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Atrial Fibrillation

Atrial fibrillation is the term used to describe a special case of the heart, beating with an irregular or abnormal rhythm. Irregularities in the heart beat are generally termed as arrhythmia. It can refer to a situation in which the heart beats too slow, too fast or with an abnormal rhythm. Atrial Fibrillation is the most common type of arrhythmia. It is so called because of the fact that there is a fibrillating or twitching movement of the heart muscles as opposed to their normal coordinated contractions during a heartbeat.

What Causes Atrial Fibrillation?

The heart beats by means of an electrical system. Atrial Fibrillation is caused when there arises some abnormality in the conduction of the electrical signals travelling through the heart causing them to become rapid and irregular. This is a consequence of the damage in the electrical conducting system caused by conditions such as Coronary Artery Disease or High Blood Pressure. These unsystematic electrical signals cause the two upper chambers of the heart, the atria, to contract very fast and erratically or to "fibrillate". As a result, the blood accumulates in the atria and is not completely pumped into the ventricles, the lower chambers of the heart. Thus the coordination between the atria and the ventricles is disrupted.

Atrial Fibrillation is also known to occur in patients without any other indication of a heart disease. This is more frequent in younger people and this condition is referred to as lone atrial fibrillation. Various other causes for Atrial fibrillation include hyperthyroidism or overactive thyroid, alcohol use, pulmonary embolism which refers to a blockage in the main artery of the lung, pneumonia, left ventricular hypertrophy or an enlargement of the ventricular walls, coronary heart disease, high blood pressure, myocardial infarction, age etc.

What are the symptoms of Atrial Fibrillation?

The symptoms associated with Atrial Fibrillation are as follows:

  • Palpitations or rapid, irregular heart beats.
  • Shortness of breath
  • Chest pain
  • Dizziness
  • Fatigue

Atrial Fibrillation affects both men and women. The risk increases with age and according to the statistics, one in four individuals who are aged 40 years or older, will develop Atrial Fibrillation during their lifetime. It is common in people who have diseases such as coronary heart disease, rheumatic heart disease, pericarditis etc. People who are obese or have high blood pressure also have a high risk factor. Atrial Fibrillation can be potentially lethal if left untreated as it leads to consequences like stroke which may further lead to permanent brain damage. The risk of stroke increases with age and if proper anticoagulation therapy is not initiated by means of blood thinners like warfarin, stroke may affect 1.3 percent of people suffering from AF who are 50-59 years old.

How is Atrial Fibrillation Diagnosed?

In some cases patients having Atrial Fibrillation do not experience any direct symptoms suggestive of it. Therefore the condition is diagnosed following a physical examination or an electrocardiogram test in most cases. The doctors may also check the patients medical history and family histories.include:

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, including lifestyle changes, medications, catheter-based procedures and surgery. The type of treatment that is recommended for you is based on your heart rhythm and symptoms.

Medications

Initially, medications are used to treat atrial fibrillation. Medications may include:

Rhythm control medications (anti arrhythmic drugs)

Antiarrhythmic medications help return the heart to its normal sinus rhythm or maintain normal sinus rhythm.

There are several types of rhythm control medications, including: procainamide (Pronestyl); disopyramide (Norpace); flecainide acetate (Tambocor); propafenone (Rythmol); sotalol (Betapace); dofetilide (Tikosyn) and amiodarone (Cordarone).

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. Your doctor may need to prescribe several different anti arrhythmic medications to determine the right one for you.

Some rhythm control medications may actually cause more arrhythmias, so it is important to talk to your doctor about your symptoms and any changes in your condition.

Rate control medications

Rate control medications, such as digoxin (Lanoxin), beta-blockers [metoprolol (Toprol, Lopressor)], and calcium channel blockers such as verapamil (Calan) or diltiazem (Cardizem), are used to help slow the heart rate during atrial fibrillation. These medications do not control the heart rhythm, but do prevent the ventricles from beating too rapidly.

Anticoagulant medications

Anticoagulant or antiplatelet therapy medications, such as warfarin (Coumadin) or aspirin, reduce the risk of blood clots and stroke, but they do not eliminate the risk. Regular blood tests are required when taking Coumadin to evaluate the effectiveness of the drug. Talk to your doctor about the anticoagulant medication that is right for you.

Lifestyle Changes

In addition to taking medications, there are some changes you can make to improve your heart health.

  • If your irregular heart rhythm occurs more often with certain activities, tell your doctor. Sometimes, your medications may need to be adjusted.
  • Quit smoking.
  • Limit your intake of alcohol. Moderation is the key. Ask your doctor for specific alcohol guidelines.
  • Limit the use of 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, as some of these medications contain ingredients that may increase the risk of irregular heart rhythms. Read medication labels 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 atrial fibrillation, or when medications are not tolerated, a procedure may be necessary to treat the abnormal heart rhythm, such as: electrical cardio version, pulmonary vein antrum isolation procedure, ablation of the AV node followed by pacemaker placement, or surgical ablation (Maze procedure or minimally invasive surgical treatment).

Electrical cardio version : A cardio version electrically "resets" the heart. Medications alone are not always effective in converting atrial fibrillation to a more normal rhythm. Sometimes cardio version is used to restore a normal heart rhythm and allow the medication to successfully maintain the normal rhythm. Cardio version frequently restores a normal rhythm, although its effect may not be permanent. After a short-acting anesthesia is given that puts the patient to sleep, an electrical shock is delivered through patches placed on the chest wall. This shock will synchronize the heartbeat and restore a normal rhythm.

Catheter ablation : Catheter ablation may be an option for people who cannot tolerate medications or when medications are not effective in maintaining a normal heart rhythm. Pulmonary vein ablation and ablation of the AV node are the two types of catheter ablation procedures used to treat atrial fibrillation. Both are performed by an electro physiologist (doctor who specializes in treating heart rhythm conditions).

Because atrial fibrillation usually begins in the pulmonary veins or at their attachment to the left atrium, energy is applied around the connections of the pulmonary veins to the left atrium during the pulmonary vein ablation procedure (also called pulmonary vein antrum isolation or PVAI).

First, the doctor inserts catheters (long, flexible tubes) into the blood vessels of the leg, and sometimes the neck, and guides the catheters into the atrium. Energy is delivered through the tip of the catheter to the tissue targeted for ablation. Frequently, other areas involved in triggering or maintaining atrial fibrillation are also targeted.

Small circular scars eventually form and prevent the abnormal signals that cause atrial fibrillation from reaching the rest of the atrium. However, the scars created during this procedure may take from 2 to 3 months to form. Once the scars form, they block any impulses firing from within the pulmonary veins, thereby electrically "disconnecting" them or "isolating" them from the heart. This allows the SA node to once again direct the heart rhythm and a normal sinus rhythm is restored.

Because it takes several weeks for the lesions to heal and form scars, it is common to experience atrial fibrillation early during the recovery period. Rarely, atrial fibrillation may be worse for a few weeks after the procedure and may be related to inflammation where the lesions were created. In most patients, these episodes subside within 1 to 3 months.

Ablation of the AV node : During this type of 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. This prevents the electrical signals of the atrium from reaching the ventricle. This result is permanent, and therefore, the patient needs a permanent pacemaker to maintain an adequate heart rate. Although this procedure can reduce atrial fibrillation symptoms, it does not cure the condition. Because the patient will continue to have atrial fibrillation, 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

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

Certain patients are candidates for surgical treatment of atrial fibrillation. These include patients with one or more of the following characteristics:

  • Atrial fibrillation that persists after optimal treatment with medications
  • Unsuccessful catheter ablation
  • metoprolol (Lopressor, Lopressor LA, Toprol XL)
  • Blood clots in the left atrium
  • History of stroke
  • Enlarged left atrium
  • Other conditions requiring heart surgery

During the Maze procedure, a series of precise incisions or lesions are made in the right and left atria to confine the electrical impulses to defined pathways to reach the AV node. These incisions prevent the abnormal impulses from affecting the atria and causing atrial fibrillation.

The surgical Maze procedure can be performed traditionally with a technique in which precise surgical scars are created in the atria. It may also be performed using newer technologies designed to create lines of conduction block with radiofrequency, microwave, laser, ultrasound or cryothermy (freezing). With these techniques, lesions and ultimately scar tissue is created to block the abnormal electrical impulses from being conducted through the heart and to 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.

Your doctor will talk with you about the procedure that is best for you based on your medical condition.

If a patient has atrial fibrillation and requires surgery to treat other heart problems (such as valve disease or coronary artery disease), the surgeon may perform the surgical treatment for atrial fibrillation at the same time. Virtually all surgical approaches include excision or exclusion of the atrial appendage. 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 is removed and the tissue is closed with a special stapling device.