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Abnormal Electrical Impulses

Tachycardia is caused by abnormal electrical impulses that control the heart.

Normal Heart Rhythm

Normal Heart Rhythm

Sinus Node Sends Sequential Electrical Impulse

Every beat of your heart begins in the right atrium, one of your heart's two upper chambers. From there, your heart's natural pacemaker, called the sinus node, sends an electrical signal that causes the atria to contract, allowing the ventricles, the lower chambers, to fill with blood.

Electrical Signal Travels Across the AV Node

A split second later, the electrical impulse travels across the atrioventricular (AV) node into the ventricles. This causes the ventricles to contract, pushing blood throughout the body.


Electrical Impulse Interruption

If you have a tachycardia, the electrical impulse process is interrupted somewhere along the electrical path, resulting in a heartbeat that is too rapid.


Tachycardias can be caused by heart-related conditions such as:

  • High blood pressure
  • Coronary artery disease
  • Valve disease
  • Heart failure
  • Thyroid disease
  • Electrolyte imbalances


Triggered by the use of certain substances, such as:

  • Caffeine
  • Alcohol
  • Tobacco
  • Dietary supplements
  • Over-the-counter medications
  • Illegal drugs
  • Prescription drugs

Contact Information

Cardiovascular Medicine
Division of the CardioVascular Institute
Beth Israel Deaconess Medical Center
330 Brookline Avenue
Boston, MA 02215