Inferior vena cava isolation for non–pulmonary vein–origin atrial fibrillation identified via self-reference mapping using a high-density grid catheter

Figure 1. Identification of non–pulmonary vein (PV) foci via self-reference mapping using a high-density (HD) grid catheter. When non-PV focus was initiated, the earliest excited site on the HD grid catheter was tagged. The green tag in MAP1 indicates the earliest activation, suggesting that tachycardia originates from the posterior or lateral wall of the right atrium. We then moved the HD grid catheter toward the lateral wall; similarly, the red tag in MAP2 indicates the earliest activation, reinforcing the posterior wall. When the HD grid catheter was positioned between MAP1 and MAP2, the yellow tag marked the earliest site, suggesting that the origin of tachycardia was the lower part of the posterior wall. Further mapping with the lower HD grid catheter revealed the earliest activation in the inferior vena cava–right atrial junction, indicated using a blue tag. Finally, after slightly retracting the HD grid catheter and tagging the earliest activation site with a black tag, the location was found to almost perfectly overlap with the previously marked blue tag, confirming the origin of the tachycardia at this precise site. When the HD grid catheter was slightly adjusted to the side,…

Figure 2. Abnormal excitations with an exit block. Intracardiac electrograms and angiograms during abnormal excitations with an exit block were recorded using a high-density grid catheter positioned within the inferior vena cava (IVC) (A). Intracardiac electrograms were recorded during the onset of atrial fibrillation (B). The first abnormal excitation had a 170 ms coupling interval, which was 10 ms longer than that of the exit block. The first abnormal excitation was conducted to the right atrium (RA), whereas the second abnormal excitation, which exhibited a conduction block at the RA-IVC junction, failed to propagate to the RA. Eventually, the clustering of abnormal excitations led to the induction of AF. CS = coronary sinus; H = halo catheter; LAO = left anterior oblique; RAO = right anterior oblique; Ring = a ring catheter positioned at the left atrial septum.

Figure 3. Venograms and voltage maps before and after ablation. Venograms illustrating the anatomy of the inferior vena cava (IVC) and the right atrium highlight the positioning of the high-density (HD) grid catheter within the IVC (A). Voltage maps recorded before and after ablation are shown. All green and black tags indicate sites within the IVC where abnormal potentials associated with localized conduction block between the IVC and right atrium were recorded using the HD grid catheter (B), whereas red tags mark the ablation sites (C). After linear ablation at the posteroseptal border between the right atrium and IVC, the IVC potentials disappeared, indicating complete electrical isolation of the IVC. LAO = left anterior oblique; L→R = left-to-right view; P→A = posterior-to-anterior view; RAO = right anterior oblique.