Ventricular Tachycardia

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Topic Overview

If you have supraventricular tachycardia (SVT), go to the topic Supraventricular Tachycardia.

What is ventricular tachycardia?

Ventricular tachycardia is a fast heart rhythm that starts in the lower part of the heart (ventricles). If left untreated, some forms of ventricular tachycardia may worsen and lead to ventricular fibrillation, which can be life-threatening.

What causes ventricular tachycardia?

Sometimes it is not known what causes ventricular tachycardia, especially when it occurs in young people. However in most cases, ventricular tachycardia is caused by underlying heart disease, such as a previous heart attack, a congenital heart defect, hypertrophic or dilated cardiomyopathy, or myocarditis. Occasionally ventricular tachycardia occurs after heart surgery.

Some medications—including antiarrhythmic medications, used to treat other types of abnormal heart rhythms—can cause ventricular tachycardia. Less common causes include blood imbalances, such as low potassium levels and other electrolyte imbalances.

Nonprescription decongestants, herbal remedies (especially those that contain ma huang or ephedra), diet pills, and "pep" pills often contain stimulants that can trigger episodes of ventricular tachycardia. Illegal drugs (such as stimulants, like cocaine) should also be avoided. It is important to be aware of which substances have an effect on you and how to avoid them.

What are the symptoms?

In ventricular tachycardia, the heart beats too rapidly and the ventricles cannot effectively pump oxygen-rich blood to the rest of the body. This results in:

• Palpitations, an uncomfortable awareness of the heart beating rapidly or irregularly.
• Dizziness or lightheadedness.
• Shortness of breath.
• Chest pain, or angina.
• Near-fainting or fainting (syncope).

Some people who have short bouts of ventricular tachycardia do not have symptoms.

How is ventricular tachycardia diagnosed?

If an electrocardiogram (EKG, ECG) can be performed while ventricular tachycardia is occurring, it often provides the most useful information. An electrocardiogram is a tracing of the electrical activity of your heart. It is usually done along with a history and physical examination, lab tests, and a chest X-ray.

Because ventricular tachycardia can occur intermittently and may not always be captured by an EKG at the doctor's office, you may be asked to use a portable EKG to record your heart rhythm on a continuous basis, usually over a 24-hour period. This is referred to by several names, including ambulatory electrocardiography, ambulatory EKG, Holter monitoring, 24-hour EKG, or cardiac event monitoring.

Your doctor may recommend further tests, including an echocardiogram, to evaluate your heart's function, a stress test or coronary angiogram to determine whether a part of the heart is not getting enough blood, and/or an electrophysiology study. During an electrophysiology (EP) study, electrical currents are sent through a catheter into the heart to try to trigger ventricular tachycardia and record the flow of electricity through the heart. In this way, the EP study can locate specific areas of heart tissue that give rise to abnormal electrical impulses, which may be causing the ventricular tachycardia. This information is used to determine the best treatment.

How is it treated?

If you are having symptoms and are in a sustained tachycardia, you will require immediate treatment. Your doctor will try intravenous medications or electrical cardioversion to return the heart to a normal rhythm.

To prevent the arrhythmia from recurring, you may need to take antiarrhythmic medications. However, these medications may have side effects; so instead doctors often recommend a type of permanent pacemaker, called an implantable cardioverter defibrillator (ICD). This device is placed under the skin in your chest and continuously monitors your heart's rhythm. If ventricular tachycardia occurs, the ICD applies an electrical shock to the heart to restore a normal rhythm. Once a normal rhythm is restored, the device goes back to continuous monitoring mode. Sometimes, both medications and an ICD are necessary.

In some cases a procedure called radiofrequency catheter ablation is used to destroy small areas of heart tissue responsible for the arrhythmia. In this procedure, thin, flexible wires are inserted into a blood vessel in the thigh, groin, neck, or elbow and threaded to the heart. Through these wires, radio waves (radiofrequency energy) can be delivered to the specific heart tissue that is generating abnormal electrical impulses (previously located in the EP study). The radio waves cause the area of heart muscle to be heated and selectively destroyed (ablated), eliminating the ventricular tachycardia.

It is very important that any underlying causes of ventricular tachycardia be identified and treated, if possible. For example, if a low potassium level is causing ventricular tachycardia, it needs to be corrected to prevent a recurrence. If the ventricular tachycardia results from a medication, the medication needs to be stopped. If underlying heart disease caused the ventricular tachycardia, the heart disease needs to be treated. Treating the underlying coronary artery disease provides the best treatment for ventricular tachycardia caused by a heart attack.

What is the latest research?

Several preliminary studies have suggested that omega-3 fatty acids found in fish oil reduce the risk of ventricular tachycardia and sudden death. In a recent small study, omega-3 fatty acids were given to people who had at least one episode of sustained ventricular tachycardia. The omega-3 fatty acids appeared to stabilize heart tissue and reduce the risk of ventricular tachycardia during electrophysiological testing.¹ More studies to determine whether someday fish oil might provide a natural alternative to antiarrhythmic medications are ongoing.

What precautions should I take?

If you have palpitations, dizziness, near-fainting, or chest pain, call 911 or other emergency services immediately.

The American Heart Association recommends that you start driving a car again only when ventricular tachycardia has not recurred after 6 months of treatment.²

People with this condition should avoid caffeine-containing foods, which can trigger ventricular tachycardia. Caffeine is present in coffee, tea, colas, various other soft drinks, and chocolate. Also, fad diets such as liquid-based programs or high-protein regimens can affect the concentrations of electrolytes in your bloodstream; this can, in turn, cause problems with your heart.

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Last updated:	September 26, 2006
Author:	Monica Rhodes
Reviewed By:	Caroline S. Rhoads, MD - Internal Medicine, Laurence Epstein, MD - Cardiac Electrophysiologist
Editors:	Kathleen M. Ariss, MS, Pat Truman