What are arrhythmias in children?

An arrhythmia is an abnormal heart rhythm. When a child has an arrhythmia, abnormal electrical signals sent through the heart muscle may cause the heart to beat too fast (tachycardia), too slow (bradycardia), or in an irregular way. When the heart doesn't beat normally, it may be unable to pump blood to the body efficiently. That means the brain, lungs, and other organs may not get enough blood and oxygen. The organs then can't work as well and may become damaged over time.

Arrhythmias in children may include:

• Long-Q-T syndrome (LQTS). This is a condition that is typically passed from parents to children (inherited), but not always. Many children have no symptoms. But fainting is common in those who do. It may also cause cardiac arrest and sudden death.

• Premature atrial contraction (PAC) and premature ventricular contraction (PVC). PACs or PVCs are abnormal beats that start in the upper chambers of the heart (atria) or the lower chambers of the heart (ventricles). They are often viewed as completely normal and harmless.

• Sinus tachycardia. This is a fast heart rate (which depends on age) that occurs with fever, excitement, and exercise. It is considered normal.

• Supraventricular tachycardia (SVT). This is the most common type of tachycardia in children. An abnormal electric circuit or focal site in the atria can cause rapid heart rates. Treatment may be needed if it happens often or lasts long. SVT is also called PAT (paroxysmal atrial tachycardia) and PSVT (paroxysmal supraventricular tachycardia).

• Wolff-Parkinson-White (WPW) syndrome. This is a type of SVT. Normally, the electrical pathway from the top chambers of the heart to the bottom chambers passes through the AV node. This is a group of tissues that serves as a bridge between the 2 chambers. In WPW, an additional electrical pathway exists between the top and bottom chambers. This allows electricity to pass outside of the normal pathway. It's present since birth. A fast heart rate is a common symptom. Many children don't have symptoms. In rare cases, sudden cardiac death may occur.

• Ventricular tachycardia (VT). This is a potentially life-threatening arrhythmia. It's marked by very fast electrical signals that start in the ventricles, rather than the atria. It may be caused by heart disease, may occur following heart surgeries, or may be caused by a genetic condition. A child may feel weak, tired, dizzy, or may faint (syncope). They may also feel their heartbeat (palpitations).

• Sick sinus syndrome. In this condition, the heart's natural pacemaker (sinus node) doesn't work as it should. This causes slow heart rates. It's rare in children. But it may occur in children who have had open heart surgery. A child may not have symptoms. A child with symptoms may be tired or dizzy or may faint.

• Complete heart block. This occurs when the electrical signal from the upper to lower chambers is blocked. With this condition the heart often beats much more slowly. It's possible to be born with this condition. Or a child may develop the condition following surgery, heart disease, or an infection. Symptoms may include low energy, weakness, or fainting.

What causes arrhythmias in a child?

The cause of an arrhythmia may be unknown. Some known causes in children include:

• Heart problem that is present at birth (congenital)

• Heart problem that is inherited

• Infection

• Abnormal levels of certain chemicals in the blood

• Normal reaction to exercise, fever, or emotions

• Changes in the structure of the heart

• Electrical conduction abnormality

• As a result of heart surgery

What are the symptoms of an arrhythmia in a child?

A child with an arrhythmia may not have any symptoms. For those who do, these are the most common symptoms:

• Feeling weak

• Feeling tired

• Feeling like the heart is fluttering (heart palpitations)

• Low blood pressure

• Feeling dizzy

• Fainting (syncope)

• Not feeding or eating well

The symptoms of an arrhythmia may look like other health conditions or heart problems. Make sure your child sees their healthcare provider for a diagnosis.

How is an arrhythmia diagnosed in a child?

Your child's healthcare provider will ask about your child's health history and family history. They will look for signs and symptoms of an arrhythmia. The provider will give your child an exam focusing on the heart. Your child may need to see a pediatric cardiologist. This is a doctor with special training to treat children with heart problems. Your child may need tests, including:

• Electrocardiogram (ECG). This simple test measures the electrical activity of the heart. An ECG may show an arrhythmia. The test may be a:

  • Resting ECG. Your child will lie down while electrodes are connected to the ECG machine by wires. The ECG records the heart's electrical activity for a minute or so.

  • Stress test (exercise ECG). Your child is attached to the ECG machine as described above. They will walk on a treadmill or pedal a stationary bike while the ECG is recorded. This test is done to check the heart during exercise.

• Holter monitoring. Your child will have their heart rhythm checked over 24 to 48 hours. A small portable monitor is worn while your child goes about their normal activities.

• Electrophysiologic study (EPS). For this test, the doctor puts a small, thin tube (catheter) into a large blood vessel in a leg or arm. The doctor moves the catheter to your child's heart. This test can find out the type of electrical signal causing the problem, and where the signal is.

• Tilt table test. This test may be done if your child faints often. The test checks your child's heart rate and blood pressure as they change position.

• Echocardiography (echo). This test uses sound waves to make detailed pictures of your child's heart structure and function.

• Implanted loop recorder. This heart monitoring device may be used when the healthcare provider thinks your child is at high risk for arrhythmia and other testing has not given a straightforward result. This test may only be used in children who are high risk. The device is put under the skin and is used for long-term monitoring.

• MRI. May be used to assess for an abnormal structure of the heart that may be a focus for abnormal electrical activity.

How is an arrhythmia treated in a child?

Treatment will depend on your child’s symptoms, age, and general health. It will also depend on how severe the condition is. Some children don't need treatment. If your child needs treatment, they will likely be cared for by a pediatric cardiologist. Treatment may include:

• Medicines. Medicines can ease symptoms or suppress arrhythmias.

• Radiofrequency ablation. This procedure involves a cardiac catheterization that uses a special catheter to locate and destroy the tissue causing the abnormal electrical signals. 

• Surgery. Surgery can stop an abnormal heart rhythm.

• Pacemaker. An artificial pacemaker may be needed for an abnormally slow heart rate or complete heart block. The pacemaker is a small device that is put inside the belly (abdomen) or chest. It gives a small amount of electricity to the heart to keep it beating regularly.

• Implantable cardioverter defibrillator (ICD). This device is put in the chest or abdomen. It automatically sends a shock to stop an abnormal and dangerous rhythm. Some ICDs also work as pacemakers.

• Electrical cardioversion.  During this procedure, an electric shock is given. This briefly stops the abnormal electrical action in the heart. It "resets" the heart's normal pacemaker. The heart can then restart in a normal rhythm.

What are possible complications of an arrhythmia in a child?

Complications can happen, depending on the type of arrhythmia and how serious it is. Complications may include:

• Damage to the brain, kidneys, lungs, liver, or other organs

• Heart failure

• Blood clots. A blood clot in the brain may cause a stroke.

• Sudden cardiac death

How can I help my child live with an arrhythmia?

Some arrhythmias don't cause any problems. Some are more serious. A child with a serious arrhythmia will need frequent checkups.

Talk with your child's healthcare provider about managing your child's arrhythmia. Your child may need regular tests. Or your child may not be able to take part in some sports or activities.

When should I call my child's healthcare provider?

Call your child's healthcare provider if your child has symptoms of an arrhythmia. These include:

• Feeling weak or tired

• Having heart palpitations

• Feeling dizzy

• Fainting (syncope)

• Not feeding or eating well

Key points about arrhythmias in children

• An arrhythmia is an abnormal heart rhythm. It may be a heart rate that is too fast, too slow, or irregular.

• The cause may not be known. In some cases, it is caused by a problem that's present at birth, a problem that's inherited, or an infection.

• There may not be any symptoms. Or a child may have moderate to very serious symptoms.

• Your child may need to see a pediatric heart doctor (cardiologist) for a diagnosis. Your child may also need tests.

• Some children don't need treatment. If treatment is given, your child may need medicine, radiofrequency ablation, a device, or surgery.

Next steps

Tips to help you get the most from a visit to your child’s healthcare provider:

• Know the reason for the visit and what you want to happen.

• Before your visit, write down questions you want answered.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.

• Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.

• Ask if your child’s condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if your child does not take the medicine or have the test or procedure.

• If your child has a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.