Definition of Atrial fibrillation/flutter:

Atrial fibrillation/flutter is a common type of abnormal heartbeat in which the heart rhythm is fast and irregular.

Causes, incidence, and risk factors:

Normally, the four chambers of the heart (two atria and two ventricles) contract (squeeze) in a very organized way, so the heart can pump all the blood the body needs without working too hard.

The electrical impulse that signals your heart to contract begins in the sinoatrial node (also called the sinus node or SA node). This node is your heart's natural pacemaker.

• The signal leaves the SA node and travels through the two upper chambers of the heart (atria).
• Then the signal passes through another node (the AV node), and finally, through the lower chambers (ventricles).

In atrial fibrillation, the electrical impulse of the heart is not regular. The atria contract very quickly and not in a regular pattern. This makes the ventricles beat abnormally, leading to an irregular (and usually fast) pulse. As a result, the heart cannot pump as much blood as the body needs.

In atrial flutter, the ventricles may beat very fast, but in a regular pattern.

If the atrial fibrillation/flutter is part of a condition called sick sinus syndrome, the sinus node may not work properly. The heart rate may alternate between slow and fast beats. As a result, there may not be enough blood to meet the body's needs.

Atrial fibrillation can affect both men and women. It becomes more common as you get older.

Other causes of atrial fibrillation include:

• Alcohol use (especially binge drinking)
• Congestive heart failure
• Coronary artery disease (especially after a heart attack or coronary artery bypass surgery)
• Heart surgery
• Heart valve disease (especially mitral stenosis and mitral regurgitation)
• High blood pressure (hypertension)
• Hypertrophic cardiomyopathy
• Medications
• Overactive thyroid gland (hyperthyroidism)
• Pericarditis