Atrial fibrillation or flutter
Auricular fibrillation; AFib; A-fib; Afib; Supraventricular arrhythmia; AF; AFL
Atrial fibrillation (Afib) and atrial flutter are common types of abnormal heart rhythms (arrhythmias) which affect the upper chambers (atria) of the heart.
In atrial flutter, the heart beats too fast, but mostly continues to contract in a regular rhythm. AFib is a closely related condition in which the atria contract in a chaotic manner, or "quivers." This creates an irregular heart rhythm that is also usually too fast. Afib and atrial flutter often occur in the same person at different times.
A lot of things can make your heart beat faster, like kissing the person you love or watching a scary movie. But sometimes, your heart beats not only faster but also out of rhythm. That can be a problem if this continues over a long period of time and isn't treated. Let's talk about a condition called atrial fibrillation. If you can listen to your heart through a stethoscope, your heart beat should sound something like this, or lub dub, lub dub, lub dub. If you have atrial fibrillation, the top two chambers of your heart contract too quickly, and in an irregular pattern. So what you'd hear if you listened through a stethoscope would be more like this. Atrial fibrillation doesn't just sound funny, this irregular beat can prevent your heart from pumping enough blood out to the rest of your body. Age may cause atrial fibrillation. As you get older, it's more common to have an irregular heartbeat. You're also more likely to have atrial fibrillation if you've had another heart problem, like valve disease, coronary artery disease, or heart failure. Some people get atrial fibrillation because they drink too much alcohol or take certain medicines. To find out you may have atrial fibrillation. You'll feel your heart race and flutter-and not just once in a while, but often. You may also have trouble breathing and feel tired and dizzy. Your doctor can listen for fluttering while listening to your heart with a stethoscope. You may also need a test that records your heart's rhythms, like an ECG, which you have in your doctor's office, or a Holter monitor that you wear around for a day. Your doctor may also prescribe imaging tests to look at your heart and check whether its electrical system is working properly. If you do have atrial fibrillation, your doctor can give you medicine to slow your racing heart. Often, the next step is to restore the normal heart rhythm with an electric shock, a process called Cardioversion. However, if the atria haven't been contracting well for 48 hours or more, blood clots may have formed there. These patients are usually given anti-coagulant medicines before Cardioversion to prevent the clots from moving to the brain and causing a stroke when normal rhythm is restored. If Cardioversion doesn't solve the problem, a procedure called Cardiac ablation can be done to destroy the bad areas of your heart that are causing your heart to beat abnormally. Usually doctors can treat atrial fibrillation so that it becomes a minor nuisance, instead of a big problem. But, the condition can come back, even after it's been treated. If it continues, atrial fibrillation can lead to heart failure. To avoid complications from atrial fibrillation, call your doctor if you're feeling flutters in your chest, and they don't go away.
The interior of the heart is composed of valves, chambers, and associated vessels.
The external structures of the heart include the ventricles, atria, arteries and veins. Arteries carry blood away from the heart while veins carry blood into the heart. The vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.
The coronary arteries supply blood to the heart muscle. The right coronary artery supplies both the left and the right heart; the left coronary artery supplies the left heart.
The intrinsic conduction system sets the basic rhythm of the beating heart by generating impulses which stimulate the heart to contract.
The heart has four chambers and four main blood vessels that either bring blood to the heart, or carry blood away. The four chambers are the right atrium and right ventricle and the left atrium and left ventricle. The blood vessels include the superior and inferior vena cava. These bring blood from the body to the right atrium. Next is the pulmonary artery that carries blood from the right ventricle to the lungs. The aorta is the body's largest artery. It carries oxygen-rich blood from the left ventricle to the rest of the body. Beneath the tough fibrous coating of the heart, you can see it beating. Inside the chambers are a series of one-way valves. These keep the blood flowing in one direction. Dye injected into the superior vena cava, will pass through all the heart's chambers during one cardiac cycle. Blood first enters the heart's right atrium. A muscle contraction forces the blood through the tricuspid valve into the right ventricle. When the right ventricle contracts, blood is forced through the pulmonary semilunar valve into the pulmonary artery. Then it travels to the lungs. In the lungs, the blood receives oxygen then leaves through the pulmonary veins. It returns to the heart and enters the left atrium. From there, blood is forced through the mitral valve into the left ventricle. This is the muscular pump that sends blood out to the rest of the body. When the left ventricle contracts, it forces blood through the aortic semilunar valve and into the aorta. The aorta and its branches carries the blood to all the body's tissues.
Atrial fibrillation (AF) is the most common sustained arrhythmia in adults. It affects more than 2 million individuals in the United States, and as many as 160,000 new cases are diagnosed each year. The incidence of atrial fibrillation increases with age, and it is often associated with hypertension, valvular and pulmonary disease, metabolic disorders, and coronary artery disease. It is usually triggered by rapid firing from the pulmonary veins, followed by disorganized and asymmetrical impulse through the atria resulting in over 400 beats/min. The ventricles also respond in an irregular way. A serious consequence resulting from AF is clot formation in the atrium, especially when the atria have enlarged and have areas of pooling blood, which subsequently leads to embolism. Risk of thromboembolism is greater in people with diabetes, hypertension, history of embolism, diseases of the valves, and heart failure. In atrial flutter, regular atrial rates range from 250 to 350 beats/min. Most people with atrial flutter have some type of underlying heart problem such as hypertension, coronary artery disease, pericarditis, or valvular heart disease. It can also be caused by a congenital heart defect. Atrial flutter increases the patient’s risk of thromboembolism by 3% per year. Prevention and treatment of atrial flutter should be approached as described for atrial fibrillation. Long-term anticoagulation therapy is recommended for both conditions to reduce the risk of thromboembolism. Radiofrequency catheter ablation is very effective and has minimal risks. It can even be considered as an alternative to drug therapy.
Causes
When working well, the 4 chambers of the heart contract (squeeze) in an organized way.
Electrical signals direct your heart to pump the right amount of blood for your body's needs. The signals begin in an area called the sinoatrial node (also called the sinus node or SA node).
In people with AFib, the electrical impulse of the heart is not regular. This is because the sinoatrial node no longer controls the sequence of heart muscle contractions (rhythm) in the upper chambers of the heart (atria).
In AFib:
- The atria do not contract in an organized pattern.
- The lower chambers of the heart (ventricles) contract in an irregular manner that is often too fast.
- As a result, the heart cannot pump enough blood to meet the body's needs.
In people with atrial flutter, the atria beat very rapidly, but in a regular pattern.
These problems can affect both men and women. They become more common with increasing age.
Common causes of AFib include:
- Alcohol use (especially binge drinking)
- Coronary artery disease
- Heart attack or heart bypass surgery
- Heart failure or an enlarged heart
- Heart valve disease (most often the mitral valve)
- Hypertension
- Medicines
- Overactive thyroid gland (hyperthyroidism)
- Pericarditis
- Sick sinus syndrome
Symptoms
You may not be aware that your heart is not beating in a normal pattern. When symptoms are present, they may include one or more of the following:
- Pulse that feels rapid, racing, pounding or thumping, fluttering, irregular, or too slow.
- Sensation of feeling the heart beat (palpitations).
- Confusion.
- Dizziness, lightheadedness.
- Fainting.
- Fatigue.
- Weakness.
- Loss of ability to exercise.
- Shortness of breath and anxiety.
- Sweating.
- Chest pain or pressure, which may be a sign of a heart attack. Call 911 or the local emergency number right away if you have chest pain or pressure.
Exams and Tests
Your health care provider may hear a fast heartbeat while listening to your heart with a stethoscope. Your pulse may feel fast, uneven, or both.
The normal heart rate is 60 to 100 beats per minute. In Afib or flutter, the heart rate may be as high as 250 to 350 beats per minute and is very often over 100 beats per minute. Blood pressure may be normal or low.
An ECG (a test that records the electrical activity of the heart) may show AFib or atrial flutter.
If your abnormal heart rhythm comes and goes, you may need to wear a special monitor to diagnose the problem. The monitor records the heart's rhythms over a period of time.
- Event monitor (3 to 4 weeks)
- Holter monitor (24-hour test)
- Implanted loop recorder (extended monitoring)
Tests to find heart disease may include:
- Echocardiogram (ultrasound imaging of the heart)
- Tests to examine the blood supply of the heart muscle
- Tests to study the heart's electrical system
Treatment
Cardioversion treatment may be used to get the heart back into a normal rhythm right away. There are two options for treatment:
- Electric shocks to your heart
- Medicines given through a vein
These treatments may be done as emergency methods, or planned ahead of time.
Daily medicines taken by mouth are used to:
- Slow the irregular heartbeat and maintain normal heart rhythm -- These drugs may include beta-blockers, calcium channel blockers, digoxin, and anti-arrhythmics.
- Prevent blood clots -- Blood-thinning medicines are often given to reduce the risk of blood clots that can result from ongoing irregular heart rhythms.
- Prevent AFib from coming back -- These drugs work well in many people, but they can have serious side effects. AFib returns in many people, even while they are taking these medicines.
A procedure called radiofrequency ablation can be used to scar areas in your heart where the heart rhythm problems are triggered. This can prevent the abnormal electrical signals that cause AFib or flutter from moving through your heart. You may need a heart pacemaker after this procedure. All people with AFib will need to learn how to manage this condition at home.
People with AFib will most often need to take blood thinner medicines. These medicines are used to reduce the risk of developing a blood clot that travels in the body (and that can cause a stroke, for example). The irregular heart rhythm that occurs with AFib makes blood clots more likely to form.
Blood thinner medicines include heparin, warfarin (Coumadin), apixaban (Eliquis), rivaroxaban (Xarelto), edoxaban (Savaysa) and dabigatran (Pradaxa). Antiplatelet drugs such as aspirin or clopidogrel may also be prescribed. However, blood thinners increase the chance of bleeding, so not everyone can use them.
Another stroke prevention option for people who cannot safely take these medicines is the Watchman Device, which has recently been approved by the FDA. This is a small basket-shaped implant that is placed inside the heart to block off the area of the heart where most of the clots form. This limits clots from forming.
Your provider will consider your age and other medical problems when deciding which stroke prevention methods are best for you.
Outlook (Prognosis)
Treatment can often control this disorder. Many people with AFib do very well with treatment.
AFib tends to return and get worse. It may come back in some people, even with treatment.
Clots that break off and travel to the brain can cause a stroke.
When to Contact a Medical Professional
Contact your provider if you have symptoms of AFib or flutter.
Prevention
Talk to your provider about steps to treat conditions that cause atrial fibrillation and flutter. Avoid binge drinking.
References
Calkins H, Tomaselli GF, Morady F. Atrial fibrillation: clinical features, mechanisms, and management. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 66.
Jogler JA, Chung MK, Armbruster AL, et al. 2023 ACC/AHA/ACCP/HRS Guideline for the diagnosis and management of atrial fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2024;149(1):e1–e156. PMID: 38033089
Zimetbaum P, Goldman L. Supraventricular ectopy and tachyarrhythmias. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 52.
Version Info
Last reviewed on: 1/1/2023
Reviewed by: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Internal review and update on 02/19/2024 by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
