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About the heart's electrical system

The heart’s electrical system provides the energy to help your child's heart pump blood.

  • Also called the cardiac conduction system
  • An EKG is a graphic picture of the heart’s electrical activity

Your heart’s electrical system controls the pumping of blood. Under normal circumstances, your child’s heart beats 60 to 140 times a minute.

The heart’s electrical system includes:

  • Sinoatrial node
    • Also known as the sinus node or SA node
    • Located in the right atrium
    • The heart’s natural pacemaker
  • Atrioventricular node
    • Also known as the AV node
    • Located on the interatrial septum
  • Bundle of His
    • Also known as the AV bundle or atrioventricular bundle
    • Located on the walls of your heart’s ventricles

Researchers at Boston Children’s Hospital are dedicated to exploring the heart’s electrical system. Ongoing research includes looking at creating replacement heart valves using a patient’s own tissue, the evaluation of radio-frequency ablation to treat arrhythmia, and the study of new drugs in preventing aortic aneurysms.

How does the heart beat?

During a single heartbeat, your child’s heart’s chambers relax and contract to pump blood.

  • The sinoatrial node — or the “pacemaker” — sends an electrical stimulus to initiate pumping.
  • Right and left atria are stimulated first, then the right and left ventricles.
  • The impulse then travels to the atriventural node, through the His, and into the ventricles. His provides electrical stimuli to both ventricles.

Each contraction represents one heartbeat.

How does my child’s heart’s electrical system relate to arrhythmia?

Almost all heart tissue can start a heartbeat, or become the "pacemaker." An arrhythmia may occur when:

  • The Sinoatrial node develops an abnormal rate
  • The normal conduction pathway is interrupted
  • Another part of the heart takes over as pacemaker