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What are arrhythmias?
Arrhythmias are disorders of the regular rhythmic beating of the heart. The heart may be beating too fast (tachycardia), too slow (bradycardia), or irregularly. Arrhythmias can occur in a healthy heart and be of minimal consequence. They also may indicate a serious problem and lead to heart disease, stroke, or sudden cardiac death. (AHA 2007)
 The heart muscle contracts or beats as a result of electrical stimulation. The source of that electricity is in natural pacemaker cells, located in an upper chamber of the heart. The heart has four chambers: the right and left atria, on top, and the right and left ventricles, on the bottom. Abnormal rhythms, also known as arrhythmias, can originate in either the atria or the ventricles. They can be either fast or slow. Abnormal rhythms are important because they reduce the effectiveness of the heart as a pump.
According to the American Heart Association's Statistical Update 2007, about 2.2 million people in the United States have atrial fibrillation — the most common form of heart arrhythmia. The rate of atrial fibrillation increases with age. An estimated 3-5% of people over the age of 65 have atrial fibrillation.
The most serious cardiac rhythm disturbance, however, is believed to be ventricular fibrillation. This condition occurs when electrical activity causes the ventricles to contract rapidly and without synchronization, resulting in little or no blood being pumped from the heart. Medical help is needed immediately to avoid collapse and sudden death. If treated in time with electric shock, ventricular fibrillation can be converted into normal rhythm. While only 7,000 individuals are hospitalized for ventricular fibrillation each year, the overwhelming number of sudden cardiac deaths from coronary disease (about 340,000 a year) is thought to be from this form of arrhythmia.
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Abnormal Heart Rhythms: Symptoms
Symptoms of arrhythmias may include slow or fast heart beat (palpitations), skipping beats, fainting, dizziness or light-headedness, shortness of breath, chest pain, paleness, or even cardiac arrest.
Abnormal Heart Rhythms: Diagnosis
The diagnosis of the different arrhythmias is made by observing an electrocardiogram. For those who experience only intermittent symptoms, home ambulatory electrocardiogram monitors are available. A Holter monitor is worn for 24 hours, for example, and it records the electrocardiogram for that entire time, picking up any instances of the abnormal rhythm that occurs during that period. In contrast, an event recorder is worn continuously. It does not record anything unless the patient activates it, however.
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Abnormal Heart Rhythms: Treatment
Treatment for heart arrhythmias depends upon the underlying cause of the problem. Treatment options vary and may include lifestyle changes, medications, electronic devices, procedures, and surgery.
Lifestyle changes may include increasing physical activity; maintaining a healthy weight and eating a healthy diet; avoiding tobacco; limiting caffeine, alcohol, and all substances that may affect arrhythmias; avoiding and/or managing stress, anxiety, and fear; and getting regular check-ups and treating all health-related problems, including high blood pressure, diabetes, cholesterol, etc.
Medications, such as aspirin and warfarin (Coumadin), are sometimes used to control the rhythms, reduce blood pressure, or reduce the risk of clotting. The choice of medication will depend upon the patient's type of rhythm disorder, other medical problems, and overall health.
Electronic devices are used in certain abnormal rhythms when medications are ineffective. A pacemaker is an implantable device that monitors (or senses) and regulates (or paces) the rhythm and sends electrical impulses to speed up the heart if beating too slowly. In recent years, pacemakers that sense and stop fast rhythms have come into use.
 Implantable cardioverter defibrillators (also called, automatic internal cardiac defibrillators [AICDs]) continuously monitor the heart’s rhythm and automatically deliver shocks for various life-threatening arrhythmias such as ventricular tachycardia (rhythm originating from the lower heart chambers that is very rapid) and ventricular fibrillation (unorganized heart rhythm originating from the lower heart chamber) and some less serious rhythms, such as atrial fibrillation (unorganized heart rhythm originating from the upper heart chambers). This is the most successful therapy to treat the life-threatening arrhythmia, ventricular fibrillation, which is the major cause of sudden cardiac death.
Cardiac ablation is an X-ray guided procedure that involves inserting thin catheters through the blood vessels to the heart muscle and delivering a specific amount of energy (either radiofrequency energy, which cauterizes the tissue, or cold, which freezes the tissue) to destroy the tissue responsible for disturbing the electric flow, thereby restoring the heart's normal rhythm.
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For more information, please visit the following web sites, which have additional glossaries about medical conditions:
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