Atrial fibrillation is an abnormality of heart
rhythm in which chambers of the heart contract in a
disorganized manner, producing an irregular heart
rate. Atrial fibrillation can lead to heart failure
(shortness of breath, edema, palpitations) and chest
pains and, when left untreated, can lead to stroke.
Atrial fibrillation is a common
The condition is
increasingly common with advancing age. It's not
uncommon in people in their 50s and 60s, but it
becomes more common in older age groups.
In atrial fibrillation, the heart's two upper
chambers (atria) beat chaotically (fibrillate). They
also don't beat in coordination with the two lower
chambers of the heart (ventricles). The result is an
irregular and often rapid heart rate.
Atrial fibrillation is often caused by changes in
your heart that occur with age or as a result of
heart disease. It may occur sporadically or be a
Although atrial fibrillation usually isn't
life-threatening, it can lead to complications such
as stroke and
congestive heart failure. Treatments
for atrial fibrillation are individualized. But they
may include medications, surgical procedures and
medical devices that help your heart beat more
Signs and symptoms
heart in atrial fibrillation doesn't beat efficiently. It may not be
able to pump an adequate amount of blood out to your body with each
heartbeat, causing a drop in your blood pressure.
Although some people with atrial fibrillation have no symptoms, others
Short of breath
Atrial fibrillation may also result in these signs and symptoms:
A fast pulse
which are sensations of a racing, uncomfortable, irregular heartbeat
or a flopping in your chest
Atrial fibrillation may occur only once in a while, in which 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. Or you may have chronic atrial fibrillation, in
which symptoms last until they're medically treated.
Some people with atrial fibrillation have no symptoms and are unaware of
their condition until it's discovered by their doctor during a physical
examination. But if you experience frequent palpitations or a fast heart
rate, see your doctor.
To pump blood, your heart muscles must contract and relax in a
coordinated rhythm. Contraction and relaxation are controlled by
electrical signals that travel through your heart muscles.
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 pacemaker. The sinus node produces the impulse that starts
Atrial fibrillation involves a disruption of your heart's electrical
system, which when functioning properly, sends signals from the sinus
node through the atrioventricular (AV) node to the ...
During normal rhythm, the impulse travels first through the atria, 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. A split second later, as the signal passes through the
AV node to the ventricles, the ventricles contract, pumping blood out to
your body. Each contraction is a heartbeat.
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 because the AV node is like a highway on-ramp; only so many
cars can get on at one time. The result is an irregular and fast heart
rhythm. The heart rate in atrial fibrillation may range from 100 to 160
beats a minute. A normal range is 60 to 100 beats a minute.
Abnormalities in the heart's structure are the most common causes of
atrial fibrillation. Diseases affecting the heart's valves or pumping
system also are likely causes, as is long-term high blood pressure.
However, a third of the people who have atrial fibrillation don't have
underlying heart disease. In them, the cause is often unknown. Possible
Damage to the
within individual heart cells
Emphysema or other
Exposure to heart
stimulants, such as caffeine or tobacco, or to alcohol
thyroid or other metabolic imbalance
triggers, or "hot spots" often located in the veins that return
blood from your lungs to your heart (pulmonary veins) that cause
the atria to fibrillate
The older you are, the greater your risk of atrial fibrillation. As you
age, the electrical and structural properties of the atria can change.
This may lead to the breakdown of the normal atrial rhythm.
Screening and diagnosis
To make a diagnosis of atrial fibrillation, your doctor may conduct
cardiac tests such as the following:
Patches with wires (electrodes) are attached to your skin to measure
electrical impulses given off by your heart. Impulses are recorded
as waves displayed on a monitor or printed on paper.
This is a portable version of an ECG. It's especially useful in
diagnosing rhythm disturbances that occur at unpredictable times.
The monitor is worn under your clothing. It records information
about the electrical activity of your heart as you go about your
normal activities for a day or two.
In this test, sound waves are used to produce a video of your heart.
Sound waves are directed at your heart from a wand-like device
(transducer), which is held on your chest. The sound waves that
bounce off your heart are reflected back through your chest wall and
processed electronically to provide video images of your heart in
These help your doctor rule out thyroid problems or blood chemistry
abnormalities that may lead to atrial fibrillation.
In echocardiography, a wand that generates sound waves is positioned
over the heart. This video shows how it works: Reflected sound waves are
processed to produce continuous images of the heart ...
Sometimes, atrial fibrillation can lead to the following complications:
In atrial fibrillation, blood may pool in your heart and form clots.
If a blood clot forms, it might become dislodged 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, a history of heart failure, a previous stroke, and
on other factors. Depending on your medical condition, your risk of
stroke in atrial fibrillation may range from less than 1 percent to
more than 10 percent a year. Medications such as blood thinners can
greatly lower your risk.
Atrial fibrillation 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 for atrial fibrillation may include medications, surgical
procedures and medical devices that help the heart beat more easily. The
goals of treating atrial fibrillation include restoring the heart to a
normal rhythm (rhythm control), slowing the heart rate (rate control)
and preventing blood clots.
Cardioversion: Restoring the heart to a normal rhythm
order to correct atrial fibrillation to reset your heart to its
regular rhythm (sinus rhythm) doctors often perform a procedure called
cardioversion. This can be done in two ways:
This uses medications, called antiarrhythmics, that are designed to
stop the atria's quivering and restore normal sinus rhythm. Commonly
used medications include amiodarone (Cordarone, Pacerone),
propafenone (Rythmol), flecainide (Tambocor) and sotalol (Betapace).
The drugs effectively maintain sinus rhythm for at least one year in
50 percent to 65 percent of people. However, they can cause side
effects such as nausea and fatigue as well as some long-term risks.
In rare instances, they may actually cause an increase in heart
This is a brief procedure in which an electrical shock is delivered
to your heart through paddles or patches placed on your chest. The
shock stops your heart's electrical activity for a split second.
When it begins again, it may resume normal rhythm. The procedure is
performed under light anesthesia. Beforehand, doctors occasionally
prescribe ibutilide (Corvert). This antiarrhythmic medication can
improve the procedure's success rate, especially if electrical
cardioversion alone hasn't achieved sinus rhythm.
Cardioversion isn't always effective. It may successfully restore
regular heart rhythm in more than 90 percent of people, but more than
half of those people will eventually go back into atrial fibrillation.
In many instances, antiarrhythmic medications are needed indefinitely.
Before undergoing cardioversion, you may be given a blood-thinning
medication for several weeks to reduce the risk of blood clots in the
atria and the risk of stroke. Alternatively, you may undergo
transesophageal echocardiography a test to exclude the presence of a
blood clot just before cardioversion. In transesophageal
echocardiography, a tube is passed down your esophagus and detailed
ultrasound images are made of your heart.
Slowing the heart rate
atrial fibrillation can't be converted, the goal is to slow the heart
rate (rate control). Traditionally, doctors have prescribed the
medication digoxin (Lanoxin). It can control heart rate at rest but not
as well during activity. A newer approach is to use calcium channel
blockers or beta blockers. These more consistently control heart rate
both at rest and during activity. In general, your heart rate should be
under 80 beats a minute when you're at rest, and shouldn't exceed 110 to
120 beats a minute when you're moving moderately, such as with a hallway
Preventing blood clots
may be at especially high risk of stroke if you have atrial fibrillation
and heart disease. In this situation, doctors will likely prescribe
blood-thinning medications (anticoagulants), such as warfarin (Coumadin)
or aspirin, in addition to medications designed to treat your irregular
some situations, people with difficult-to-control atrial fibrillation
who haven't been helped by other treatments may benefit from more
invasive techniques, such as:
ablation with pacemaker implantation.
This involves applying radiofrequency energy to your
atrioventricular (AV) node through a long, thin tube (catheter) to
destroy this small area of tissue. The procedure prevents the atria
from sending too many electrical impulses to the ventricles. The
atria continue to fibrillate, though, and anticoagulation medication
is still required. In 98 percent of people, this procedure causes a
complete block of the heart's electrical impulses. A pacemaker is
then implanted to establish a normal rhythm. In a study, 85 percent
of people who had this procedure reported improved quality of life
and increased ability to exercise.
In this open heart surgery, a maze of incisions made in the atria
blocks the flow of excess electrical impulses within the chambers.
The surgery has an 80-percent to 90-percent success rate. Some
people require a pacemaker after the procedure.
A pacemaker is a medical device that helps regulate the heartbeat.
The device, smaller than a matchbox, is placed under the skin near
the collarbone. A wire extends from the device to the heart. If a
pacemaker detects a heart rate that's too slow or no heartbeat at
all, it emits electrical impulses that stimulate your heart to speed
up or begin beating again. The most common use of pacemakers is for
people with atrial fibrillation in one of two situations. First, if
the medications used to prevent atrial fibrillation or control the
heart rate lead to excessively slow heartbeats, then you need a
pacemaker. Second, pacemakers are needed after AV nodal ablation.
For people with occasional atrial fibrillation, new types of
pacemakers may help prevent recurrences. These pacemakers eliminate
irregular heartbeats that can trigger atrial fibrillation, and can
smooth the pulse after atrial fibrillation starts.
In many people with atrial fibrillation and an otherwise relatively
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 atria fibrillate. When
present, these triggers are most commonly found in the pulmonary
veins, the veins that return blood from the lungs to the heart.
Catheter ablation (cautery) to electrically isolate the veins can
stop them from starting atrial fibrillation. In the procedure,
energy is applied through the tip of the catheter at the junction of
the pulmonary veins and the left atrium. This eliminates the
arrhythmia without the need for medications or implantable devices.
This procedure is most likely to work in younger people without
significant valvular heart disease and with frequent atrial
Many people with atrial fibrillation need to make important lifestyle
changes that improve the overall health of their heart. Your doctor may
advise that you eat heart-healthy foods, reduce your salt intake which
can help lower blood pressure increase your physical activity and quit
Mental stress can exacerbate atrial fibrillation. Taking steps to reduce
stress in your life may help calm your nerves and your heart. Cutting
back on caffeine and alcohol, which can over stimulate the heart and
trigger an episode of atrial fibrillation, may also be beneficial.