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Electrocardiogram of a normal heart rhythm

 Electrocardiogram of ventricular tachycardia

Alternative Names
irregular heartbeat

An arrhythmia of the heart is an abnormality of the rhythm or rate of the heartbeat. The arrhythmia is caused by a disturbance of the normal electrical activity within the heart.

What is going on in the body?
Arrhythmias can be divided into 2 main groups: tachycardias and bradycardias. Tachycardias cause a rapid heartbeat, with over 100 beats per minute. Bradycardias cause a slow heartbeat, with less than 60 beats per minute. The rhythm of the heart may be regular during an arrhythmia. In other words, each beat of the atria, or upper chambers of the heart, is followed by one beat of the ventricles, or lower chambers of the heart. The beat may also be irregular and may begin in an abnormal area of the heart.

What are the signs and symptoms of the condition?
Symptoms vary depending on the type of arrhythmia, but may include: What are the causes and risks of the condition?
Most arrhythmias are caused by heart disease, including: Arrhythmias may also be caused by:
  • disease in the electrical system of the heart
  • chemicals such as adrenaline, alcohol, or caffeine
  • certain prescription medications, including tricyclic antidepressants, such as amitriptyline and nortriptyline
  • certain over-the-counter medications, such as pseudoephedrine
Arrhythmias may or may not be life threatening. In general, arrhythmias that begin in the upper part of the heart are less dangerous than those that begin in the lower chambers.

What can be done to prevent the condition?
A person can reduce the risk for developing arrhythmias by: How is the condition diagnosed?
Arrhythmias can be detected by an electrocardiogram, which shows the pattern of electrical activity within the heart muscle. A device called a Holter monitor can also be used. This device records all heartbeats within a 24-hour period.

More complicated arrhythmias can be identified by a cardiac catheterisation. In this procedure, a doctor inserts a catheter into the heart through a vein in the leg. The electrical impulses of the heart can then be measured to determine exactly what type of arrhythmia is present.

What are the long-term effects of the condition?
Untreated arrhythmias can cause heart attacks, strokes, and even death.

What are the risks to others?
Arrhythmias are not contagious and pose no risk to others.

What are the treatments for the condition?
Different treatments are available, depending on the type of arrhythmia being treated. Medications such as amiodarone, procainamide, and propranolol can be used to control the rate or restore the rhythm of the heart.

Calcium channel blockers, such as verapamil, have been used over 20 years. However, findings of two recent studies show that people who take a calcium channel blocker have a much higher incidence of complications than people taking other medications for heart disease. One study, for example, found that the risk of heart attack was 27% greater, and the risk of congestive heart failure was 26% higher.

A pacemaker may be inserted to control an arrhythmia or speed up a heart that is beating too slowly. Certain types of implantable pacemakers called cardiac defibrillators can sense a life-threatening arrhythmia and send an electrical shock to the heart. Often a person's life can be saved this way without a trip to the hospital.

What are the side effects of the treatments?
The side effects of treatment for arrhythmias vary according to the medications used, but include allergic reactions. Calcium channel blockers can cause swelling of the legs, as well as a higher risk of heart attack and congestive heart failure.

Implanting a pacemaker is a minor surgical procedure, with some risk of infection, bleeding, and allergic reaction to the anaesthesia.

What happens after treatment for the condition?
Unless a severe or life-threatening arrhythmia is present, a person can generally resume normal activities once treatment is successful. Most individuals with a treated arrhythmia are encouraged to begin a regular exercise program. The person should make every effort to reduce coronary risk factors. This may include smoking cessation, control of other diseases such as diabetes and high blood pressure, and eating a healthy diet to minimise heart disease. Medications may need to be adjusted to achieve the best response.

How is the condition monitored?
A person with an arrhythmia will have regular visits with their doctor. The doctor will monitor the effectiveness of medications, and evaluate the need for a pacemaker. Any new or worsening symptoms should be reported to their doctor.

Author: Marvin Kendrick, MD
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Potential conflict of interest information for reviewers available on request

This website and article is not a substitute for independent professional advice. Nothing contained in this website is intended to be used as medical advice and it is not intended to be used to diagnose, treat, cure or prevent any disease, nor should it be used for therapeutic purposes or as a substitute for your own health professional's advice.  All Health and any associated parties do not accept any liability for any injury, loss or damage incurred by use of or reliance on the information.


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