Atrial fibrillation (AFib) is a heart rhythm abnormality caused by a problem with the heart’s electrical system. Normally, the heart’s electricity flows from the top chambers (atria) to the bottom chambers (ventricles), causing the normal contraction. In atrial fibrillation the electrical flow is chaotic causing the heartbeat to become irregular.

Warning Sign: Uneven Pulse

Atrial fibrillation causes an irregular heart rate. If you check your pulse, you will often feel a “fluttering.” When atrial fibrillation is new in onset or poorly controlled by medications you will often feel your heart racing. This rapid, abnormal heart rate can be dangerous if not treated and controlled quickly.

AFib vs. Normal Heart Rhythm

When the heart beats with a normal rhythm, electricity flows from the top of the heart to the bottom of the heart, causing the heart muscle to contract and moving the blood through the body. In AFib, the electricity flows chaotically and the bottom chambers of the heart contract irregularly.

Warning Sign: Dizziness

If your heart goes into atrial fibrillation you may experience dangerous and frightening symptoms. AFib may cause symptoms such as:

  • Dizziness
  • Feeling of palpitations
  • Shortness of breath
  • Chest pain
  • Fatigue or exercise intolerance

AFib and Stroke

Atrial fibrillation is a risk factor for stroke. About 15 percent of all people who have strokes have AFib. Because of the irregular and chaotic flow of blood through the heart, small blood clots can form in the heart chambers when you have atrial fibrillation. These clots can travel through the bloodstream to the brain, causing a stroke. This is why people with chronic AFib are usually on blood-thinning medications.