Abnormal Heartbeat

An abnormal heartbeat, also known as an arrhythmia, is often characterized as the heart feeling like it's skipping a beat. Arrythmia has several causes, such as when the electrical signals do not travel normally throughout the heart, causing it to beat out of normal rhythm (known as sinus rhythm).

If you have a medical history that includes a previous heart attack, smoking, a congenital heart defect, or chronic stress you are at higher risk of having an arrhythmia. 

There are many different types of arrhythmias, from occasional fluttering and palpitations to atrial fibrillation to lethal arrhythmias like ventricular tachycardia and ventricular fibrillation that can stop the heart and lead to death.

This article discusses the symptoms and potential causes of abnormal heartbeat. It also covers risk factors and when to seek tests or treatment for your symptoms.

listening to heartbeat

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Symptoms of Abnormal Heartbeat

Arrhythmias present in a wide array of ways, including silently (no symptoms). The feeling of an abnormal heartbeat can be scary. Some of the most common symptoms associated with a cardiac arrhythmia include: 

  • Palpitations (such as a racing, skipping, or fluttering sensation in your chest)
  • Dizziness or light-headedness
  • Feeling faint
  • Fatigue
  • Sweating

In more severe cases, an arrhythmia may also cause:

  • Chest pain
  • Shortness of breath
  • Heart failure
  • Cardiac arrest
  • Difficulty feeding (in infants)

Types of Abnormal Heartbeat

Below are the different types of abnormal heartbeat.

Atrial Fibrillation (AF or A-Fib)

Colloquially called A-fib, atrial fibrillation is the most common type of arrhythmia, and it is often characterized by a faster than normal, chaotic rhythm.

Your healthcare provider may describe this rhythm as “irregularly irregular.”  A-fib occurs when a trigger, such as a structural defect in the heart or medication, disrupts the smooth passing of an electrical signal through the sinoatrial (SA) node of the atrium. As a result, a chaotic rhythm with no discernible pattern occurs.

Associated symptoms include:

  • Palpitations
  • Shortness of breath (dyspnea)
  • Exercise intolerance
  • Weakness

Supraventricular Tachycardia (SVT)

Your heart usually beats between 60 and 100 times per minute. If you have episodes of abnormally fast heart rate at rest—that is over 100 beats per minute—you might have supraventricular tachycardia.

In SVT, the upper chamber of the heart (the atria) and the bottom chamber (the ventricles) are not in sync. These extra electrical impulses in the atria cause the heart to beat rapidly, not allowing the ventricles enough time to adequately fill with blood. SVT, which is usually first experienced in childhood, may be associated with:

  • Syncope (temporary loss of consciousness)
  • Heart palpitations
  • Dizziness
  • Chest pain


Normally the heart beats between 60 and 100 times per minute. If your heart beats more slowly than that—below 60 times—you may have bradycardia.

It is normal for your heart to be at or around 60 beats per minute (BPM) when you are sleeping or if you exercise routinely, but sometimes a slow heart rate can be a sign of an underlying issue such as:

  • Hypothyroidism (underactive thyroid)
  • A problem with your SA node
  • Heart disease

Sometimes bradycardia is also associated with symptoms of:

  • Fatigue
  • Light-headedness
  • Shortness of breath
  • Confusion
  • Exercise intolerance

Heart Block

Heart block usually represents a delay or disturbance in the transmission of an impulse from the atria to the ventricles. In these cases, the heart may beat more slowly than normal. 

There are three types of heart block:

  • First-degree heart block: The mildest form, which usually does not cause symptoms and is picked up incidentally on an electrocardiogram (ECG or EKG). Of note, electrical signals are slowed, but they all reach the ventricles.
  • Second-degree heart block: This heart block usually presents with a slower heartbeat and symptoms such as dizziness, feeling faint, feeling that your heart skips beats, chest pain, nausea, and shortness of breath. Not all signals reach the ventricles and some heartbeats are dropped.
  • Third-degree heart block: This is a complete atrioventricular block. In other words, none of the electrical signals from the atria reach the ventricles. Third-degree heart block is the most severe form of heart block and is associated with sudden cardiac arrest. Associated symptoms are similar to those in second-degree heart block. Most people with a third-degree heart block will need medical treatment and possibly the use of a pacemaker to prevent future episodes from occurring.

Ventricular fibrillation (VF or V-Fib)

This rare arrhythmia is a rapid and disorganized rhythm of heartbeats that occurs in the main pumping chamber of the heart. V-fib is a medical emergency. If left untreated, it can lead to rapid loss of consciousness and sudden death.

Causes of an Abnormal Heartbeat

Any condition that compromises your heart tissue or changes the conduction pathways that control the normal rhythmic pattern of your heartbeat can cause an arrhythmia. 

 The most common causes of an abnormal heartbeat are:

  • Heart disease
  • Electrolyte imbalances in your blood
  • Structural abnormalities of the heart
  • Infection
  • Abnormal electrical pathways
  • Medications

What Medications Can Cause an Abnormal Heartbeat

A host of medications can trigger arrhythmias, including antiarrhythmic drugs (medications that prevent and/or treat an abnormal heartbeat) themselves. Much research has been done about the adverse effects of proarrhythmic drugs, because in rare cases they have been shown to induce life-threatening ventricular tachycardias and conduction disorders.

Some drugs trigger atrial fibrillation, which is rarely deadly in and of itself, but it can cause substantial discomfort and death, as well as increase your risk of stroke.

Drug-induced arrhythmias and sudden death are uncommon events that occur in unpredictable ways but it is important to know your risk and the medications associated with these events—especially for those with structural abnormalities or at high risk of heart disease. 

Most drugs that cause arrhythmias do so in one of several ways, as follows:

  • Adrenergic or vagal stimulation, which can improve cardiac output by accelerating heart rate and increasing the force of contractions.
  • The drug is directly toxic to the heart (cardiotoxicity).
  • The drug changes the way electrical signals are conducted in the atria of the heart change atrial conduction, refractoriness or automaticity. 
  • The drug constricts coronary blood vessels cutting of blood flow (vasoconstriction and ischemia).
  • The drug causes local electrolyte disturbances in the heart.

The following medications have been associated with heart arrhythmias, particularly atrial fibrillation, QT prolongation, and/or Torsades de Pointes:

  • Cardiac stimulants: Dopamine, dobutamine, dopexamine, arbutamine
  • Vasodilators: Flosequinan, isosorbide mononitrate, losartan
  • Antiarrhythmics: Adenosine, verapamil, diltiazem, digoxin, atenolol
  • Cholinergics: Acetylcholine
  • Diuretics: Thiazides
  • Alpha agonists: Pseudoephedrine
  • Corticosteroids: Methylprednisolone at high doses
  • Cytostatics: Gemcitabine, melphalan, cisplatin, docetaxel, 5-FU
  • Cytokines and immunomodulators: Interferon-gamma, interleukin-3, interleukin-6
  • Cholinergics: Physostigmine, donepezil
  • Anticholinergics: Atropine
  • Antidepressants: Fluoxetine, trazodone
  • Antipsychotics: Clozapine
  • Antimigraine: Sumatriptan
  • Erectile dysfunction drugs: Sildenafil
  • Drugs for premature labor: Hexoprenalin, terbutaline, magnesium sulfate
  • Miscellaneous: Nicotine, anabolic steroids, fluorescein, etanercept, azathioprine

Are There Tests to Diagnose the Cause of My Abnormal Heartbeat?

Most people don’t experience an abnormal heart rhythm during a medical visit, but taking a detailed medical history (asking you about your medications, lifestyle habits, and past medical history) and performing a focused physical exam (listening to your heart with a stethoscope and measuring your blood pressure and pulse) can help your healthcare provider diagnose a potential arrhythmia.

To determine what might be causing your abnormal heartbeat, your healthcare provider may recommend/perform one of these tests:

  • Electrocardiogram (ECC or EKG)An EKG—a test involving attaching small electrodes to your chest to track the heart's electrical activity—can give information about the heart’s rhythm, size, and any possible damage. An EKG is one of the gold standard tools used to detect an arrhythmia. Of note, a Holter monitor is a portable EKG that can track your heart rhythm over the course of 24 hours.
  • Blood tests: Blood tests can detect electrolyte (potassium and sodium) imbalances and potential signs of infection.
  • Echocardiogram: This test uses ultrasound to display images of the heart to evaluate its structure and function.
  • Exercise stress test: Also known as a treadmill test, this exam tracks your heart rate and rhythm while you walk or run on a treadmill or ride a stationary bicycle.

Consult your healthcare provider if your test results are unclear or if you have any questions. After taking these exams check in with your healthcare provider so they can explain the results and discuss your treatment options. 

How to Treat Abnormal Heartbeat

There is no one-size-fits-all approach to treating arrhythmia, and a treatment that works for one person may not work for another person. The most effective way to manage your condition is to diagnose the type of arrhythmia and resolve the underlying cause of your abnormal heartbeat. 

The goals of arrhythmia treatment are to:

  • Minimize stroke risk
  • Control heart rate
  • Restore normal heart rhythm
  • Prevent cardiac arrest or sudden cardiac death

Less serious types of arrhythmia may be well managed with antiarrhythmic medication and regular checkups. For more serious or recurrent cases, you may need to undergo a procedure to treat your arrhythmia. Procedures may include:

  • Electrical cardioversion: A medical procedure performed by a cardiologist that aims to reset the heart by delivering an electrical shock to the heart, converting an abnormal or fast heart rhythm to a normal heart rhythm.
  • Ablation therapy: A procedure performed by an electrophysiologist (type of cardiologist) using a catheter to destroy abnormal tissue—usually by burning (radiofrequency ablation) or freezing (cryoablation)—responsible for the arrhythmia. 

When to See a Healthcare Provider

If your abnormal heartbeat is accompanied by severe chest pain, shortness of breath, light-headedness, feeling faint, or does not go away with your typical treatment, then seek immediate medical attention as untreated arrhythmia can lead to heart failure and sudden cardiac arrest.

In rare cases, an arrhythmia may be severe enough to disrupt the heart's ability to pump blood, causing oxygenated blood to be restricted throughout the body. This may cause you to lose consciousness.

If this occurs to someone else, call 911 immediately and start performing cardiopulmonary resuscitation (CPR), especially if the person is not breathing or you suspect that their heart has stopped beating. An EMT (emergency medical technician) may take over CPR when they arrive and use an automated external defibrillator (AED) to jump-start the heart.


An abnormal heartbeat (arrhythmia) occurs when the electrical signals cannot travel smoothly throughout the heart, causing your heart to quiver and beat out of rhythm.

A Word From Verywell

An abnormal heartbeat should be a cause for concern. If your abnormal heartbeat is accompanied by severe chest pain, shortness of breath, light-headedness or feeling faint, or if it does not go away with your typical treatment, it is important to seek immediate medical attention.

A healthcare provider can help determine the cause and subsequent treatment for your abnormal heartbeat.

Frequently Asked Questions

  • What causes an abnormal heartbeat?

    An abnormal heartbeat is caused by a disruption in the heart, such as damaged heart muscle tissue or a structural anomaly that distorts electrical signals throughout the heart.

    When electrical impulses cannot travel smoothly throughout the heart, it can cause your heart to quiver and beat out of rhythm, which compromises its ability to pump blood effectively throughout the body.

  • Is an abnormal heartbeat a sign of a heart issue?

    An abnormal heartbeat doesn’t necessarily mean you have a heart issue like heart disease or heart failure, but it may be a sign of a larger heart problem if it is associated with symptoms like chest pain, shortness of breath, dizziness, and fatigue.

  • How can I get rid of my abnormal heartbeat?

    Antiarrhythmic medications and procedures such as placing a pacemaker, electrical cardioversion, and ablation therapy can resolve your abnormal heartbeat.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. NHS. Arrhythmias.

  2. Keidar N, Elul Yn, Schuster A, Yaniv Y. Visualizing and quantifying irregular heart rate irregularities to identify atrial fibrillation events. Frontiers in Physiology. VOLUME 12. 2021. doi:10.3389/fphys.2021.637680   

  3. Children's Hospital of Philadelphia. Supraventricular tachycardia.

  4. American Heart Association. Bradycardia.

  5. Tisdale JE, Chung MK, Campbell KB, et al. Drug-induced arrhythmias: a scientific statement from the American Heart Association. Circulation. 2020;142(15). doi:10.1161/CIR.0000000000000905

By Shamard Charles, MD, MPH
Shamard Charles, MD, MPH is a public health physician and journalist. He has held positions with major news networks like NBC reporting on health policy, public health initiatives, diversity in medicine, and new developments in health care research and medical treatments.