What physiological event is represented by the 'sawtooth' baseline pattern observed in atrial flutter?

The sawtooth baseline pattern, often called flutter waves, is caused by a macro-reentrant circuit within the right atrium of the heart. In a normal heartbeat, an electrical signal travels from the top of the heart to the bottom in a single path. In atrial flutter, an electrical impulse gets trapped in a continuous, circular loop around the tric....