Types of Arrhythmia in Children

Updated:Dec 21,2016

Doctor Listening To young Boy's Heart

There are many different kinds of abnormal heart rhythms that may occur in children and adults. Learn about the types of arrhythmias that may occur and how they might manifest in children. If an abnormal rhythm occurs, it's important to find out what kind it is. Treatment recommendations depend on its type. Arrhythmias can cause the heart rate to be irregular, fast or slow (View an animation of arrhythmia). Fast rhythms are called tachycardia. Slow ones are called bradycardia.

Abnormal Heart Rhythms

Long Q-T Sydrome is a disorder of the heart’s electrical system, like other arrhythmias.  Since the hearts electrical activity is controlled by the flow of ions (that is electrically charged particles such as calcium, sodium, potassium and chloride), these ions move in and out of the cells of the heart.  This flow is controlled by very small ion channels. When the heart contracts, it emits an electrical signal. This signal can be recorded on an electrocardiogram (ECG) and produces a characteristic waveform.  The different parts of this waveform are designated by letters — P, Q, R, S and T.  The Q-T interval represents the time for electrical activation and inactivation of the ventricles, the lower chambers of the heart.  A doctor can measure the time it takes for the Q-T interval to occur (in fractions of a second) and can tell if it occurs in a normal amount of time. If it takes longer than normal, it's called a prolonged Q-T interval.

What are the symptoms of LQTS?

People with LQTS may not have any symptoms. People who do have symptoms often exhibit fainting (syncope) and abnormal rate and/or rhythm of the heartbeat (arrhythmia), a fluttering feeling in the chest. People with this syndrome may show prolongation of the Q-T interval during physical exercise, intense emotion (such as fright, anger or pain) or when startled by a noise. Some arrhythmias are potentially fatal, causing sudden death. In one type of inherited LQTS, the person may also be deaf.

People with LQTS don't necessarily have a prolonged Q-T interval all the time. At the time that they have an electrocardiogram (such as during a routine physical examination), the Q-T interval may actually be normal. Alternatively, some healthy young people may not have a routine ECG, and LQTS may be suspected because of their family history or because of unexplained fainting episodes. In any family where repeated episodes of fainting or a history of sudden death exists, an investigation of the cause, including LQTS, should be undertaken.

How is LQTS treated?
There are treatments for LQTS, including medications such as beta blockers. Sometimes a surgical procedure is performed, and some people may benefit from an implantable defibrillator. Avoid drugs and electrolyte imbalance known to prolong the Q-T interval.

Checklist for Parents of Children with Arrhythmias

Parents of all children should learn CPR and how to reduce the risk of injuries and sudden infant death syndrome (SIDS).  This information is available with all American Heart Association child and infant CPR courses. 

Learn the CPR Guidelines
Get an American Heart Association CPR Anytime Personal Learning Program
Find an Emergency Cardiovascular Care class near you

CPR skills, including recognition of signs of breathing difficulties and cardiac arrest, are particularly important if a child has heart disease and is at risk for sudden arrhythmias including sudden death. 
Learn about special considerations for cardiac arrest in children.

This content was last reviewed September 2016. 


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