Pediatric Arrhythmia (Abnormal Heart Rhythm)

Pediatric cardiologist Seshadri Balaji with a patient
Pediatric cardiologist Seshadri Balaji is an internationally recognized heart rhythm specialist for children. Dr. Balaji has advanced training in conditions that make the heart beat too fast, too slow or with an irregular rhythm.

OHSU Doernbecher Children’s Hospital provides advanced testing and an array of treatment options for children with an arrhythmia. We offer:

  • A team of children’s heart experts available 24/7.
  • The most advanced technology for diagnosing and treating arrhythmias, such as 3D electroanatomic mapping.
  • Complete medical, catheter or surgical care for arrhythmias, tailored to your child’s needs.

Understanding arrhythmia

What is an arrhythmia?

An arrhythmia is any change to the heartbeat’s normal rate or rhythm. The heartbeat may be too fast or too slow, or the heart may skip beats or have extra beats. Most arrhythmias are harmless and cause no symptoms.

Sometimes, an abnormal heartbeat affects the heart’s ability to effectively pump blood. With treatment, an arrhythmia is rarely life-threatening. It is often curable or manageable.

What causes arrhythmia?

Arrhythmias are caused by a problem with the electrical signals that control the heartbeat. These signals are part of the cardiac conduction system.

Think of it like the electrical wiring in your home: The sinoatrial node, or sinus node, is the heart’s natural pacemaker. It sends electrical signals along a pathway (the “wiring”) through the heart to tell each part precisely when to squeeze, like turning on a light. The process repeats many times a minute. Each time produces one heartbeat.

Diagram of the heart's electrical system
The heart’s electrical system controls the heartbeat. The sinoatrial node, known as the heart’s natural pacemaker, starts each heartbeat by sending an electrical pulse. The pulse triggers a squeeze (contraction). Arrhythmias arise when the system develops a problem.

Although arrhythmias are more common in adults, they can affect children of all ages, including babies in the womb. Most heart rhythm problems occur in children with otherwise normal hearts. Less often, they are the result of a heart defect present at birth (congenital heart defect).

Arrhythmia symptoms

Symptoms vary depending on the type of arrhythmia. Many children show no symptoms and are unaware they have an abnormal heart rhythm.

Common symptoms include:

  • Fatigue
  • Shortness of breath
  • Heart palpitations
  • Feeling faint, weak, lightheaded or dizzy
  • Tiring easily
  • Chest pain
  • Sweating
  • Pale or ashen skin
  • Fainting

Diagnosing an arrhythmia

The cardiologist will use a stethoscope to listen to your child’s heart. The doctor will also ask about symptoms, and will review your child's and family’s health histories. Tests can identify the type of arrhythmia.

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Treating arrhythmias

Not all arrhythmias need treatment, and many that do can be cured or well controlled. Options include:

  • Medication to lower the heart rate or adjust the way the heart conducts electrical currents.
  • A pacemaker or implantable defibrillator, small devices placed under the skin that stimulate the heart to keep a regular rhythm.
  • Ablation, in which we guide a thin tube (catheter) to the heart through a blood vessel. Through the catheter, we “zap” the area that is disrupting the heart’s rhythm.
  • Cardioversion, in which the heart is given a shock to restore it from an abnormally fast rhythm back to a normal rhythm and rate.

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Types of arrhythmias

To best understand the following conditions, it might help to review the “How the heart works” section on our Understanding Pediatric Heart Conditions page.

Arrhythmias are classified by the part of the heart where they begin – the upper chambers (atria) or lower chambers (ventricles).

Diagram of the heart's four chambers
One way arrhythmias are defined is by whether they start in the upper chambers (atria) or lower chambers (ventricles).

Arrhythmias are also described by their rate and rhythm:

  • Tachycardia means the heart beats faster than normal.
  • Bradycardia means the heartbeat is slower than normal.
  • Fibrillation means the heart rhythm is chaotically fast.
  • Heart block means the connection between the upper and lower chambers is interrupted.

Fast heart rhythms (tachycardia)

Not all types of tachycardia need treatment. Most of the time, an elevated heart rate is a normal response to stress from strenuous exercise, intense emotion or fever. An underlying condition such as anemia or a thyroid condition can also cause tachycardia.

Atrial fibrillation: The upper chambers beat at a rapid rate but in an organized way. This prevents blood from moving well into the lower chambers. It is rare in children and usually treated with medication.

Atrial flutter: The heart’s upper chambers beat at a rapid and chaotic rate, making it harder for the heart to pump blood effectively.

Sinus tachycardia: This is a normal increase in heart rate from exercise, fever or anxiety.

Supraventricular tachycardia: This disruption in electrical activity in the heart’s upper chambers often begins in the teen years. It’s the most common cause of an abnormally fast heartbeat. Wolff-Parkinson-White syndrome is the main cause of supraventricular tachycardia in children.

Ventricular fibrillation: This is the most serious type of arrhythmia and requires immediate care. Misfiring electrical signals cause the ventricles to quiver (beat chaotically fast) instead of to beat normally, making the heart unable to pump blood.

Ventricular tachycardia: Electrical signals in the ventricles are activated many more times than normal. This reduces the amount of blood the heart pumps.

Slow heart rhythm (bradycardia)

Bradycardia, rare in children, may not be a cause for concern. For instance, a teen athlete may develop a more efficient heart and a lower-than-usual resting heart rate.

Rarely, a slower-than-normal heartbeat may make it hard for the heart to pump enough blood through the body. This could cause symptoms such as fatigue or fainting. When that happens, bradycardia is most often treated with a pacemaker to restore a regular heart rhythm.

Complete heart block: This condition happens when the electrical signals that cause a heartbeat are partly or fully blocked between the upper and lower chambers. It’s often seen in newborns and can be a result of heart surgery. It’s treated with a pacemaker.

Sick sinus syndrome: This condition occurs when the sinoatrial node misfires electrical signals. It can cause a heart rate that’s too slow or too fast. If the heart rate is critically slow, it is treated with a pacemaker.

Sinus bradycardia: This is a normal slowing of the heart rate, for example during sleep or in an athlete at rest.

Premature beats (extra beats)

Premature beats, or contractions, happen when a heart chamber squeezes before it’s supposed to. It can cause a fluttering or “skipping a beat” feeling. Most of the time, premature beats are harmless and need no treatment. Uncommonly, they are a sign of a heart problem.

Premature ventricular contractions: These happen when the heart’s electrical system causes a ventricle to squeeze (contract) sooner than it should. This common condition usually needs no treatment and only monitoring.

Premature atrial contractions: These are like premature ventricular contractions, but they happen when an atrium squeezes sooner than it should. They usually need no treatment.

Risk of sudden cardiac death

An inherited condition can cause an abnormal heart rhythm that can lead to sudden death. A risk of sudden cardiac death may be linked to conditions such as Long QT syndrome, Wolff-Parkinson-White syndrome and other heart-related genetic syndromes.

A risk of sudden cardiac death can be identified through tests and genetic screening. There are steps and treatments to lower risk. If your child is at risk, your entire family will be screened. (See the video "Kids and sudden cardiac death: What are the symptoms?" on this page to learn the warning signs.)

For families

Call 503-346-0640 to:

  • Request an appointment.
  • Seek a second opinion.
  • Ask questions.

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700 S.W. Campus Drive
Portland, OR 97239
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Know the warning signs

Dr. Seshadri Balaji explains the warning signs of a risk of sudden cardiac death.