An arrhythmia is an irregular heartbeat. An arrhythmia may feel like a racing heart or fluttering. 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.

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

In this article, we define arrhythmia, as well as its causes and symptoms. We also explain the possible treatments and different types.

person checking for arrhythmiaShare on Pinterest
Carol Yepes/Getty Images

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.

What is a normal heartbeat?

Doctors identify a healthy heartbeat by counting the number of times the heart beats every minute (bpm) during rest. This is known as the resting heart rate.

The range for a healthy resting heart rate varies between people, but the American Heart Association suggests it is usually between 60 and 100 bpm.

This rate can change. It is often lower at night. Athletes may also have a resting heart rate of less than 60 bpm because their hearts are highly efficient.

The heart should beat with a regular rhythm, consisting of double “ba-bum” beats with even spaces in between each.

One of these beats is the heart contracting to provide oxygen to blood that has already circulated, and the other involves the heart pushing oxygenated blood around the body.

A person can measure their heart rate using their pulse. This is a point at which they can feel the heartbeat through the skin. The best locations on the body for this are:

  • the wrists
  • the insides of the elbows
  • the side of the neck
  • the top of the foot

How do you take your pulse?

There are several types of arrhythmia.

Atrial fibrillation

A-fib is the irregular beating of the atrial chambers and nearly always involves tachycardia. A-fib is common and mainly develops in adults over 65 years of age.

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

What are the types of atrial fibrillation?

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 properly.

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

Some people may experience both flutter and fibrillation.

What is the difference between A-fib and atrial flutter?

Supraventricular tachycardia

Supraventricular tachycardia (SVT) refers to 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. VT often happens if the heart has a scar 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.

Find out more about ventricular fibrillation here.


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

Causes include various types of heart disease, chest trauma, genetic factors, the use of certain drugs and medications, hypothermia, and a range of other health conditions.

What is bradyarrhythmia?

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.

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 A-fib

When A-fib symptoms occur, they often have a rapid onset and may involve:

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

Any interruption to the electrical impulses that stimulate heart contractions may cause arrhythmia.

This usually results from:

  • a problem with the electrical signals that control the heartbeat
  • damage to heart tissue
  • a high level of strain or stress
  • an imbalance of fluids or electrolytes in the blood
  • changes in hormone levels
  • some medications

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

They will ask the individual about:

  • any symptoms
  • personal and family medical history
  • lifestyle factors, such as tobacco and alcohol use

They will also carry 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:

Some people with arrhythmia do not experience active symptoms. However, treatment is still essential because life threatening complications can arise, such as a stroke and heart failure.


A-fib means that the heart is not pumping effectively. This can cause blood to collect in pools and form clots.

If a clot dislodges, it may travel to a brain artery, causing a potentially fatal blockage, or stroke. Stroke can cause brain damage and require emergency treatment.

Heart failure

Prolonged tachycardia or bradycardia can result in heart failure. When the heart fails, it cannot pump enough blood to the body and its organs. Treatment can usually help improve this.

Heart attack

A heart attack happens when blood stops flowing to a part of the heart muscle. Without oxygen, the heart cells will begin to die. It can lead to cardiac arrest.

Cardiac arrest

A cardiac arrest is when the heart suddenly stops working. Blood is unable to flow to the brain and other organs. Within minutes, damage will start to occur due to the lack of oxygen.

What is the difference between a heart attack and a cardiac arrest?

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.
Was this helpful?

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

Here are a few of them:

In the United States, white people are more likely to receive a diagnosis of A-fib than Black, Hispanic, or Asian Americans. However, Black people are more likely to have severe complications, such as an ischemic stroke, according to the National Heart, Lung and Blood Institute.

Some monitoring studies have found higher rates of A-fib in white people, but other researchers have argued that the results did not take into account statistical bias. Unbiased monitoring showed a similar risk among all participants, they concluded.

How does cocaine affect the heart?

In some cases, a doctor may monitor the heart rhythm but not offer 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:

  • Vagal or Valsalva maneuver are movements and exercises that might stop some types of arrhythmia.
  • Medications to reduce the frequency of episodes or promote electrical conduction through the heart.
  • Cardioversion is an electric shock treatment or medication that resets the heart to its regular rhythm.
  • An implantable cardioverter-defibrillator (ICD) near the left collarbone enables monitoring of the heart rhythm. If the rate speeds up, it stimulates the heart to return to its normal speed.
  • In the Maze procedure and other types of cardiac ablation surgery, a surgeon makes incisions in the heart that heal into scars and form blocks that guide the electrical impulses. This helps the heart beat efficiently.
  • Surgery can resolve an aneurysm that may be causing arrhythmia.
  • Heart bypass surgery involves grafting blood vessels from elsewhere in the body onto the coronary arteries. The circulation can bypass narrowed parts, and blood supply to the heart muscle improves.

What is a coronary artery bypass graft?

Treatments for bradycardia

Treatment for bradycardia may involve the following:

  • intravenously medicating with 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

A pacemaker is a small device that a doctor places under the skin of the chest or abdomen to help control abnormal heart rhythms. Pacemakers use electrical pulses to prompt the heart to beat at a regular minimum rate.

Treatment for atrial fibrillation

Treatment options for A-fib include:

It is not always possible to prevent heart problems, including arrhythmia.

Steps a person can take to reduce their risk include:

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

Here are some questions people often ask 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 aged 65 years or older. Others are having diseases such as diabetes and high blood pressure and using certain medications and drugs.

Is arrhythmia serious?

It 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?

This will depend on the type of arrhythmia, but common warning signs 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.

Arrhythmia is when the heart does not beat as it should. In most cases, the heart should beat at a rate of 60–100 beats per minute. If the heartbeat is faster, slower, or irregular, a doctor will diagnose arrhythmia.

There are many causes of arrhythmia, but underlying heart disease is often a factor. Other causes include the use of certain medications. Often, arrhythmias are not serious, but they can be a sign of a more serious condition. 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 getting regular exercise, maintaining a moderate weight, and seeking treatment for underlying conditions can help.