Atypical left atrial flutters.

Left atrial flutters are not as common as peri-tricuspidian circuits. Their systematic study is much more recent and had greatly benefited from the use of 3 D mapping systems. Reentry has been demonstrated as being the mechanism but the circuits are not stereotypical like in the right atrium. Multiple macroreentrant circuits with one or more loops have been described as well as small re-entrant circuits. The complexity and variability of these circuits is related to the presence of zone of block, slow conduction and electrically silent areas. They create the conditions for the arrhythmia maintenance as they stabilize the circuit and prevent short circuiting. Most of the patients with left atrial flutter have an underlying structural heart disease, but their arrhythmia is amenable to curative catheter ablation.