Atrial fibrillation is a condition that occurs when there is a problem in the heart's electrical system. This can cause the upper part of the heart to quiver instead of beating efficiently. The condition is often associated with current heart problems, but there are other risk factors. While atrial fibrillation is rarely cured, it can usually be managed with medication and changes in diet and lifestyle.
Atrial fibrillation is a type of abnormal heart rhythm -- also known as an arrhythmia. Sometimes, the condition is called "a-fib" for short. It occurs when something goes wrong with the heart's electrical control system.
Because it can be scary to experience an episode of atrial fibrillation, a lot of people worry that they are having a heart attack, or will have one later. But the condition is different from a heart attack. By itself, atrial fibrillation is rarely life-threatening, although its complications can be, and having it doesn't mean that you will have a heart attack in the future.
Atrial fibrillation is the most common form of abnormal heartbeat. Each year, more than two million people in the United States are diagnosed with the condition. Most of them find that their symptoms can be controlled with proper treatment. Atrial fibrillation is more common in men than in women. It is also more common in older people than in the rest of the population.
Atrial fibrillation can cause heart palpitations, chest pain, dizziness, shortness of breath, weakness, and fatigue, although many people experience no symptoms at all. It is estimated that approximately two million people in the United States experience atrial fibrillation. While the condition itself is not generally fatal, it can lead to increased risk of stroke, heart failure and heart attack.
Heart disease and high blood pressure are the two main known causes of atrial fibrillation. Both of these conditions can cause damage to the heart, making it more susceptible to cardiac arrhythmia. Other common causes are heart abnormalities or defects, illness, sleep apnea, and metabolic or chemical imbalances in the body.
The heart is composed of four chambers. The top two chambers are known as the atria and the bottom two chambers are known as the ventricles. All of the chambers must contract or expand at precisely the right time to ensure that blood is received from the body, oxygenated and then pumped back out to the body effectively.
After the body has depleted the oxygen in the blood, it enters the heart through the right atria. From the right atria the blood is pumped to the right ventricle, where it is pumped to the lungs, which replenishes the blood with oxygen. Once replenished with oxygen, the blood is transported from the lungs to the left atria, where it is pumped into the left ventricle. From the left ventricle, the oxygen-rich blood flows into the aorta, which is the largest artery in the body. From the aorta, blood reenters the bloodstream and is distributed throughout the body.
In a healthy heart, regular electrical impulses tell the heart when to expand and contract. During atrial fibrillation, the electrical impulses are irregular and very rapid. This causes the left and right atria to quiver instead of beating effectively. As a result of the irregular heartbeat, the atria may not fully pump out all of the blood that is in it, possibly causing blood to pool and collect.
When blood is allowed to collect, clots are more likely to form. If a piece of a formed blood clot breaks away and flows out of the heart, it may lodge in an artery of the brain causing a stoppage of blood flow to the brain, resulting in a stroke. It has been estimated that approximately 15% of patients who experienced a stroke also experienced atrial fibrillation.
Heart palpitations, a faster-than-normal pulse, and chest tightness are common symptoms and signs of atrial fibrillation. When the condition reduces the amount of blood the heart pumps, the body may not get enough oxygen. This can cause symptoms like shortness of breath and dizziness. Atrial fibrillation can also lead to heart attack or stroke, so it's important to know how signs of these conditions differ from atrial fibrillation symptoms.
The most common symptoms of atrial fibrillation are:
Heart palpitations (the feeling like your heart is racing or pounding)
Feeling like your heart is fluttering
An irregular heartbeat or pulse that is faster than normal
Tightness or discomfort in your chest.
These symptoms occur because the electrical signals in your heart are causing it to beat at an unusually fast and irregular rate.
Atrial fibrillation can decrease the amount of blood your heart pumps with each beat by as much as 20 to 30 percent. As a result, other symptoms will occur when your body isn't getting enough oxygen and nutrients. These include:
Shortness of breath
Feeling dizzy or lightheaded
Feeling too tired to exercise or even complete normal everyday tasks.
These atrial fibrillation symptoms often get worse during physical activity.
Atrial fibrillation may be:
Occasional. In this case it's called paroxysmal atrial fibrillation. You may have symptoms that come and go, lasting for a few minutes to hours and then stopping on their own.
Chronic. With chronic atrial fibrillation, your heart rhythm is always abnormal.
In addition to the symptoms explained previously, there are a number of other symptoms that can occur due to atrial fibrillation complications. Some of these complications include:
Stroke
Heart attack
Serious bleeding.
Stroke
If any of the following symptoms happen suddenly, you may be having a stroke:
Weakness or numbness in the face, arms, or legs, especially if it's only on one side of your body
Loss of vision or other visual difficulties, especially if it's only in one eye
Difficulty speaking or understanding speech
Developing a severe headache for no apparent reason
Feeling dizzy, losing your balance, or falling for no apparent reason, especially if it happens along with the other symptoms mentioned.
If you experience any symptoms that you think are the result of a stroke, call either your doctor or 911.
Heart Attack
While atrial fibrillation by itself is rarely life-threatening, there are a few warning signs that you should be aware of that may mean you are having a heart attack (known medically as a myocardial infarction) and need urgent medical attention. The more common signs of a heart attack include:
Pain, pressure, tightness, heaviness, or another uncomfortable feeling in the center of your chest that lasts for more than a few minutes
Pain in your chest that spreads to the shoulders, neck, or arms
An uncomfortable feeling in your chest, along with feeling lightheaded, fainting, sweating, feeling nauseated, or having trouble breathing.
Less common symptoms of a heart attack include:
Pain in your neck, jaw, back, or abdomen (stomach)
Vomiting or feeling dizzy or nauseated
Feeling short of breath or having difficulty breathing
Feeling anxious or a sense of impending doom
Weakness or fatigue for no reason
Heart palpitations (feeling like your heart is fluttering)
Sweating profusely or going into a cold sweat
Paleness.
Some of these symptoms may also occur if you are having severe atrial fibrillation symptoms. If you experience any symptoms that you think are the result of a heart attack, call either your doctor or 911.
Serious Bleeding
Warfarin (Coumadin) is a medicine that may be prescribed for atrial fibrillation treatment. Like all medicines, Coumadin can have side effects. The risk of experiencing side effects is higher if you are not taking the right Coumadin dosage. This is why regular blood tests and talking often with your healthcare team are so important.
Contact your healthcare provider right away if you have any unusual bleeding, for example:
Increased bleeding when you brush your teeth
Nosebleeds
Menstrual bleeding that's heavier than usual or unexpected
Blood in your feces or urine
Black feces
Vomiting up blood or something that looks like old coffee grounds
Coughing up blood
Bruising for no reason.
Other unusual symptoms include:
Fever
Diarrhea
Infection
Pain or swelling in your joints
Dizziness
Difficulty breathing
Sudden, severe headache
Chest pain
Feeling more weak and tired than usual.
Some of these can be signs that you have internal bleeding and may need immediate medical attention. Your dose of Coumadin might need to be adjusted as well.
Atrial fibrillation occurs when the electrical system that controls your heartbeat is no longer working properly. Normally, after an electrical signal is sent from the SA (sinoatrial) node, it travels across the atria and causes the muscles in both chambers to contract uniformly. In people who have atrial fibrillation, this signal from the SA node generates several more electrical signals that chaotically crisscross the atria, causing different patches of the atrial muscle to contract at different times. This causes the atria to quiver, or fibrillate, sometimes as fast as 350 to 700 times a minute -- much faster than a normal heart rate.
When atrial fibrillation occurs, there's a lack of coordination between the patches of muscle, which means that the whole chamber doesn't contract at the same time. As a result, less blood is squeezed into the ventricle from the atrium. Because of this, blood can get backed up in the atrium, then into the blood vessel that leads into it, and, with time, even farther back throughout the rest of the body.
Normally, the electrical signals from the SA node continue through the AV (atrioventricular) node to the ventricles, causing them to contract as well. But in atrial fibrillation, the signals to the ventricles are either irregular or incomplete, so the contractions of the atria and the ventricles are no longer synchronized. This causes the ventricles to beat more rapidly and irregularly, too. They may contract before they have filled with blood, and this means that your body gets less oxygen and nutrients.
Atrial fibrillation can be fast or slow. The normal heart rate is considered to be between 60 and 100 beats per minute. Usually, people with atrial fibrillation who have a heart rate below 100 beats per minute have fewer symptoms than those with heart rates greater than 100 beats per minute.
In many cases, doctors can identify the causes of atrial fibrillation. Most people who have atrial fibrillation already have some form of heart or vascular disease. Some of the specific things that can lead to atrial fibrillation include:
Heart problems
Surgery
Other medical conditions
Certain medical conditions (such as abnormally high blood pressure)
Alcohol
Smoking
Stimulant chemicals (such as caffeine or cocaine).
It is also known that atrial fibrillation is more common in men than in women, and the condition is also more common in the elderly.
Heart Problems
Most people who have atrial fibrillation already have some form of heart or vascular disease.
Common heart problems that cause atrial fibrillation include:
Hypertensive heart disease, which can occur as a result of untreated high blood pressure
Rheumatic heart disease, which occurs when rheumatic fever causes damage to the heart
Coronary artery disease
Congestive heart failure
Heart attack
Wolff-Parkinson-White syndrome, a condition in which abnormal electrical activity in the heart causes a rapid heart rate
Paroxysmal supraventricular tachycardia, which are occasional bursts of rapid heart rate that start in the atria
Angina, which is chest pain that may also radiate to the shoulder and down the arm
Congenital heart problems
Cardiomyopathies, which are diseases that damage the heart muscle
Problems with the heart valves
Infection in the heart or the pericardium, which is the sac surrounding the heart
Tumors of the heart and pericardium.
Surgeries That May Cause Atrial Fibrillation
Atrial fibrillation can also occur in people who have had surgery on their heart or lungs. Surgeries that can result in atrial fibrillation include:
Coronary artery bypass graft (CABG)
Correction of heart defects
Heart transplant.
Other Medical Conditions
Other health conditions that can lead to atrial fibrillation include:
Disorders of the thyroid gland
Uncontrolled high blood pressure
Pulmonary embolism, which occurs when a blood clot blocks off one of the arteries in the lungs
Low levels of oxygen in the blood because of chronic lung problems, such as asthma and emphysema
Diabetes
Electrolyte imbalance, which occurs when your body isn't able to control the levels of certain chemicals in your body, like calcium and potassium
Autonomic dysfunction, which is when the autonomic, or involuntary, part of the nervous system doesn't control the heart properly.
In otherwise healthy people, atrial fibrillation can be caused by binge drinking or long-term, excessive drinking. Going through withdrawal from alcohol can also lead to atrial fibrillation. Both overuse of and withdrawal from alcohol can cause someone who has paroxysmal atrial fibrillation to develop a more severe form of the condition.
Smoking and Stimulant Chemicals
Atrial fibrillation can also be caused by smoking and the use of stimulant chemicals, such as caffeine, cocaine, and those found in some over-the-counter decongestant medications.
For people who only experience occasional episodes, treatment for atrial fibrillation may be as simple as avoiding things that aggravate the condition (such as tobacco, alcohol, and caffeine). In more serious cases, treatment options may include medication, electrical cardioversion, and surgery. Even if your atrial fibrillation does not require treatment, careful monitoring can prevent it from worsening.
In some people, a specific event or an underlying condition, such as a thyroid disorder, may trigger atrial fibrillation. If the condition that triggered your atrial fibrillation can be treated, you might not have any more heart rhythm problems — or at least not for quite some time. If your symptoms are bothersome or if this is your first episode of atrial fibrillation, your doctor may attempt to reset the rhythm.
The treatment option best for you will depend on how long you've had atrial fibrillation, how bothersome your symptoms are and the underlying cause of your atrial fibrillation. Generally, the goals of treating atrial fibrillation are to:
Reset the rhythm or control the rate
Prevent blood clots
The strategy you and your doctor choose depends on many factors, including whether you have other problems with your heart and if you're able to take medications that can control your heart rhythm. In some cases, you may need a more invasive treatment, such as surgery or medical procedures using catheters.
Resetting
your heart's rhythm
Ideally,
to treat atrial fibrillation, the heart rate and rhythm are reset to
normal. To correct your condition, doctors may be able to reset your
heart to its regular rhythm (sinus rhythm) using a procedure called
cardioversion, depending on the underlying cause of atrial
fibrillation and how long you've had it. Cardioversion can be done in
two ways:
Cardioversion with drugs. This form of cardioversion uses medications called anti-arrhythmics to help restore normal sinus rhythm. Depending on your heart condition, your doctor may recommend trying intravenous or oral medications to return your heart to normal rhythm. This is often done in the hospital with continuous monitoring of your heart rate. If your heart rhythm returns to normal, your doctor often will prescribe the same anti-arrhythmic or a similar one to try to prevent more spells of atrial fibrillation.
Electrical cardioversion. In this brief procedure, an electrical shock is delivered to your heart through paddles or patches placed on your chest. The shock stops your heart's electrical activity momentarily. When your heart begins again, the hope is that it resumes its normal rhythm. The procedure is performed with sedation, so you shouldn't feel the electric shock.
Before cardioversion, you may be given a blood-thinning medication, such as warfarin (Coumadin), for several weeks to reduce the risk of blood clots and stroke. Unless the episode of atrial fibrillation lasted less than 24 hours, you'll need to take warfarin for at least four to six weeks after cardioversion to prevent a blood clot from forming even after your heart is back in normal rhythm. Warfarin is a powerful medication that can have dangerous side effects if not taken exactly as directed by your doctor. If you have any concerns about taking warfarin, talk to your doctor.
Or, instead of taking warfarin, you may have a test called transesophageal echocardiography — which can tell your doctor if you have any heart blood clots — just before cardioversion. In transesophageal echocardiography, a tube is passed down your esophagus and detailed ultrasound images are made of your heart. You'll be sedated during the test.
Maintaining
a normal heart rhythm
After
electrical cardioversion, anti-arrhythmic medications often are
prescribed to help prevent future episodes of atrial fibrillation.
Commonly used medications include:
Amiodarone (Cordarone, Pacerone)
Dronedarone (Maltaq)
Propafenone (Rythmol)
Sotalol (Betapace)
Dofetilide (Tikosyn)
Flecainide (Tambocor)
Although these drugs can help maintain a normal heart rhythm in many people, they can cause side effects, including:
Nausea
Dizziness
Fatigue
Rarely, they may cause ventricular arrhythmias — life-threatening rhythm disturbances originating in the heart's lower chambers. These medications may be needed indefinitely. Even with medications, the chance of another episode of atrial fibrillation is high.
Heart
rate control
Sometimes atrial
fibrillation can't be converted to a normal heart rhythm. Then the
goal is to slow the heart rate to between 60 and 100 beats a minute
(rate control). Heart rate control can be achieved two ways:
Medications. Doctors have prescribed the medication digoxin (Lanoxin). It can control heart rate at rest, but not as well during activity. Most people require additional or alternative medications, such as calcium channel blockers or beta blockers. Other blood pressure lowering medications, such as angiotensin-converting enzyme (ACE) inhibitors, also are sometimes used to lower blood pressure and reduce the risk of atrial fibrillation complications.
Atrioventricular (AV) node ablation. If medications don't work, or you have side effects, AV node ablation may be another option. The procedure involves applying radiofrequency energy to the pathway connecting the upper and lower chambers of your heart (AV node) through a long, thin tube (catheter) to destroy this small area of tissue.
The procedure prevents the atria from sending electrical impulses to the ventricles. The atria continue to fibrillate, though, and anticoagulant medication is still required. A pacemaker is then implanted to establish a normal rhythm. After AV node ablation, you'll need to continue to take blood-thinning medications to reduce the risk of stroke, because your heart rhythm is still atrial fibrillation.
Other
surgical and catheter procedures
Sometimes medications or cardioversion to control atrial
fibrillation doesn't work. In those cases, your doctor may recommend
a procedure to destroy the area of heart tissue that's causing the
erratic electrical signals and restore your heart to a normal rhythm.
These options can include:
Radiofrequency catheter ablation. In many people who have atrial fibrillation and an otherwise normal heart, atrial fibrillation is caused by rapidly discharging triggers, or "hot spots." These hot spots are like abnormal pacemaker cells that fire so rapidly that the upper chambers of your heart quiver instead of beating efficiently.
Radiofrequency energy is directed to these hot spots through a catheter inserted in an artery near your groin and threaded up to your heart. This catheter is used to destroy these hot spots, scarring the tissue so the erratic electrical signals are normalized. This corrects the arrhythmia without the need for medications or implantable devices. In some cases, other types of catheters that can freeze the heart tissue (cryotherapy) are used.
Surgical maze procedure. The maze procedure is done during an open-heart surgery. Using a scalpel, doctors create several precise incisions in the upper chambers of your heart to create a pattern of scar tissue. Because scar tissue doesn't carry electricity, it interferes with stray electrical impulses that cause atrial fibrillation. Radiofrequency or cryotherapy also can be used to create the scars, and there are several variations of the surgical maze technique. The procedure has a high success rate, but because it usually requires open-heart surgery, it's generally reserved for people who don't respond to other treatments or when it can be done during other necessary heart surgery, such as coronary artery bypass surgery or heart valve repair. Some people need a pacemaker implanted after the procedure.
Preventing
blood clots
Most people who
have atrial fibrillation or who are undergoing certain treatments for
atrial fibrillation are at especially high risk of blood clots that
can lead to stroke. The risk is even higher if other heart disease is
present along with atrial fibrillation. Your doctor may prescribe
blood-thinning medications (anticoagulants) such as:
Warfarin (Coumadin). If you're prescribed warfarin, carefully follow your doctor's instructions on taking it. Warfarin is a powerful medication that can have dangerous side effects. You'll need to have regular blood tests to monitor warfarin's effects.
Dabigatran (Pradaxa). Another option for preventing blood clots is dabigatran. Dabigatran is as effective as warfarin at preventing blood clots that can lead to strokes, and doesn't require blood tests to make sure you're getting the proper dose. Talk to your doctor about taking dabigatran as an alternative to warfarin if you're concerned about your risk of stroke.
Rivaroxaban (Xarelto). Rivaroxaban is another anticoagulant medication that's as effective as warfarin for preventing strokes. Rivaroxaban is a once-daily medication. Like any other anticoagulant, follow your doctor's dosing instructions carefully and don't stop taking rivaroxaban without talking to your doctor first.
You may need to take medications to prevent blood clots in addition to medications designed to treat your irregular heartbeat. Many people have spells of atrial fibrillation and don't even know it — so you may need lifelong anticoagulants even after your rhythm has been restored to normal.
You may need to make lifestyle changes that improve the overall health of your heart, especially to prevent or treat conditions such as high blood pressure. Your doctor may suggest that you:
Eat heart-healthy foods
Use less salt, which can help lower blood pressure
Increase your physical activity
Quit smoking
Avoid drinking more than one drink of alcohol for women or more than two drinks for men a day
There are some things you can do to try to prevent recurrent spells of atrial fibrillation. You may need to reduce or eliminate caffeinated and alcoholic beverages from your diet, because they can sometimes trigger an episode of atrial fibrillation. It's also important to be careful when taking over-the-counter (OTC) medications. Some, such as cold medicines containing pseudoephedrine, contain stimulants that can trigger atrial fibrillation. Also, some OTC medications can have dangerous interactions with anti-arrhythmic medications.