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Arrhythmias

Abnormal heart rhythms; Bradycardia; Tachycardia; Fibrillation

An arrhythmia is a disorder of the heart rate (pulse) or heart rhythm. The heart can beat too fast (tachycardia), too slow (bradycardia), or irregularly.

An arrhythmia can be harmless, a sign of other heart problems, or an immediate danger to your health.

Causes

Normally, your heart works as a pump that brings blood to the lungs and the rest of the body.

To help this happen, your heart has an electrical system that makes sure it contracts (squeezes) in an orderly way.

  • The electrical impulse that signals your heart to contract begins in an area of the heart called the sinoatrial node (also called the sinus node or SA node). This is your heart’s natural pacemaker.
  • The signal leaves the SA node and travels through the heart along a set electrical pathway.
  • Different nerve messages signal your heart to beat slower or faster.

Arrhythmias are caused by problems with the heart’s electrical conduction system.

  • Abnormal (extra) signals may occur.
  • Electrical signals may be blocked or slowed.
  • Electrical signals travel in new or different pathways through the heart.

Some common causes of abnormal heartbeats are:

  • Abnormal levels of potassium or other substances in the body
  • Heart attack, or a damaged heart muscle from a past heart attack
  • Heart disease that is present at birth (congenital)
  • Heart failure or an enlarged heart
  • Overactive thyroid gland

Arrhythmias may also be caused by some substances or drugs, including:

  • Alcohol, caffeine, or stimulant drugs
  • Heart or blood pressure medicines
  • Cigarette smoking (nicotine)
  • Drugs that mimic the activity of your nervous system
  • Medicines used for depression or psychosis

Sometimes medicines used to treat one type of arrhythmia will cause another type of abnormal heart rhythm.

Some of the more common abnormal heart rhythms are:

Symptoms

When you have an arrhythmia, your heartbeat may be:

  • Too slow (bradycardia)
  • Too quick (tachycardia)
  • Irregular, uneven, possibly with extra or skipped beats

An arrhythmia may be present all of the time or it may come and go. You may or may not feel symptoms when the arrhythmia is present. Or, you may only notice symptoms when you are more active.

Symptoms can be very mild, or they may be severe or even life threatening.

Common symptoms that may occur when the arrhythmia is present include:

Exams and Tests

The health care provider will listen to your heart with a stethoscope and feel your pulse. Your blood pressure may be low or normal or even high as a result of being uncomfortable.

An ECG will be the first test done.

Heart monitoring devices are often used to identify the rhythm problem, such as a:

  • Holter monitor (where you wear a device that records and stores your heart rhythm for 24 hours)
  • Event monitor or loop recorder (worn for 2 weeks or longer, where you record your heart rhythm when you feel an abnormal rhythm)
  • Other long-term monitoring options

An echocardiogram is often ordered to examine the size or structure of your heart.

Coronary angiography to see how blood flows through the arteries in your heart.

A special test, called an electrophysiology study (EPS), is done to take a closer look at the heart's electrical system.

Treatment

When an arrhythmia is serious, you may need urgent treatment to restore a normal rhythm. This may include:

  • Electrical "shock" therapy (defibrillation or cardioversion)
  • Implanting a short-term heart pacemaker
  • Medicines given through a vein or by mouth

Sometimes, better treatment for your angina or heart failure will lower your chance of having an arrhythmia.

Medicines called anti-arrhythmic drugs may be used:

  • To prevent an arrhythmia from happening again
  • To keep your heart rate from becoming too fast or too slow

Some of these medicines can have side effects. Take them as prescribed by your provider. DO NOT stop taking the medicine or change the dose without first talking to your provider.

Other treatments to prevent or treat abnormal heart rhythms include:

  • Cardiac ablation, used to destroy areas in your heart that may be causing your heart rhythm problems
  • An implantable cardioverter defibrillator, placed in people who are at high risk of sudden cardiac death
  • Permanent pacemaker, a device that senses when your heart is beating irregularly, too slowly, or too fast. It sends a signal to your heart that makes your heart beat at the correct pace.

Outlook (Prognosis)

The outcome depends on several factors:

  • The kind of arrhythmia you have. (Some abnormal heart rhythms may be life threatening if not treated right away, or DO NOT respond well to treatment.)
  • Whether you have coronary artery disease, heart failure, or valvular heart disease.

When to Contact a Medical Professional

Call your provider if:

  • You develop any of the symptoms of a possible arrhythmia.
  • You have been diagnosed with an arrhythmia and your symptoms worsen or DO NOT improve with treatment.

Prevention

Taking steps to prevent coronary artery disease may reduce your chance of developing an arrhythmia.

References

Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Heart Rhythm. 2017. S1547-5271(17)31249-3. PMID: 29097320 www.ncbi.nlm.nih.gov/pubmed/29097320.

Olgin JE. Approach to the patient with suspected arrhythmia. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 62.

Tomaselli GF, Rubart M, Zipes DP. Mechanisms of cardiac arrhythmias. In: Zipes DP, Libby P, Bonow RO, Mann DL, Tomaselli GF, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 11th ed. Philadelphia, PA: Elsevier; 2019:chap 34.

Tracy CM, Epstein AE, Darbar D, et al. 2012 ACCF/AHA/HRS focused update of the 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2012;60(14):1297-1313. PMID: 22975230 www.ncbi.nlm.nih.gov/pubmed/22975230.

  • Arrhythmias

    Arrhythmias

    Animation

  •  

    Arrhythmias - Animation

    This animation shows the cardiac conduction system and the arrhythmias of a fast and slow beating heart.

  • Cardiac arrhythmia: Heart palpitations and other symptoms

    Cardiac arrhythmia: Heart palpitations and other symptoms

    Animation

  •  

    Cardiac arrhythmia: Heart palpitations and other symptoms - Animation

    A wide range of symptoms, including palpitations, dyspnea, syncope, fatigue, dizziness, chest pain, and lightheadedness can be produced by different types of cardiac arrhythmia.

  • Cardiac accessory pathway disorders overview

    Cardiac accessory pathway disorders overview

    Animation

  •  

    Cardiac accessory pathway disorders overview - Animation

    A look at different types of cardiac accessory pathway problems including tachycardias and Wolff-Parkinson-White syndrome.

  • Heart, section through the middle

    Heart, section through the middle - illustration

    The interior of the heart is composed of valves, chambers, and associated vessels.

    Heart, section through the middle

    illustration

  • Heart, front view

    Heart, front view - illustration

    The external structures of the heart include the ventricles, atria, arteries and veins. Arteries carry blood away from the heart while veins carry blood into the heart. The vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

    Heart, front view

    illustration

  • Normal heart rhythm

    Normal heart rhythm - illustration

    An electrocardiogram (ECG) test measures the electrical activity of the heart. A normal resting heart rate is 60 to 100 beats per minute.

    Normal heart rhythm

    illustration

  • Bradycardia

    Bradycardia - illustration

    Bradycardia heart rhythms are characterized by a slowness of the heartbeat, usually at a rate under 60 beats per minute (normal resting rate is 60 to 100 beats per minute).

    Bradycardia

    illustration

  • Ventricular tachycardia

    Ventricular tachycardia - illustration

    Ventricular tachycardia is a rapid resting heart rate initiated within the ventricles, typically at 160 to 240 beats per minute (normal resting rate is 60 to 100 beats per minute).

    Ventricular tachycardia

    illustration

  • Atrioventricular block,  ECG tracing

    Atrioventricular block, ECG tracing - illustration

    This picture shows an ECG (electrocardiogram, EKG) of a person with an abnormal rhythm (arrhythmia) called an atrioventricular (AV) block. P waves show that the top of the heart received electrical activity. Each P wave is usually followed by the tall (QRS) waves. QRS waves reflect the electrical activity that causes the heart to contract. When a P wave is present and not followed by a QRS wave (and heart contraction), there is an atrioventricular block, and a very slow pulse (bradycardia).

    Atrioventricular block, ECG tracing

    illustration

  • Conduction system of the heart

    Conduction system of the heart - illustration

    The intrinsic conduction system sets the basic rhythm of the beating heart by generating impulses which stimulate the heart to contract.

    Conduction system of the heart

    illustration

  • Arrhythmias

    Animation

  •  

    Arrhythmias - Animation

    This animation shows the cardiac conduction system and the arrhythmias of a fast and slow beating heart.

  • Cardiac arrhythmia: Heart palpitations and other symptoms

    Animation

  •  

    Cardiac arrhythmia: Heart palpitations and other symptoms - Animation

    A wide range of symptoms, including palpitations, dyspnea, syncope, fatigue, dizziness, chest pain, and lightheadedness can be produced by different types of cardiac arrhythmia.

  • Cardiac accessory pathway disorders overview

    Animation

  •  

    Cardiac accessory pathway disorders overview - Animation

    A look at different types of cardiac accessory pathway problems including tachycardias and Wolff-Parkinson-White syndrome.

  • Heart, section through the middle

    Heart, section through the middle - illustration

    The interior of the heart is composed of valves, chambers, and associated vessels.

    Heart, section through the middle

    illustration

  • Heart, front view

    Heart, front view - illustration

    The external structures of the heart include the ventricles, atria, arteries and veins. Arteries carry blood away from the heart while veins carry blood into the heart. The vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

    Heart, front view

    illustration

  • Normal heart rhythm

    Normal heart rhythm - illustration

    An electrocardiogram (ECG) test measures the electrical activity of the heart. A normal resting heart rate is 60 to 100 beats per minute.

    Normal heart rhythm

    illustration

  • Bradycardia

    Bradycardia - illustration

    Bradycardia heart rhythms are characterized by a slowness of the heartbeat, usually at a rate under 60 beats per minute (normal resting rate is 60 to 100 beats per minute).

    Bradycardia

    illustration

  • Ventricular tachycardia

    Ventricular tachycardia - illustration

    Ventricular tachycardia is a rapid resting heart rate initiated within the ventricles, typically at 160 to 240 beats per minute (normal resting rate is 60 to 100 beats per minute).

    Ventricular tachycardia

    illustration

  • Atrioventricular block,  ECG tracing

    Atrioventricular block, ECG tracing - illustration

    This picture shows an ECG (electrocardiogram, EKG) of a person with an abnormal rhythm (arrhythmia) called an atrioventricular (AV) block. P waves show that the top of the heart received electrical activity. Each P wave is usually followed by the tall (QRS) waves. QRS waves reflect the electrical activity that causes the heart to contract. When a P wave is present and not followed by a QRS wave (and heart contraction), there is an atrioventricular block, and a very slow pulse (bradycardia).

    Atrioventricular block, ECG tracing

    illustration

  • Conduction system of the heart

    Conduction system of the heart - illustration

    The intrinsic conduction system sets the basic rhythm of the beating heart by generating impulses which stimulate the heart to contract.

    Conduction system of the heart

    illustration

 

Review Date: 5/16/2018

Reviewed By: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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