Disorder in the normal heart rhythm. Any disturbance in the creation of the electrical stimulus or its conduction can cause irregular heart rate (arrhythmia). Arrhythmias can be paroxysmal and intermittent or chronic. They can originate in the upper cardiac compartments (vestibules or atria) or from the lower compartments (ventricles). Arrhythmias can be rapid or slow, without any clinical significance or life-threatening. The therapeutic approach depends on the sort, risk level, frequency of the appearance of the disturbance and its clinical consequences.