Sunday June 29th 2014

- Patients stories

Donald F. Seemann

ICD for Ventricular Fibrillation

    Syndicated Columnist Judy Foreman

    On undergoing Catheter Ablation.

    Former Vice-President Richard Cheney

Why former Vice President Richard Cheney has an ICD.

    Author Deborah Daw Heffernan

    Living with an ICD.

    Roger Blanchette

    Sudden Cardiac Death, a survivor's story.

    Lawrence Beckmen

After frightening episodes of fainting, Lawrence Beckmen's healthy and happy lifestyle was restored.

    Sebastian Hitzig

    Millions of patients have been helped by pacemakers and ICDs. No story is as remarkable as that of Sebastian Hitzig.


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The Normal Heart
signs and symptoms
Heart Diseases &Disorders
Substances Causing Arrhythmia

Risk Factors and Preventionon


Ejection Fraction

Atrial Fibrilliation

Atrial Fibrillation causes

Non cardiovascular syncope

Patients quiz


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Cardiac arrest

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Tilt table

Too fast heart beat

Long QT syndrome

Heart failure prevention

Heart failure risks

What to ask your doctor?

When to see a specialist?

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NASPE-Heart Rhythm Society is located at Six Strathmore Road, Natick, MA 01760 Phone: 508-647-0100 Fax: 508-647-0124
Copyright NASPE-Heart Rhythm Society

 Atrial Fibrillation (also called AF or A Fib) is a common heart rhythm disorder caused by a problem in the conduction of electrical impulses in the upper chambers, or atria, of the heart. A Fib and other rapid heartbeats that arise in the atria, or in the juncture between the atria and the lower chambers (ventricles) are called "supraventricular tachycardias."

More than 2 million people in the U.S. have A Fib, and about 160,000 new cases are diagnosed each year. A Fib is uncommon among young people, although it can occur in people of any age. The likelihood of developing the condition, however, increases as we get older. After age 65, between 3 percent and 5 percent of people have atrial fibrillation. Approximately 9 percent of people who are age 80 or older have the condition.

Atrial flutter (AFL) is another supraventricular (above the ventricles) tachycardia (rapid heartbeat) that is very similar to atrial fibrillation. Instead of many disorganized signals, however, AFL is caused by a single electrical wave that circulates very rapidly in the atrium.

What Causes A Fib?

In A Fib, the electrical signals that coordinate the muscle of the upper chambers (atria) of the heart become rapid and disorganized, typically causing the atria to beat faster than 300 beats per minute. (The normal rate when the heart is at rest is about 60 to 80 beats per minute). When this happens, the atria may contract poorly and no longer effectively force blood into the lower chambers (ventricles). As a result, the flow of blood to the body may be reduced. Atrial fibrillation may occur from time-to-time, or it may be a permanent condition.

Types of Atrial Fibrillation

Paroxysmal A Fib. Episodes of A Fib that end spontaneously are called paroxysmal A Fib. This type of atrial fibrillation usually comes on suddenly, and its symptoms can range from mild to severe. The irregular heart rhythm may last for a few seconds, minutes, hours or longer before the heart resumes a normal rhythm on its own.

Persistent A Fib. With this condition, the irregular heart rhythm continues indefinitely unless it is treated. According to a study conducted by the Canadian Registry of Atrial Fibrillation (CARAF), many patients with paroxysmal A Fib will progress over the course of several years to persistent A Fib.

Permanent A Fib. In this situation, normal rhythm cannot be restored. 

Health Risks

In younger people who have no other disease that affects the heart, atrial fibrillation or flutter usually is not considered serious. Some people with atrial fibrillation, however, are at increased risk of stroke, heart failure or heart muscle disease.

Sometimes, A Fib can damage heart muscle and alter the normal electrical signals to the heart. This may change the patterns of contraction and relaxation of heart muscle. This is known as electrical remodeling.

According to the Framingham Heart Study, people with A Fib or flutter have a 3 to 5 times greater risk of stroke, especially individuals who are older than 65, have already had a stroke, or have high blood pressure, diabetes or congestive heart failure.

An Increased Risk of Stroke

During an episode of A Fib or AFL, the heart muscle does not contract normally to force open the heart valves that pass blood from the atrium to the ventricle. The valve opens passively, but some blood may not enter the ventricle as it should. Instead, it pools in parts of the atrium, increasing the risk that clots will form in the stagnant blood. Even small blood clots can cause problems if they leave the heart and are released into the general circulation. They may clog arteries in the body and disrupt the blood supply to vital organs. A stroke occurs when a clot lodges in the arteries that supply blood to the brain.

Atrial Flutter

Atrial flutter (AFL) is very similar to atrial fibrillation. Both conditions are types of supraventricular (above the ventricles) tachycardia (rapid heart beat). This means that the upper chambers (atria) of the heart beat too fast. This produces muscle contractions that are out of sync with the lower chambers (ventricles).

Sometimes, the muscle of the atria contracts, or beats, as many as 250 to 400 beats per minute. Usually the individual's pulse may be less rapid. This is because the heart has a built-in "gate" (the atrioventricular (AV) node) that controls the number of electrical impulses that travel from the atria to the ventricles.

The pumping of the heart is controlled by steady electrical signals produced by the heart's natural  pacemaker, the sinoatrial (SA) node, located in the right atrium. The SA node passes signals through the atria to the atrioventricular (AV) node. The AV node is the electrical "gate" or "junction box" that receives the signals and passes them along to the ventricles. When the AV node receives signals that are too rapid, such as in atrial flutter (and A Fib) its job is to slow them down so that there will be enough time for the blood in the atria to enter the ventricles. The signals passed from the AV node travel along fibers called bundle branches, causing the ventricles to contract and pump blood out to the body.

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