Your heart has its own pacemaker—a system of electrical impulses that helps control the rhythm and the number of times your heart beats per minute. As it beats, the heart muscle squeezes oxygen-rich blood out to the body and then relaxes to fill with blood again. Usually, this happens 60 to 80 times per minute. But if you have supraventricular tachycardia, or SVT, it means your heart beats faster than normal—usually more than 100 beats per minute.
Many people feel their heart race from time to time, for example when they exercise or are under extreme stress. However, SVT is due to a problem with your heart's electrical system. SVT begins in the upper two chambers called the atria. With SVT, your heart is pumping so fast that it does not relax enough to be able to completely fill with blood. This reduces the amount of blood supplied to the brain and body. As a result, you may feel chest tightness, short of breath or dizzy, although some people have no symptoms at all.
In most cases, SVT is not cause for alarm. But if you notice your heart racing or fluttering, you should call your doctor or seek immediate medical care. Learn all you can to stay in tune with your heart's rhythm. Use this condition center to learn more about living with supraventricular tachycardia. You can also read about the latest research, create a list of questions to ask your doctor and much more.