Atrial Fibrillation (AFib)

Written by eHealth Navigator

What is atrial fibrillation (AFib)?

Atrial fibrillation is a type of arrhythmia. With atrial fibrillation, the electrical signals in the atria (the two small chambers of the heart) are fired in a very fast and uncontrolled manner. The atria quiver instead of contract. The electrical signals then arrive in the ventricles in an irregular fashion. When atria do not contract effectively, the blood may pool and/or clot. If a blood clot becomes lodged in an artery in the brain, a stroke (brain attack) may occur. About 15 percent of strokes occur in persons with atrial fibrillation.

What are the symptoms of atrial fibrillation?
•  Racing, irregular heartbeat
•  Fluttering in the chest
•  Heart palpitations
•  Dizziness
•  Shortness of breath
•  Chest pain
•  Weakness
•  Faintness
•  Fatigue when exercising
•  Sweating

However, in some people, atrial fibrillation may cause no symptoms at all.

This is why, as for many people, your doctor may have discovered that you have AFib during a routine physical exam or testing for another condition. Your doctor most likely confirmed your diagnosis through a thorough physical exam and medical history. He or she also likely used an electrocardiogram (note EKG or ECG both stand for electrocardiogram) and other tests to look for the underlying cause of the disorder and any complications.

How is atrial fibrillation treated?

According to the latest recommendations from the American College of Physicians and the American Academy of Family Physicians, for most patients with atrial fibrillation slowing the heart rate with cardiac medication (such as atenolol, metoprolol, diltiazem, or verapamil) is the most common treatment. Patients with atrial fibrillation should receive blood thinners (such as aspirin or wafarin or dabigatran) to prevent stroke unless they have a condition that would make anticoagulation dangerous (such as alcoholism with frequent falls).

Slowing the heart rate to normal is know as cardioversion.

If medications aren't working for you. Catheter ablation and surgical maze procedures would be the next consideration for many patients.
•  Catheter ablation done by an electrophysiologist (a cardiologist specializing in heart rhythms) in the electrophysiology (EP) lab. A catheter-based energy source is inserted through the groin, neck, or arm and threaded to the heart, where it scars the tissue. This is the least invasive of these procedures.
•  Cox Maze (III) procedure is an open-heart surgery done by a cardiothoracic surgeon using a "cut-and-sew" procedure to scar the tissue. It is considered the gold standard for curing atrial fibrillation, but is very complicated and rarely done today and has thus given way to the two procedures below.
•  Maze procedure is a surgical ablation done by a cardiothoracic surgeon. It uses the same open-heart procedure as Cox maze III, but uses an energy source to scar the tissue. It is typically combined with other heart surgery.
•  Mini maze procedure is a minimally-invasive surgical ablation that uses an energy source to scar the tissue. It doesn't require opening the chest, so it has a shorter recovery time. It is less invasive than the other surgery options, and is slightly more invasive than catheter ablation.

Background on how your heart beats?

The electrical heart conduction pathway must be followed to ensure the heart pumps properly. The heartbeat starts in the right atrium when a special group of cells (the sinus node or "pacemaker" of the heart) sends an electrical signal.  The signal spreads throughout the atria and to the atrioventricular (A-V) node.  The A-V node connects to a group of fibers in the ventricles that conduct the electric signal.  The impulse travels down these specialized fibers to all parts of the ventricles.

Normally, as the electrical impulse moves through the heart, the heart contracts - about 60 to 100 times a minute. Each contraction represents one heartbeat. The atria contract a fraction of a second before the ventricles so their blood empties into the ventricles before the ventricles contract.

Under some conditions almost all heart tissue is capable of starting a heartbeat, or becoming the pacemaker. An arrhythmia occurs when:

•  the heart's natural pacemaker develops an abnormal rate or rhythm.
•  the normal conduction pathway is interrupted.
•  another part of the heart takes over as pacemaker.

What is an electrocardiogram (ECG)?

The electrical activity of the heart is measured by an electrocardiogram (ECG or EKG). By placing electrodes at specific locations on the body (chest, arms, and legs), a graphic representation, or tracing, of the electrical activity can be obtained. Changes in an ECG from the normal tracing can indicate arrhythmias, as well as other heart-related conditions.

How does the physician know what an ECG means?

Almost everyone knows what a basic ECG tracing looks like. But what does it mean?

•  The first little upward notch of the ECG tracing is called the "P wave." The P wave indicates that the atria (the two upper chambers of the heart) are electrically stimulated to pump blood to the ventricles.
•  The next part of the tracing is a short downward section connected to a tall upward section. This next part is called the "QRS complex." This part indicates that the ventricles (the two lower chambers of the heart) are electrically stimulated to pump out blood.
•  The next short flat segment is called the "ST segment." The ST segment indicates the amount of time from the end of the contraction of the ventricles to the beginning of the "T wave".
•  The next upward curve is the T wave. The T wave indicates the recovery period of the ventricles.

When your physician studies your ECG, he/she looks at the size and length of each part of the ECG. Variations in size and length of the different parts of the tracing may be significant. The tracing for each lead of a 12-lead ECG will look different, but will have the same basic components as described above. Each lead of the 12-lead is "looking" at a specific part of the heart, so variations in a lead may indicate a problem with the part of the heart associated with the lead.

Last Updated on Tuesday, 17 September 2013 1:51PM