Arrhythmia

Arrhythmias (or dysrhythmias) are problems that affect the electrical system of the heart muscle,producing abnormal heart rhythms. They can cause the heart to pump less effectively. ECG is the best tool for diagnosis of arrhyhmias. Arrhythmias may be seen on 12-lead ECGs or on strips of one or more leads. Some arrhythmias are obvious at first glance and don’t require intense analysis; others require systematic analysis of surface ECG followed invasive evaluation in the form of eletrophysiologic study for diagnosis.Many arrhythmias have no known underlying cause. However, a number of factors can contribute to arrhythmias. They include coronary artery disease, high blood pressure, diabetes, smoking,excessive use of alcohol, drug abuse and stress. Certain substances, including some over-the- counter and prescription medications, dietary supplements and herbal remedies are known to cause arrhythmias in some people.

Bradyarrhythmia refers to any rhythm with rate less than 60 beats/minute. Tachyarrhythmia means any rhythm with rate more than 100 beats/minute. Two important issues that are basic to the understanding the rhythm disturbances are:

• Mechanism of the rhythm abnormality

• Site of origin of the arrhythmia

There are broadly two major mechanisms of that produce arrhythmias:

• Disorders of impulse of formation (automaticity) and

• Disorders of impulse conduction (block or re-entry)