This rhythm strip shows atrial flutter with 2:1 block. The characteristic features demonstrated here include a rapid, regular atrial rate typically in the range of three hundred per minute and an atrial wave form that has a saw-tooth configuration. When untreated, as in this case, the ventricle typically responds to very other atrial beat, producing in this example, a heart rate of 165 beats per minute. With treatment, A-V block increases, reducing the ventricular response.