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Background: Little is known regarding the characterization of electrical substrate in both atria in patients with atrial fibrillation (AF)., Methods: Eight consecutive patients undergoing AF ablation (five paroxysmal, three persistent) underwent electrical substrate characterization during sinus rhythm. Mapping of the left (LA) and right atrium (RA) was performed with the use of the HD Grid catheter (Abbott). Bipolar voltage maps were analyzed to search for low voltage areas (LVA), the following electrophysiological phenomena were assessed: (1) slow conduction corridors, and (2) lines of block. EGMs were characterized to search for fractionation. Electrical characteristics were compared between atria and between paroxysmal versus persistent AF patients., Results: In the RA, LVAs were present in 60% of patients with paroxysmal AF and 100% of patients with persistent AF. In the LA, LVAs were present in 40% of patients with paroxysmal AF and 66% of patients with persistent AF. The areas of LVA in the RA and LA were 4.8±7.3 cm 2 and 7.8±13.6 cm 2 in patients with paroxysmal AF versus 11.7±3.0 cm 2 and 2.1±1.8 cm 2 in patients with persistent AF. In the RA, slow conduction corridors were present in 40.0% (paroxysmal AF) versus 66.7% (persistent AF) whereas in the LA, slow conduction corridors occurred in 20.0% versus 33.3% respectively (p = ns). EGM analysis showed more fractionation in persistent AF patients than paroxysmal (RA: persistent AF 10.8 vs. paroxysmal AF 4.7%, p = .036, LA: 10.3 vs. 4.1%, p = .108)., Conclusion: Bi-atrial involvement is present in patients with paroxysmal and persistent AF. This is expressed by low voltage areas and slow conduction corridors whose extension progresses as the arrhythmia becomes persistent. This electrophysiological substrate demonstrates the important interplay with the pulmonary vein triggers to constitute the substrate for persistent arrhythmia., (© 2022 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals LLC.)

Background: Irrigated-tip catheter technology has been used for the elimination of resistant accessory pathways (AP) in adults with Wolff-Parkinson-White (WPW) syndrome. However, there are persistent concerns regarding the safety of irrigated catheters in the pediatric population. In this report we present our experience, in terms of effectiveness and safety, of irrigated catheter technology in children and adolescents who underwent ablation of WPW., Methods: We prospectively followed up all patients less than 18 years old (n = 41, mean age of 12.8 years old) who were referred to our center for radiofrequency (RF) catheter ablation of WPW between January 2010 and July 2011. Catheter ablation was performed in all patients using an open irrigated-tip catheter (Celsius Thermocool 3.5 mm, 7F, B-type, Biosense Webster, Diamond Bar, CA, USA). Power was started from 15 W up to 30 W in right-sided AP; RF pulses in left-sided APs were delivered at 40 W while 20 W was delivered inside the coronary sinus., Results: Mean procedure time was 26.4 minutes and mean fluoroscopy time was 12.2 minutes. Overall procedural success was obtained in 39/41 (95.1%) patients after the first procedure. No complications were observed after the procedure. All patients attended their scheduled follow-up visit at 3, 6, and 12 months and no recurrences were observed based on 12-lead electrocardiogram and 24-hour Holter monitoring., Conclusions: RF ablation of APs using open irrigated-tip catheters can be performed in children and adolescents with a high acute and long-term success rate, very short procedure times, and acceptable fluoroscopy times., (©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.)