Atrial flutter and atrial fibrillation are arrhythmias that occur in the atria and have a faster impulse frequency than atrial tachycardia. Atrial flutter occurs when the frequency of the atrial ectopic pacing point reaches 250-350 beats/min and the atrial contractions are rapid and coordinated. If the frequency is >350 beats/min and irregular, then it is atrial fibrillation. Both are common arrhythmias, occurring most often in patients with wind heart disease, coronary artery disease, hyperthyroidism, cardiomyopathy and hypertension, but also in those without organic heart disease (idiopathic atrial fibrillation).