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Arrhythmias


What Are Arrhythmias?

Arrhythmias 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 make it beat too slowly, too quickly, or irregularly. This can cause the heart to pump inconsistently, leading 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 don't "communicate" properly with the heart muscle, and the heart starts beating in an abnormal rhythm — this is an arrhythmia (also called dysrhythmia).

Arrhythmias can be congenital (meaning a person is born with one) or happen later, and they can be temporary or permanent.

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 also can happen for no apparent reason. 

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 usually come and go at random. Sometimes arrhythmias can cause no symptoms at all — in these cases, the arrhythmia is only found 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. 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 people get older. Typical normal resting heart rate ranges are:

A doctor can determine whether a heart rate is too 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. 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

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 — can be due to:

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. 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.

A doctor might recommend these types of ECG/EKG tests:

How Are Arrhythmias Treated?

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 you've been having any symptoms, talk to your parent or call your doctor.

Date reviewed: January 2017


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

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