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Atrial Fibrillation
AF is a common disturbance of the heart's rhythm. It is a condition
in which the heart quivers, or fibrillates, instead of beating
normally. There are 2.4 million people suffering from AF in the US
alone. It becomes more common with age; about 2.3% of people over
40, 6% of people over 65, and 10% of people in their 80s have AF.
Experts say that the number of people with AF will double in the
next 20 years.
How the heart works
To better understand AF, it is helpful to first understand how a
normal heart works. The human heart is made up of four chambers -
two chambers on top (the atria) and two chambers below (the
ventricles). The left and right sides of the heart perform different
functions: the left side pumps blood rich in oxygen to supply all
parts of the body, while the right side of the heart pumps blood
back to the lungs to pick up more oxygen. The chambers of the heart
are separated by four valves that open and close to direct the flow
of blood.
During a normal heartbeat, an electrical impulse begins in the right
atrium and travels throughout electrical pathways in the heart. This
organized electrical stimulation results in a single smooth wave of
contradiction that allows the heart to pump blood at a regular rate
and with a regular rhythm.
Abnormal heart rhythms in AF
Normally, the electrical signal that tells your heart to beat comes
from the sinoatrial node, or SA node, in the right atrium. During
AF, signals start irregularly from several areas of the atria,
making the heartbeat abnormal. When AF occurs, the electrical
signals become disorganized and rapid, and as a result, the upper
chambers of the heart quiver (fibrillate) instead of beating
normally. This keeps the upper and lower chambers of the heart from
working together properly, which can decrease the heart's ability to
pump blood.
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