Arrhythmias Explained

Arrhythmia Causes

What Causes an Arrhythmia?

An arrhythmia can occur when the electrical signals that control the heartbeat are delayed or blocked. This can happen when the special nerve cells that produce the electrical signal don’t work properly or when the electrical signal doesn’t travel normally through the heart. An arrhythmia also can occur when another part of the heart starts to produce electrical signals, adding to the signals from the special nerve cells and disrupting the normal heartbeat.

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

A heart attack or an underlying condition that damages the heart’s electrical system also can cause an arrhythmia. These conditions include high blood pressure (hypertension), coronary artery disease, heart failure, overactive or under active thyroid gland (too much or too little thyroid hormone produced), and rheumatic heart disease.

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

Arrhythmia Risk Factors

Who Is At Risk for an Arrhythmia?

Populations Affected

Millions of Americans have arrhythmias. They are very common in older adults. About 2.2 million Americans have atrial fibrillation (a common type of arrhythmia that can cause problems).

Most serious arrhythmias happen in adults older than 60. This is because older adults are more likely to have heart disease and other health problems that can lead to arrhythmias. Older adults also tend to be more sensitive to the side effects of medicines, some of which can cause arrhythmias. Some medicines used to treat arrhythmias can cause arrhythmias as a side effect.

Some types of arrhythmia happen more often in children and young adults. Paroxysmal supraventricular tachycardias (a fast heart rate that begins and ends suddenly), including Wolff-Parkinson-White syndrome, are more common in young people.

Major Risk Factors

Arrhythmias are more common in people who have a disease or condition that weakens the heart, such as:

• Heart attack
• Heart failure or cardiomyopathy, which weakens the heart and changes the way electrical signals move around the heart
• Heart tissue that is too thick or stiff or that hasn’t formed normally
• Leaking or narrowed heart valves, which make the heart work too hard and can lead to heart failure
• Congenital problems (problems that are present at birth) with the heart’s structure or function

Other conditions also can increase the chances of arrhythmia, such as:

• High blood pressure
• Infections that damage the heart muscle or the sac around the heart
• Diabetes, which increases the risk of high blood pressure and coronary artery disease
• Sleep apnea (when breathing becomes shallow or stops during sleep), which can stress the heart because it doesn’t get enough oxygen
• Overactive or underactive thyroid gland (too much or too little thyroid hormone in the body)

In addition to certain diseases and conditions, several other risk factors increase a person’s chance of having an arrhythmia. Heart surgery, certain drugs (such as cocaine or amphetamines), or an imbalance of chemicals or other substances (such as potassium) in the bloodstream can increase a person’s chance of having an arrhythmia.