(arrhythmia) An abnormal heart rhythm caused by a disturbance in the heart's electrical system.

(arrhythmia) An arrhythmia is a problem with the rate or rhythm of your heartbeat. It means that your heart beats too quickly, too slowly, or with an irregular pattern. When the heart beats faster than normal, it is called tachycardia. When the heart beats too slowly, it is called bradycardia. The most common type of arrhythmia is atrial fibrillation, which causes an irregular and fast heart beat. Many factors can affect your heart's rhythm, such as having had a heart attack, smoking, congenital heart defects, and stress. Some substances or medicines may also cause arrhythmias. Symptoms of arrhythmias include Fast or slow heart beat; Skipping beats; Lightheadedness or dizziness; Chest pain; Shortness of breath; Sweating . Your doctor can run tests to find out if you have an arrhythmia. Treatment to restore a normal heart rhythm may include medicines, an implantable cardioverter-defibrillator (ICD) or pacemaker, or sometimes surgery. NIH: National Heart, Lung, and Blood Institute

(arrhythmia) Any cardiac rhythm other than the normal sinus rhythm. Such a rhythm may be either of sinus or ectopic origin and either regular or irregular. An arrhythmia may be due to a disturbance in impulse formation or conduction or both.

(arrhythmia) Any variation from the normal rate or rhythm (which may include the origin of the impulse and/or its subsequent propagation) in the heart.

(arrhythmias, cardiac) Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.

The normal heart beats in a regular, coordinated way because electrical impulses generated and spread by myocytes with unique electrical properties trigger a sequence of organized myocardial contractions. Arrhythmias and conduction disorders are caused by abnormalities in the generation or conduction of these electrical impulses or both.

Heart rhythm problems (heart arrhythmias) occur when the electrical impulses that coordinate your heartbeats don't work properly, causing your heart to beat too fast, too slow or irregularly.

Arrhythmia, variation from the normal rate or regularity of the heartbeat, usually resulting from irregularities within the conduction system of the heart. Arrhythmias occur in both normal and diseased hearts and have no medical significance in and of themselves, although they may endanger heart...