by Wood D

Atrial Fibrillation

Definition

Atrial fibrillation is a fast and abnormal pattern of contractions in the upper part of the heart. The two upper chambers of the heart are called the atria. The main job of the atria is to push blood into the lower chambers of the heart which then send blood out to the body. Atrial fibrillation can decrease the amount of blood that reaches the lower chambers and the body. Blood can also pool in the atria during atrial fibrillation. This increases the risk of blood clots and stroke. Atrial fibrillation may be:
  • Occasional (Paroxysmal)—atrial fibrillation starts and stops over brief periods usually less than 48 hours
  • Persistent—continuous over more than 7 days
  • Longstanding persistent—continuous for more than a year
  • Permanent
Atrial Fibrillation
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Causes

The contractions of the heart are stimulated and controlled by electrical impulses. Normally these impulses start from a collection of cells in the heart called the SA node and travel through the heart in an organized pattern. The top part of the heart normally contracts first, then the lower chambers called the ventricles.
If the electrical signal starts in other areas of the heart or can't travel normally through the heart it can cause atrial fibrillation. The change in electrical signals may be due to:
  • Structural problem or damage of the heart
  • Metabolic disorders—how your body processes food
  • Endocrine disorders—abnormal amounts of hormone in your body
  • Certain medications
Sometimes the cause of atrial fibrillation is unknown.

Risk Factors

Atrial fibrillation is more common in men and in people aged 55 years and older. Other factors that may increase your chance of atrial fibrillation include:
Certain lifestyle habits and dietary options can also stimulate the heart and increase the risk of atrial fibrillation:
  • Smoking
  • Excessive alcohol use
  • Excessive use of stimulants like caffeine
  • Physical and/or emotional stress

Symptoms

Atrial fibrillation may not cause any symptoms. Symptoms that do occur may range from mild to severe depending on the impact of blood flow through the heart and your overall health.
The rapid contractions may cause:
  • Irregular or rapid pulse or heart beat
  • Racing feeling in the chest
  • A pounding feeling in the chest
If the atrial fibrillation is affecting the amount of blood that is being pumped out to the body it may cause:
  • Lightheadedness, which can lead to fainting
  • Sweating
  • Pain or pressure in the chest
  • Shortness of breath
  • Fatigue or weakness
  • Inability or difficulty exercising

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will be done to look for any signs of heart disease. The doctor will also listen to your heart and take your pulse to look for any abnormalities. To examine the electrical activity of your heart you doctor may do the following tests:
  • EKG—electrodes are placed on the skin to measure electrical activity. Generally, over a short period of time while at office or hospital.
  • Holter monitor—EKG that you wear over a 24-48 hours period while you go about normal activities. It can help show abnormal electrical patterns that may be missed during normal EKGs because they do not occur all the time.
  • Stress testing—EKG during exercise to see any arrhythmias that may be associated with physical activity.
To help determine potential causes or look for potential complications your doctor may order:

Treatment

The goal of treatment will depend on the cause of the atrial fibrillation and how much it impacts your life. When possible the overall goal is to stop the fibrillation or slow it down and decrease complications. In some cases, atrial fibrillation may return to normal without treatment.
If a medical condition is causing the atrial fibrillation, treatment will focus on the underlying condition. The doctor may also adjust or eliminate medications that are causing the fibrillation.
Options for atrial fibrillation that needs treatment include:
  • Medication—to help slow the heart rate or keep the heart in a regular rhythm
  • Weight management—reaching or maintaining a healthy weight
  • Cardioversion —This procedure uses an electrical current or drugs to help normalize the heart rhythm.
  • Surgical procedures—to redirect or slow the electrical impulses of the heart
    • Ablation —An area of the heart that is responsible for atrial fibrillation may be surgically removed or altered.
    • Maze procedure and mini-maze procedure —a pattern of scar tissue is created to block fast or irregular impulses.

Medication

Medications may be used to:
  • Slow the heart rate
  • Keep the heart in a regular rhythm
  • Prevent clot formation

Clot and Stroke Prevention

If the atrial fibrillation continues, medication may be recommended to decrease the chance of blood clots. This will decrease the risk of a stroke from blood clots but can also increase the risk of severe bleeding. Most anti-clotting medication require regular monitoring.
If anti-clotting medication can not be tolerated a procedure called left atrial appendage closure (LAAC) may be considered. This procedure seals a small area of the atria where clots tend to form.

Reducing Triggers

Certain habits can increase the incidence or severity of atrial fibrillation. Recommended changes to help manage atrial fibrillation may include:
  • Eliminate smoking
  • Reducing or eliminating caffeine
  • Reducing stress

Prevention

It is not always possible to prevent atrial fibrillation but properly managing chronic medical conditions may help.

RESOURCES

American Heart Association
http://www.heart.org
Heart Rhythm Society
http://www.hrsonline.org

CANADIAN RESOURCES

Canadian Cardiovascular Society
http://www.ccs.ca
Heart and Stroke Foundation
http://www.heartandstroke.com

References

Atrial fibrillation. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115288/Atrial-fibrillation. Updated September 27, 2016. Accessed September 29, 2016.
Atrial fibrillation. CardioSmart website. Available at: http://cardiosmart.org/HeartDisease/CTT.aspx?id=222. Accessed November 9, 2012.
Cardioversion. Cleveland Clinic website. Available at: http://my.clevelandclinic.org/services/heart/services/cversion. Updated December 28, 2011. Accessed November 9, 2012.
Explore atrial fibrillation. National Heart Lung and Blood Institute website. Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/af. Updated July 1, 2011. Accessed November 9, 2012.
Left atrial appendage and closure. Cleveland Clinic website. Available at: http://my.clevelandclinic.org/services/heart/services/arrhythmia-treatment/left-atrial-appendage-closure. Updated May 2016. Accessed July 14, 2016.
12/13/2010 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T115288/Atrial-fibrillation: Lubitz SA, Yin X, et al. Association between familial atrial fibrillation and risk of new-onset atrial fibrillation. JAMA. 2010;304(20):2263-2269.
5/11/2012 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T115288/Atrial-fibrillation: Osbak PS, Mourier M, et al. A randomized study of the effects of exercise training on patients with atrial fibrillation. Am Heart J. 2011;162(6):1080-1087.
1/2/2014 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T115288/Atrial-fibrillation: Abed HS, Wittert GA, et al. Effect of weight reduction and cardiometabolic risk factor management on symptom burden and severity in patients with atrial fibrillation: A randomized clinical trial. JAMA. 2013;310(19):2050-2060.
7/1/2015 DynaMed Plus Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T115288/Atrial-fibrillation: Qureshi WT, O'Neal WT, Khodneva Y, et al. Association between opioid use and atrial fibrillation: The Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. JAMA Intern Med. 2015;175(6):1058-1060.

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