Transposition of the great arteries (TGA) is a heart condition
that is present at birth, and often is called a congenital heart
defect. TGA occurs when the two main arteries going out of the
heart—the pulmonary artery and the aorta—are switched in position,
or “transposed”.
Normally, blood returning to the heart from the body is pumped from
the right side of the heart through the pulmonary artery to the
lungs. There, it receives oxygen and returns to the left side of the
heart. Then, the oxygen-rich blood is pumped from the left side of
the heart through the aorta to the body. In TGA, blood returning
from the body bypasses the lungs and is pumped back out to the body.
This occurs because the main connections are reversed. The pulmonary
artery, which normally carries oxygen-poor blood from the right side
of the heart to the lungs, now arises from the left side and carries
oxygen-rich blood returning from the lungs back to the lungs. The
aorta, which normally carries blood from the left side of the heart
to the body, now arises from the right side and carries oxygen-poor
blood back out to the body. The result of transposition of these two
vessels is that too little oxygen is in the blood that is pumped
from the heart to the rest of the body.
TGA might also be referred to as transposition of the great vessels
(TGV), but TGA is the more common term.
To learn more about transposition of the great arteries click on
one of the following links or scroll down the page.
What We Know About Transposition of the
Great Arteries
- How often does transposition of the great arteries occur?
- What problems do children with transposition of the great
arteries have?
What We Still Do Not Know About
Transposition of the Great Arteries
- What causes transposition of the great arteries?
- Can transposition of the great arteries be prevented?
Resources for Families and Individuals
Affected by Transposition of the Great Arteries
What
We Know About Transposition of the Great Arteries |
How often does transposition of the great arteries occur?
CDC estimates that each year about 1,901babies in the United States
are born with TGA (1). In other words, about 5 out of every 10,000
babies born in the United States each year is born with TGA.
What problems do children with transposition of the great
arteries have?
Because the main arteries are switched, there are two separate blood
circulations instead of a single connected one. Thus, blood with
oxygen from the lungs does not get to the rest of the body. This
means that TGA is a cyanotic (lacking oxygen) heart defect that
leads to a bluish-purple coloring of the skin and shortness of
breath.
Symptoms appear at birth or very soon afterwards. How bad the
symptoms are depends on whether there is a way for the two separate
blood circuits to mix, allowing some oxygen-rich blood to get out to
the body. This mixing can occur through other defects, such as a
hole between the bottom chambers of the heart (a ventricular septal
defect), or through a shunt that normally is present at birth.
Symptoms also can depend on whether other defects are present as
well. Common symptoms of TGA include:
- Blueness of the skin
- Shortness of breath
- Poor feeding
Surgery might be needed shortly after birth. In most hospitals, a
type of surgery called an arterial switch procedure can be used to
permanently correct the problem within the first week of life.
Without corrective surgery, severe cases of TGA can be fatal
during the first 6 months of life. Babies who have surgery to
correct TGA sometimes have the following associated conditions later
in life:
- Leaky heart valves
- Problems with the arteries that supply the heart muscle with
blood (coronary arteries)
- Abnormal heart rhythm (arrhythmias)
- A decline in function of the heart muscle or heart valves
- Heart failure
- Damage to the lungs and difficulty breathing
Babies with TGA will require lifelong follow-up with a
cardiologist. Even so, with proper treatment, most babies with TGA
grow up to lead healthy, productive lives.
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What
We Still Do Not Know About Transposition of the Great
Arteries |
What causes transposition of the great arteries?
The cause of TGA is unknown at this time. Scientific researchers
have found that some diseases and behaviors might be associated with
a higher risk for TGA. These include:
- The mother having a viral illness during pregnancy
- The mother having poor nutrition during pregnancy
- The mother using an excessive amount of alcohol during
pregnancy
- The mother being older than 40 years of age
- The mother having diabetes during pregnancy
- The baby having Down syndrome
CDC works with many researchers to study risk factors that can
increase the chance of having a baby with TGA, as well as outcomes
of babies with the defect. Following are examples of what this
research has found:
- TGA seems to be occur more often among White babies than
non-White babies, although more research is needed (2).
- No strong link exists between caffeine use by a mother
during pregnancy and the risk for TGA (3).
- There are signs that the rate of TGA is decreasing over time
(2).
Can transposition of the great arteries be prevented?
There is no known way to prevent this defect, but some of the
problems experienced later in life by babies born with TGA can be
prevented or lessened if the defect is found early.
Even so, mothers can take steps before and during pregnancy to have
a healthy pregnancy. Steps include taking a daily multivitamin with
folic acid (400 micrograms), not smoking, and not drinking alcohol
during pregnancy.
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Resources for Families and Individuals Affected by
Transposition of the Great Arteries |
American Heart Association
Mayo Clinic
Medline
References
- Canfield MA, Honein MA, Yuskiv N, Xing J, Mai CT, Collins
JS, et al. National Estimates and Race/Ethnic-Specific Variation
of Selected Birth Defects in the United States, 1999-2001. Birth
Defects Res Part A Clin Mol Teratol. 2006;76(11); 747-56.
- Lorenzo DB, Correa A, Erickson JD. Racial and temporal
variations in the prevalence of heart defects. Pediatrics.
2001;107(3): 1-8
- Browne ML, Bell EM, Druschel CM, et al. Maternal caffeine
consumption and risk of cardiovascular malformation. Birth
Defects Res A Clin Mol Teratol. 2007;79: 533-43.
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Date:
March 11, 2009
Content source: National Center on Birth Defects and Developmental
Disabilities