Atrial fibrillation (AF or afib) is an abnormal heart rhythm which involves the two upper chambers of the heart. In a normal heart rhythm, the impulse generated by the sinoatrial node spreads through the heart and causes contraction of the heart muscle and pumping of blood. In AF, the regular electrical impulses of the sinoatrial node are replaced by disorganized, rapid electrical impulses which result in irregular heart beats.
Atrial fibrillation is the most common cardiac arrhythmia. The risk of developing atrial fibrillation increases with age. AF affects four percent of individuals in their 80s. When a patient spontaneously alternates between AF and a normal rhythm, the condition is known as paroxysmal atrial fibrillation. When a patient continues with AF as the dominant cardiac rhythm without reversion to the normal rhythm, the condition is known as chronic atrial fibrillation.
Atrial fibrillation is often asymptomatic, but may result in symptoms of palpitations, fainting, chest pain, or even heart failure. It is also a leading cause of stroke as the erratic motion of the atria leads to blood stagnation which increases the risk of blood clots that may travel from the heart to the brain and other areas.
Atrial fibrillation may be treated with medications which either slow the heart rate or revert the heart rhythm back to normal. Synchronized electrical cardioversion may also be used to convert AF to a normal heart rhythm. Surgical and catheter-based therapies may also be used to prevent atrial fibrillation in certain individuals. People with AF are often given anticoagulants such as warfarin to protect them from strokes.