What Causes Heart Block?
Heart block has a number of causes. You can be born
with this disorder (congenital) or acquire it.
Congenital Heart Block
One form of congenital heart block occurs in the
babies of women who have autoimmune diseases, such as lupus. People who have
these diseases make proteins called antibodies.
In pregnant women, these antibodies can cross the
placenta. (The placenta is the organ that attaches the umbilical cord to the
mother's womb.) They can damage the baby's heart and lead to congenital heart
block.
Congenital
heart defects (problems with heart's structure) also may cause congenital
heart block. Often, doctors don't know what causes these defects.
Acquired Heart Block
A number of factors, such as diseases, surgery,
medicines, and other conditions, can cause acquired heart block.
The most common cause of acquired heart block is
damage to the heart from a
heart
attack. Other diseases that can cause heart block include
coronary
artery disease, myocarditis (inflammation of the heart muscle),
heart
failure, rheumatic fever, and
cardiomyopathy.
Other diseases may increase the risk for heart
block. These include
sarcoidosis
and the degenerative muscle disorders, Lev's disease and Lenegre's disease.
Certain types of surgery also may damage the heart's
electrical system and lead to heart block.
Exposure to toxic substances and taking certain
medicines, including digitalis and beta blockers, also may cause heart block.
Doctors closely watch people who are taking these medicines for signs of
problems.
In some cases, atrioventricular (AV) heart block has
been linked to genetic mutations (changes in the genes).
An overly active vagus nerve can cause first-degree
heart block. Activity in this nerve slows the heart rate. Well-trained athletes
and young people are at higher risk for first-degree heart block due to this
cause.
In some cases, acquired heart block may go away if
the factor causing it is treated or resolved. For example, heart block that
occurs after a heart attack or surgery may go away after recovery.
Also, if a medicine is causing heart block, the
condition may go away if the medicine is stopped or the dosage is lowered.
However, you shouldn't change the way you take your medicines unless your
doctor tells you to. |