Arrhythmias can be seen in a variety of states, including for physiological arrhythmias, commonly sinus arrhythmias, seen in the elderly, women and children who are thin and frail, and sinus arrhythmias caused by respiratory factors, which often require no special management. For more severe arrhythmias, atrial fibrillation and ventricular fibrillation are common. For ventricular fibrillation it can lead to sudden death, while for patients with atrial fibrillation it can lead to cardiac insufficiency and also to the development of arterial thrombotic events, the most common complication being stroke. For atrial fibrillation, it is common in patients with all types of organic heart disease. In patients with hyperthyroidism, electrolyte disorders, severe infections, and in patients with idiopathic changes in the elderly, atrial fibrillation can also occur, and anticoagulants are recommended to control the ventricular rate, and if necessary, medications related to cardioversion of the rhythm are required.