Atrial Fibrillation (AF or AFib)

Atrial fibrillation occurs when the four chambers of the heart beat in an irregular rhythm.  The two upper
chambers of the heart are the atria and the two lower chambers are the ventricles.  The sequence and timing of
the contractions of these four chambers is usually tightly controlled by electrical impulses originating from an
area located in the upper part of the right atrium known as the sinoatrial (SA) node.  Electrical impulses from the
SA node signal the two atria to contract and empty the blood within the atria into the ventricles.  The electrical
impulse then reaches and stimulates another area known as the atrioventricular (AV) node located in between
the atria and the ventricles.  The AV node relays the signal down to the ventricles and causes the ventricles to
contract.  The right ventricle functions to pump blood into the lung tissues for oxygenation and the left ventricle
functions to supply oxygenated blood to the rest of the body.

During AF, many electrical impulses are sent out from the SA node simultaneously to stimulate the AV node.  As
a result of these rapid irregular impulses, the heartbeat becomes irregular and disorganized.  The irregular
heartbeat also causes the blood to become relatively stagnant in the left atrium and increases the risk of blood
clot formation which may lead to stroke.

The symptoms of AF include shortness of breath, heart palpitations, dizziness, and chest pain.  AF can lead to
heart failure and stroke.

AF can be treated with antiarrhythmic drug.  Another option is heart rate control medication, such as
beta-blockers and calcium channel blockers.  Antithrombotic drugs (blood thinner) are usually prescribed at the
same time to reduce the risk of blood clot formation.
Atrial Fibrillation
Cardiovascularweb