When your heart beats too fast, the medical term is tachycardia. Two types are supraventricular tachycardia (SVT) and ventricular tachycardia (V-tach). Here’s what you need to know.

Story by: David Steen Martin; Reviewed by Kent E. Morris, M.D. on December 28, 2023

When your heart is beating too fast, the heart doesn’t have time to fill up with the normal amount of blood between beats. As a result, you might feel lightheaded or dizzy.

The medical term for an abnormally fast heart rate is tachycardia. Two types of tachycardia are supraventricular tachycardia (SVT) and ventricular tachycardia (V-tach). Though the names sound similar, they are very different.

The names describe where the abnormal rhythm begins in the heart.

Ventricular tachycardia begins in the lower two chambers, called ventricles. Supraventricular tachycardia begins in the upper two chambers of the heart, above the ventricles. With either SVT or V-tach, the heart can beat 120 times or more times per minute.

In addition to lightheadedness, SVT and V-tach share other common symptoms, including chest pain, weakness or fatigue, and shortness of breath.

SVT versus V-tach

While SVT is usually harmless, V-tach can be life threatening. V-tach can lead to a dangerous abnormal heartbeat called ventricular fibrillation and cardiac arrest.

“SVT and V-tach can feel the same to patients, but they are very different, and they are treated differently,” said Kent E. Morris, M.D., an electrophysiologist with Norton Heart & Vascular Institute Heart Rhythm Center.

SVT is the result of an abnormal electrical pathway in the heart and can be triggered by stress, drinking alcohol or caffeine, smoking cigarettes or as a side effect to some medications.

V-tach is most commonly related to another cardiovascular condition. Patients with V-tach or more likely to have had a heart attack, , coronary artery disease, an enlarged heart or abnormal heart valves.

An electrophysiologist or other provider can distinguish between SVT and V-tach by looking at an electrocardiogram (EKG), which measures the heart’s electrical signals. Each has a telltale signature.

If your V-tach progresses to ventricular fibrillation, your heart beat can reach 300bpm and you would need medical attention right away.

SVT typically lasts a few minutes but can continue for several hours. With V-tach, episodes are shorter but those lasting more than a few seconds can be life threatening.

Because V-tach is life-threatening, seek medical attention to find out if your racing heartbeat is SVT versus V-tach.

If your heart races more than 30 seconds, you should call 911. You may be experiencing a heart emergency, especially if you have other heart conditions or have other symptoms of heart attack. It is unsafe to drive yourself in a heart emergency, even if you are driving a short distance to the emergency department.

SVT may require no treatment. If you know that you experience SVT, there are also simple techniques you can perform on your own to get your fast heartbeat back to normal. Some common interventions are putting a cold washcloth on your face or holding your breath and bearing down. If you continue to have repeat episodes of SVT, there may be medications or minimally invasive procedures that can be done to help reduce or eliminate your episodes.

Because it is more dangerous, V-tach may require stronger medications called antiarrhythmics or a heart ablation procedure to stop the abnormal electrical signals causing the irregular heartbeat. Some people with V-tach need an implantable device called a cardioverter-defibrillator (ICD), which senses abnormal rhythms and sends out electrical impulses to correct them.