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Arrhythmias


An  is an abnormal heart rhythm. Most arrythmias are caused by an electrical "short circuit" in the heart.

The heart normally beats in a consistent pattern, but an arrhythmia can make it beat too slowly, too quickly, or irregularly. This erratic pumping can lead to a variety of symptoms, including fatigue, dizziness, and chest pain.

Many arrhythmias don't need medical care, but some can pose a health problem and need to be evaluated and treated by a doctor.

What Causes Arrhythmias?

A unique electrical conduction system in the heart causes it to beat in its regular rhythm. 

The electrical signals start from a group of cells called the sinus node, located in the right atrium. The sinus node acts as the heart's pacemaker and makes sure the heart is beating at a normal and consistent rate. The sinus node normally speeds up the heart rate in response to things like exercise, emotions, and stress, and slows the heart rate during sleep.

But sometimes the electrical signals don't "communicate" properly with the heart muscle, and the heart can start beating in an abnormal rhythm — this is an arrhythmia (also called dysrhythmia).

Arrhythmias also can be due to chemical imbalances in the blood; infections; diseases that irritate the heart; medicines (prescription, over-the-counter, and some herbal remedies); injuries to the heart from chest trauma or heart surgery; use of illegal drugs, alcohol, or tobacco; caffeine; and stress.

Arrhythmias can be temporary or permanent. An arrhythmia can be congenital (meaning a baby is born with it) or happen later.

Signs and Symptoms

Arrhythmias make the heart beat less effectively, interrupting blood flow to the brain and the rest of the body. When the heart beats too fast, its chambers can't fill with enough blood. When it beats too slowly or irregularly, it can't pump enough blood out to the body.

If the body doesn't get the supply of blood it needs to run smoothly, a person might have:

Arrhythmias can be constant, but most come and go at random. Some cause no detectable symptoms at all. In these cases, the arrhythmia is only found during a physical examination or a heart function test.

What's a Normal Heart Rate?

Heart rate is measured by counting the number of beats per minute. Someone's normal heart rate depends on things like the person's age and whether he or she leads an active lifestyle. 

The resting heart rate decreases as kids get older. Typical normal resting heart rate ranges are:

A doctor can determine whether a heart rate is abnormally fast or slow, depending on a person's situation. An older child or adult with a slow heart rate, for example, might have symptoms when the heart rate drops below 50 beats per minute. But trained athletes have a lower resting heart rate, so a slow heart rate in them isn't considered abnormal if it causes no symptoms.

Types of Arrhythmias

There are several types of arrhythmias, including:

Premature Atrial Contraction (PAC) and Premature Ventricular Contraction (PVC)

Premature contractions are usually considered minor arrhythmias. The person may feel a fluttering or pounding in the chest caused by an early or extra beat. PACs and PVCs are very common, and are what happens when it feels like your heart "skips" a beat. Actually, the heart doesn't skip a beat — an extra beat comes sooner than normal. Occasional premature beats are common and considered normal, but in some cases they can be a sign of an underlying medical problem or heart condition.

Tachycardias

A tachycardia is an abnormally fast heartbeat. Tachycardias fall into two major categories — supraventricular and ventricular:

Bradycardias

A bradycardia is an abnormally slow heartbeat. Bradycardias can be due to:

Diagnosing Arrhythmias

Doctors use several tools to diagnose arrhythmias. It's very important to know a child's medical history and give this information to the doctor. The doctor will use the medical history, along with a physical exam, to begin the evaluation.

If an arrhythmia is suspected, the doctor will order an electrocardiogram (EKG) to measure the heart's electrical activity. For this painless test, the child will lie down and have small metal tabs (called electrodes) fixed to the skin with sticky papers. The electrodes have wires attached to them, which connect to the EKG machine. The electrical signals from the heart are then briefly recorded, usually for just 10 seconds. This information is sent to a computer, where it's interpreted and drawn as a graph.

These types of EKG tests might be recommended:

Treating Arrhythmias

Many arrhythmias don't need treatment. For those that do, these options might be used:

When to Call the Doctor

Many arrhythmias are minor and aren't a significant health threat. But some can indicate a more serious problem. If your child has symptoms of an arrhythmia, call your doctor.

Date reviewed: January 2017


Note: All information on KidsHealth® is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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