Atrial Flutter
The most common form of atrial flutter results from a reentrant circuit in the right atrium. Typically, reentry proceeds counterclockwise up the atrial septum and down the lateral wall of the right atrium, inscribing inverted (ie, "sawtooth") flutter waves in surface ECG leads II, III, and avF, and upright P waves in V1. Clockwise reentry using this same circuit can also occur, giving upright P waves inferiorly and inverted P waves in V1. These reentry circuits use an isthmus of tissue between the tricuspid valve annulus and the inferior vena cava. Linear ablation of this isthmus cures these common forms of atrial flutter and can be achieved in >90% of patients with this form of atrial flutter.
There are other forms of atrial flutter involving other anatomic elements in the right atrium or left atrium. These are usually found in patients with a history of previous heart surgery or with diffuse atrial myopathy. The latter can be idiopathic, or associated with congenital heart disease or valvular heart disease. These types of tachycardias though more challenging than the typical form of atrial flutter described above, are often amenable to catheter-mediated radiofrequency ablation.
