Abstract
In this article, several uncommon cases of different atrial flutter (AFL) types are described. Electrocardiogram (ECG), the standard and widespread method of rhythm disturbances detection, sometimes can be insufficient for correct diagnosis in such cases. Different features of atrioventricular (AV) conduction and multiple atrial macro re-entry circles may considerably influence the surface ECG. Another distorting factor of AFL appearance is possibility of ECG elements superposition and overlapping. Some atypical forms of AFL can be poorly visible and sometimes cannot be differentiated from other types of supraventricular arrhythmias on surface 12-lead ECG.