A 70-year-old man revealed a rare type of atrioventricular nodal reentrant tachycardia (AVNRT) involving distinct retrograde pathways, Superior Slow Pathway (SSP) and Inferolateral Left Atrial Slow Pathway (ILA-SP). Radiofrequency ablation was successfully performed on the non-coronary cusp and in the left atrium, respectively, to eliminate the tachycardias. Due to the anomalous electrical conduction patterns, careful diagnosis and ablation strategies were necessary to avoid the risk of atrioventricular block. These findings underscore the diversity and complexity of AVNRT and highlight the importance of tailored therapeutic approaches.

Background: Local impedance (LI) can indirectly measure catheter contact and tissue temperature during radiofrequency catheter ablation (RFCA). However, data on the effects of catheter contact angle on LI parameters are scarce. This study aimed to evaluate the influence of catheter contact angle on LI changes and lesion size with 2 different LI-sensing catheters in a porcine experimental study. Methods: Lesions were created by the INTELLANAV MiFi™ OI (MiFi) and the INTELLANAV STABLEPOINT™ (STABLEPOINT). RFCA was performed with 30 watts and a duration of 30 seconds. The CF (0, 5, 10, 20, and 30 g) and catheter contact angle (30°, 45°, and 90°) were changed in each set (n=8 each). The LI rise, LI drop, and lesion size were evaluated. Results: The LI rise increased as CF increased. There was no angular dependence with the LI rise under all CFs in the MiFi. On the other hand, the LI rise at 90° was lower than at 30° under 5 and 10 g of CF in STABLEPOINT. The LI drop increased as CF increased. Regarding the difference in catheter contact angles, the LI drop at 90° was lower than that at 30° for both catheters. The maximum lesion widths and surface widths were smaller at 90° than at 30°, whereas there were no differences in lesion depths. Conclusion: The LI drop and lesion widths at 90° were significantly smaller than those at 30°, although the lesion depths were not different among the 3 angles for the MiFi and STABLEPOINT.

Introduction Detail 3D mapping have been useful for effective radiofrequency catheter ablation. Rhythmia system can create the atrio-ventricular dual chamber mapping, which reveals the atrial and ventricular potentials all at once in the same map. The aim of this study was to investigate the utility of Rhythmia system for catheter ablation of accessory pathways (AP). Methods From July 2015 to August 2020, 111 patients underwent ablation of APs. The dual chamber mappings were created in 50 patients [median age 15 (10-54), 32 male(64.0%)], while 61 patients underwent the radiofrequency (RF) ablations with conventional single chamber 3D mappings. The background characteristics and procedure details were compared between the dual chamber mapping group and conventional single chamber mapping group. Results The number of RF application [1 (1-3) vs 3 (1-6), p=0.0023], RF time [9.2 (2.0-95.7) vs 95.6 (4.1-248.7), p=0.0023], RF energy [248.4 (58.7-3328.2) vs 2867.6 (134.2-7728.4), p=0.0115] were significantly lower in dual chamber group. Fluoroscopy time [19.9 (14.2-26.1) vs 26.5 (17.7-43.4), p=0.0025], and fluoroscopy dose [52.5 (31.3-146.0) vs 119.0 (43.7-213.5), p=0.0249] were also significantly lower than in single chamber mapping group. Conclusion The dual chamber mappings were useful for effective ablation with reducing the radiation exposure.

Background The ablation index (AI) has been reported to be useful for a durable pulmonary vein isolation (PVI) to treat atrial fibrillation (AF). No study has reported the optimal AI value for the SVC isolation (SVCI). In this study, we aimed to investigate the optimal AI for the SVCI. Methods Thirty-six AF patients who underwent an initial SVCI were enrolled. Ablation was performed at a total of 549 points. The sites where dormant conduction was induced or additional ablation was needed were defined as touch-up sites (n=36). We compared the energy deliver time, power, CF, Force-Time Integral (FTI), and AI between the touch up sites and control sites (n=513). Results The median RF delivery time, power, CF, and FTI were all significantly lower at the touch up sites (touch up sites vs. control sites; energy delivery time, sec, 20.3[12.3-21.7] vs. 21.6[19.8-25.2], p=0.0003; power, W, 23.5[15-24] vs. 24[20-25], p<0.0001; CF, g, 7[6-10.8] vs. 11[9-15], p<0.0001; FTI, 126.5[99.3-208.8] vs. 244[183.5-340.5], p<0.0001). The AI also was significantly lower at the Touch up sites (touch up sites vs. control sites; AI, 350.1±43.6 vs. 277.2±21.8, p<0.0001). The median value of the AI at the control sites was 350 and no reconnections were seen where the minimum AI value was more than 308. Conclusion The AI value at the touch up sites was significantly lower than that at the control sites. The optimal AI value for the SVCI should be 350, and at least 308 would be needed.