Arrhythmia: Overview

What is arrhythmia?

An arrhythmia is an abnormal heartbeat (too fast, too slow, or irregular) that can cause the heart to pump less blood to the body than it should. Sometimes arrhythmias are harmless. Other times, an arrhythmia is dangerous and can do damage to the heart muscle and the entire body.

In the normal heart, a group of nerves in the upper right heart chamber (right atrium) sends small electrical shocks to the heart muscles that make them contract and expand in a regular, rhythmic fashion. This creates a heartbeat and ensures that the heart is pumping adequate amounts of blood to the body (known as normal cardiac output).

But in some cases, the nerve group doesn't send the correct electrical pulses. In other cases those electrical pulses don't travel through the heart appropriately, or they go too fast or too slow. This creates an arrhythmia.

What types of arrhythmia do we treat?

The most common types of arrhythmia we treat at the Children's Hospital Colorado Arrhythmia Center include:

  • Supraventricular tachycardia (SVT): This condition causes the heart to speed up inappropriately. The rapid heartbeat is usually well-tolerated and stops on its own after about an hour. Other times, the rapid heartbeat does not slow down and causes fainting or lightheadedness, and emergency treatment (911) is necessary.
  • Ventricular tachycardia (VT): In this condition, the heart's electrical impulses originate in the bottom chambers (ventricles) instead of the atria. The impulses are also too fast (like SVT) and are often much more dangerous than SVT.
  • Atrial flutter: In this condition, electrical impulses come from the top of the heart chambers (atria) too quickly. An atrial flutter is usually seen in children following cardiac surgery.