Heart & Vascular Atrial fibrillation

Subject: Heart & Vascular Atrial fibrillation Sun Jan 02, 2011 9:17 pm

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 is an
irregular and often rapid heart rate that commonly causes poor blood
flow to the body and symptoms of heart palpitations, shortness of breath
and weakness.

Atrial fibrillation can also cause fatigue and stroke. It's often caused
by changes in your heart that occur as a result of heart disease or
high blood pressure. 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 medical emergency. 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

Atrial fibrillation may be:

* 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, symptoms may last until they're treated.

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.

Causes

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 muscle.

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 damages 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
* Congenital heart defects
* An overactive thyroid 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

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
Atrial flutter is similar to atrial fibrillation, but slower. If you
have atrial flutter, the abnormal heart 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 common concern in someone with atrial
flutter. As with atrial fibrillation, atrial flutter is usually not
life-threatening when it's properly treated.

Risk factors

Risk factors for atrial fibrillation include:

* Age. The older you are, the greater your risk of developing atrial fibrillation.
* Heart disease. Anyone with heart disease, including valve
problems, history of heart attack and heart surgery, has an increased
risk of atrial fibrillation.
* High blood pressure. Having high blood pressure, especially if
it's not well controlled with lifestyle changes or medications, can
increase your risk of atrial fibrillation.
* Other chronic conditions. People with thyroid problems, sleep
apnea and other medical problems have an increased risk of atrial
fibrillation.
* Drinking alcohol. For some people, drinking alcohol can trigger an
episode of atrial fibrillation. Binge drinking — having five drinks in
two hours for men, or four drinks for women — may put you at higher
risk.
* Family history. An increased risk of atrial fibrillation runs in some families.

Complications

Sometimes atrial fibrillation can lead to the following complications:

*

Stroke. In atrial fibrillation, the chaotic rhythm may cause blood
to pool in your 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.

Preparing for your appointment

If you think you may have atrial fibrillation, it is urgent 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

* Be aware of any pre-appointment restrictions. At the time you make
the appointment, be sure to ask if there's anything you need to do in
advance, such as restrict your dietary intake. You may need to do this
if your doctor orders blood tests.
* Write down any symptoms you're experiencing, including any that may seem unrelated to atrial fibrillation.
* Write down key personal information, including any family history
of heart disease, stroke, high blood pressure or diabetes, and any major
stresses or recent life changes.
* Make a list of all medications, as well as any vitamins or supplements that you're taking.
* Take a family member or friend along, if possible. Sometimes it
can be difficult to soak up all the information provided to you during
an appointment. Someone who accompanies you may remember something that
you missed or forgot.
* Write down questions to ask your doctor.

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:

* What is likely causing my symptoms or condition?
* What are other possible causes for my symptoms or condition?
* What kinds of tests will I need?
* What is the best course of action?
* What foods should I eat or avoid?
* What's an appropriate level of physical activity?
* How often should I be screened for heart disease or other complications of atrial fibrillation?
* What are the alternatives to the primary approach that you're suggesting?
* I have other health conditions. How can I best manage them together?
* Are there any restrictions that I need to follow?
* Should I see a specialist? What will that cost, and will my
insurance cover seeing a specialist? (You may need to ask your insurance
provider directly for information about coverage.)
* Is there a generic alternative to the medicine you're prescribing?
* Are there any brochures or other printed material that I can take home with me? What Web sites do you recommend visiting?
* 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:

* When did you first begin experiencing symptoms?
* Have your symptoms been continuous, or occasional?
* How severe are your symptoms?
* What, if anything, seems to improve your symptoms?
* What, if anything, appears to worsen your symptoms?

Tests and diagnosis

To diagnose atrial fibrillation, your doctor may do tests that involve the following:

* Electrocardiogram (ECG). In this noninvasive test, 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.
* Holter monitor. This is a portable machine that records all of
your heartbeats. You wear the monitor 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. You can press a button if you
feel symptoms, so your doctor can know what heart rhythm was present at
that moment.
* Event recorder. This device is similar to a Holter monitor except
that not all of your heartbeats are recorded. There are two recorder
types: One uses a phone to transmit signals from the recorder while
you're experiencing symptoms. The other type is worn all the time
(except while showering) for as long as a month. Event recorders are
especially useful in diagnosing rhythm disturbances that occur at
unpredictable times.
* Echocardiogram. In this noninvasive test, sound waves are used to
produce a video image of your heart. Sound waves are directed at your
heart from a wand-like device (transducer) that's held on your chest.
The sound waves that bounce off your heart are reflected through your
chest wall and processed electronically to provide video images of your
heart in motion, to detect underlying structural heart disease.
* Blood tests. These help your doctor rule out thyroid problems or
other substances in your blood that may lead to atrial fibrillation.
* Chest X-ray. X-ray images help your doctor see the condition of
your lungs and heart. Your doctor can also use an X-ray to diagnose
conditions other than atrial fibrillation that may explain your signs
and symptoms.

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

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 during anesthesia.

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)
* Propafenone (Rythmol)
* Sotalol (Betapace)
* Dofetilide (Tikosyn)

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. Traditionally, 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.
*

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 radio frequency 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 directed to these hot spots through a
catheter inserted in an artery near your collarbone or leg may be 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 often 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 can also 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) 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. 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.

Lifestyle and home remedies

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
* Reduce your salt intake, 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

Prevention

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.

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