Ventricular tachycardia (v-tach or VT) is a very fast heart rhythm that begins in the ventricles. The condition most commonly affects people who have heart disorders, such as coronary artery disease and cardiomyopathy.

A heart rhythm is considered ventricular tachycardia if it has more than 100 beats per minute, with at least three ventricular heartbeats in a row. It’s caused by a malfunction in the heart’s electrical system.

Ventricular tachycardia may only last for a few seconds or for much longer. It may not cause symptoms, but when symptoms do occur, they may include lightheadedness, dizziness, and fainting.

Ventricular tachycardia VT heart rate compared with normal heart rate infographic Share on Pinterest
Illustration by Antonio Jimenez

Ventricular tachycardia may eventually lead to low blood pressure and ventricular fibrillation, a condition in which the heart beats in a rapid, inadequate heart rhythm. In this condition, the heartbeat is so fast and irregular that it causes the heart to stop working. This can be fatal.

It’s important to get prompt treatment for this condition.

Keep reading to learn the symptoms, causes, risk factors, and treatment for ventricular tachycardia.

If it lasts only a short length of time, there may be no observable symptoms of ventricular tachycardia.

Symptoms of ventricular tachycardia may include:

Those who experience ventricular tachycardia for 30 seconds or longer may experience a drop in blood pressure or unstable blood pressure. This may mean that not enough blood is being delivered to the organs. This may be fatal.

Seek immediate emergency medical attention if you suspect someone is experiencing ventricular tachycardia.

Your heart rate is controlled by electrical impulses that trigger each contraction and determine the rhythm of the heart. When this process is disrupted and the electrical signals are sent too quickly, ventricular tachycardia can occur. The rapid heartbeat doesn’t give the ventricles enough time to fill with blood before the heart contracts.

The ventricles are the two lower chambers of the heart. They fill with blood from the top chambers of the heart and send it to the rest of the body. As a result, if you experience ventricular tachycardia, your heart may not be able to pump enough blood to the rest of the body.

The exact cause of ventricular tachycardia isn’t always known. In most cases, it’s triggered by another heart condition.

Known causes of ventricular tachycardia include:

  • Cardiomyopathy. This is a type of heart disease that weakens the heart muscle.
  • Structural heart disease. This form of heart disease may be caused by damage from a previous heart attack or infection, or may result from a heart abnormality present at birth.
  • Ischemic heart disease. This heart disease is caused by narrow heart arteries limiting blood flow to the heart, often due to buildup of plaque. It can also be called coronary heart disease.
  • Heart failure. Heart failure occurs when the heart is too weak to pump enough blood.
  • Myocarditis. Myocarditis happens when the heart muscle is inflamed, most often due to an infection.
  • Long QT syndrome. This condition affects the heart’s normal electrical activity and can either be inherited or acquired.
  • Congenital coronary artery anomalies. This is a rare condition you can be born with where the coronary artery is in an abnormal location.
  • Electrolyte abnormalities. Imbalances in electrolytes, such as magnesium or potassium, in your body may cause ventricular tachycardia.
  • Acid-base abnormalities. Acid-base abnormalities may occur if your blood pH is too acidic or not acidic enough, or too alkaline or not alkaline enough.

Certain forms of ventricular tachycardia are inherited, which means they’re passed down from a parent to a child. These include:

  • catecholaminergic polymorphic ventricular tachycardia
  • arrhythmogenic right ventricular dysplasia
  • long QT syndrome

In rare cases, ventricular tachycardia can be caused by certain medications, excessive caffeine or alcohol consumption, or intense exercise.

You may be more at risk for ventricular tachycardia if you:

  • are an older adult
  • have a heart condition
  • have had a previous heart attack
  • have a family history of ventricular tachycardia

Ventricular tachycardia may cause severe complications, especially the longer it lasts.

The complications may include:

  • Ventricular tachycardia storm. This consists of three or more episodes of sustained ventricular tachycardia in 24 hours. This is associated with poor survival rates both in the short and long term.
  • Heart failure. Without treatment, 30 percent of people with sustained ventricular tachycardia may experience heart failure.
  • Sudden cardiac death. Sustained ventricular tachycardia is associated with a risk for sudden death.

Your doctor will make a diagnosis by performing a physical exam and running certain tests. During the exam, your doctor will listen to your heart, and if you’re responsive, they may ask about your symptoms. They’ll also check your pulse and blood pressure.

If ventricular tachycardia is suspected, your doctor will order certain tests. These may include:

  • Electrocardiogram (ECG). An ECG measures the electrical activity of the heart. It records a picture of the heart’s electrical activity, allowing doctors to spot abnormalities.
  • Cardiac MRI (CMRI). This imaging test uses strong magnets and radio waves to produce clear, cross-sectional images of the heart. This lets doctors look at the heart in more detail.
  • Transesophageal echocardiography. In this procedure, an ultrasound probe is inserted into the esophagus. The probe uses high-frequency sound waves to create detailed images of the heart. These pictures give doctors a better view of the heart structures and valves.

Ventricular tachycardia is an emergency health condition. Doctors may classify this irregular heart rhythm according to the severity.

Classification of ventricular tachycardia is based on:

  • duration, or the length of the episode
  • morphology, or the heartbeat pattern
  • hemodynamic effect, or the effect on the heart’s ability to pump blood

The types of ventricular tachycardia include:

  • nonsustained, which stops spontaneously without causing problems with blood flow
  • sustained, which lasts longer than 30 seconds and causes decreased blood flow
  • monomorphic, in which each heartbeat resembles the next one
  • polymorphic, in which heartbeats vary

The goal of treatment is to correct the heart rhythm immediately and to prevent future episodes. In an emergency, treatment for ventricular tachycardia may include:

  • CPR
  • electrical defibrillation
  • antiarrhythmic medication

Long-term treatment may be needed to prevent heart arrhythmias in the future.

Long-term treatment options can include:

  • Implantable cardioverter defibrillator. This device is placed in the chest or abdomen to correct abnormal heart rhythms. It delivers a shock when it detects an abnormal heart rhythm.
  • Radiofrequency ablation. In this procedure, an electrical current produced by a radio wave destroys abnormal tissues that are causing the heart to beat incorrectly.
  • Antiarrhythmic medication. These drugs slow down your heart rate and help your ventricles fill with blood. However, they aren’t always prescribed because they can cause side effects and, according to a 2017 review of studies, may not be as effective as other methods.
  • Beta blockers. These drugs reduce both the speed and force of your heartbeat while also lowering your blood pressure. Beta blockers can have side effects but may be often prescribed because the risk outweighs them.

The outlook for people with ventricular tachycardia is usually good if treatment is received quickly. When the disorder goes untreated, however, people are at a greater risk for sudden cardiac arrest and other serious conditions.

Implanted devices can help prevent complications from occurring. Once in place, these devices can keep the heart beating and functioning properly by delivering a shock when an irregular rhythm is detected. If you don’t meet the criteria for an implanted device, medication may be prescribed to lower your risk of arrhythmia.

If you have structural heart disease or another risk factor for ventricular tachycardia, there may be ways to lower your risk for developing this heart rhythm through medication or an implantable device to regulate your heartbeat.

Other prevention methods may include:

  • avoiding certain drugs that prolong your QT interval — the time it takes for your heart to contract and recover
  • keeping your potassium and magnesium levels in a normal range
  • keeping thyroid and kidney function in the normal range

Ventricular tachycardia is a serious condition where the heart beats with a very fast rhythm. If this rapid heartbeat is sustained longer than 30 seconds, it can mean that the heart cannot pump enough blood to the body. This can lead to sudden cardiac death.

Ventricular tachycardia most often occurs in those with structural heart disease or other heart conditions.

This condition can be successfully treated with medication and implantable devices to regulate your heartbeat.