What Is Arrhythmia?

Arrhythmias are disorders in which the electrical impulses in your heart do not work properly, causing a slow, fast, or irregular heart rhythm. Arrhythmias range from asymptomatic to uncomfortable, dangerous to lethal.

A healthy heart moves blood efficiently from chamber to chamber and then out to the rest of the body. A cascade of electrical signals carried by nerves synchronizes the cycle. These signals provide the regular pace for the heart, normally 60 to 100 beats per minute. Interruption of that electrical flow can result in rapid, slow, or irregular heartbeats known as arrhythmias.

Causes of Arrhythmia

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

Signs and Symptoms of Arrhythmia

Occasionally people experience palpitations, or heightened awareness of their heartbeat. It is common for the heart to race during exertion or emotional stress.

When the rhythm disturbances are prolonged or linger, they may be clues to an underlying heart condition. Certain abnormal heartbeats can be life threatening, even in the absence of overt heart disease symptoms. Watch for the following signs associated with palpitations and see a doctor if they persist:

• Fatigue
• Long pauses between heartbeats
• Unusual sweating
• Shortness of breath
• Chest pain
• Light-headedness and dizziness
• Fainting

Risk factors that may contribute to arrhythmia include:

• Aging
• Genetics
• Coronary artery disease
• Heart failure
• Heart valve disease
• Diabetes
• High blood pressure (hypertension)
• Thyroid disease
• Certain medications
• Congenital birth defects
• Recreational drug use, caffeine intake, and alcohol consumption

Types of Arrhythmia

Arrhythmias cause a variety of problems that range from mild to severe:

• Premature Heartbeats
  In some cases, premature heartbeats, or heartbeats that occur early, may be a warning sign of heart disease. Smokers or people who drink too much caffeine are more likely to experience these erratic heartbeats.
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• Atrial Fibrillation and Atrial Flutter
  These are the most common forms of arrhythmia. They are a leading cause of stroke and can lead to heart failure.
  
  Atrial fibrillation occurs when the upper chambers of the heart, the atria, beat out of sync with the lower chambers, called the ventricles. The resulting quivering leaves blood pooled in the atria, putting patients at risk for blood clots that can cause a stroke. The ventricles often compensate by contracting more rapidly, enlarging and weakening the heart.
  
  Temporary atrial fibrillation can revert to normal on its own. If it persists, doctors can implant a pacemaker to regulate the rhythms.
  
  Atrial flutter is similar to atrial fibrillation, but with more regular intervals between beats.
  
  Jonathan Halperin, MD, PhD, Director of Clinical Cardiology Services and Professor of Cardiology, was instrumental in developing new guidelines for the treatment of atrial fibrillation. The results of his NIH-sponsored clinical trial Stroke Prevention in Atrial Fibrillation (SPAF) prevent tens of thousands of strokes every year.
  
  "Atrial fibrillation is a huge problem and will soon reach epidemic proportions in this country," says Nicholas Skipitaris, MD, Assistant Professor and Medical Director, Cardiac Electrophysiology Operations. "It can be very debilitating, especially in patients who have other heart issues. At Mount Sinai, we're working hard to develop and hone the techniques to fix it.

• Paroxysmal Supraventricular Tachycardia
  This too-rapid rhythm results from an electrical short-circuit in the upper portion of the heart. Symptoms include lightheadedness or shortness of breath. Episodes generally are not life threatening but do require treatment.
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• Wolff-Parkinson-White Syndrome
  People with this condition experience potentially dangerous rapid heartbeats. A redundant electrical path that sends duplicate signals from the atrium to the ventricles causes it.
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• Ventricular Tachycardia
  If this rhythm lasts for more than a few seconds, it can lead to the much more dangerous ventricular fibrillation and then death. This abnormally fast heartbeat originates in the ventricles.
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• Ventricular Fibrillation
  In ventricular fibrillation, signals fire rapidly and chaotically, leaving the ventricles quivering and preventing blood from reaching the rest of the body. A heart attack or other heart ailment usually causes this condition.
  
  Ventricular fibrillation is the most common cause of sudden cardiac death, with many patients dying before they reach the hospital. Timely emergency medical care is critical.

• Bradycardia
  This slowed heart rate can cause patients to faint or feel as if they will faint. They may also experience chest pain, fatigue, or shortness of breath. Aging, chemical imbalance, or low thyroid hormone levels can cause bradycardia. Uneven electrical flow across the heart can also be a factor.