The terms of cardial arrhytmia covers very large number of very different conditions in which there is abnormal electrical activity in the heart. Any heart disorder, including congenital abnormalities of structure (e.g. accessory atrioventricular connection) or function (e.g. hereditary ion channelopathies), can disturb rhythm. Systemic factors that can cause or contribute to a rhythm disturbance include electrolyte abnormalities (particularly low K or Mg), hypoxia, hormonal imbalances (e.g. hypothyroidism, hyperthyroidism), and drugs and toxins (e.g. alcohol, caffeine). The heart beat may be too fast or too slow, and may be regular or irregular. Some arrhythmias do not cause symptoms, and are not associated with increased mortality. Some types of arrhytmia results in cardiac arrest or sudden death. The simplest specific diagnostic test for assessment of heart rhythm is the electrocardiogram (ECG). Asymptomatic arrhythmias without serious risks do not require treatment even if they worsen. Symptomatic arrhythmias may require treatment to improve quality of life. Potentially life-threatening arrhythmias require treatment. Management included treatment of cause and,  if necessary, direct antiarrhythmic therapy, including antiarrhythmic drugs, cardioversion-defibrillation, pacemakers, radiofrequency (RF) ablation or a combination, is used.