Overview

Your heart’s electrical system tells your heart when to contract and pump blood to the rest of your body. With AFib, these electrical impulses don’t work the way they should, short-circuiting in a sense. As a result, the heart beats too quickly and irregularly. 

AFib is sometimes called a quivering heart. That’s because the two upper parts of the heart (called the atria) quiver. When this happens, the normal communication between the upper and lower chambers of the heart is disrupted and becomes very disorganized.

Because of this, many people with AFib feel zapped of energy fairly quickly or notice being out of breath simply walking up one flight of stairs, particularly when their heart rate is very fast. That’s because you may not be getting enough oxygen; the heart isn’t able to squeeze enough nutrient-rich blood out to the body. 

AFib types are defined by how often an irregular rhythm occurs:

• Paroxysmal: Comes and goes and generally stops on its own.
• Persistent: Lasts more than a week. If AFib lasts more than 12 months, it is called “long-standing persistent” and can be hard to restore to normal rhythm.
• Permanent: The heart’s normal rhythm can’t be restored.

Some cases of AFib are due to a heart valve problem.

If you have AFib, you’re not alone. It’s the most common type of irregular heartbeat, affecting more than 3 million Americans. If untreated, it can lead to blood clots, stroke and heart failure.

Because your heartbeat is out of sync, your heart has a harder time pumping blood out of the body. When this happens, blood can collect in the chambers of the heart and form blood clots. If a blood clot travels through the bloodstream to the brain, it can cause a stroke. Strokes related to AFib tend to be more severe and deadly.