What is ventricular tachycardia?

Ventricular tachycardia (say "ven-TRICK-yuh-ler tack-ih-KAR-dee-uh"), or VT, is a type of fast heart rhythm. It starts in the lower part of the heart (ventricles).

Some forms of VT may get worse and lead to ventricular fibrillation. Both conditions can be life-threatening.

What causes it?

Sometimes it's not known what causes VT. But in most cases, it's caused by heart disease. This includes having a previous heart attack or congenital heart disease. It also includes hypertrophic cardiomyopathy, dilated cardiomyopathy, and myocarditis. Sometimes VT occurs after heart surgery. Inherited heart rhythm problems can also cause VT. These include long QT syndrome and Brugada syndrome.

Some medicines can cause VT. These include antiarrhythmic medicines, other heart medicines, and antibiotics. Less common causes include blood imbalances. Examples are low potassium levels and other electrolyte imbalances.

Herbal remedies that contain ephedra, also known as ma huang, can trigger VT. Drugs (such as stimulants, like cocaine) also may cause it.

What are the symptoms?

VT may not cause symptoms. When it does, you may feel dizzy or light-headed. You may have shortness of breath and chest pain or pressure. You may have palpitations. These are an uncomfortable awareness of the heart beating very fast or not in a regular way. Or you may faint or nearly faint.

How is VT diagnosed?

Your doctor will do an exam and ask about your past health.

Your doctor will also do an electrocardiogram (EKG, ECG). This is a tracing of the electrical activity of your heart. VT can come and go. It may be hard to capture with an EKG at your doctor's office. So the doctor may want you to wear a heart monitor. It records your heart rhythm over a few days or longer.

You may have lab tests and a chest X-ray.

Your doctor may also recommend other tests, such as:

• Imaging tests, like an echocardiogram. These tests show the structure of your heart.
• A stress test. It can show if the heart muscle is getting enough blood or if heart arteries are narrowed.
• An electrophysiology (EP) study. It can find specific areas of your heart that may be causing the VT.

The results of these tests can help your doctor decide what treatment options you have.

How is it treated?

To prevent VT and relieve symptoms, you may take heart rhythm medicines.

Some people may have a catheter ablation. This procedure destroys small areas of heart tissue that cause the irregular heartbeat. It may make VT happen less often. Or it may stop VT from happening again.

Your doctor may recommend a device that can prevent sudden death. It can detect a life-threatening abnormal heartbeat and help restore a normal rhythm. This device might be implanted (ICD, or implantable cardioverter-defibrillator). Or it might be worn as a vest.

If you have VT that won't stop, it's a medical emergency. You may need a shock to try to get your heart back into a normal rhythm. This can be from an automated external defibrillator (AED), by paramedics, or through treatment in an emergency room. A doctor may give you medicines if your condition is stable.