An abnormal heart rhythm, or heartbeat The rhythm can be too fast, too slow, or irregular (beating at an off-beat rhythm) Some arrhythmias aren't a problem, but more serious arrhythmias can mean the heart is working less effectively, and may cause symptoms of palpitations, weakness, dizziness, chest pain, and shortness of breath
Irregular heart action caused by disturbances in cardiac impulses Bradycardia -- slowness of heart action Tachycardia -- rapid heart action
An irregular heart rhythm, or an abnormality in the timing or pattern of the heartbeat, causing the heart to beat too rapidly, too slowly, or irregularly
A disturbance of the normal and regular heart rhythm There are several different types of arrhythmias; some are dangerous, but most are not
Variation from the heartbeat's normal rate or rhythm, caused by problems in the heart's pacemaker or in nerves conducting its signals. Occasional arrhythmias are normal. Tachycardia is a fast regular rhythm; bradycardia is a slow rhythm. Premature atrial or ventricular beats are extra contractions in normal rhythm. Ongoing arrhythmia in some heart diseases can reduce the heart's ability to supply the body with blood and can lead to heart failure. Severe arrhythmias can trigger atrial fibrillation or ventricular fibrillation. Arrhythmias are detected by electrocardiography and treated by electric shock (often with an implanted pacemaker) or by drugs such as quinidine and digitalis