Pediatric Arrhythmias
Normal Electrical System Pathway

What is an arrhythmia?

An arrhythmia is any change in the regular, even rhythm of the heartbeat. If your child has an arrhythmia, his or her heart might beat too fast or too slow, or it might skip a beat or have extra beats. An arrhythmia might result from a physical condition — such as a heart defect —or in response to outside factors, such as a fever, infection, and certain medications. Even crying and playing can briefly alter a child’s heart rate.

Most arrhythmias are harmless, but some can be serious and even life-threatening. If your child’s heart beats too fast (a condition known as tachycardia), or too slow (bradycardia), it might affect the heart’s ability to pump blood efficiently to the rest of the body. Irregular blood flow can damage organs, including the kidneys, liver, heart, and brain.

How does an arrhythmia occur?

The pumping action of the heart is powered by an electrical pathway that runs through the nerves in the walls of the heart. With each heartbeat, an electrical signal is generated and travels from the top of the heart to the bottom.

The signal begins in a group of cells in the right atrium (the upper right chamber of the heart) called the sinoatrial node (SA node). From there, the signal travels through special pathways to stimulate the right and left atria, causing them to contract and send blood into the ventricles (the bottom chambers of the heart).

The current continues through its circuit to another group of cells called the atrioventricular node (AV node), which is between the atria and the ventricles. From there, the electric current moves on to another pathway called the bundle of His, where the signal branches out to stimulate the right and left ventricles, causing them to contract and send blood to the lungs and the rest of the body.

When the circuit is working properly, the heart beats at a regular, smooth pace. When something interrupts the circuit, the heartbeat can become irregular, and an arrhythmia occurs.

Types of arrhythmias

There are many types of arrhythmias, which can grouped into three general categories: supraventricular (atrial) arrhythmias, ventricular arrhythmias, and bradyarrhythmias.

Atrial arrhythmias in children include:

  • Premature atrial contractions (PACs) — early beats that start in the atria
  • Supraventricular tachycardia (SVT) — a rapid, usually regular rhythm, starting from above the ventricles (SVT begins and ends suddenly)
  • AV nodal reentrant tachycardia (AVNRT) — a rapid heart rate due to more than one pathway through the AV node
  • Atrial fibrillation — a condition in which many impulses begin and spread through the atria, competing for a chance to travel through the AV node
  • Atrial flutter — an arrhythmia caused by one or more rapid circuits in the atrium
  • Wolff-Parkinson-White syndrome — a condition in which an electrical signal may arrive at the ventricle too quickly due to an extra conduction pathway or a shortcut from the atria to the ventricles

Ventricular arrhythmias in children include:

  • Premature ventricular contractions (PVCs) — early extra beats beginning in the ventricles. These occur when the electrical signal starts in the ventricles, causing them to contract before receiving signals from the atria
  • Ventricular tachycardia (V-tach) — a life-threatening condition in which electrical signals start from the ventricles in a fast and irregular rate
  • Ventricular fibrillation — an irregular, disorganized firing of impulses from the ventricles


  • Sinus node dysfunction — a slow heart rhythm due to an abnormal SA node
  • Heart block — a delay or complete block of the electrical impulse from the SA node to the ventricles

What causes arrhythmias in children?

An arrhythmia can occur as a result of internal factors, such as a disease of the heart muscle itself (cardiomyopathy) or a heart defect the child had when he or she was born (congenital heart disease). Other common causes of arrhythmia in children include:

  • Infections
  • Chemical imbalances
  • Fever
  • Medications

How will I know if my child has an arrhythmia? What are the symptoms?

Recognizing symptoms of an arrhythmia depends on the age and maturity of your child. Older children can tell you about feeling lightheaded or feeling his or her heart fluttering or "skipping beats." For infants and toddlers, you might notice changes such as paleness of the skin, irritability, and disinterest in eating. Some common symptoms of arrhythmias include: