CausesBy Mayo Clinic staff
How the heart works
The heart is divided into four hollow chambers, two on the right and two on the left. In performing its basic job — pumping blood throughout the body — the heart uses its left and right sides for different tasks. The right side of the heart moves blood to the lungs through vessels called pulmonary arteries. In the lungs, blood picks up oxygen, then returns to the heart's left side through the pulmonary veins. The left side of the heart then pumps the blood through the aorta and out to the rest of the body.
How heart defects develop
Most heart defects develop when a baby is still in the womb.
A baby's heart starts beating just 22 days after conception. At that point in time, the heart has a simple tube shape. Between days 22 and 24, the heart begins to bend to the right and fold in on itself to form a loop. By 28 days after conception, the tube has a vaguely heart-like shape with structures that will form into the heart's two sides and the large blood vessels that carry blood in and out of them.
It's usually at this point in a baby's development that heart defects may begin to develop. Researchers aren't sure exactly what causes defects to begin, but they think some medical conditions, medications and genetics may play a role.
Why congenital heart disease resurfaces in adulthood
Some adults may find that problems with their heart defects arise later in life, even if their defects were treated in childhood. This is because heart defects are seldom cured — they are often repaired, so your heart function is improved, but it is often not completely normal.
There are many reasons why heart defects re-emerge in adults. In some cases, the treatment you received in childhood may have been successful, but the problem worsens later in life. It's also possible that problems in your heart, which weren't serious enough to repair when you were a child, have worsened and now require treatment.
There are other complications of childhood surgeries to correct congenital heart disease that can occur later in life. Many treatments to repair heart defects may leave scar tissue behind in your heart that causes an increased chance of abnormal heart rhythm (arrhythmia).
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