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What
causes atrial fibrillation?
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Most
common causes
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Less
common causes
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- Hyperthyroidism
- Pericarditis
- Viral infection
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In at least ten percent
of the cases, no underlying heart disease is found. In
these cases, AF may be related to alcohol or excessive caffeine use, stress,
certain drugs, electrolyte or metabolic imbalances, or severe infections.
In some cases, no cause can be found.
The risk of AF increases with age, particularly after age 60
How is atrial fibrillation diagnosed?
The most commonly
used tools to diagnose atrial fibrillation include:
- Electrocardiogram
(ECG): The ECG draws a picture on graph paper of the electrical
impulses traveling through the heart muscle.
- Holter
monitor: A small external recorder, worn over a short period
of time, usually one to three days. Electrodes (sticky patches) are
placed on the skin of your chest. Wires are attached from the electrodes
to the monitor. The electrical impulses are continuously recorded and
stored in the monitor. After the monitor is removed, a technician uses
a computer to analyze the data to evaluate the heart's rhythm.
- Portable
event monitor (also called a loop recorder): A monitor that
is worn for about a month for patients who have less frequent arrhythmia
episodes and symptoms. Electrodes (sticky patches) are placed on the
skin of your chest. Wires are attached from the electrodes to the monitor.
The patient presses a button to activate the monitor when symptoms occur.The
device records the electrical activity of the heart several seconds
before and after the event. The patient then transmits the device's
recorded information over a telephone line to the doctor's office for
evaluation.
- Transtelephonic
monitor: When you develop symptoms of atrial fibrillation,
a strip of your current heart rhythm can be transmitted to your doctor's
office over the telephone using a monitor with two bracelets or by placing
the monitor against your chest wall.
These monitoring devices
help the doctor learn if you are having irregular heart beats, what kind
they are, how long they last, as well as what may cause them. Click
here to learn more about diagnostic tests.
What
are the dangers of atrial fibrillation?
Many people live for
years with atrial fibrillation without problems. However, chronic atrial
fibrillation can result in future problems:
- Because the atria
are beating rapidly and irregularly, blood does not flow through them
as quickly. This makes the blood more likely to clot. If the clot is
pumped out of the heart, it can travel to the brain, resulting in a
stroke. People with atrial fibrillation are five to seven times more
likely to have a stroke than the general population. Clots can also
travel to other parts of the body (kidneys, heart, intestines), causing
damage.
- Atrial fibrillation
can decrease the heart's pumping ability by as much as 20 to 25 percent.
Atrial fibrillation, combined with a fast heart rate over a long period
of time, can result in heart failure.
- Chronic atrial
fibrillation is associated with an increased risk of death.
What are the symptoms of atrial fibrillation?
You may have atrial
fibrillation without having any symptoms at all. If you have symptoms,
they may include:
- Heart palpitations
- Sudden pounding, fluttering or racing sensation in the chest
- Lack of
energy or feeling over-tired
- Dizziness
- Feeling lightheaded or faint
- Chest discomfort
- Pain, pressure, or discomfort in the chest
- Shortness
of breath - Having difficulty breathing during normal activities
or even at rest
How
is atrial fibrillation treated?
The goals of treatment
for atrial fibrillation include regaining a normal heart rhythm (sinus
rhythm), controlling the heart rate, preventing blood clots and reducing
the risk of stroke.
Many options are available
to treat atrial fibrillation. These include medications, lifestyle changes,
procedures and surgery. The choice of treatment for you is based on your
heart rhythm and symptoms.
Medications
Initially, medications
are used to treat atrial fibrillation. The medications may include:
- Rhythm
control medications (antiarrhythmic drugs)
These medications help return the heart to its normal sinus rhythm or
maintain normal sinus rhythm. There are several types of rhythm control
medications, including: Quinidex (quinidine); Pronestyl (procainamide);
Norpace (disopyramine); Toprol, Lopressor (metoprolol); Tambocor (flecainide
acetate); Rythmol (propafenone); Betapace (sotalol); Tikosyn (dofetilide)
and Cordarone (amiodarone).
You may have to stay in the hospital when you first start taking these
medications so your heart rhythm and response to the medication can
be carefully monitored. These medications are effective 30 to 60 percent
of the time, but may lose their effectiveness over time. You may need
to try several medications so your doctor can find the best one for
you.
Some rhythm control medications may actually cause more arrhythmias,
so it is important to discuss your symptoms and any changes in your
condition with your doctor.
- Rate control
medications (to slow the heart rate)
Rate control medications, such as Lanoxin (digoxin), beta-blockers (example:
metoprolol) and calcium channel blockers (example: verapamil, diltiazem),
are used to help slow the heart rate during atrial fibrillation. These
medications do not control the heart rhythm.
- Medications
to prevent blood clots and reduce the risk of stroke
Anticoagulant or antiplatelet therapy medications, such as Coumadin
(warfarin), reduce the risk of blood clots and stroke. Although anticoagulant
or antiplatelet drugs reduce the risk of stroke, they do not eliminate
the risk. Regular blood tests are required when taking this medication
to evaluate the effectiveness of the drug.
Some people may be treated with aspirin instead of Coumadin. Talk to
your doctor about the anticoagulant medication that is right for you.
Check the drug
search to find out more about your medications. It is important to
know:
- the names of your
medications
- what they are for
- how often and at
what times to take them
Lifestyle
changes
In addition to taking
medications, there are some changes you can make to improve your heart
health.
- If you notice your
irregular heart rhythm occurs more often with certain activities, you
should avoid them.
- Quit smoking.
- Limit your intake
of alcohol. Moderation is the key. Ask your doctor for specific alcohol
guidelines.
- Limit or stop using
caffeine. Some people are sensitive to caffeine and may notice more
symptoms when using caffeinated products (such as tea, coffee, colas
and some over-the-counter medications).
- Beware of stimulants
used in cough and cold medications. Some of these types of medications
contain ingredients that promote irregular heart rhythms. Read the label
and ask your doctor or pharmacist what type of cold medication is best
for you.
Procedures
When medications do
not work to correct or control AF, or when medications are not tolerated,
a procedure may be necessary, such as: electrical cardioversion, catheter
ablation, pulmonary vein isolation, ablation of the AV node, or device
therapy.
- Electrical
cardioversion: If
medications are not able to control a persistent irregular heart rhythm
(such as AF), cardioversion may be required. Cardioversion frequently
restores a normal rhythm, although its effect may not be permanent.
After a short-acting anesthesia is given, an electrical shock is delivered
to your chest wall to synchronize the heartbeat and restore a normal
rhythm.
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Cardioversion
treatment
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- Catheter
ablation: Catheter
ablation therapy is an option for people who cannot tolerate medications
or when medications fail to maintain a normal heart rhythm.
Two types of ablation
can be performed including pulmonary vein antrum isolation or ablation
of the AV node. Both are performed by an electrophysiologist (doctor
who specializes in treating heart rhythm conditions).
- Pulmonary
vein antrum isolation:
Research has shown that almost all atrial fibrillation signals come
from the four pulmonary veins. During this procedure, special catheters
are inserted into the heart. Two catheters are inserted into the right
atrium and two into the left atrium. The left atrium is accessed through
a transeptal puncture.
Intracardiac echocardiogram
is used to visualize the left atrium during the procedure. One catheter
in the left atrium is used to map or locate the abnormal impulses coming
from the pulmonary veins. The other catheter is used to deliver the
radiofrequency energy to ablate, or create lesions outside the pulmonary
veins. The procedure is repeated for all four pulmonary veins.
The lesions heal
and within 4 to 8 weeks, form a circular scar around the pulmonary veins.
The scar blocks any impulses firing from within the pulmonary veins,
thereby "disconnecting" the pathway of the abnormal rhythm
and curing atrial fibrillation.
Ablation
of the AV node: During an ablation, catheters are
inserted through the veins (usually in the groin) and guided to the
heart. Radiofrequency energy is delivered through the catheter to sever
or injure the AV node. The end result is a permanent, very slow heart
rate because the electrical impulses from the top chamber of the heart
cannot travel down to the lower chamber. Therefore, the patient needs
a permanent pacemaker to maintain an adequate, sufficient heart rate.
This procedure improves atrial fibrillation symptoms, but does not cure
the condition. An anticoagulant medication is prescribed to reduce the
risk of stroke. Important note:
Due to better treatment alternatives, AV node ablation is
rarely used to treat atrial fibrillation.
- Device Therapy
Implantable
atrial defibrillator: a device used to treat AF symptoms.
When the symptoms of AF occur, the person can turn on the device and
treat the AF when appropriate and convenient. Or, the device can be
set to operate automatically. The atrial defibrillator can be programmed
to identify when a person is having an episode of atrial fibrillation.
When it occurs, the device delivers low-dose therapy to convert AF
to a normal heart rhythm. This procedure improves atrial fibrillation
symptoms, but does not cure the condition.
 Permanent
Pacemaker: A pacemaker is a device that sends small electrical
impulses to the heart muscle to maintain a suitable heart rate. Pacemakers
are implanted in people with AF who have a slow heart rate. The pacemaker
has a pulse generator (that houses the battery and a tiny computer)
and leads (wires) that send impulses from the pulse generator to the
heart muscle, as well as sense the heart's electrical activity.
Newer pacemakers
have many sophisticated features, designed to help with the management
of arrhythmias and to optimize heart rate-related function as much
as possible.
Surgical
treatment
Patients with chronic
AF not relieved by medication or procedures, or patients who have other
conditions requiring heart surgery, are candidates for surgical
treatment of atrial fibrillation.
During the Maze
procedure, a series of precise incisions are made in the right
and left atria to confine the electrical impulses to defined pathways
to reach the AV node.
Surgical
Pulmonary vein isolation is a modification of the Maze procedure
in which the surgeon uses alternative energy sources instead of incisions
to create lesions. The alternative energy sources used during surgical
pulmonary vein isolation include: radiofrequency, cryothermy, microwave
and laser. The goal of all four energy sources is to produce lesions and
ultimately scar tissue to block the abnormal electrical impulses from
being conducted through the heart and promote the normal conduction of
impulses through the proper pathway.
Many of these approaches
can be performed with minimally invasive (endoscopic or "keyhole")
surgical techniques.
Radiofrequency
Ablation: A special radiofrequency energy catheter is used to
heat the tissue and produce lesions on the heart similar to the lesions
of the Maze procedure. There are a variety of surgical techniques related
to the type of catheter used, the dose of energy, and the types of lesions
created.
Cryothermy:
(also called cryoablation) Very cold temperatures are transmitted through
a probe (called a cryoprobe) to create lesions. This technique is used
commonly during arrhythmia surgery to replace the incisions made during
the Cox Maze procedure.
Microwave
Technology: A special wand-like catheter is used to direct microwave
energy to create several lesions on the heart. The lesions block the conduction
of abnormal electrical beats and restore a normal heartbeat.
Laser: Lasers
rapidly create the lesions or lines of conduction block. Laser technology
offers promise for the development of additional minimally invasive approaches.
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Excision
of the Left Atrial Appendage
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The
left atrial appendage is a small, ear-shaped tissue flap located
in the left atrium. This tissue is a potential source of blood clots
in patients who have atrial fibrillation. During surgical procedures
to treat atrial fibrillation, the left atrial appendage may be removed
and the tissue is closed with a special stapling device.
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Some patients may
have atrial fibrillation in addition to other heart problems (such as
valve or coronary artery disease), which require surgery. In these cases,
the surgeon may combine the surgical treatment for atrial fibrillation
with other surgical therapies to correct the atrial fibrillation and the
coexisting heart condition.
Click
here for more information about surgical treatment of atrial fibrillation.
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