Atrial fibrillation
Definition :
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.
Symptoms:
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:
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.
Causes:
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:
Atrial flutter
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.
Complications:
Sometimes atrial fibrillation can lead to the following complications:
Treatments and drugs:
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:
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:
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:
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:
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:
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:
Definition :
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.
Symptoms:
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:
- Palpitations, which are sensations of a racing, uncomfortable, irregular heartbeat or a flopping in your chest
- Decreased blood pressure
- Weakness
- Lightheadedness
- Confusion
- Shortness of breath
- Chest pain
- Occasional. In this case it's called paroxysmal (par-ok-SIZ-mul) 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.
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.
Causes:
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:
- High blood pressure
- Heart attacks
- Abnormal heart valves
- Heart defects you're born with (congenital)
- An overactive thyroid gland or other metabolic imbalance
- Exposure to stimulants such as medications, caffeine or tobacco, or to alcohol
- Sick sinus syndrome — improper functioning of the heart's natural pacemaker
- Emphysema or other lung diseases
- Previous heart surgery
- Viral infections
- Stress due to pneumonia, surgery or other illnesses
- Sleep apnea
Atrial flutter
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.
Complications:
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.
- Heart failure. Atrial fibrillation, especially if not controlled, may weaken the heart, leading to heart failure — a condition in which your heart can't circulate enough blood to meet your body's needs.
Treatments and drugs:
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
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.
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)
- Nausea
- Dizziness
- Fatigue
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.
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.
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.
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