May also be called: Rapid Heart Rate; Rapid Heartbeat

Tachycardia (tak-ih-KAR-dee-uh) is an abnormally rapid heartbeat.

More to Know

The heart has its own electrical system that controls the heart rate and contraction of the heart, which pumps blood throughout the body. Normal heart rates vary based on a person's age.

A rapid heart rate can be caused by many different factors. Sometimes tachycardia is the body's response to a trigger like fever, anxiety, exercise, or pain, just to name a few. It also can be due to an abnormal rhythm in the heart (called a dysrhythmia), such as supraventricular tachycardia (SVT).

Congenital heart abnormalities, high blood pressure, medications, dehydration, caffeine, smoking, and recreational drug use also can cause tachycardia. Tachycardias can lead to dizziness, shortness of breath, chest pain, fainting, and heart palpitations (a sensation of feeling the heart beat fast or irregularly). Some tachycardias are life threatening and can lead to blood clots, causing a stroke, heart failure, and sudden death.

Keep in Mind

Most tachycardias resolve without causing any problems. However, some require immediate medical attention and can be life threatening if they're not treated. Be sure to talk to your doctor if you are concerned about tachycardia or its related symptoms.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.