In a typical heart rhythm, a tiny cluster of cells at the sinus node sends out an electrical signal (sinus node impulse). The signal follows a specific path through the upper chambers (atria) and into the lower chambers (ventricles), causing them to squeeze and pump out blood. In atrial fibrillation, electrical signals fire from many areas in the atria, causing the chambers to beat chaotically. Some or all of these chaotic signals enter the ventricles, causing a fast, irregular heartbeat.
Atrial fibrillation (A-fib) is an irregular and often very rapid heart rhythm (arrhythmia) that can lead to blood clots in the heart. A-fib increases the risk of stroke, heart failure and other heart-related complications.
During atrial fibrillation, the heart's upper chambers (the atria) beat chaotically and irregularly — out of sync with the lower chambers (the ventricles) of the heart. For many people, A-fib may have no symptoms. However, A-fib may cause a fast, pounding heartbeat (palpitations), shortness of breath or weakness.
Episodes of atrial fibrillation may come and go, or they may be persistent. Although A-fib itself usually isn't life-threatening, it's a serious medical condition that requires proper treatment to prevent stroke.
Treatment for atrial fibrillation may include medications, therapy to reset the heart rhythm and catheter procedures to block faulty heart signals.
A person with atrial fibrillation may also have a related heart rhythm problem called atrial flutter. Although atrial flutter is a different arrhythmia, the treatment is quite similar to atrial fibrillation.
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Some people with atrial fibrillation (A-fib) don't notice any symptoms. Those who do have atrial fibrillation symptoms may have signs and symptoms such as:
- Sensations of a fast, fluttering or pounding heartbeat (palpitations)
- Chest pain
- Reduced ability to exercise
- Shortness of breath
Atrial fibrillation may be:
- Occasional (paroxysmal atrial fibrillation). A-fib symptoms come and go, usually lasting for a few minutes to hours. Sometimes symptoms occur for as long as a week and episodes can happen repeatedly. Symptoms might go away on their own. Some people with occasional A-fib need treatment.
- Persistent. With this type of atrial fibrillation, the heart rhythm doesn't go back to normal on its own. If a person has A-fib symptoms, cardioversion or treatment with medications may be used to restore and maintain a normal heart rhythm.
- Long-standing persistent. This type of atrial fibrillation is continuous and lasts longer than 12 months.
- Permanent. In this type of atrial fibrillation, the irregular heart rhythm can't be restored. Medications are needed to control the heart rate and to prevent blood clots.
When to see a doctor
If you have any signs or symptoms of atrial fibrillation, make an appointment with your doctor.
If you have chest pain, seek immediate medical help. Chest pain could mean that you're having a heart attack.
To understand the causes of A-fib, it may be helpful to know how the heart typically beats.
The typical heart has four chambers — two upper chambers (atria) and two lower chambers (ventricles). Within the upper right chamber of the heart (right atrium) is a group of cells called the sinus node. The sinus node is the heart's natural pacemaker. It produces the signal that starts each heartbeat.
In a regular heart rhythm:
- The signal travels from the sinus node through the two upper heart chambers (atria).
- The signal passes through a pathway between the upper and lower chambers called the atrioventricular (AV) node.
- The movement of the signal causes your heart to squeeze (contract), sending blood to your heart and body.
In atrial fibrillation, the signals in the upper chambers of the heart are chaotic. As a result, the upper chambers shake (quiver). The AV node is then bombarded with signals trying to get through to the lower heart chambers (ventricles). This causes a fast and irregular heart rhythm.
The heart rate in atrial fibrillation may range from 100 to 175 beats a minute. The normal range for a heart rate is 60 to 100 beats a minute.
Causes of atrial fibrillation
Problems with the heart's structure are the most common cause of atrial fibrillation. Possible causes of atrial fibrillation include:
- Coronary artery disease
- Heart attack
- Heart defect that you're born with (congenital heart defect)
- Heart valve problems
- High blood pressure
- Lung diseases
- Physical stress due to surgery, pneumonia or other illnesses
- Previous heart surgery
- Problem with the heart's natural pacemaker (sick sinus syndrome)
- Sleep apnea
- Thyroid disease such as an overactive thyroid (hyperthyroidism) and other metabolic imbalances
- Use of stimulants, including certain medications, caffeine, tobacco and alcohol
- Viral infections
Some people who have atrial fibrillation have no known heart problems or heart damage.
Things that can increase the risk of atrial fibrillation (A-fib) include:
- Age. The older a person is, the greater the risk of developing atrial fibrillation.
- Heart disease. Anyone with heart disease — such as heart valve problems, congenital heart disease, congestive heart failure, coronary artery disease, or a history of heart attack or heart surgery — has an increased risk of atrial fibrillation.
- High blood pressure. Having high blood pressure, especially if it's not well controlled with lifestyle changes or medications, can increase the risk of atrial fibrillation.
- Thyroid disease. In some people, thyroid problems may trigger heart rhythm problems (arrhythmias), including atrial fibrillation.
- Other chronic health conditions. People with certain chronic conditions such as diabetes, metabolic syndrome, chronic kidney disease, lung disease or sleep apnea have an increased risk of atrial fibrillation.
- Drinking alcohol. For some people, drinking alcohol can trigger an episode of atrial fibrillation. Binge drinking further increases the risk.
- Obesity. People who have obesity are at higher risk of developing atrial fibrillation.
- Family history. An increased risk of atrial fibrillation occurs in some families.
Blood clots are a dangerous complication of atrial fibrillation that can lead to stroke.
In atrial fibrillation, the chaotic heart rhythm can cause blood to collect in the heart's upper chambers (atria) and form clots. If a blood clot in the left upper chamber (left atrium) breaks free from the heart area, it can travel to the brain and cause a stroke.
The risk of stroke from atrial fibrillation increases as you grow older. Other health conditions also may increase your risk of a stroke due to A-fib, including:
- High blood pressure
- Heart failure
- Some valvular heart disease
Blood thinners are commonly prescribed to prevent blood clots and strokes in people with atrial fibrillation.
Healthy lifestyle choices can reduce the risk of heart disease and may prevent atrial fibrillation. Here are some basic heart-healthy tips:
- Eat a nutritious diet
- Get regular exercise and maintain a healthy weight
- Don't smoke
- Avoid or limit alcohol and caffeine
- Manage stress, as intense stress and anger can cause heart rhythm problems
Sept. 18, 2021