (KATH-e-ter-i-ZA-shun), a thin, flexible tube called a
catheter is put into a vein in the arm, groin (upper thigh), or neck and
threaded to the heart.
Special dye is injected through the catheter into a
blood vessel or a chamber of the heart. The dye allows the doctor to see the
flow of blood through the heart and blood vessels on an x-ray image.
The doctor also can use cardiac catheterization to
measure the pressure and oxygen level inside the heart chambers and blood
vessels. This can help the doctor determine whether blood is mixing between the
two sides of the heart.
How Is Tetralogy of Fallot Treated?
Tetralogy of Fallot must be repaired with open-heart
surgery, either soon after birth or later in infancy. The goal of surgery is to
repair the four defects of tetralogy of Fallot so the heart can work as
normally as possible. Repairing the defects can greatly improve a child's
health and quality of life.
The pediatric cardiologist and cardiac surgeon will
decide the best time to do the surgery. Their decision will be based on your
baby's health and weight, how severe the defects are, and how severe your
baby's symptoms are.
Sometimes, teenagers or adults who had tetralogy of
Fallot repaired in childhood need additional surgery to correct heart problems
that develop over time. See
“Living
With Tetralogy of Fallot” for more information.
Types of Surgery
Complete Intracardiac Repair
Surgery to repair tetralogy of Fallot is done to
improve blood flow to the lungs and to make sure that oxygen-rich and
oxygen-poor blood flows to the right places. The surgeon will:
- Widen the narrowed pulmonary blood vessels. The
pulmonary valve is widened or replaced, and the passage from the right
ventricle to the pulmonary artery is enlarged. These procedures improve blood
flow to the lungs. This allows the blood to get enough oxygen to meet the
body's needs.
- Close the
ventricular
septal defect (VSD). A patch is used to cover the hole in the septum. This
patch stops oxygen-rich and oxygen-poor blood from mixing between the
ventricles.
Fixing these two defects resolves problems caused by
the other two defects. When the right ventricle no longer has to work so hard
to pump blood to the lungs, it will return to a normal thickness. Fixing the
VSD means that only oxygen-rich blood will flow out of the left ventricle into
the aorta.
The incision (cut) that the surgeon makes to reach
the heart usually heals in about 6 weeks. The surgeon or a
hospital staff member will explain when it's okay to give your baby a bath,
pick him or her up under the arms, and take your baby for his or her regular
shots (immunizations).
Temporary or Palliative Surgery
It was common in the past to do temporary surgery
during infancy in babies who had tetralogy of Fallot. This surgery improved
blood flow to the lungs. A complete repair of the four defects was done later
in childhood.
Now, most babies who have tetralogy of Fallot have
their defects fully repaired in infancy. However, some babies are too weak or
too small to have the full repair. They must have temporary surgery first. This
surgery improves oxygen levels in the blood. It also gives the baby time to
grow and get strong enough for the full repair.
In the temporary surgery, the surgeon places a tube
called a shunt between a large artery branching off the aorta and the pulmonary
artery. One end of the shunt is sewn to the artery branching off the aorta. The
other end is sewn to the pulmonary artery.
The shunt creates an additional pathway for blood to
travel to the lungs to get oxygen. The shunt is removed when the baby's heart
defects are fixed during the full repair.
After temporary surgery, your baby may need
medicines to keep the shunt open while waiting for the full repair. These
medicines are stopped after the shunt is removed.
Living With Tetralogy of Fallot
The outlook for a child born with tetralogy of
Fallot is much better today than in the past. Advances in testing and treatment
mean that most children who have this
congenital
heart defect survive to adulthood. However, they need long-term care from
specialists to stay as healthy as possible.
Caring for Your Child at Home
Feeding and Nutrition
Babies who have tetralogy of Fallot can tire while
nursing or feeding. Small, frequent meals may be easier for your baby to
handle.
Your child also may need extra nutrition. A
supplement or an extra feeding can give the baby more calories, vitamins, or
iron. Your child's doctors will work with you to determine what extra nutrition
your baby needs.
Tet Spells
“Tet spells” can occur in babies whose
tetralogy of Fallot hasn’t yet been repaired. Lowering your baby's anxiety
or stress can help prevent tet spells and save the baby's energy. For example,
slowly picking up your baby and speaking in a soothing voice can avoid
startling him or her, which may prevent or reduce crying.
Talk to your doctor about how you can manage your
child’s tet spells. Your doctor may suggest that you:
- Bring the child's knees up tight against his or
her chest (this is called the knee–chest position) or have your child
squat down. This will increase blood flow to the lungs.
- Try to calm your child.
- Call 9–1–1 if the symptoms don't
improve right away.
Activity Restrictions
Some children who have tetralogy of Fallot may need
to limit certain types of physical activity. The limits vary with each child.
Talk to your child’s doctor about whether:
- Your child needs to restrict activity or
exercise
- Your child can play in organized sports,
especially contact sports
- You need a note for your child’s school or
coaches about limiting your child's exercise
Ongoing Medical Care
Children who have tetralogy of Fallot should have
ongoing medical care. This includes:
- Seeing a pediatric cardiologist for heart
checkups as directed
- Seeing a pediatrician or family health care
provider for routine exams
- Making sure your child takes medicines as
prescribed
Children who have severe heart defects, like
tetralogy of Fallot, may be at slightly increased risk for
infective
endocarditis (IE). IE is a serious infection of the inner lining of your
heart chambers and valves.
In a few situations, your child's doctor or dentist
may give your child antibiotics before medical or dental procedures (such as
surgery or dental cleanings) that could allow bacteria into the bloodstream.
Your child’s doctor will tell you whether your child needs to take
antibiotics before such procedures.
To reduce the risk of IE, gently brush your young
child’s teeth every day as soon as they begin to come in. As your child
gets older, make sure he or she brushes every day and sees a dentist regularly.
Talk with your child’s doctor and dentist about how to keep your
child’s mouth and teeth healthy.
Consider having your child wear a medical alert
bracelet or necklace. This alerts anyone caring for your child that the child
has tetralogy of Fallot.
You may want to work with your health care providers
to put together a packet of medical records and information that covers all
aspects of your child's heart defect, including:
- Diagnosis
- Procedures or surgeries
- Prescribed medicines
- Recommendations about medical followup and how
to prevent complications
- Health insurance
Keeping your health insurance current is important.
For example, if you plan to change jobs, find out whether your new health
insurance will cover care for your child's congenital heart defect.
Some health insurance plans may not cover medical
conditions that were covered under a previous plan.
Special Needs for Teenagers and Adults
As children who have tetralogy of Fallot grow up and
become teens, it's important that they understand the condition, how it was
treated, and what kind of care may still be needed.
This understanding will help them take
responsibility for their health. It also will help ensure a smooth transition
when they start getting care from a cardiologist instead of a pediatric
cardiologist. A cardiologist treats adults who have heart problems.
It's also very important for teens to have health
insurance as adulthood approaches. Review your current health insurance plan.
Find out whether you can extend coverage to your child beyond the age of 18.
Some policies may allow you to keep your child on your plan if he or she
remains in school or is disabled.
Some teenagers or young adults need additional
surgery. For example, the pulmonary valve can narrow again over time, reducing
blood flow. The valve may need to be widened or replaced. The cardiologist will
discuss with you and your teenager the need for any additional heart surgeries.
Over time, people who have had surgery to repair
tetralogy of Fallot also may face a number of other heart problems.
Leaking Heart Valves
The heart has four valves that open and close with
each heartbeat. These valves ensure that blood flows in only one direction.
If a valve doesn't seal tightly, blood can leak back
into the chamber it came from. This is called backflow or regurgitation
(re-GUR-ji-TA-shun), and it can lead to symptoms and complications.
The most frequent problem that occurs after
tetralogy of Fallot repair is pulmonary backflow, or leaking from the pulmonary
valve. Backflow from the tricuspid valve and aortic valve also can occur.
Surgery is needed to repair or replace the leaking valve.
Arrhythmias
Arrhythmias
(ah-RITH-me-ahs) are another complication that may develop. Arrhythmias are
problems with the rate or rhythm of the heartbeat.
Arrhythmias linked to tetralogy of Fallot include
ventricular tachycardia,
atrial
fibrillation, and atrial flutter. For more information, see
“Types
of Arrhythmia.”
Medicines are used to control these arrhythmias.
Medical procedures or surgery also may be needed to treat arrhythmias.
Pulmonary Artery Branch Stenoses
Over time, the pulmonary valve can narrow again.
This will reduce blood flow to the lungs, making the heart work harder than it
should. Several surgical techniques can be used to fix this problem.
Right Ventricular Aneurysms
The patch used to fix the
ventricular
septal defect (VSD) can cause areas of the ventricle to weaken. The areas,
called aneurysms (AN-u-risms), can bulge or “balloon” out.
Aneurysms
make it hard for the heart to function as well as it should. This problem must
be repaired with surgery.
Residual Ventricular Septal Defects
Sometimes, VSDs still leak even after they’ve
been repaired. VSDs are repaired again if they’re large or are causing
problems with the function of the right ventricle.
Coronary Heart Disease
As people who have repaired tetralogy of Fallot
approach middle age, they can develop
coronary
heart disease (CHD), just as adults who don’t have heart defects can.
CHD, also called coronary artery disease, is a
condition in which a fatty substance called plaque (plak) builds up in the
coronary (heart) arteries. CHD can lead to chest pain, shortness of breath, and
heart
attack.
Preventing CHD is especially important because the
procedures done to relieve CHD, like
coronary
artery bypass grafting, can cause complications in people who have repaired
tetralogy of Fallot.
Other Considerations
Many women with repaired tetralogy of Fallot who
become pregnant are able to have successful, full-term pregnancies. Others may
have difficult pregnancies.
Women with tetralogy of Fallot who want to become
pregnant (or who are pregnant) should talk to their doctors about:
- Health risks during pregnancy
- Medicines they can take during pregnancy
- Any new or worsening symptoms
These women also should consult specialists who take
care of pregnant women who have heart conditions, such as congenital heart
defects.
Adults who were born with tetralogy of Fallot should
consider job changes carefully, because health benefits may change. Some health
plans have waiting periods or clauses to exclude some types of coverage. Before
making any job changes, find out whether the change will affect your health
insurance.
Several laws protect the employment rights of people
who have health conditions, such as congenital heart defects. The Americans
with Disabilities Act and the Work Incentives Improvement Act try to ensure
fairness in hiring for all people, including those who have health conditions.
Key Points
- Tetralogy of Fallot is a rare, complex
congenital
heart defect. A congenital heart defect is a problem with the heart's
structure that's present at birth.
- Tetralogy of Fallot involves four heart defects:
- Together, these four defects mean that not
enough blood is able to reach the lungs to get oxygen, and oxygen-poor blood
flows out to the body.
- Doctors don't know what causes most cases of
tetralogy of Fallot. Certain conditions or factors that occur during pregnancy
may raise your risk for having a child with tetralogy of Fallot. Heredity and
some genetic disorders also may play a role in causing this condition.
- An important sign of tetralogy of Fallot is
cyanosis. Cyanosis is a bluish tint to the skin, lips, and fingernails. Other
signs and symptoms include a
heart
murmur, delayed growth and development, and clubbing. Clubbing is the
widening or rounding of the skin or bone around the tips of the fingers.
- Babies who have unrepaired tetralogy of Fallot
sometimes have “tet spells.” A tet spell occurs when the oxygen level
in the blood suddenly drops. This causes the baby to become very blue. He or
she also may have trouble breathing, become very tired and limp, not respond to
a parent’s voice or touch, become very fussy, or lose consciousness.
- Doctors diagnose tetralogy of Fallot based on a
baby’s signs and symptoms, a physical exam, and the results from tests and
procedures. Signs and symptoms of the heart defect usually occur during the
first weeks of life.
- Tetralogy of Fallot must be repaired with
open-heart surgery, either soon after birth or later in infancy. The goal of
surgery is to repair the four defects of tetralogy of Fallot so the heart can
work as normally as possible.
- Surgery involves widening or replacing the
pulmonary valve and enlarging the passage from the right ventricle to the
pulmonary artery. This improves blood flow to the lungs. Surgeons also close
the VSD with a patch. The patch stops oxygen-rich and oxygen-poor blood from
mixing between the ventricles. Fixing these two defects resolves problems
caused by the other two defects.
- Some babies who are very small or weak have a
temporary procedure that improves blood flow to the lungs and gives the baby
time to grow and get strong enough for the full repair.
- Advances in treatment mean that most children
who are born with tetralogy of Fallot survive to adulthood. However, these
children need lifelong care from specialists to stay as healthy as possible.
- Teenagers and adults who had surgery to repair
tetralogy of Fallot may have long-term heart problems, such as heart function
problems,
arrhythmias
(irregular heartbeats), or problems resulting from the original repair. These
problems are treated with medicines, procedures, and surgery.
Links to Other Information About Tetralogy of
Fallot
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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