Atrial fibrillation, or afib, is the most common type of arrhythmia — a condition in which the heart beats too fast, too slowly, or irregularly.
The heart's internal electrical system normally causes it to beat in a steady, rhythmic fashion.
Afib results from the abnormal firing of electrical signals, which causes the atria (upper heart chambers) to quiver rapidly (fibrillate) instead of contracting completely.
These electrical signals also cause the atria and ventricles (lower chambers of the heart) to beat rapidly or out of sync, potentially causing symptoms.
Some people with afib don't experience any noticeable symptoms and don't realize their heart isn't beating in a normal pattern.
Symptoms of afib can include:
- Rapid or irregular heartbeat
- Heart palpitations (feeling like your heart is fluttering, pounding, or "skipping a beat")
- Shortness of breath
- Dizziness or lightheadedness
- Weakness, especially during exercise
- Chest pain
- Abnormal sweating
Some of these symptoms are caused by the ventricles pumping out blood at irregular intervals to the lungs and the rest of the body.
Normally, the heart's left and right atrium pump blood into the left and right ventricle, which then pump blood into the lungs, and to the rest of the body, respectively.
But afib can prevent the atria from fully contracting and pumping all of their blood into the ventricles, causing blood to pool in the atria.
The pooled blood can lead to the formation of a blood clot, or thrombus.
If the clot breaks off, it can travel through the bloodstream (becoming what's known as an embolus) and block an artery in the brain, causing stroke. It can also block other major arteries — for example, in the abdomen, leading to a poor or absent blood flow to the intestines.
Afib increases a person's risk of stroke by four to six times, according to the National Institute of Neurological Disorders and Stroke.
Also, in people with afib, the ventricles contract and relax too quickly to completely fill with blood.
As a result, the ventricles don't pump enough blood to meet the body's needs, and blood pressure plummets — ultimately causing heart failure.
Symptoms of heart failure include fatigue and shortness of breath. These symptoms develop because blood gets backed up in the pulmonary veins, causing fluid to accumulate in the lungs.
Your doctor will diagnose afib based on your medical and family history, a physical exam, and various tests.
Your doctor will ask you a series of questions to better understand your current health status and risk for afib, including questions about your:
- Signs and symptoms
- Personal and family history of heart-related health problems and other health issues, such as lung disease, diabetes, and thyroid problems
- Personal habits, such as how often you smoke, drink alcohol, or consume caffeine
Your doctor will then conduct a physical exam, including listening to the rhythm and rate of your heartbeat with a stethoscope and taking your blood pressure.
Your doctor will also listen to your lungs (for evidence of heart failure) and check for symptoms related to thyroid issues, such as fluid retention.
An electrocardiogram (EKG or ECG) is the most useful and common test to diagnose afib. This test records the electrical activity of your heart, and can accurately determine the rate and rhythm of your heartbeat.
But because an EKG only records your heart activity for a few seconds, it can't detect afib that repeatedly starts and stops suddenly, which is called paroxysmal afib.
If your doctor suspects you may have paroxysmal afib, you'll need to wear a special heart monitor, such a Holter monitor (which records activity for 24 to 48 hours) or an event monitor (which records for several weeks).
- What are the Symptoms of Atrial Fibrillation (afib or AF)? American Heart Association.
- What Are the Signs and Symptoms of Atrial Fibrillation? National Heart, Lung and Blood Institute.
- Atrial Fibrillation (afib); Cleveland Clinic.
- Atrial fibrillation or flutter; MedlinePlus.
- Why Atrial Fibrillation (AF or afib) Matters; American Heart Association.
- NINDS Atrial Fibrillation and Stroke Information Page; National Institute of Neurological Disorders and Stroke.
Last Updated: 7/21/2016