What Is Tetralogy of Fallot?
Tetralogy of Fallot is a
congenital
(kon-JEN-i-tal) heart defect (a problem with the heart's structure that's
present at birth). Congenital heart defects change the normal flow of blood
through the heart. This rare and complex heart defect occurs in about
5 out every 10,000 babies. It affects boys and girls equally.
Tetralogy of Fallot involves four defects:
Ventricular Septal Defect
The heart has a wall that separates the chambers on
its left side from those 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 to flow from the left ventricle into the right
ventricle instead of flowing into the aorta, the main artery leading out to the
body.
Pulmonary Stenosis
This is a narrowing of the pulmonary valve and the
passageway through which blood flows from the right ventricle to the pulmonary
arteries. Normally, oxygen-poor blood from the right ventricle flows through
the pulmonary valve into the pulmonary arteries 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 can get to the lungs.
Right Ventricular Hypertrophy
This is when 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 location of the aorta. In a
healthy heart, the aorta is attached to the left ventricle, allowing only
oxygen-rich blood to go 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 can flow directly into the
aorta instead of into the pulmonary artery to the lungs.
Overview
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
normal structure and blood flow in the interior of the heart. Figure B shows a
heart with the four defects of tetralogy of Fallot.
Babies and children with tetralogy of Fallot have
episodes of cyanosis (si-a-NO-sis), which 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.
Outlook
Over the past few decades, the diagnosis and
treatment of tetralogy of Fallot has greatly improved. As a result, the
majority of children with this heart defect grow to adulthood. However, they
need lifelong medical care from a specialist to make sure they stay as healthy
as possible.
How the Heart Works
To understand tetralogy of Fallot, it's helpful to
know how a healthy heart works.
Your child's heart is a muscle about the size of his
or her fist. The heart works like a pump and beats 100,000 times a day.
The heart has two sides, separated by an inner wall
called the septum. The right side of the heart pumps blood to the lungs to pick
up oxygen. Then, oxygen-rich blood returns from the lungs to the left side of
the heart, and the left side pumps it to the body.
The heart has four chambers and four valves and is
connected to various blood vessels. Veins are the blood vessels that carry
blood from the body to the heart. Arteries are the blood vessels that carry
blood away from the heart to the body.
A Healthy Heart Cross-Section
The illustration shows a
cross-section of a healthy heart and its inside structures. The blue arrow
shows the direction in which oxygen-poor blood flows from the body to the
lungs. The red arrow shows the direction in which oxygen-rich blood flows from
the lungs to the rest of the body.
Heart Chambers
The heart has four chambers or "rooms."
- The atria (AY-tree-uh) are the two upper chambers
that collect blood as it comes into the heart.
- The ventricles are the two lower chambers that
pump blood out of the heart to the lungs or other parts of the body.
Heart Valves
Four valves control the flow of blood from the atria
to the ventricles and from the ventricles into the two large arteries connected
to the heart.
- The tricuspid (tri-CUSS-pid) valve is in the
right side of the heart, between the right atrium and the right ventricle.
- The pulmonary valve is in the right side of the
heart, between the right ventricle and the entrance to the pulmonary artery,
which carries blood to the lungs.
- The mitral (MI-trul) valve is in the left side of
the heart, between the left atrium and the left ventricle.
- The aortic (ay-OR-tik) valve is in the left side
of the heart, between the left ventricle and the entrance to the aorta, the
artery that carries blood to the body.
Valves are like doors that open and close. They open
to allow blood to flow through to the next chamber or to one of the arteries,
and then they shut to keep blood from flowing backward.
When the heart's valves open and close, they make a
"lub-DUB" sound that a doctor can hear using a stethoscope.
- The first sound—the
“lub”—is made by the mitral and tricuspid valves closing at
the beginning of systole (SIS-toe-lee). Systole is when the ventricles
contract, or squeeze, and pump blood out of the heart.
- The second sound—the
“DUB”—is made by the aortic and pulmonary valves closing at
beginning of diastole (di-AS-toe-lee). Diastole is when the ventricles relax
and fill with blood pumped into them by the atria.
Arteries
The arteries are major blood vessels connected to
your heart.
- The pulmonary artery carries blood pumped from
the right side of the heart to the lungs to pick up a fresh supply of oxygen.
- The aorta is the main artery that carries
oxygen-rich blood pumped from the left side of the heart out to the body.
The coronary arteries are the other important
arteries attached to the heart. They carry oxygen-rich blood from the aorta to
the heart muscle, which must have its own blood supply to function.
Veins
The veins are also major blood vessels connected to
your heart.
- The pulmonary veins carry oxygen-rich blood from
the lungs to the left side of the heart so it can be pumped out to the body.
- The vena cava is a large vein that carries
oxygen-poor blood from the body back to the heart.
For more information on how a healthy heart works,
see the Diseases and Conditions Index article on
How
the Heart Works. This article contains animations that show how your heart
pumps blood and how your heart's electrical system works.
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.
Having some conditions or factors 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 this heart defect. An
adult with tetralogy of Fallot may have an increased chance of having a baby
with this defect.
Children with 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 symptom of tetralogy of Fallot is
cyanosis, or a bluish tint to the skin, lips, and fingernails. Low levels of
blood in the oxygen cause this symptom.
Babies with 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 may also:
- 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
have fainting spells. This heart defect is now repaired in infancy to prevent
symptoms like this.
Another common symptom of tetralogy of Fallot is a
heart
murmur. A heart murmur is an extra or unusual sound that a doctor can hear
while listening to the heart during a physical exam. When a heart defect causes
an abnormal flow of blood through the heart, it will make a certain sound.
However, not all 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 with healthy hearts because they tire easily while feeding.
Children with this heart defect also may have
“clubbing,” an abnormal, rounded shape to the skin or bone around
the fingernails.
How Is Tetralogy of Fallot Diagnosed?
Doctors perform a physical exam on the baby and
order medical tests to diagnose tetralogy of Fallot. The signs and symptoms
usually appear during the first weeks of life. Your infant's doctor may see the
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
Doctors who specialize in heart problems are called
cardiologists. Pediatric cardiologists take care of babies and children who
have heart problems. Other specialists who treat heart defects include cardiac
surgeons (doctors who repair heart defects using surgery).
Physical Exam
During the physical exam, the doctor:
- Listens to your baby's heart and lungs with a
stethoscope.
- Looks for signs and symptoms, such as bluish
color of skin and lips and rapid breathing.
- Looks at general appearance. Some children with
tetralogy of Fallot have a characteristic facial appearance because they have
DiGeorge syndrome.
Diagnostic Tests and Procedures
The doctor will order several tests to diagnose
tetralogy of Fallot. These tests will help the doctor determine the exact
nature of the defects and how serious they are.
Echocardiogram
This test, which is harmless and painless, uses
sound waves to create a moving picture of the heart. During an
echocardiogram,
ultrasound waves bounce off the structures of the heart. A computer converts
the sound waves into pictures on a video screen. 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 an important test for
diagnosing tetralogy of Fallot because it shows the four problems with the
heart's structure and how the heart is reacting to these problems. This test
helps the cardiologist decide the best time to repair these defects and what
type of surgery is needed. Echocardiograms also are used to check a child's
condition over time, after the defect has been repaired.
EKG (Electrocardiogram)
An
EKG
detects and records the electrical activity of the heart. This simple and
painless test is used to assess the heart rhythm. An EKG shows how fast the
heart is beating and whether the heart's rhythm is steady or irregular. This
test also can help determine whether the right ventricle is enlarged
(ventricular hypertrophy).
Chest X Ray
A chest x ray takes a picture of the heart and
lungs. It can show whether the heart is enlarged or whether the lungs have
extra blood flow or extra fluid, which can be a sign of
heart
failure.
Pulse Oximetry
Pulse oximetry shows how much oxygen is in the
blood. A sensor is placed on the fingertip or toe (like an adhesive bandage).
The sensor is attached to a small computer unit that displays a number that
tells 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. A dye that can be seen on an x ray is injected through
the catheter into a blood vessel or a chamber of the heart. This allows the
doctor to see the flow of blood through the heart and blood vessels on the
x-ray image.
Cardiac catheterization also can be used to measure
the pressure inside the heart chambers and blood vessels. It can 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 defects so the heart can work as normally as
possible. Achieving this goal can greatly improve a child's health and quality
of life.
Your baby's heart doctor and heart surgeon will
determine when to do the surgery. Their decision will be based on the baby's
health and weight, how severe the defects are, and how severe the baby's
symptoms are.
Sometimes, teenagers or adults who had the tetralogy
of Fallot defects 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 passageway from the right
ventricle to the pulmonary arteries is enlarged. These procedures improve blood
flow to the lungs, allowing 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. 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 the lungs, it can 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 from the surgery usually heals in about
6 weeks. The surgeon or another member of the hospital staff will explain when
it's okay to give the baby a bath, pick up the baby under the arms, and take
the baby for his or her regular shots (immunizations).
Temporary or Palliative Surgery
It was common in the past to do a temporary surgery
during infancy to improve blood flow to the lungs, and then do a complete
repair later in childhood. Now, most babies with 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 and gives the baby time to grow and get
strong enough for the full repair.
In the temporary procedure, 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, and 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 complete 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 the majority of children with this
congenital
heart defect survive to adulthood. However, they do need long-term care by
specialists to stay as healthy as possible.
Babies and Children With Tetralogy of Fallot
Caring for Your Child at Home
Babies with tetralogy of Fallot can tire while
nursing or feeding. Small, frequent meals may be easier for your baby to
handle. He or she 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 decide what extra nutrition your baby may need.
Lowering your baby's anxiety or stress can help
prevent "tet spells" and save the baby's energy. For example, picking up your
baby slowly and speaking in a soothing voice can avoid startling him or her,
which may prevent or lessen crying.
Tet Spells
Talk to your doctor about how you can manage your
baby's or child's tet spells. Your doctor may suggest that you:
- Bring the baby's or 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 with tetralogy of Fallot may need to
limit certain types of exercise. The limits vary with each child. Talk to your
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 the school or coaches about
limiting your child's exercise
Routine Medical Care
Regular medical care for your child is important.
This includes:
- Seeing a pediatric cardiologist for heart
checkups as directed
- Seeing your child's pediatrician or family health
care provider for routine exams
- Making sure your child takes medicines as
prescribed
Children with severe heart defects, like tetralogy
of Fallot, are at increased risk for
bacterial endocarditis. This is a serious infection of the
heart valves or lining of the heart. These children may need to take
antibiotics before medical and dental procedures (such as surgery or dental
cleanings) that could allow bacteria to enter the bloodstream. Talk to your
child's doctor about whether your child needs to take antibiotics before such
procedures.
Consider having your child wear a medical alert
bracelet or necklace. This tells anyone caring for your child that the child
has a congenital heart defect.
You may want to work with your health care providers
to put together a packet with 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 you or your family member
had before joining the new plan.
Special Needs for Teenagers and Adults
As children with tetralogy of Fallot grow up and
become teens, it's important that they understand their heart defect, how it
was treated, and what kind of care may still be needed. This understanding will
help the teen take responsibility for his or her health. It also will help
ensure a smooth transition from care by a pediatric cardiologist to care by a
specialist in adult congenital heart disease.
It's also very important for teens to have health
insurance as adulthood approaches. Review your current health insurance plan.
Find out how coverage can be extended 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 over time, reducing blood
flow. The valve may need to be widened or replaced. Your 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, such as:
Leaking Heart Valves
Heart valves make sure that blood flows only in one
direction. If the valve doesn't seal tightly, blood can leak back into the
chamber it came from. This backward flow of blood is called 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 regurgitation, or leaking from the
pulmonary valve. Regurgitation of the tricuspid valve and aortic valve also can
occur. Surgery is necessary to repair or replace the leaking valve.
Arrhythmias
Arrhythmias—problems with the speed or rhythm
of the heartbeat—also can occur. Arrhythmias linked to tetralogy of
Fallot include ventricular tachycardia,
atrial
fibrillation, and atrial flutter. Ventricular tachycardia is when the
ventricles (lower chambers of the heart) beat too fast. Atrial fibrillation is
a fast and irregular contraction of the atria (the upper chambers of the
heart). Atrial flutter is a fast but regular contraction of the atria.
Medicines are used to control these arrhythmias. In
rare cases, a person may need a procedure or surgery to fix the problem.
Pulmonary Artery Branch Stenoses
Over time, the pulmonary blood vessels that were
enlarged to repair the tetralogy of Fallot defect 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 patches used when repairing tetralogy of Fallot
can create weakened areas in the ventricle that can bulge or
“balloon” out. These aneurysms (AN-u-risms) 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, a ventricular septal defect still leaks
even after it has been repaired. It's repaired again if it's large or is
causing problems with the function of the right ventricle.
Coronary Artery Disease
As people with repaired tetralogy of Fallot approach
middle age, they can develop CAD, just as adults without a heart defect can.
CAD occurs when coronary arteries become blocked due to the buildup of a
material called plaque (plak) on the inside of the blood vessels. This can lead
to chest pain, shortness of breath, and sometimes
heart
attack.
Preventing CAD is especially important because any
procedures, like
coronary
artery bypass grafting, that are done to relieve symptoms of CAD can cause
complications in people with 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 doctor about:
- Health risks during pregnancy
- Medicines they can take during pregnancy
- Any new or worsening symptoms
These women also may want to consult specialists who
take care of pregnant women with health conditions.
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 kinds 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 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 with health conditions such as heart defects.
Key Points
- Tetralogy of Fallot is a rare, complex
congenital
heart defect (a problem with the heart's structure that's present at
birth).
- Tetralogy of Fallot involves four defects in the
heart:
- A large ventricular septal defect (VSD)
- Pulmonary stenosis
- Right ventricular hypertrophy
- An overriding aorta
- 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 factors during pregnancy, heredity, and some
genetic disorders may increase the risk of having a baby with tetrology of
Fallot.
- Cyanosis, or a bluish tint to the skin, lips, and
fingernails, is an important symptom of tetralogy of Fallot. Other symptoms
include a
heart
murmur, slower-than-normal growth and development, and clubbing (a rounded
shape to the skin or bone around the fingernails).
- An
echocardiogram
is an important test for diagnosing tetralogy of Fallot and for following the
problem over time. This test helps diagnose problems with how the heart is
formed and how well it's working. Other tests used to diagnose this defect
include
EKG
(electrocardiogram), chest x ray, pulse oximetry, and
cardiac
catheterization.
- Tetralogy of Fallot must be repaired with
open-heart surgery, either soon after birth or later in infancy. 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.
- Treatment involves widening or replacing the
pulmonary valve and enlarging the passageway from the right ventricle to the
pulmonary arteries. These procedures improve the flow of blood to the lungs,
allowing it to pick up enough oxygen for the body's needs. Surgeons also close
the VSD with a patch. The patch stops the mixing of oxygen-poor and oxygen-rich
blood in the ventricles. Fixing these two defects resolves problems caused by
the other two defects.
- Advances in treatment mean that most children
born with tetralogy of Fallot grow to adulthood. They need lifelong care by
trained specialists to stay as healthy as possible.
- Adults who had surgery to repair tetralogy of
Fallot may have long-term heart problems, such as heart function problems,
arrhythmias,
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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