The electrocardiogram in atrial flutter is typically characterized by its "sawtooth" flutter waves (F waves - arrows below) best demonstrated in the inferior leads (II, III, aVF and V1). A rapid regular atrial rhythm is generally demonstrated between 250 and 350 bpm, and the qRS rate is determined by the ratio of atrioventricular conduction. Although the usual ratio of AV conduction is 2:1 (as illustrated below), 1:1, 3:1, 4:1, 6:1 and other variable ratios are also demonstrated, albeit less frequently. Typically, this results in a ventricular heart rate between 150 and 170 bpm. Atrial flutter is relatively uncommon and is most often seen in patients presenting with acute ischemic heart disease or pulmonary embolism. Nevertheless, it can present as a chronic condition in patients who suffer from organic heart disease.