Ventricular tachycardia (V-tach or VT) is a potentially life-threatening arrhythmia (abnormal heart rhythm) in which the heart beats too rapidly. It starts in the ventricles, the heart's pumping chambers. More to Know Ventricular tachycardia occurs when electrical signals in the heart muscle are sent too quickly. This is often due to an underlying heart problem such as an enlarged heart (cardiomyopathy), heart valve disease, coronary artery disease, or high blood pressure. Scar tissue that develops following a heart attack or heart surgery can also cause ventricular tachycardia, as can certain medications, electrolyte imbalances, recreational drugs, and other factors. In some cases the cause is unknown. In addition to heart palpitations, or feeling like the heart is racing, symptoms of ventricular tachycardia may include shortness of breath, chest pain, light-headedness and dizziness. Fainting, unconsciousness, cardiac arrest, and even death can occur when the heart rate is dangerously high or an episode of ventricular tachycardia lasts more than a few seconds. For this reason, it’s important to call 911 or go to the emergency room for treatment if you see signs of ventricular tachycardia. Keep in Mind While ventricular tachycardia is a very serious condition, many people see improvement when the underlying condition can be managed. All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts. Back to Articles Related Articles The Heart Your heart beats and sends oxygen throughout your entire body. Find out how it works and how heart problems can be fixed. Read More Arrhythmias Arrhythmias are abnormal heartbeats usually caused by an electrical "short circuit" in the heart. Many are minor and not a significant health threat, but others can indicate a more serious problem. Read More A to Z: Dysrhythmia Learn more about dysrhythmia: an abnormality in the heart's beat or rhythm caused by electrical impulses functioning improperly. Read More Your Heart & Circulatory System Your heart is a hard-working muscle. Find out more in this article for kids. Read More A to Z: Atrial Flutter Atrial flutter is an abnormal heart rhythm that causes the heart to beat too fast. Read More A to Z: Palpitations Learn about arrhythmias and conditions that affect the heart and heartbeat. Read More A to Z: Paroxysmal Supraventricular Tachycardia (PSVT) Paroxysmal supraventricular tachycardia (PSVT) is a type of arrhythmia in which the heart beats very rapidly. Read More A to Z: Tachycardia Learn more about types of arrhythmias and problems of the heart. Read More Arrhythmia (Abnormal Heartbeat) An arrhythmia is an abnormal heartbeat usually caused by an electrical "short circuit" in the heart. Many are minor and not a health threat, but some can indicate a more serious problem. Read More Heart and Circulatory System The heart and circulatory system (also called the cardiovascular system) make up the network that delivers blood to the body's tissues. Read More Heart and Circulatory System The heart and circulatory system are our body's lifeline, delivering blood to the body's tissues. Brush up on your ticker with this body basics article. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.