An abnormal heart rhythm is when your heart beats too fast, too slow, or irregularly. It’s also called an arrhythmia.

Your heart contains a complex system of valves, nodes, and chambers. They control how and when blood is pumped throughout your body. If these are disrupted, damaged, or compromised, it can change your heart rate or rhythm.

Arrhythmias can cause no symptoms, or you may feel some symptoms. They may include:

  • discomfort
  • fluttering or pounding in your chest
  • pain in your chest
  • shortness of breath
  • lightheadedness
  • fatigue
  • fainting

Not all arrhythmias are life threatening or cause health complications. But to be safe, you should report any abnormal heart rhythm to a doctor.

The most common types of abnormal heart rhythms include:

Tachycardia

Tachycardia means that your heart is beating too fast. For example, a typical heart beats 60 to 100 times per minute in adults. Tachycardia is any resting heart rate over 100 beats per minute (bpm).

There are three subtypes of tachycardia:

  • Sinus tachycardia: This is an increased heart rate that can occur in response to exercise, pain, dehydration, excitement, fever, or illness. With sinus tachycardia, your heartbeat returns to its usual rate once you get better or become calm.
  • Supraventricular tachycardia: Supraventricular tachycardia originates in the upper chambers of your heart, known as the atria.
  • Ventricular tachycardia: Ventricular tachycardia is a very fast heart rate that occurs in the lower chambers, known as the ventricles.

Atrial fibrillation

This disorganized heart rhythm occurs in the upper chambers of your heart. It’s the most common arrhythmia.

Atrial fibrillation, or AFib, occurs when many unstable electrical impulses misfire, causing your atria to quiver erratically.

AFib causes your heart to beat irregularly and can increase your heart rate to 80 to 180 bpm, which is much faster than the typical 60 to 100 bpm.

Atrial flutter

An atrial flutter typically occurs in the right atrium, one of your heart’s two upper chambers. It may occur in the left atrium as well.

Atrial flutter is a type of arrhythmia that originates in the atrium and results in rapid atrial rhythm. It’s due to an abnormal circuit of electrical activity. In atrial flutter, your heart’s overall rhythm can be regular, but your heart rate is often fast.

Atrial flutter also increases your risk of stroke.

Bradycardia

If you have bradycardia, you have a slow heart rate (less than 60 bpm). Bradycardia generally occurs when the electrical signals traveling from the atria to the ventricles become disrupted.

Some athletes have slower heart rates because they’re in excellent physical condition, which isn’t usually the result of a heart problem.

Bradycardia can result from:

  • medications, including certain blood pressure and antiarrythmic medications
  • hypothyroidism
  • hypothermia
  • other heart conditions

Ventricular fibrillation

Ventricular fibrillation is a life threatening arrhythmia in which the ventricles beat rapidly and erratically. This impairs the flow of blood from your heart and leads to cardiac arrest.

It’s a serious condition that results in death if not immediately treated with defibrillation.

Premature contractions

A premature contraction is a beat that occurs early. It can occur in the atrium (premature atrial contraction) or in the ventricle (premature ventricular contraction).

In either case, when feeling your pulse, it may feel as though your heart pauses or skips a beat.

If you have an abnormal heart rhythm, you may experience some or all of these symptoms:

Several factors may cause an abnormal heart rhythm. These can include:

High blood pressure

High blood pressure means too much force is required to push the blood through your blood vessels. It creates more resistance to blood flow and can affect how your heart works. Over time, high blood pressure can lead to heart disease.

Coronary heart disease

Coronary heart disease is a serious heart problem that occurs when cholesterol and other deposits block your coronary arteries.

This plaque prevents oxygen and important nutrients from reaching your heart.

Heart conditions or damage to the heart

Having a heart condition or an injury to your heart can lead you to develop an atypical heart rate. Some of these conditions may have other symptoms as well.

They may include:

  • changes in your heart’s muscle after illness or injury
  • healing after heart surgery
  • structural abnormalities of your heart
  • heart failure, which happens when your heart can’t pump an adequate amount of blood
  • damage to your heart after a heart attack

Medications

Some medications or substances may cause your heart rate to change.

Medications that may cause your heart rate to increase include:

  • caffeine
  • nicotine
  • decongestants, such as phenylephrine or pseudoephedrine
  • amphetamines, which are drugs that stimulate the brain
  • asthma medications, such as an albuterol inhaler
  • other recreational drugs, such as cocaine

Medications that can cause your heart rate to decrease may include:

  • beta-blockers, which treat high blood pressure
  • calcium channel blockers
  • certain antiarrhythmic medications, such as digoxin and amiodarone, clonidine, and donepezil

Anxiety or emotional distress

Anxiety or other emotional distress can increase your heart rate as part of your body’s fight-or-flight response. This can cause sinus tachycardia.

You may feel heart palpitations. Your accelerated heart rate typically slows once you calm down.

Illness or fever

Having an illness or fever may temporarily cause sinus tachycardia. This may temporarily raise your heart rate.

Once your illness resolves, your heart rate typically returns to its normal rate.

Other causes

Other factors can also cause alterations in your heart’s rhythm. These can include:

  • pain
  • electrolyte imbalances, such as low potassium, calcium, and magnesium
  • sleep apnea
  • blood clots
  • anemia
  • hypothyroidism
  • other health conditions

The risks for arrhythmia can include:

  • smoking
  • previous heart conditions, or a family history of heart conditions
  • diabetes
  • stress
  • being overweight
  • being physically inactive
  • a diet high in fats and cholesterol
  • high blood pressure or other health problems
  • drinking alcohol in excess
  • drug misuse
  • sleep apnea

A doctor typically performs a physical examination, which may include using a stethoscope to listen to your heart. They may also use an electrocardiogram (EKG) machine to examine your heart’s electrical impulses. This can help them determine whether your heart rhythm is abnormal and identify the cause.

Other tools that doctors use to diagnose an arrhythmia include:

  • Echocardiogram: This test is also known as a cardiac echo. It uses sound waves to take pictures of your heart.
  • Rhythm monitoring: You’ll wear ambulatory rhythm monitoring such as a Holter monitor or event recorders for at least 24 hours while doing your daily activities. These monitors allow your doctor to track changes in your heart’s rhythm throughout the day.
  • Stress test: For this test, a doctor has you walk or jog on a treadmill to see how exercise affects your heart.

The Healthline FindCare tool can provide options in your area if you need help finding a cardiologist.

The treatment for an arrhythmia depends on its cause.

You may need to make lifestyle changes, such as increasing your activity level or changing your diet (for example, limiting caffeine intake). If you smoke, a doctor may recommend you consider quitting smoking and provide resources or medication to help.

You might also require medication to control your heart rate and any secondary symptoms. This may include rate-controlling medication or antiarrhythmics to control your heart’s rate and rhythm.

Certain arrhythmias, such as AFib and atrial flutter, can increase your risk of a stroke. A doctor may recommend blood-thinning medications to lower your risk of stroke.

For serious abnormalities that don’t go away with behavioral changes or medication, a doctor may recommend:

  • pharmacologic cardioversion, which uses medication, or electrical cardioversion, which uses an electrical shock to your heart
  • other heart testing and procedures, such as cardiac catheterization, to diagnose a heart problem
  • catheter ablation to identify and destroy tissue that causes abnormal rhythms
  • implantation of a pacemaker or cardioverter defibrillator
  • surgery to correct an abnormality

Although arrhythmias can be quite serious, they can often be managed with treatment. Along with treatment, a doctor may monitor your condition with regular checkups.

Once your arrhythmia is under control, a doctor may discuss ways to keep it from returning.

Certain lifestyle choices can go a long way toward helping you control your condition. A doctor will probably recommend that you:

Arrhythmia can occur if your heart rate is too fast or too slow or irregular. You may experience it with other symptoms, such as the feeling that your heart is pounding.

It can occur with conditions that affect the heart and certain medications, substances, or emotional states.

If you experience an abnormal heart rhythm, consider making an appointment with a doctor to determine the cause.