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 get worse and lead to ventricular fibrillation, which can be life-threatening.

Ventricular tachycardia is a fast but regular rhythm. It can lead to ventricular fibrillation which is fast and irregular. With ventricular fibrillation, the heart beats are so fast and irregular that the heart stops pumping blood. Ventricular fibrillation is a leading cause of sudden cardiac death.

What causes ventricular tachycardia?

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

Some medicines—including antiarrhythmic medicines, which are 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) also may cause ventricular tachycardia. 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. Ventricular tachycardia can be life-threatening.

Symptoms include:

• 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).
• Weak pulse or no pulse.

This heart rhythm is dangerous for most people. If it lasts more than just a few seconds, it can turn into ventricular fibrillation which causes sudden death.

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, it is a medical emergency. You will require immediate treatment. You may need CPR or a shock from an automatic defibrillator (also known as an AED). Paramedics or your doctor may try intravenous medicines or electrical cardioversion to return your heart to a normal rhythm.

To prevent the arrhythmia from recurring, you may need to take antiarrhythmic medicines. But these medicines 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. After a normal rhythm is restored, the device goes back to continuous monitoring mode. Sometimes, both medicines and an ICD are needed.

Heart Rate Problems: Should I Get an ICD?

In some cases a procedure called 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, heat or freezing cold temperatures can be delivered to the specific heart tissue that is generating abnormal electrical impulses (previously located in the EP study). The heat or freezing cold destroy (ablate) this heart tissue and can stop ventricular tachycardia from happening again.

It is very important that any causes of ventricular tachycardia be identified and treated, if possible. For example, if the ventricular tachycardia results from a medicine, the medicine needs to be stopped.

What precautions should you take?

If you have had an episode of ventricular tachycardia or ventricular fibrillation, your doctor may recommend that you don't drive a car for a few months. This precaution is to make sure you don't have any other episodes that could make driving unsafe.

If you want to lose weight, do not use diets that rely on a liquid-based program or a high-protein regimen. These types of diets can affect the concentrations of electrolytes in your blood. This can, in turn, cause problems with your heart.

When to call a doctor

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

If you have an ICD

If you have an ICD, be sure you have a plan for what to do if you get a shock. Talk to your doctor if you need to make a plan. In general, your plan depends on how you feel after you get a shock and how many times you get a shock.

After one shock:

• Call 911 or other emergency services immediately if you feel bad or have symptoms like chest pain.
• Call your doctor soon if you feel fine right way. Your doctor may want to talk about the shock and schedule a follow-up visit.

After a second shock within 24 hours:

• Call your doctor immediately, even if you feel fine right away.