In transposition of the great vessels, the major blood vessels
attached to the heart—the aorta and the pulmonary artery—are reversed. This
reversal results in the blood going to the wrong places. This leads to low oxygen levels in the body.
The aorta, which normally carries oxygen-rich blood from the left
side of the heart to the body, instead receives oxygen-poor blood from the
right side of the heart. The pulmonary artery, which normally carries
oxygen-poor blood from the right side of the heart to the lungs, instead
receives oxygen-rich blood from the left side of the heart.
In transposition of the great vessels, the right lower chamber of
the heart (rather than the left lower chamber) pumps blood to the body.
But the right side of the heart normally is not strong enough to pump
blood effectively to the whole body. This increased workload on the right side
of the heart can lead to a weakened heart.
There are several types of transposition of the great vessels. Each
has slightly different placement of the vessels and openings that result in
mixing of blood between the two sides of the heart. The most common form of
transposition of the great vessels results in oxygen-poor blood being pumped to
Certain other heart defects must be present
to allow a child with transposition of the great vessels to live. Other defects
ultimately compensate for the transposition of the great vessels by allowing
oxygen-rich blood to mix with oxygen-poor blood so that some oxygen can get to the tissues of the body. Surgery is usually
needed for long-term survival.
John Pope, MD - Pediatrics & Larry A. Latson, MD - Pediatric Cardiology
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