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What causes an arrhythmia?

There are many causes of arrhythmias, or irregular and abnormal heart rate, and many arrythmias whose cause is unknown.  Ischemia, lack of sufficient blood flow to the heart, can cause arrythmias. Arrythmias can also arise from scar tissue in the heart from areas of previous decreased blood flow (area of prior heart attack).  

Other causes of arrythmias are increased age, over activity of the thyroid gland, enlargement of the heart chambers, and heart valve disease. Arrythmias can also occur after heart surgery.

An arrhythmia can occur if the electrical signals that control the heartbeat are delayed or blocked. This can happen if the special nerve cells that produce electrical signals don't work properly, or if electrical signals don't travel normally through the heart.

An arrhythmia also can occur if another part of the heart starts to produce electrical signals. This adds to the signals from the special nerve cells and disrupts the normal heartbeat.

Smoking, heavy alcohol use, use of certain drugs (such as cocaine or amphetamines), use of certain prescription or over-the-counter medicines, or too much caffeine or nicotine can lead to arrhythmias in some people.

Strong emotional stress or anger can make the heart work harder, raise blood pressure, and release stress hormones. In some people, these reactions can lead to arrhythmias.

A heart attack or an underlying condition that damages the heart's electrical system also can cause arrhythmias. Examples of such conditions include high blood pressure, coronary heart disease, heart failure, overactive or underactive thyroid gland (too much or too little thyroid hormone produced), and rheumatic heart disease.

In some arrhythmias, such as Wolff-Parkinson-White syndrome, the underlying heart defect that causes the arrhythmia is congenital (present at birth). Sometimes, the cause of an arrhythmia can't be found.

This answer from the National Heart, Lung and Blood Institute has been reviewed and/or edited by Dr. William D. Knopf.

Dr. Indrajit Choudhuri, MD
Cardiologist (Heart Specialist)

Cardiac or "heart" arrhythmias occur because there is a change in the heart's electrical system (yes, it has an electrical system!) that causes its normal rhythm (sinus rhythm) to change to a different one. Many heart rhythms are known and they develop for various reasons, most commonly heart and lung disease.

Heart and lung diseases put excess strain on the heart and can change or even damage the heart's electrical system. The change in the electrical system then manifests as an arrhythmia—an abnormal heart rhythm.

Other than heart and lung diseases, problems with practically every other organ system can lead to arrhythmias. Other common causes include thyroid disease, obesity, infections, surgery, drug use (prescription, over-the-counter, or recreational), alcohol and even for no apparent reason.

An arrhythmia (also referred to as dysrhythmia) is an abnormal rhythm of the heart, which can cause the heart to pump less effectively.

The heart’s beating becomes irregular when the sinus node—the group of heart cells that generate the electrical signal that triggers the heart’s contraction—malfunctions or the signal is disrupted before it makes its way through the heart muscle. Arrhythmias can also occur when another group of cells takes over the function of the sinus node. Arrhythmias can affect both the upper chambers, or atria, and the lower chambers, or ventricles.

Many activities, conditions, and substances can potentially cause or lead to an arrhythmia. These include:

  • A genetic heart abnormality
  • Heart disease
  • Changes in the heart muscle, also called cardiomyopathy
  • Injury or scarring from a heart attack
  • Healing after heart surgery
  • Heart-valve disorders
  • Hyperthyroidism
  • High blood pressure
  • Obesity
  • Electrolyte imbalances (such as sodium or potassium) in the blood
  • Stress
  • Obstructive sleep apnea
  • Excessive alcohol or caffeine intake
  • Smoking
  • Drug abuse
  • Dietary supplements
  • Over-the-counter medications such as certain cough and cold remedies
  • Prescription drugs, including some medications prescribed for high blood pressure, heart disease, and arrhythmias
  • Exposures in the workplace or environment such as industrial-plant pollution, automobile emissions, paint thinners, or propane gas

An arrhythmia is kind of like watching Elaine dance in front of her coworkers in that infamous Seinfeld episode. In both cases, a serious lack of rhythm is the problem.

Many health choices (too many hot dogs, or diet pills, or smoking), or conditions (high blood pressure, inflammation, type 2 diabetes, hyperthyroidism, and a few hundred more) damage the heart’s electrical system and can lead to abnormal arrhythmias.

During a regular heartbeat, electrical pulses cause the heart muscle to contract in a regular, rhythmic pattern, pumping blood throughout the body. These electrical pulses follow a specific pathway through the heart and are regulated by a natural pacemaker. Arrhythmia occurs if the heart's natural pace maker develops an abnormal rhythm, the electrical pulses cannot follow their path through the heart, or a secondary pacemaker in the heart takes over. Scar tissue and reduced blood flow both hinder the heart's ability to regulate its beating, resulting in an arrhythmia. Heart disease, high blood pressure, diabetes, smoking, drug abuse, excessive caffeine or alcohol use, some medications, and stress can all lead to an arrhythmia.

Dr. Vivek Y. Reddy, MD
Cardiac Electrophysiologist

Factors that can disrupt the heart's normal pace and contribute to arrhythmia include:

  • Damage to or scarring of heart tissue
  • Heart attack
  • Heart disease
  • High blood pressure (hypertension)
  • Smoking
  • Stress
  • Drug abuse
Dr. Douglas E. Severance, MD
Family Practitioner

Arrhythmias usually happen when the heart's natural pacemaker—called the sinus node or SA node—is sped up or slowed down with an irregular rhythm. Atrial fibrillation is one type of arrhythmia that results in an uneven and rapid heartbeat. But your heart rate can also rev up as a result of caffeinated drinks, energy drinks, too much chocolate, alcohol, cigarette smoking, sinus medications, diet pills, or medical conditions such as hyperthyroidism. On the flip side, your heartbeat can slow down because of certain medications or health conditions like hypothyroidism.

Most of the time, when you remove the problem substance or treat the arrhythmia, the abnormality goes away. For example, if drinking too much caffeine sends your heart racing, cutting back should allow your heart to go back to normal. Or if decongestants for a cold or sinusitis cause your heart to beat rapidly, stopping the medication would resolve the issue.

If you have a more serious problem with your heart—such as damage from a heart attack or valve problems from mitral valve prolapse—you will need medications or other treatments to manage the co-existing arrhythmias. If you have high blood pressure, medications to lower it may help resolve an arrhythmia.

Heart rhythm disturbances may be caused by blocked arteries.

Arrhythmias (heart rhythm problems) can result from a number of different conditions. Some of these are lack of oxygen to the heart (often caused by atherosclerosis), heart valve disease, or damage to the heart muscle. People may experience arrhythmias as palpitations, a "fluttering" or "racing" heart, or skipped heartbeats.

It is not always clear what causes an arrhythmia. Possible causes include heart disease, aging, myocardial ischemia (reduced blood flow to heart muscle), electrical conduction disorders, stress, caffeine, tobacco, alcohol, diet pills, and cough medication. In the case of tachycardia, complicating factors include heart attack, heart valve disease, angina, and emphysema.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.