Orthodromic Reciprocating Tachycardia Relying on Aberrant Conduction: Need for a Lager Circuit

Background: Aberrant conduction during orthodromic reciprocating tachycardia (ORT) can prolong the ventriculo-atrial conduction time, which is found essential for the reentry in certain situations. Materials: and Methods We searched for ORT cases relying on aberrancy from 220 cases in our center. Results: 3 patients showed the phenomenon of aberrancy-dependent ORT. All accessory pathways were located at anterolateral regions of atrioventricular annulus. None of them had baseline bundle branch block. Creating functional bundle branch block was necessary to induce the tachycardias. In 2 cases, termination directly associated with resolution of aberration was observed. While in the other case, reentry required both interventricular block and slow pathway conduction. Conclusions: We conclude that extra transseptal time caused by aberrancy can be an integral part of ORT, which can explain the infrequent or late onset and unsustainable episodes of ORT in certain patients and is useful in understanding the circuit and localizing the pathway.