Atrial flutter is a common atrial arrhythmia, second only to atrial fibrillation.  Atrial flutter affects approximately 200,000 patients annually.
During normal rhythm, the heart’s intrinsic pacemaker (or sino-atrial node) produces an electrical impulse that travels through specialized conducting tissue throughout the atria (the hearts upper chambers), stimulating the atrial myocardium (or heart muscle) to contract, pumping blood from the atria into the ventricles. The electrical signal also spreads through a connecting pathway between the atria and ventricles (the hearts lower chambers) called the atrioventricular (AV) node. As the impulse passes through the AV node and spreads through out the ventricles, the myocardium of the ventricles contract, pumping blood out of the heart. Each contraction results in a heartbeat.
Unlike atrial fibrillation which is characterized by a chaotic generation and spread of electrical impulses in the atria (the hearts upper chambers), atrial flutter is characterized by a regular, organized spread of electrical signals through the atria. However during atrial flutter, the electrical signals follow a different circuit that involves the tricuspid annulus of the right atrium, the atrial septum and the atrial free wall.
During atrial flutter the atria contracts at rates between 240-400 beats per minute. Since this arrhythmia also frequently includes some form of A-V block, atrial depolarization is often conducted at a 2:1 ratio, though it can also be conducted at a 4:1 ratio, and less commonly at a 3:1 or 5:1 ratio.
Men are affected more often than women, with a 2:1 male-to-female ratio. As in atrial fibrillation, the prevalence of atrial fibrillation increases with age.
Atrial flutter is often seen in patients with heart failure, valvular disease, chronic obstructive pulmonary disease, hyperthyroidism, pericarditis or pulmonary embolism.
Abraham Salacata, MD, FACC