Arrhythmias

Arrhythmias

What Are Arrhythmias?

Arrhythmias (also called dysrhythmias) are abnormal heartbeats usually caused by an electrical "short circuit" in the heart.

The heart normally beats in a consistent pattern, but an arrhythmia can cause it to beat too slowly, too quickly, or irregularly. This can cause the heart to pump inconsistently, which can lead to symptoms like fatigue, dizziness, and chest pain.

What Causes Them?

Your heart has its own electrical system that sends electrical signals around the heart, telling it when to contract and pump blood around the body. The electrical signals start in a group of cells, called the sinus node, located in the right atrium. The sinus node is the heart's pacemaker and makes sure the heart beats at a normal and consistent rate. The sinus node normally increases your heart rate in response to exercise, emotions, and stress, and slows your heart rate during sleep.

But sometimes the electrical signals flowing through the heart don't "communicate" well with the heart muscle, and the heart can start beating in an abnormal pattern, or arrhythmia.

Arrhythmias can either be temporary or permanent and they can be caused by several things — but they also can happen for no apparent reason. Arrhythmias can be congenital, meaning a person is born with the condition.

Other causes of arrhythmias include chemical imbalances in the blood, infections or other diseases that cause irritation or inflammation of the heart, medications (prescription or over-the-counter), and injuries to the heart from chest trauma or heart surgery. Other factors like illegal drugs, alcohol, tobacco, caffeine, stress, and some herbal remedies can also cause arrhythmias.

Signs and Symptoms

Because arrhythmias can cause the heart to beat less effectively, blood flow to the brain and to the rest of the body can be interrupted. If the heart is beating too fast, the heart's chambers can't fill with the right amount of blood. If it's beating too slowly or irregularly, the right amount of blood can't be pumped out to the body.

Because the body isn't getting the supply of blood it needs to run smoothly, these symptoms can occur:

Arrhythmias can be constant, but usually come and go at random. Sometimes arrhythmias can cause no symptoms at all — in these cases, the arrhythmia can only be discovered during a physical exam or a heart function test, like an electrocardiogram (ECG/EKG).

What's a Normal Heart Rate?

Heart rate is measured by counting the number of beats per minute. Normal heart rate can be different for each person, depending on factors like age and whether the person leads an active lifestyle or not (for example, athletes often have a low resting heart rate).

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

Your doctor can determine whether or not your heart rate is abnormally fast or slow, since the significance of an abnormal heart rate depends on the situation. For example, a teen or adult with a slow heart rate might begin to show symptoms when the heart rate drops below 50 beats per minute. However, keep in mind that trained athletes have a lower resting heart rate — so a slow heart rate in these people isn't considered abnormal if no symptoms are associated with it.

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, in which 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. It doesn't skip a beat — an extra beat actually comes sooner than normal. Occasional premature beats are common and considered normal, but in some cases they can indicate an underlying medical problem or heart condition.

Tachycardias

Tachycardias are arrhythmias that involve an abnormally rapid heartbeat. They fall into two major categories — supraventricular and ventricular:

Bradycardias

Bradycardias — arrhythmias characterized by an abnormally slow heartbeat — include:

How Are Arrhythmias Diagnosed?

Arrhythmias can be diagnosed in several ways. The doctor will use a person's medical history information, along with a physical examination, to begin the evaluation. If an arrhythmia is suspected, the doctor will probably recommend an ECG/EKG to measure the heart's electrical activity.

There's nothing painful about an ECG/EKG — it's just a procedure where a series of electrodes (small metal tabs) are attached to the skin with sticky papers. Then, information about the electrical activity of the heart is transferred to a computer, where it's interpreted and drawn as a graph.

A doctor might recommend the following types of ECG/EKG tests:

How Are Arrhythmias Treated?

Someone may have an arrhythmia but may feel no symptoms at all. Many arrhythmias don't require treatment; however, some can pose a health problem and need to be evaluated and treated by a doctor.

Depending on the type and severity of the arrhythmia, one of the following options might be recommended by a doctor:

When to Call the Doctor

Although many arrhythmias are minor and don't represent a significant threat to a person's health, some can indicate a more serious health problem. If you've been having any symptoms, talk to your parent or call your doctor.

Reviewed by: Joel D. Temple, MD
Date reviewed: August 2012





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

© 1995-2014 The Nemours Foundation/KidsHealth. All rights reserved.





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