Three-dimensional retrograde atrial activation maps obtained during atrioventricular nodal re-entrant tachycardia provides insights into the location of nodal inputs

Three patients who had three-dimensional (3D) atrial local activation time maps measuring ventriculo-atrial intervals during atrioventricular node re-entrant tachycardia (AVNRT) were identified. Three-dimensional mapping of the clinical tachycardia was performed with the Ensite Nav-X system (St Jude Medical, St Paul, MN, USA). Patients 1 and 2 presented with typical slow–fast AVNRT. Earliest atrial activation (fast pathway) was localized at the left-atrial superior septal position, the right-sided His Bundle, and at the antero-superior aspect of the coronary sinus (CS) os. Patient 3 presented with atypical slow–slow AVNRT. Earliest atrial activation (see figure) was located antero-superiorly to the CS os. In all patients, successful slow pathway modification was achieved antero-inferior to the CS os. Our findings highlight the need to consider non-traditional anatomical sites of atrioventricular node inputs. The earliest atrial activation site does not correspond well to the successful site of ablation in typical AVNRT. Our inability to localize continuous atrial activation during AVNRT despite extensive bi-atrial mapping confirms that the majority of the circuit may either be electrically quiescent or sub-endocardial. Conflict of interest: none declared. The full-length version of this report can be viewed at: http://www.escardio.org/communities/EHRA/publications/ep-case-reports/Documents/insights-into-location-of-nodal-inputs.pdf