A 63-year-old woman presents with symptoms of palpitations and atrial flutter on the ECG. Which of the following is the most likely mechanism of this arrhythmia?

Atrial flutter is characterized by regular atrial activation with an atrial rate of > 240 beats/min. The ventricular response depends on the conduction of the AV node, usually there is 2:1 or 3:1 conduction. It is now known that the predominant mechanism for atrial flutter is right atrial macro reentry with circular activation. Atrial flutter typically originates from the right atrium and most often involves a large circuit that travels around the area of the tricuspid valve. This type of atrial flutter is referred to a typical atrial flutter. Less commonly, atrial flutter can result from circuits in other areas of the right or left atrium.