Three Dimensional Electroanatomical Mapping of Lower Loop Reentry in Patients with Intracardiac Operation

Introduction: The aim of this study was to clarify the characteristics of lower loop reentry (LLR. in patients who underwent cardiac surgery.Methods: Of 194 patients from 2000 to 2007 with negative flutter waves in the inferior leads (II, III, and aVf), 4 patients had LLR and reentrant circuits identified by a 3D activation sequence mapping system. We studied the characteristics of the surface electrocardiogram (ECG. patterns of those LLRs.Results: All 4 patients had a history of an intracardiac operation. The 3D activation sequence mapping system during the LLR exhibited a clockwise (CW. wavefront around the inferior vena cava (IVC. from the caudal view. During the LLR, the right atrium (RA. free wall was activated in a caudal-cranial sequence and a collision of two activation wavefronts from the lower RA and upper RA occurred at the RA free wall.Conclusions: The 3D activation mapping during the AT revealed an activation wavefront propagating around the IVC and the diagnosis of LLR. Detailed 3D electroanatomical mapping and pacing study are needed to identify the reentrant circuit of LLR in patients with previous intracardiac surgery.