by Carson-DeWitt R

Arrhythmias

Definition

The heart should work in a regular, steady pattern. Arrhythmias are breaks in the pattern. It may happen in a short burst or last over a long periods of time. Arrhythmias may be:
  • Very slow heart rate—bradycardia
  • Very fast heart rate—tachycardia
  • Irregular rhythm
  • Skipped contractions (beats) of the heart
Most will not affect overall health. Some arrhythmias can slow the flow of blood to the body or increase the risk of other health problems such as stroke.

Causes

The action of the heart is controlled by an electrical signal. The signal starts in a group of cells called the sinoatrial (SA) node and moves from the top to the bottom of the heart. The heart will contract first in the upper areas of the heart called the atria and then the lower areas of the heart called the ventricles. Arrhythmias may occur if:
  • The sinus node is damaged and cannot send normal electrical signals
  • The electrical signal cannot travel smoothly through the heart
  • Other influences like hormones or drugs make the SA node overreact
  • Other areas of the heart start an action that does not match the pattern of the SA node
Conduction Pathways of the Heart
IMAGE
Copyright © Nucleus Medical Media, Inc.

Risk Factors

Factors that may increase your risk of arrhythmias include:

Symptoms

Not all arrhythmias will cause symptoms. Some arrhythmias may be felt as a fluttering in the chest, skipped heartbeat, or fast heartbeat.
Arrhythmias that slow the flow of blood through the heart will also slow the flow of blood to the body. If the flow is slowed enough it can lead to:
  • Fainting
  • Lightheadedness
  • Weakness
  • Fatigue
  • Shortness of breath
  • Chest pain

Diagnosis

The doctor will ask about your symptoms, medical history, and family history. A physical exam will be done including listening to your heart, taking your pulse, and looking for any signs of heart problems.
The electrical activity will be checked with one of the following:
  • EKG—Records the heart's activity for a period of time.
  • Holter monitor—An EKG that records heart activity over 24-48 hours. It can help find arrhythmias that do not occur in a regular pattern.
  • Exercise stress test—An EKG that is taken while you do a physical activity. It can help find arrhythmias that only appear with physical stress.
  • Electrophysiological study—Wires are passed through blood vessels to the heart. The wire sends electrical signals to the heart to try to start an arrhythmia. This will help to find where the arrhythmias is starting in the heart.
To help find what may be causing problems or to look for problems of the heart structure the doctor may also order:
  • Blood tests and urine tests—to look for abnormal levels of substances in the blood that may stimulate arrhythmias
  • Imaging tests such as:

Treatment

Not all arrhythmias need to be treated. Many are harmless and will not cause problems. When arrhythmias cause symptoms serious enough to affect your daily life or increase the risk of other conditions, treatment may be needed. The goal of treatment is to return your heart to a normal rhythm. The type of treatment will depend on your specific arrhythmia and your overall health. Options include:
  • Medications—Can be used to slow down or speed up your heart rate. May also fix imbalances in the body that are causing the arrhythmia.
  • Cardioversion—Paddles send an electrical signal to reset the pattern of the heart.
  • Medical device implantation—A device is placed by the heart to track the heart's activity. It can also send an electrical signal to correct dangerous rhythms. Options include:
  • Destruction or scarring of certain areas of the heart to stop the flow of bad electrical signals. It can also stop some signals from starting Options include:
    • Ablation—An area of the heart that starts a bad electrical signal is removed or scarred.
    • Maze procedure and mini-maze procedure—A pattern of scar tissue is made in the upper chambers of the heart. It makes a special path for the electrical signal to pass.

Prevention

Not all arrhythmias can be prevented. To help reduce your chance of certain arrhythmias:
  • Carefully manage other heart or medical conditions that increase the risk of arrhythmias.
  • Avoid substances that trigger arrhythmia or make it worse. This includes caffeine, alcohol, or tobacco.
  • Follow general advice for a healthy heart:
    • Maintain a healthy weight.
    • Talk to your doctor about a safe exercise program .
    • Do not smoke. If you smoke, find out ways you can quit .
    • Eat a healthful diet that is low in saturated fat and rich in whole grains, fruits, and vegetables.

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

Arrhythmias. American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/Arrhythmia/Arrhythmia%5FUCM%5F002013%5FSubHomePage.jsp. Accessed November 8, 2012.
Arrhythmia. Texas Heart Institute website. Available at: http://www.texasheartinstitute.org/HIC/Topics/Cond/Arrhythmia.cfm. Updated October 2012. Accessed November 8, 2012.
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.
Explore arrhythmia. National Heart Lung and Blood website. Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/arr. Updated July 1, 2011. Accessed November 8, 2012.
Sick sinus syndrome. EBSCO DynaMed Plus website. Available at:http://www.dynamed.com/topics/dmp~AN~T113692/Sick-sinus-syndrome. Updated December 8, 2015. Accessed September 29, 2016.
Ventricular arrhythmias. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T909129/Ventricular-arrhythmias. Updated September 27, 2016. Accessed June 28, 2016.

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