Atrial Fibrillation
Key points
- Atrial fibrillation is a type of cardiac arrhythmia (abnormality of heart rate or rhythm).
- Atrial fibrillation often causes no symptoms at all.
- Your doctor will ask about your family history of cardiovascular disorders and will review your personal medical history, including any possible risk factors for atrial fibrillation.
- The duration of atrial fibrillation depends on the underlying cause.
What Is It?
Atrial fibrillation is a type of cardiac arrhythmia (abnormality of heart rate or rhythm). Atrial fibrillation produces a rapid and irregular heartbeat, during which the atria (the upper two chambers of the heart that receive blood) quiver or "fibrillate" instead of beating normally.
During a normal heartbeat, the electrical impulses that cause the atria to contract come from the sinus node, a small area of the right atrium. During atrial fibrillation, however, these impulses come from all over the atria, triggering 300 to 500 contractions per minute within the heart's upper chambers. Under normal circumstances, the atrioventricular node would receive these impulses and conduct them to the ventricles (the lower two chambers of the heart that do the pumping). During atrial fibrillation, however, the atrioventricular node becomes overwhelmed by all of the impulses it receives from the atria, and the result is an irregular and rapid heartbeat — 80 to 160 beats per minute versus a normal range of 60 to 100 beats per minute.
The rapid and irregular heartbeat produced by atrial fibrillation cannot pump blood out of the heart efficiently. As a result, blood tends to pool in the heart chambers, increasing the risk of a blood clot formaing inside the heart. Blood clots can travel from the heart into the bloodstream and circulate through the body. Ultimately, they may become lodged in an artery, causing pulmonary embolism, stroke and other disorders.
In general, anything that disturbs the normal electrical impulses in the heart can trigger a cardiac arrhythmia, causing the heart to beat too quickly, too slowly or erratically. The major factors that increase the risk of atrial fibrillation are:
- Age
- Coronary artery disease
- Rheumatic heart disease (caused by rheumatic fever)
- High blood pressure (hypertension)
- Diabetes
- Thyrotoxicosis (an excess of thyroid hormones)
In many people, the underlying cause of atrial fibrillation is more serious than the arrhythmia itself.
Symptoms
Atrial fibrillation often causes no symptoms at all. When symptoms do occur, there may be palpitations (awareness of a rapid heartbeat), fainting, dizziness, weakness, shortness of breath and angina pectoris (chest pain caused by a reduced blood supply to the heart muscle). Some people with atrial fibrillation have periods of completely normal heartbeats.
Diagnosis
Your doctor will ask about your family history of cardiovascular disorders and will review your personal medical history, including any possible risk factors for atrial fibrillation. Your doctor also will ask you to describe your specific cardiac symptoms, including any possible triggers for your palpitations, dizziness or shortness of breath.
Frequently asked questions
What is atrial fibrillation?
Atrial fibrillation is a type of cardiac arrhythmia (abnormality of heart rate or rhythm). Atrial fibrillation produces a rapid and irregular heartbeat, during which the atria (the upper two chambers of the heart that receive blood) quiver or "fibrillate" instead of beating normally. During a normal heartbeat, the electrical impulses that cause the atria to contract come from the sinus node, a small area of the right atrium. During atrial fibrillation, however, these impulses come from all over the atria, triggering 300 to 500 contractions per minute within the heart's upper chambers.
What are the symptoms of atrial fibrillation?
Atrial fibrillation often causes no symptoms at all. When symptoms do occur, there may be palpitations (awareness of a rapid heartbeat), fainting, dizziness, weakness, shortness of breath and angina pectoris (chest pain caused by a reduced blood supply to the heart muscle). Some people with atrial fibrillation have periods of completely normal heartbeats.
How is atrial fibrillation diagnosed?
Your doctor will ask about your family history of cardiovascular disorders and will review your personal medical history, including any possible risk factors for atrial fibrillation. Your doctor also will ask you to describe your specific cardiac symptoms, including any possible triggers for your palpitations, dizziness or shortness of breath. During your physical examination, the doctor will check your heart rate and rhythm, together with your pulses. In atrial fibrillation, the pulse, which reflects the activity of the ventricles, often is mismatched with the heart sounds, because all of the atrial beats are not reaching the ventricles.
Written and revised by
Andrey Nailor, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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