An arrhythmia is an irregular heartbeat that may feel like a racing or fluttering heart. It is not always serious but can sometimes indicate a potentially fatal heart problem.

Arrhythmias — sometimes called dysrhythmias — occur when the electrical signals that coordinate heartbeats are not working correctly.

The heart may beat too quickly, too slowly, too early, or with an irregular rhythm. In contrast, a “normal sinus rhythm” refers to how the heart beats when it is working properly.

If they are highly irregular or result from a weak or damaged heart, arrhythmias can cause severe and potentially fatal symptoms and complications.

Read on to learn more about arrhythmia, including the types, causes, and symptoms. This article also discusses treatment options, how doctors diagnose arrhythmia, possible complications, and more.

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Cardiac arrhythmia refers to conditions in which the heart beats irregularly, too slowly, or too quickly.

There are several types, including:

Arrhythmias are not always serious, but some can increase the risk of stroke or cardiac arrest.

Learn about what a heart rate should be.

There are several types of arrhythmia.


AFib is the irregular beating of the atrial chambers and nearly always involves tachycardia. It is common and mainly develops in adults over 65 years.

Instead of a single, strong contraction, the chamber fibrillates or quivers, often producing a rapid heartbeat.

Atrial flutter

While fibrillation causes many random and different quivers in the atrium, atrial flutter usually stems from one area in the atrium not conducting correcty.

Atrial flutter can be a serious condition and usually leads to fibrillation without treatment.

Some people may experience both flutter and fibrillation.

Supraventricular tachycardia

Supraventricular tachycardia (SVT) is a rapid heartbeat that begins in the upper chambers of the heart. It prevents blood from filling the heart’s chambers fully between contractions.

Doctors classify atrial fibrillation and flutter under SVT.

Ventricular tachycardia

Ventricular tachycardia (VT) refers to abnormal electrical impulses that start in the lower chambers and cause an abnormally fast heartbeat.

A possible cause of VT is scarring from a previous heart attack.

Ventricular fibrillation

Ventricular fibrillation (VFib) is an irregular heart rhythm consisting of rapid, uncoordinated, and fluttering contractions of the ventricles. The ventricles of the lower chamber do not pump blood but quiver instead.

VFib can be life threatening and has links to heart disease. A heart attack often triggers it.


Bradycardia is when the heart rhythm is slower than usual, below 60 beats per minute (bpm) for most people. It happens when there is a problem with the sinoatrial node, the heart’s natural pacemaker.

Possible causes include:

  • various types of heart disease
  • chest trauma
  • genetic factors
  • the use of certain drugs and medications
  • hypothermia

Long QT syndrome

Long QT syndrome refers to a heart rhythm disorder that a person is born with. It sometimes causes rapid, uncoordinated heartbeats. It can be life threatening and causes a rhythm known as QT prolongation.

It can also occur due to genetic susceptibility or taking certain medications.

Learn more about long QT syndrome.

There are many risk factors for arrhythmias, and different types may have different risk factors.

Examples of risk factors for arrhythmias include:

  • aging, as it is more common in older adults
  • family history of arrhythmia
  • smoking
  • using certain recreational drugs, such as cocaine or amphetamines
  • excess alcohol consumption
  • certain medications, such as antibiotics and over-the-counter cold and allergy medications
  • some conditions, such as:
    • obesity
    • diabetes
    • kidney disease
    • lung disease
    • sleep apnea
    • heart and blood vessel diseases

Arrhythmia does not always cause noticeable symptoms. However, a doctor may detect an arrhythmia during a routine examination.

Having symptoms does not necessarily mean the arrhythmia is severe. Some people have life threatening arrhythmias with no symptoms, while others with symptoms may not have a severe arrhythmia.

Symptoms depend on the type of arrhythmia.

Symptoms of tachycardia

The symptoms of a rapid heartbeat include:

Symptoms of bradycardia

Bradycardia can cause the following symptoms:

Symptoms of AFib

When AFib symptoms occur, they often have a rapid onset and may involve:

  • angina
  • breathlessness
  • dizziness
  • palpitations
  • fainting or nearly fainting
  • weakness

To diagnose arrhythmia, a doctor will need to identify the unusual heartbeat and try to find the source of the change.

They may start by asking questions about any symptoms and carrying out a physical exam to:

  • measure the heart rate, pulse, and blood pressure
  • listen for a heart murmur
  • check for symptoms such as swelling due to fluid retention

A doctor may also recommend:

Sometimes, a doctor may monitor the heart rhythm but not recommend treatment.

A person may need treatment if they have:

  • an underlying condition
  • a risk of complications
  • severe symptoms

The various arrhythmias require different treatments.

Treatments for tachycardia

There are several treatments for tachycardia. The precise options will depend on the type and cause, but may include:

Treatments for bradycardia

Treatment for bradycardia may involve the following:

  • intravenous atropine if tests show that blood pressure is unstable
  • warming up the person before deciding on treatment if bradycardia is due to hypothermia
  • providing appropriate treatment for a heart problem or other underlying condition
  • implanting a pacemaker

Treatment for AFib

Treatment options for AFib include:

Learn more about medications for arrhythmia.

Some people with arrhythmia do not experience active symptoms. However, treatment is still essential because life threatening complications can arise.

Possible complications of arrhythmia include:

Contacting a doctor as soon as a person has concerns about arrhythmia or other heart problems can help reduce the likelihood of complications.

Is it a heart attack?

Heart attacks occur when there is a lack of blood supply to the heart. Symptoms include:

  • chest pain, pressure, or tightness
  • pain that may spread to arms, neck, jaw, or back
  • nausea and vomiting
  • sweaty or clammy skin
  • heartburn or indigestion
  • shortness of breath
  • coughing or wheezing
  • lightheadedness or dizziness
  • anxiety that can feel similar to a panic attack

If someone has these symptoms:

  1. Dial 911 or the number of the nearest emergency department.
  2. Stay with them until the emergency services arrive.

If a person stops breathing before emergency services arrive, perform manual chest compressions:

  1. Lock fingers together and place the base of hands in the center of the chest.
  2. Position shoulders over hands and lock elbows.
  3. Press hard and fast, at a rate of 100–120 compressions per minute, to a depth of 2 inches.
  4. Continue these movements until the person starts to breathe or move.
  5. If needed, swap over with someone else without pausing compressions.

Use an automated external defibrillator (AED) available in many public places:

  1. An AED provides a shock that may restart the heart.
  2. Follow the instructions on the defibrillator or listen to the guided instructions.
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It is not always possible to prevent arrhythmia.

Steps a person can take to reduce their risk can include:

  • seeking help for any underlying condition and following the treatment plan
  • getting enough regular exercise or physical activity
  • avoiding the use of tobacco and recreational drugs
  • limiting alcohol consumption
  • checking with a doctor before using any medications or supplements

Here are some common questions about arrhythmia.

What is the main cause of arrhythmia?

Overall risk factors for arrhythmia include having an existing heart condition, being born with unusual structural features in the heart, and being over the age of 65 years. Certain other conditions and medications can also increase the risk of arrhythmia.

Is arrhythmia serious?

Arrhythmia is not always serious, but it can indicate an underlying heart problem or a higher risk of a stroke or heart attack. Anyone with signs of arrhythmia should seek medical advice and follow the recommended treatment plan.

What are the warning signs of arrhythmia?

Common warning signs can depend on the type of arrhythmia but may include fatigue, dizziness, fainting, palpitations or pounding in the chest, shortness of breath, and sweating. Some people have no symptoms, but routine examinations reveal an unusual heartbeat.

Do arrhythmias go away?

Arrhythmia may resolve on its own in some cases. For example, a person may experience a single episode of AFib due to another illness. However, as arrhythmia can lead to serious complications, it is important to contact a doctor for an accurate diagnosis and suitable treatment plan where necessary.

Arrhythmia is when the heart does not beat as it should.

There are many causes of arrhythmia, but underlying heart disease is often a factor. Other causes include the use of certain medications. In some cases, arrhythmia may be a sign of a serious condition, and it can lead to severe complications. For this reason, it is essential to seek medical advice if a person notices symptoms of arrhythmia.

It is not always possible to prevent arrhythmias, but regular physical activity, maintaining a moderate weight, and seeking treatment for underlying conditions may help.