Filed under: Heart & Vascular
Atrial fibrillation is an irregular and often rapid heart rate that commonly causes poor blood flow to the body. During atrial fibrillation, the heart's two upper chambers (the atria) beat chaotically and irregularly — out of coordination with the two lower chambers (the ventricles) of the heart. Atrial fibrillation symptoms include heart palpitations, shortness of breath and weakness.
Episodes of atrial fibrillation can come and go, or you may have chronic atrial fibrillation. Although atrial fibrillation itself usually isn't life-threatening, it is a serious medical condition that sometimes requires emergency treatment. It can lead to complications. Treatments for atrial fibrillation may include medications and other interventions to try to alter the heart's electrical system.
A heart in atrial fibrillation doesn't beat efficiently. It may not be able to pump enough blood out to your body with each heartbeat.
Some people with atrial fibrillation have no symptoms and are unaware of their condition until it's discovered during a physical examination. Those who do have atrial fibrillation symptoms may experience:
Atrial fibrillation may be:
When to see a doctor
If you have any symptoms of atrial fibrillation, make an appointment with your doctor. Your doctor should be able to tell you if your symptoms are caused by atrial fibrillation or another heart arrhythmia.
If you have chest pain, seek emergency medical assistance immediately. Chest pain could signal that you're having a heart attack.
Your heart consists of four chambers — two upper chambers (atria) and two lower chambers (ventricles). Within the upper right chamber of your heart (right atrium) is a group of cells called the sinus node. This is your heart's natural pacemaker. The sinus node produces the impulse that starts each heartbeat.
Normally, the impulse travels first through the atria and then through a connecting pathway between the upper and lower chambers of your heart called the atrioventricular (AV) node. As the signal passes through the atria, they contract, pumping blood from your atria into the ventricles below. As the signal passes through the AV node to the ventricles, the ventricles contract, pumping blood out to your body.
In atrial fibrillation, the upper chambers of your heart (atria) experience chaotic electrical signals. As a result, they quiver. The AV node — the electrical connection between the atria and the ventricles — is overloaded with impulses trying to get through to the ventricles. The ventricles also beat rapidly, but not as rapidly as the atria. The reason is that the AV node is like a highway on-ramp — only so many cars can get on at one time.
The result is 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.
Possible causes of atrial fibrillation
Abnormalities or damage to the heart's structure are the most common cause of atrial fibrillation. Possible causes of atrial fibrillation include:
However, some people who have atrial fibrillation don't have any heart defects or damage, a condition called lone atrial fibrillation. In lone atrial fibrillation, the cause is often unclear, and serious complications are rare.
Atrial flutter is similar to atrial fibrillation, but the rhythm in your atria is more organized and less chaotic than the abnormal patterns common with atrial fibrillation. Sometimes you may have atrial flutter that develops into atrial fibrillation and vice versa. The symptoms, causes and risk factors of atrial flutter are similar to those of atrial fibrillation. For example, strokes are a concern in someone with atrial flutter. As with atrial fibrillation, atrial flutter is usually not life-threatening when it's properly treated.
Risk factors for atrial fibrillation include:
Sometimes atrial fibrillation can lead to the following complications:
Stroke. In atrial fibrillation, the chaotic rhythm may cause blood to pool in your heart's upper chambers (atria) and form clots. If a blood clot forms, it could dislodge from your heart and travel to your brain. There it might block blood flow, causing a stroke.
The risk of stroke in atrial fibrillation depends on your age (you have a higher risk as you age) and on whether you have high blood pressure, diabetes, or a history of heart failure or previous stroke, and other factors. Medications such as blood thinners can greatly lower your risk of stroke or damage to other organs caused by blood clots.
If you think you may have atrial fibrillation, it is critical that you make an appointment with your family doctor. If atrial fibrillation is found early, your treatment may be easier and more effective. Eventually, however, you may be referred to a heart specialist (cardiologist).
Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.
What you can do
Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important, in case time runs out. For atrial fibrillation, some basic questions to ask your doctor include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.
What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may save time to go over any points you want to spend more time on. Your doctor may ask:
To diagnose atrial fibrillation, your doctor may do tests that involve the following:
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:
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:
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:
Although these drugs can help maintain a normal heart rhythm in many people, they can cause side effects, including:
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:
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.
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:
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:
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.