What is atrial fibrillation?
Atrial fibrillation, or AFib, is a kind of abnormal heart rhythm or arrhythmia. Normally, a specific group of cells begin the signal to start your heartbeat. These cells are in the sinoatrial (SA) node. This node is in the right atrium, the upper right chamber of the heart. The signal quickly travels down the heart’s conducting system. It travels to the left and right ventricle, the 2 lower chambers of the heart. As it travels, the signal triggers the chambers of the heart to contract. The atria contract with each heartbeat to move blood into the ventricles.
During AFib, the signal to start the heartbeat is disorganized. This causes the atria to quiver or “fibrillate.” The disorganized signals are then transmitted to the ventricles. It causes them to contract irregularly and sometimes quickly. The contraction of the atria and the ventricles is no longer coordinated, and the amount of blood pumped out to the body will vary with each heartbeat. The ventricles may not be able to pump blood efficiently to the body.
The quivering atria can lead to blood pooling. This increases the risk of forming blood clots. These clots can then travel to the brain, causing a stroke. This is why AFib significantly increases the risk for stroke.
Sometimes AFib occurs briefly and then goes away. This is called paroxysmal atrial fibrillation. AFib that lasts for 7 days or longer is called persistent atrial fibrillation. AFib that lasts longer than a year is called long-standing persistent atrial fibrillation. Persistent AFib may be called permanent atrial fibrillation when a decision is made to no longer control the heart’s rhythm or despite best efforts, normal rhythm can’t be restored.
AFib is common in adults. The risk increases with age. It is more common in men than women.
What causes atrial fibrillation?
AFib can happen from any type of problem that changes the way the heart handles electricity. Sometimes the cause is unknown. There is a range of things that can increase this risk. Some of the risks include:
- Older age
- High blood pressure
- Coronary artery disease
- Heart failure
- Rheumatic heart disease (from previous Streptococcus infection)
- Heart valve defects (like mitral valve prolapse)
- Congenital heart defects
- Sick sinus syndrome
- Lung disease
- Obstructive sleep apnea
- Metabolic syndrome
- High-dose steroid therapy
AFib is also more likely to happen during an infection or right after surgery. Stress, caffeine, and alcohol may also set off attacks.
People who do vigorous endurance exercises, such as running marathons, can develop atrial fibrillation.
Certain people may be at greater risk of developing AFib. This is due to differences in genes they inherited from their parents. This is not yet fully understood, however.
Who is at risk for atrial fibrillation?
AF is more common in people who are over 65. It’s also more common in men than women. Underlying heart disease, high blood pressure, thyroid problems, excess alcohol use, sleep apnea and certain lung disease put people at risk for atrial fibrillation.
What are the symptoms of atrial fibrillation?
AFib can cause different symptoms. This is especially true when it is not treated. These can include:
- Heart palpitations — it might feel like your heart is skipping beats or beating too hard
- Shortness of breath
- Chest pain
- Dizziness or fainting
- Weakness and fatigue
- Swelling in the feet, ankles, and legs
Sometimes AFib has no symptoms.
How is atrial fibrillation diagnosed?
Diagnosis starts with a medical history and physical exam. An internist or primary care healthcare provider will often makes the diagnosis. You may be sent to a cardiologist for further evaluation and treatment.
An electrocardiogram (ECG) is very important for a diagnosis. Healthcare providers use this test to study the heart signal and rhythm. A skilled reader can find AFib using this test alone. If the AFib comes and goes, you might need an electrocardiogram over a longer period with a holter monitor or an event recorder to pick up the rhythm.
Other tests might be used to help plan treatment. These might include:
- Echocardiogram, to check the hearts structure and function
- Cardiac stress testing, to check the blood flow in the heart
- Blood work, to check for thyroid levels, diabetes, and possible medical conditions