What is Atrial Fibrillation?

By: Alere Staff

Our human hearts are made up of four chambers, two upper and two lower. The upper chambers are called the left atrium and right atrium. Together, they are referred to as the atria. The lower chambers are called the left and right ventricles. The walls of these four chambers of the heart are made of muscle and are very strong. In a normal, regularly beating heart, the atria fill with blood coming to the heart from the body’s circulatory system. When filled, the atria contract together and push this blood to the ventricles. The ventricles fill up with the blood they receive from the atria and then contract, sending the blood back out to the body. In the ‘lub-dub’ sound we recognize as a normal heartbeat, the ‘lub is the sound of the atria contracting and the ‘dub’ is that of the ventricles contracting.

An arrhythmia is a problem with the speed or rhythm of the heartbeat, caused by a disorder in the heart’s electrical system. Atrial fibrillation (afib or AF) is the most common arrhythmia. When a heart is in afib, the atria are beating chaotically and irregularly, out of coordination with the ventricles. This causes an irregular and often rapid heartbeat which can commonly cause reduced or poor blood flow to the body. Without the strong, regular atrial contraction, blood can pool in the upper chambers and have an opportunity to form tiny clots which can travel to other organs and parts of the body.

The average adult heart rate ranges between 60 -100 beats per minute, but patients with afib may have heart rates between 300-600 beats per minute. In cases of irregular heart rhythm, blood may not move through the heart as quickly as with a normal sinus rhythm, and blood may pool to subsequently form a clot. Therefore, the risk of blood clots is markedly increased in patients with afib. Patients with afib are also five to seven times more likely to have a stroke than people with a regular heart rhythm.1

Symptoms of afib can include heart palpitations or a sense of pounding in the chest, shortness of breath and weakness or fatigue. Episodes of atrial fibrillation can come and go or it may be a chronic condition.

If you suspect that you have atrial fibrillation, talk to your doctor. Medical treatment is needed and can include interventions and medications.

  1. Developed with the special contribution of the European Heart Rhythm Association (EHRA), Endorsed by the European Association for Cardio-Thoracic Surgery (EACTS), Authors/Task Force Members. Guidelines for the management of atrial fibrillation: The Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Eur Heart J (2010) 31 (19): 2369-2429 first published online August 29, 2010 doi:10.1093/eurheartj/ehq278.


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