Tachycardia is a rapid heart rate of more than 100 beats per minute. Sinus tachycardia, from the heart's sinus node, is a normal response to exercise, illness, or stress.

There are several types of abnormal tachycardias or arrhythmias. These can come from two places:

  • Atria (the two smaller chambers on the top of the heart)—called supraventricular tachycardias
  • Ventricles (the lower chambers of the heart)—called ventricular tachycardia

This condition can be life-threatening, but it can be treated. If you think you or someone you know has this condition, call for emergency medical services right away.

Electrical System and Chambers of the Heart
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This condition is caused by abnormal electrical impulses that control the heart.