Arrhythmias

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.

Alternative Names

Abnormal heart rhythms; Bradycardia; Tachycardia; Fibrillation

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:

Atrial fibrillation or flutter
Atrioventricular nodal reentry tachycardia (AVNRT)
Heart block or atrioventricular block
Multifocal atrial tachycardia
Paroxysmal supraventricular tachycardia
Sick sinus syndrome
Ventricular fibrillation or ventricular tachycardia
Wolff-Parkinson-White syndrome

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Symptoms

When you have an arrhythmia, your heartbeat may be:

Too slow (bradycardia)
Too quick (tachycardia)
Irregular, uneven, or skipping 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:

Chest pain
Fainting
Lightheadedness, dizziness
Paleness
Palpitations (feeling your heart beat fast or irregularly)
Shortness of breath
Sweating

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.

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)

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 cardiac 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

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

Rubart M, Zipes DP. Genesis of cardiac arrhythmias, electrophysiologic considerations. In: Bonow RO, Mann DL, Zipes DP, Libby P, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 33.

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.