Arrhythmias (Heart Rhythm Disturbances) Causes

Arrhythmias are very common, both the harmless type and the dangerous type. An arrhythmia can be caused by:

• The heart's natural pacemaker developing an abnormal rate or rhythm
• The normal electrical conduction pathway being interrupted
• Another part of the heart (other than the sinus node) taking over as pacemaker

The most common cause of dangerous arrhythmias is a heart attack. When the heart is deprived of adequate blood supply during a heart attack, its electrical activity can become erratic. Diseased heart valves and diseased heart muscle, direct injury to the heart, diseases that alter the body's chemical balance, and several kinds of medication can also upset the heart's circuitry.

The most common causes of arrhythmia include:

• Coronary artery disease (eg, heart attacks)
• Diseased myocardium (heart muscle)
• Abnormal heart valves
• Birth defects
• Stress
• Caffeine
• Tobacco
• Alcohol
• Illegal stimulants, such as cocaine and methedrine
• Diet pills
• Some over-the-counter medications, such as cough and cold medicines

Various prescription medications such as the following can also cause arrhythmias:

• Heart medicines
• Asthma medicines
• Psychoactive medicines, such as antidepressants
• Thyroid hormone replacement medicines

A risk factor is something that increases your likelihood of getting a disease or condition.

It is possible to develop arrhythmias with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of developing arrhythmias. If you have a number of risk factors, ask your doctor what you can do to reduce your risk.

Risk factors for arrhythmias include:

Medical Conditions

The following medical conditions increase your chances of developing an arrhythmia:

• Heart muscle damage after heart attack
• Coronary artery disease
• Problems with heart valves
• Rheumatic heart disease
• Endocrine disorders, such as thyroid or adrenal gland problems
• Anemia
• High blood pressure
• Cardiomyopathy
• Diabetes
• Obstructive sleep apnea
• Liver disease
• Typhoid fever
• Hypothermia
• Complication after near-drowning
• Electric shock or lightning strike
• Certain birth defects

Medications

Taking the following medication may increase your chances of developing an arrhythmia:

• Diet pills or decongestants
• Antidepressant medications
• Digitalis
• Thyroid medications
• Prescription stimulants (eg, Ritalin)

Lifestyle Habits

The following habits may increase your chances of developing an arrhythmia:

• Smoking
• Alcohol
• Stress
• Excessive caffeine intake

Illegal Drugs

Use of illegal drugs, especially stimulants such as cocaine, methedrine, and other amphetamines, increases your risk of developing an arrhythmia.

Age

As with the risk of heart disease, your risk of developing an arrhythmia increases as you age.

References:

Barsky, AJ, Cleary, PD, Coeytaux, RR, Ruskin, JN. The clinical course of palpitations in medical outpatients. Arch Intern Med.1995;155:1782.

Harrison's Principles of Internal Medicine. 14th ed. McGraw-Hill; 1998.

Lok NS, Lau CP. Prevalence of palpitations, cardiac arrhythmias and their associated risk factors in ambulant elderly. Int J Cardiol.1996;54:231.

Mayo Clinic and Foundation for Medical Education and Research website. Available at: http://www.mayo.edu/ .

National Heart, Lung, and Blood Institute website. Available at: http://www.nhlbi.nih.gov/ .

Sarter BH, Finkle JK, Gerszten RE, et al. What is the risk of sudden cardiac death in patients presenting with hemodynamically stable sustained ventricular tachycardia after myocardial infarction? J Am Coll Cardiol.1996;28:122.