Submitted by Dr T on March 12, 2011 – 11:19am
Atrial fibrillation (AF) is a common arrhythmia. There is no single cause of atrial fibrillation, although it is associated with many conditions:
Most common causes
- Hypertension (high blood pressure)
- Coronary artery disease
- Heart valve disease
- After heart surgery
- Chronic lung disease
- Heart failure
- Congenital heart disease
- Pulmonary embolism
Less common causes
- Viral infection
In at least 10 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, severe infections, or genetic factors. In some cases, no cause can be found.The risk of AF increases with age, particularly after age 60.
Symptoms may include :
- Heart palpitations – Sudden pounding, fluttering or racing sensation in the chest
- Lack of energy or feeling over-tired
- Dizziness – Feeling light-headed or faint
- Chest discomfort – Pain, pressure or discomfort in the chest
- Shortness of breath – Having difficulty breathing during normal activities and even at rest
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.
Initially, medications, are used to treat atrial fibrillation. Medications may include :
Rhythm control medications (antiarrhythmic 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 antiarrhythmic 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 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. There are new drugs, just released onto the US market, that promise a much simplified treatment without the need for regular blood tests.
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.
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 cardioversion, 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 cardioversion: A cardioversion electrically “resets” the heart. Medications alone are not always effective in converting atrial fibrillation to a more normal rhythm. Sometimes cardioversion is used to restore a normal heart rhythm and allow the medication to successfully maintain the normal rhythm. Cardioversion 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 electrophysiologist (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.
- 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.
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
- 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.
Excision of the Left Atrial Appendage
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.
(From: What is Atrial Fibrillation? http://my.clevelandclinic.org/heart/atrial_fibrillation/afib.aspx)