Abnormal Heart Rhythm Originating in the Atria
Atrial fibrillation (AF) is an abnormal heart rhythm originating in the atria, the top two chambers of your heart.
Most Common Irregular Heart Rhythm
AF is the most common irregular heart rhythm. The disorder afflicts 2.2 million Americans.
Normal Heart Rhythm vs. Atrial Fibrillation
Normal Heart Rhythm
Coordinated and Sequential Electrical Impulse
When the heart pumps blood to the rest of the body, a small area in the right atrium sends an electrical impulse across your entire heart muscle.
50 to 90 Beats Per Minute
Normally, the impulse is sent 50 to 90 times per minute, which causes your heart muscle to contract in a coordinated and sequential fashion -- first the atria (the top two chambers of your heart) and then the ventricles (the bottom two chambers).
Blood Pumps Properly Through Heart Chambers
As your heart contracts, blood moves from the right atrium into the right ventricle and then the lungs to be filled with oxygen. The blood returns from the lungs to the left atrium and ventricle to be pumped to the rest of your body, including the heart muscle itself. This gives your heart the energy to keep pumping.
Rapid and Chaotic Electrical Impulse
During atrial fibrillation, the atria beat irregularly and chaotically. The electrical impulse does not move in an orderly fashion through the heart. Instead, many small impulses spread through the atria, causing a rapid and disorganized heartbeat.
300 to 600 Beats Per Minute
The rate of impulses through the atria can range from 300 to 600 beats per minute. They collide and compete with each other. As a result, the atria don't contract in their usual coordinated fashion. Instead, they quiver or "fibrillate."
Atria Does Not Completely Empty
Without a strong, coordinated contraction, the atria don't empty as well as they should with each heartbeat. Some of the blood that normally would get pumped into the ventricles remains in the atrium.
May Lead to an Embolism or Stroke
This can lead to the development of small blood clots in the atrium. If these small clots get pumped to the body, it is known as an embolism. If the clot goes to the brain it can cause a stroke.
May Cause Palpitations
Besides affecting the atria, atrial fibrillation has an effect on the ventricles as well. The small, rapid impulses from the quivering atria bombard the ventricles, causing an irregular pulse. This results in palpitations.
Types of Atrial Fibrillation
- In some patients, AF can come and go. This is called
paroxysmal atrial fibrillation.
- In others, the condition occurs all the time. This is called
longstanding persistent atrial fibrillation.
Can Lead to Medical Complications
AF typically is not life-threatening, but is an emergency, as it can lead to complications, including stroke and heart failure. Fortunately, there are a number of effective treatments for AF.