Precaval bundle re-entry atrial tachycardia: a variant of upper loop re-entry

A 78-year-old woman without any structural heart disease underwent catheter ablation for persistent atrial fibrillation. Electrical cardioversion was performed to restore sinus rhythm before pulmonary vein isolation (PVI). Atrial tachycardia (AT) 1 (tachycardia cycle length [TCL], 210 ms) occurred spontaneously during the PVI procedure. We completed bilateral PVI and then mapped AT1. The reentrant circuit of AT1 was identified at the superior vena cava (SVC) and right atrium (RA) junction (SVC-RA junction). During radiofrequency (RF) application at the anterior side of the SVC-RA junction, AT1 transitioned into AT2 (TCL 300-310 ms) without termination (Fig. 1A). CARTO Coherent Mapping and Ripple Mapping (Biosense Webster Inc,) identified a reentrant circuit of AT2 in the area between the RA and SVC junction and the RA appendage where the Pre-caval muscle bundle (PCB) is located (Fig. 1C and Supplemental Movies). The entrainment pacing from a point with fractionated electrogram between the SVC and RA appendage showed a perfectly concealed entrainment (post-pacing interval = TCL, Fig. 1B). RF application at the site terminated the tachycardia.

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