Radiofrequency Energy Delivery Research Articles

Real-world multicenter registry on a novel focal lattice tip catheter toggling between pulsed electric field and radiofrequency for atrial tachyarrhythmia ablation

Abstract Background Pulsed field ablation (PFA) has emerged as a novel non-thermal energy source for cardiac tissue ablation. A novel focal 9mm lattice tip catheter, namely Sphere-9 (Affera Inc), has recently received regulatory approval; the technology is part of a technology that allows the delivery of either pulsed electric field or radiofrequency energy and incorporates a proprietary 3D electroanatomical mapping system. Purpose To describe the first real-world, multicenter experience with the AfferaTM system. Methods Consecutive AF patients undergoing first-time or redo atrial tachyarrhythmia ablation with the AfferaTM system in two different centres between August and November 2023 were prospectively enrolled. PFA was always used to ablate the posterior left atrium, whereas anterior applications were performed using either radiofrequency energy (RF/PF strategy) or PFA (PF/PF strategy) based on operator's discretion. Data on first-pass pulmonary vein isolation (PVI) and posterior wall isolation (PWI), as well as success rate of extrapulmonary ablation were reported. Primary safety endpoint included any technology-related periprocedural complications. Results 46 patients (mean age: 67±10; 41.3% males, 60.8% non-paroxysmal AF) were included. 5 (10.8%) patients were in atrial flutter (AFlu) at the beginning of the procedure, whereas AF was the rhythm at presentation in 19 (41.3%) others. First-time PVI was performed in 37 (80.4%) patients, 68.4% of whom received concomitant PWI. PVI was performed with PFA-only in 27% of them. First-pass isolation was achieved in 97.3% and 100% of PVI and PWI cases, respectively. Additional lesions included an anterior or posterior mitral line (6 and 15 patients), CTI (4 patients) or substrate ablation in 3 patients. Evidence of first-pass line block was documented in 96.4% of patients. The remaining 9 (19.6%) patients had already undergone a previous ablation; remapping showed 27.7% of PVs requiring reisolation. PWI was performed in 88.9% of them, for the first time (75%) or due to reconnection (25%). Additional lesions included an anterior or posterior mitral line (3 and 3 patients) or CTI in 2 patients. Evidence of first-pass line block was documented in 100% of patients. In 3 AFlu patients, the arrhythmia was mapped and termination was achieved while performing an AML (2 patients) and CTI (1 patient). Procedural duration was 96.5±15.6 min for first time and 97.8±12.6 min for redo procedures. Mean left atrial dwelling and fluoroscopy times were 75.4±17.6 min and 7.36±2.1 min, respectively. No technology-related complications were documented. Conclusions AF ablation with the focal 9-mm lattice tip catheter Sphere-9 confirmed high efficacy and safety in a real-world population.

A comparison of general anesthesia versus monitored anesthesia care during catheter ablation for ventricular tachycardia

Abstract Background Catheter ablation of ventricular tachycardia (VT) may be performed under general anesthesia (GA) or monitored anesthesia care (MAC). There is a paucity of data studying these two sedation strategies with respect to intraprocedural characteristics, and outcomes of VT ablation. Purpose The purpose of this study was to assess the effects of anesthesia techniques on VT inducibility and outcomes. Methods A single-center, retrospective study of patients undergoing catheter ablation for scar-related VT, from 2016-2022, was conducted. Data collected included demographics, comorbidities, medications, relevant laboratory abnormalities, electrocardiograms, echocardiograms, detailed procedural characteristics, and outcomes. Results One hundred sixty-eight patients who underwent a total of 200 VT ablation procedures were included. The patients undergoing GA had a greater burden of comorbidities including congestive heart failure (77.2% vs. 60.9%), hypertension (66.9% vs. 60.0%), atrial arrhythmias (50.7% vs. 43.8%), diabetes mellitus (21.3% vs. 9.4%), chronic kidney disease (44.1% vs. 31.3%), prior stroke (11.8% vs. 10.9%), myocardial infarction (31.6% vs. 29.7%), pre-existing implantable cardioverter-defibrillator (86.8% vs. 71.9%) and had a higher median number of antiarrhythmic drugs at baseline (2 vs. 1) [Figure 1]. There was a greater percentage of patients with non-ischemic cardiomyopathy (58.1% vs. 51.6%) in the GA cohort. The mean left ventricular ejection fraction was not different among the two groups (39.3 ± 13.9 vs. 42.5 ± 15.3). The GA group had more hemodynamic instability at baseline (p < 0.01), and during VT induction (p < 0.01). There was no significant difference in the number of VT induced, or tachycardia cycle length, in each group. Despite higher radiofrequency energy delivery time in the GA group as compared to the MAC group, the GA group had higher VT inducibility post-procedure and were more likely to be discharged on antiarrhythmic drugs. Even though the recurrence of VT was higher in the GA group compared to the MAC group (41.9% vs. 31.3%), the VT-free survival curves were not significantly different by Kaplan-Meier analysis (p=0.19) [Figure 2]. In a multivariate regression analysis, the sedation strategy was not an independent predictor of VT recurrence (p=NS). However, baseline hemodynamic instability was an independent predictor of VT recurrence after accounting for all intraprocedural characteristics (p=0.008). Conclusion Patients undergoing VT ablation under GA have more comorbidities and tend to be on more antiarrhythmic drugs. The GA group had more hemodynamic instability during the procedure and had greater overall VT recurrence, however, not significant in a time-based analysis. The greater overall recurrence in the GA group could be because they represent a sicker population, or the hemodynamics during the procedure preclude adequate ablation of the VT circuit elements.Figure 1Figure 2

A Case of Presumptive Marshall Bundle Conduction Between the Left Atrium and Left Superior Pulmonary Vein During Box Isolation

A 65-year-old man with symptomatic persistent atrial fibrillation was referred for initial radiofrequency catheter ablation. He underwent box isolation to simultaneously isolate all four pulmonary veins (PVs) and the posterior wall of the left atrium (LA). During the box isolation with a double lasso catheter positioned in both the left superior and right superior PVs, the atrial fibrillation terminated spontaneously. After the box lesion set was created, conduction was still observed between the LA and PVs. After an additional radiofrequency energy delivery to the bottom line of the box lesion, the activation sequence of the PVs became uniform during sinus rhythm and pacing from the coronary sinus (CS), indicating that only one more conduction pathway was present. The 3-dimensional map revealed that the earliest activation site within the box lesion was located in the anterior aspect of the left superior PV during pacing from the CS, whereas that of the LA during pacing from the superior right PV within the box was on the posterolateral LA wall below the left inferior When a 2 Fr electrode catheter was inserted into the vein of Marshall (VOM) and paced within the BOX, VOM potentials preceded CS potentials. When the left superior PV anterior wall, the earliest site of excitation within the box, was energized, simultaneous posterior pulmonary vein wall isolation was completed. We experienced a case in which Marshall bundle conduction between the left atrium and the pulmonary vein was assumed.

Randomized Controlled Trial of Anti-reflux Mucosectomy Versus Radiofrequency Energy Delivery for Proton Pump Inhibitor-refractory Gastroesophageal Reflux Disease.

The efficacy and safety of anti-reflux mucosectomy (ARMS) or radiofrequency energy delivery in the treatment of gastroesophageal reflux disease (GERD) have been reported, but the difference between the 2 remains unclear. This was a single center, randomized, comparative clinical study. Patients with symptoms of heartburn and/or regurgitation despite proton pump inhibitor treatment were randomly assigned to either ARMS group (n = 20) or radiofrequency group (n = 20). Primary outcome was the standardized GERD questionnaire (GERDQ) at 2 years after the procedures. Secondary outcomes were the proportions of patients with complete proton pump inhibitor (PPI) cessation and patients satisfied with the treatment. A total of 18 patients randomized to ARMS and 16 to radiofrequency were analyzed in this study. The operation success rate of the 2 groups was 100%. In both ARMS and radiofrequency groups, GERDQ scores at 2 years after the procedures were significantly lower than that before operation (P = 0.044 and P = 0.046). At 2 years postoperatively, the scores of GERDQ did not differ between the 2 groups (P = 0.755). There was no significant difference in the rate of discontinuation of PPIs and patient satisfaction in the ARMS and radiofrequency groups (P = 0.642 and P = 0.934). The clinical efficacy of ARMS and radiofrequency for the PPI-refractory GERD is equivalent. ARMS, the efficacy of which could be maintained for at least 2 years, is promising endoscopic management for the treatment of refractory GERD.

New Perspectives in Endoscopic Treatment of Gastroesophageal Reflux Disease

Gastroesophageal reflux disease has a high incidence and prevalence in the general population. Clinical manifestations are heterogenous, and so is the response to medical treatment. Proton pump inhibitors are still the most common agents used to control reflux symptoms and for healing esophagitis, but they are not a one-size-fits-all solution for the disease. Patients with persistent troublesome symptoms despite medical therapy, those experiencing some adverse drug reaction, or those unwilling to take lifelong medications deserve valid alternatives. Anti-reflux Nissen fundoplication is an effective option, but the risk of adverse events has limited its spread. In recent years, advancements in therapeutic endoscopy have been made, and three major endoluminal alternatives are now available, including (1) the delivery of radiofrequency energy to the esophago–gastric junction, (2) transoral incisionless fundoplication (TIF), and (3) anti-reflux mucosal interventions (ARMI) based on mucosal resection (ARMS) and mucosal ablation (ARMA) techniques to remodel the cardia. Endoscopic techniques have shown interesting results, but their diffusion is still limited to expert endoscopists in tertiary centers. This review discusses the state of the art in the endoscopic approach to gastroesophageal reflux disease.

Testing radiofrequency energy delivery and catheter entrapment in three left ventricular assist device models in mock circulation

Abstract Funding Acknowledgements Type of funding sources: None. Background The use of Left Ventricular Assist Devices (LVAD) as a bridge to heart transplantation (HTx) or as a destination therapy is increasing. Near half of the patients had ventricular arrhythmias (VA) in the first year of LVAD support. Ablation is common method for recurrent ventricular tachycardias in LVAD patients. Even there are many case reports about successful VT ablations in LVAD patients there is no report about consequences of RF energy delivery inside LVAD or ablation catheter contact – entrapment to the rotor of the LVAD. Method Mock circulation models were created for three mostly used LVAD models ( Figure 1) (HeartMate3, HeartMate2, HVAD) Sheep heart was located inside the mock circulation model and 4mm non-irrigated RF ablation catheter and RF generator used for RF energy delivery tissue ( sheep heart) , ostium, mid and rotor of the LVAD)(Figure 1). During RF delivery flow parameters of the LVAD systems were noted also external noncontact flow monitor located out flow canula of the LVAD. All LVADs out flows were tested for 24 hours after RF energy delivery for long term malfunction. Also RF ablation catheters were tested for mechanical and functional disfunctions after contact of the LVAD rotors. Results No malfunctions were observed during and after RF energy delivery inside the LVADs. Only LVAD flow parameters temporary decreased in HeartMate 3 when the catheters had a contact to the rotor of the LVAD. This phenomenon occurred irrespective of RF energy delivery status. There were no changes in HVAD and Heartmate 2. After 24 hours continuous testing of the flow of the LVADs any changes were not observed . Impedance changes were noticed during RF energy delivery. Impedance values were dropped when RF catheter moved from tissue to the ostium of the LVAD in all models. Small increases observed during contact to the rotor of the LVAD in HeartMate 3 ( Figure 2). No mechanical damage were observed on the tip of the catheters after contact to the rotors also RF lesion dimensions were compared before and after the contact and there were no differences. Conclusion RF energy delivery and catheter entrapment of the RF catheters to the rotors of the LVADs caused no changes in LVAD functioning in ex-vivo conditions in a mock circulation.

Prevention of cardiac tamponade during CLOSE-protocoll guided ablation of atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation (CA) with radiofrequency (RF) energy using the CLOSE protocol has proven safety and efficacy in a large prospective multicenter study(1) with the rate of pericardial tamponade (PT) as low as 0.9%. PT may still become hazardous in the era of uninterrupted anticoagulation and may require urgent surgical repair. Steam pop is the major cause of PT during Pulmonary vein Isolation (PVI) with RF ablation and is usually preceded by steep impedance rise measured between tissue and tip of the RF catheter. The STOCKERT SMARTABLATE RF Generator as a core part of technology for CLOSE protocol guided PVI offers the opportunity to automatically stop RF energy delivery within 0.5 seconds if catheter impedance rises above a predefined value: impedance spike cut off (ISCO). The standard – manufacturer recommended – value for ISCO is 50 Ω per 0.5 seconds. Purpose To investigate the effect of reduced ISCO during CLOSE protocol guided catheter ablation of AF on the occurrence of acute PT and pericardial effusion (PE) in a large single center series. Methods We performed CLOSE protocol guided PVI procedures using Biosense Webster CARTO PRIME 3D navigation system, Smarttouch SF ablation catheter, VIZIGO steerable sheath, invasive blood pressure measurement via radial artery. We changed the STOCKERT SMARTABLATE generator settings to ISCO of 25Ω per 0,5 seconds. Cut off during the ablation procedure by ISCO led the operator to reduce contact force, angulation/orientation of catheter/steerable sheath, changing to jet ventilation if mechanical ventilation was present. Investigation for PT by echo was performed for every drop <90mmHg systolic blood pressure. PE detection immediately after and the day after ablation procedure was performed by transthoracic echo. A retrospective analysis of all CLOSE protocoll procedures was performed. Statistical analysis was performed on the evaluable population. Results During 43 months of observation we performed 980 CLOSE protocol guided procedures: 516 PVI only, 464 PVI with additional ablations (VT, cavotricuspid isthmus, slow pathway, additional LA lines, ethanol ablation of vein of marshall). We observed 4 (0.4%) PT immediately at the end of the procedure and no additional relevant PE the day after CA. Of the 4 PT, 1 patient needed urgent surgical repair and 3 were managed conservatively with pericardiocentesis and retransfusion. Conclusions CLOSE protocol guided PVI is an effective and safe intervention for treatment of AF. The VISITAX trial reported 3 events of PT per 329 patients (0.9%). By reducing ISCO to 25 Ω per 0,5 seconds, we found less than half of the rate of PT (0.4%) compared with the VISITAX trial. The generator cut off at ISCO of 25 Ω per 0.5 seconds automatically stops a potentially dangerous ablation and can indicate potientially dangerous ablation sites. Our data are limited due to the retrospective monocentric design and therefore should be evaluated prospectively.

PO-03-042 A COOL DRINK OF WATER: CONVECTIVE ESOPHAGEAL COOLING PREVENTS THERMAL INJURY FROM RADIOFREQUENCY HEATING IN AN EX VIVO SWINE ESOPHAGUS MODEL

Esophageal heating and subsequent thermal injury are concerning adverse effects of radiofrequency (RF) energy ablation on the posterior wall of the left atrium. Active intraluminal esophageal cooling may provide thermal protection, allowing for effective delivery of RF energy to overlying myocardium without collateral damage to the underlying esophagus. To evaluate the impact of esophageal luminal cooling with a closed loop continuous flow irrigation on esophageal heating and thermal injury using an ex vivo model. A flexible tube was placed through the lumen of a swine esophagus and connected to a closed loop circuit consisting of a pump and water bath (Figure 1, panel A). The esophagus was submerged in a saline bath with a temperature of 36 °C and an impedance of 140 ohms. Ten non-contiguous RF lesions were delivered at 50 watts for 8 seconds directly on the outer esophageal wall with 4 mm irrigated RF ablation catheter. This was performed without irrigation (control), irrigation at 1.5 L/min with room temperature water (20 °C), and irrigation at 1.5 L/min with ice water (0 °C). Esophageal tissue samples were obtained from immunohistochemistry and the esophagus was cross sectioned and lesions were measured with digital calipers. Closed loop continuous flow esophageal irrigation with ice water yielded esophageal lesions with the smallest surface area (Figure 1, panel A), depth, and volume (Figure 1, panel B). Continuous esophageal irrigation with room temperature water resulted in the second smallest lesions. RF lesions without esophageal irrigation resulted in the largest and deepest lesion, as well as evidence of luminal esophageal injury (Figure 1, panel C & D). Histology showed preserved smooth muscle, glands, basement membrane and epithelium with cooled esophagus and transmural lesions with non-irrigated esophagus (Figure 1, panel C & D). Continuous endoluminal esophageal cooling reduced lesion size with RF energy delivery. There was no luminal injury with room temperature and ice water esophageal irrigation. Thus, both may be useful in prevention of endoluminal esophageal injury during poster wall RF ablation.

PO-01-119 CATHETER STABILITY ANALYSIS IN ABLATION OF PAROXYSMAL ATRIAL FIBRILLATION: IMPACT OF A NOVEL FLEXIBLE ELECTRODE TIP

Catheter electrode stability is a key factor of a successful radiofrequency (RF) ablation lesion formation. Current techniques to enhance or monitor catheter stability include the use of steerable introducers, high-frequency jet ventilation, and the incorporation of objective lesion marker placement via Electroanatomic Mapping (EAM) Systems. In addition to automatic lesion marker placement, the EnSite™ AutoMark Module records catheter location during RF energy delivery, providing insight into catheter electrode stability during ablation. To demonstrate improved stability during ablation with a flexible laser cut tip electrode vs. a solid-6-hole electrode tip during de novo PVI ablation for the treatment of PAF and concomitant CTI-lines for the treatment of typical AFL. AutoMark™ ablation data gathered during the TactiFlex AF IDE NCT04356040 (flex tip catheter) and TactiSense IDE NCT03354663 (solid tip catheter) trials was analyzed (FIGURE). Both trials were prospective, non-randomized multicenter clinical studies which enrolled 355 and 150 subjects worldwide, respectively. PVI and CTI lesions from point-by-point ablation style operators with discrete lesions were included. Anatomic region assignment of each RF episode was accomplished using machine learning. Average distance and standard deviations of the ablation electrode movement from the mean positional centroid were calculated for each RF episode. Stability was evaluated as the percent of time during an RF episode where the ablation electrode remained within 2.5mm of the ablation lesion centroid. A total of 10285 flexible tip and 2141 solid tip RF episodes were analyzed from 112 and 21 cases, respectively. The average RF episode duration for the flexible tip and solid tip lesions, was 10.6 ± 4.8 and 17.1 ± 9.8 seconds, respectively. The flexible tip and solid tip catheters remained positionally stable within a 2.5 mm sphere for 85.3% ± 22.7 and 79.9% ± 26.1 of the RF episode duration, respectively, (p <0.001) (FIGURE). In the subset of lesions <10 seconds, the difference in stability was even more pronounced (TABLE). A flexible tip ablation catheter (TactiFlex™ SE) demonstrated greater stability than a solid tip ablation catheter (TactiCath™ SE) during ablation of atrial fibrillation and CTI-dependent atrial flutter. Greater stability during lesion formation may result in more durable lesions and better patient outcomes.Tabled 1Catheter# RF EpisodesRF Episode Duration, sec (SD)Mean (SD)Median [Q1, Q3]p-valueAll RF EpisodesFlexible Tip1028510.6 (4.8)85.3% (22.7)96.9% [79.9, 100]< 0.001Solid Tip214817.1 (9.8)79.9% (26.1)92.6% [66.7, 100]< 0.001RF Episodes < 10 secFlexible Tip43406.4 (2.8)85.0% (24.2)98.7% [80.7, 100]< 0.001Solid Tip5427.3 (2.3)73.6% (32.9)89.8% [51.7, 100]< 0.001Stability of a solid tip (TactiCath™ Contact Force Ablation Catheter, Sensor Enabled™) versus flexible tip (TactiFlex™ Contact Force Ablation Catheter, Sensor Enabled™), reported as the percent time the catheter tip remained within a 2.5 mm radius sphere. Open table in a new tab

Transcatheter Electrosurgery: A Narrative Review.

Transcatheter electrosurgery describes the ability to cut and traverse tissue, at a distance, without an open surgical field and is possible using either purpose-built or off-the-shelf devices. Tissue traversal requires focused delivery of radiofrequency energy to a guidewire tip. Initially employed to cross atretic pulmonary valves, tissue traversal has enabled transcaval aortic access, recanalization of arterial and venous occlusions, transseptal access, and many other techniques. To cut tissue, the selectively denuded inner curvature of a kinked guidewire (the Flying-V) or a single-loop snare is energized during traction. Adjunctive techniques may complement or enable contemporary transcatheter procedures, whereas myocardial slicing or excision of ectopic masses may offer definitive therapy. In this contemporary review we discuss the principles of transcatheter electrosurgery, and through exemplary clinical applications highlight the range of therapeutic options offered by this versatile family of procedures.

S1069 Endoscopic vs Surgical Procedures for Gastroesophageal Reflux Disease - A Network Meta-Analysis

Introduction: Various surgical fundoplication (SF) procedures have been the mainstay therapy for medication refractory GERD. Over the last couple of decades, interventional endoscopic procedures such as radiofrequency energy delivery with Stretta, endoscopic fundoplication (EF) procedures with EsophyX and GERDx systems, and laparoscopic magnetic sphincter augmentation (Linx), have emerged as alternative options. Objective of our study was to compare the efficacy of these various procedures. Methods: A comprehensive search of the available electronic databases was conducted, and only RCTs with our procedures of interest were included in our network meta-analysis using random-effects analysis. Outcomes of interest were lower esophageal sphincter pressure (LESP), esophagitis, cessation of use of proton pump inhibitors (PPIs), and percentage of time with a pH less than 4 on a 24-hour esophageal pH monitoring (% time pH< 4) at a follow-up of one year or less. Results: Thirty-one studies with a total of 4,371 patients were included in the analysis. EF and SF were associated with significantly higher LESP compared to PPI. There was no significant difference between EF and Nissen [Mean Difference (MD): 0.23, 95%CI: -7.01-7.48], anterior (MD: 1.76, 95% CI: -5.75-9.16) or Toupet (MD: 2.4, 95%CI: -4.94-9.75) fundoplications. In contrast, Stretta was inferior to Nissen (MD: -9.00, 95%CI: -14.55 - -3.45), Toupet (MD: -6.83, 95%CI: -12.50 - -1.55) and anterior (MD: -7.5, 95%CI: -13.35 - -1.71). Regarding % time pH< 4, EF was significantly better than Nissen (MD: 4.72, 95%CI: 0.71-8.73), but not significantly different from either Toupet (MD: 3.62, 95%CI: -1.90-9.14) or anterior (MD: -0.16, 95%CI: -6.29-5.96) fundoplications, and none of the procedures were significantly different from the PPI group. Cessation of PPI usage was significantly higher for endoscopic and surgical (only Linx) procedures compared to PPI group, but none of the procedures had significant differences when compared to each other. Endoscopic and surgical procedures (only SF) did not differ significantly from each other or from the PPI group in terms of presence of esophagitis at follow-up. (Figure) Conclusion: Efficacy of EF seemed comparable to SF in the short-term. Stretta was found to be inferior to all procedures in terms of LESP. Further studies focusing on head to head trials between EF and SF, and long term outcomes of EF are required to understand the place of EF in the treatment hierarchy.Figure 1.: A. Direct, indirect and network estimates of post-intervention lower esophageal sphincter pressures; B. Direct, indirect and network estimates of percentage of time with a esophageal pH less than 4; C. Forest plot of cessation of PPI usage at follow-up comparing various interventions to PPI alone

2-year outcomes of phased radiofrequency ablation for atrial fibrillation with the second-generation PVAC Gold ablation catheter

PurposeThe second-generation multi-electrode catheter, PVAC Gold, was designed to improve the safe delivery of phased radiofrequency energy using a “single shot” approach for pulmonary vein isolation (PVI), while retaining efficacy. This large registry presents long-term performance in a daily practice setting.MethodsA total of 1011 patients undergoing first time ablation for atrial fibrillation (AF) using PVAC Gold were included, 639 patients with PVI for paroxysmal AF (PAF PVI) and 372 patients with persistent or long-standing persistent AF, divided into 175 patients receiving PVI only (PersAF PVI) and 197 patients receiving PVI with additional substrate ablation (PersAF PVI +).ResultsAt 24-month follow-up, single procedure freedom from atrial tachyarrhythmia (ATA) was 58% (368/639) in the PAF PVI group, 44% (77/175) in the PersAF PVI group, and 29% (57/197) in the PersAF PVI + group. Allowing one repeat procedure in 33% of patients, 76%, 65%, and 54% were free from ATA at 24 months, respectively. Pulmonary vein reconnection was observed in 98% of patients with recurrent arrhythmia after PVI.ConclusionsAlthough phased RF ablation with PVAC Gold is quick and safe, the efficacy outcomes are modest compared to current mainstream ablation strategies.

Acute change of cardiac autonomic regulations after thermal and non-thermal pulmonary vein ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) by thermal energy (radiofrequency energy or cryoenergy) results in collateral ganglionic plexi ablation. On the contrary, pulsed electric field (PEF) energy presumably spares neural tissue. Purpose We investigated and compared the effect of PVI on parasympathetic input into the sinus node (SAN) and AV node (AVN) when four different ablation strategies were used. Methods A study enrolled 49 patients who underwent PVI in general anesthesia (age: 57 ± 13 years, 71% males). In 17 patients, point-by-point radiofrequency energy delivery by the irritated-tip catheter was used for ablation while 7 patients were ablated using a second-generation cryoballoon catheter. In 7 patients, PEF energy was delivered using a single-shot Farawave catheter while 18 patients were ablated using Sphere9 lattice-tip catheter (Affera, Inc.); both subgroups with manufacturer-specific PEF settings. Before and after PVI, the responsiveness of the SAN and AVN was assessed by extracardiac vagal nerve stimulation (ECVS) via a diagnostic catheter in the right internal jugular vein. Five-second stimulation trains were delivered with a frequency of 50 Hz, pulse width of 0.05 ms, and output of 1 V/kg (&amp;lt;70V) both in sinus rhythm and during atrial pacing. Substantial reduction of response to ECVS was arbitrarily defined as a maximum induced pause of &amp;lt;1.5 seconds. Results At baseline, physiological response to ECVS (long sinus arrest and/or AV block) was demonstrated. After PVI, a substantial reduction of SAN response was observed in 21/24 (88%) patients after thermal PVI and 7/25 (25%) patients after non-thermal PVI (P = 0.0001). Similarly, a substantial reduction of AVN response was observed in 21/24 (88%) patients after thermal PVI and 9/25 (36%) patients after non-thermal PVI (P = 0.0003). The Figure shows on the continuous scale the post-PVI pauses in sinus rhythm (maximum P-P interval) and atrial pacing (maximum R-R interval) induced by ECVS. Conclusion Vagal responses of SAN and AVN are preserved in most AF patients after non-thermal PVI. This contrasts with the much stronger effect of thermal PVI. Whether this may influence the clinical outcome of AF ablation procedures remains to be investigated in future studies.

Impedance spike cut-off enhances safety of CLOSE-protocol guided ablation of atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation (CA) with radiofrequency (RF) energy using the CLOSE protocol has proven safety and efficacy in a large prospective multicenter study (1) with a rate of pericardial tamponade (PT) as low as 0.9%, thus with lower PT risk than reported by previous register data for PVI (2). PT may still become hazardous in the era of uninterrupted anticoagulation and may require urgent surgical repair. Steam pop is the major cause of PT during PVI with RF ablation and is usually preceded by steep impedance rise measured between tissue and tip of the RF catheter. The STOCKERT SMARTABLATE RF Generator as a core part of technology for CLOSE protocol guided PVI offers the opportunity to automatically stop RF energy delivery within 0.5 seconds if catheter impedance rises above a predefined value: impedance spike cut off (ISCO). The standard – manufacturer recommended – value for ISCO is 50 Ohms per 0.5 seconds. Purpose To investigate the effect of reduced ISCO during CLOSE protocol guided catheter ablation of AF on the occurrence of acute PT and pericardial effusion (PE) in a large single center series. Methods We performed CLOSE protocol guided PVI procedures using Biosense Webster CARTO PRIME 3D navigation system, Smarttouch SF ablation catheter, VIZIGO steerable sheath, invasive blood pressure measurement via radial artery. We changed the STOCKERT SMARTABLATE generator settings to ISCO of 25 Ohms per 0.5 seconds. Cut off during ablation by ISCO led the operator to reduce contact force, angulation/orientation of catheter/steerable sheath, changing to jet ventilation if mechanical ventilation was present. A retrospective analysis of all procedures was performed. Investigation for PT by echocardiography was performed for every drop &amp;lt; 90mmHg systolic blood pressure, immediately after and one day post ablation. Statistical analysis was performed on the evaluable population. Results During 31 months of observation we performed 627 CLOSE protocol guided procedures: 409 PVI only, 218 PVI with additional ablations (cavotricuspid isthmus, slow pathway, additional LA lines, ethanol ablation of vein of marshall). We observed 3 (0.5%) PT immediately at the end of the procedure and no additional relevant PE the day after CA. Of the 3 PT, one patient needed urgent surgical repair and two were managed conservatively with pericardiocentesis and retransfusion. Conclusions CLOSE protocol guided PVI is a very effective and safe intervention for treatment of AF. In the multicentre VISITAX trial, the rate of PT was reported with 3 events per 329 patients (0.9%). By reducing ISCO to 25 Ohms per 0.5 seconds, we could half the rate of PT found in the VISITAX trial. The generator cut off at ISCO of 25 Ohms per 0.5 seconds indicates a potentially dangerous position for ablation. Our data are limited due to the retrospective monocentric design and therefore the aformentioned approach should be evaluated prospectively.

The impact of RF wattage level on local impedance and procedural parameters in AF ablation cases

Abstract Funding Acknowledgements Type of funding sources: None. Background Local impedance (LI) measurement can provide information on catheter tip contact, but also changes in LI during ablation can inform the extent and effectiveness of RF energy delivery. To date the relationship between highly LI measurements and contact force (CF) during atrial fibrillation (AF) ablation at different levels of energy delivery is still lacking. Purpose We aimed to evaluate the impact of power setting on LI and key procedural parameters in AF ablation cases. Methods A novel CF ablation catheter equipped with dedicated algorithm was used to measure LI at the distal electrode of this catheter. Radiofrequency (RF) catheter applications ≥45 watts were categorized as high power (HP) and applications &amp;lt;45w as standard power (SP). Ablations were also grouped according to different levels of CF (&amp;lt;5g, 5-14g, 15-24g and ≥25g). Data are reported as mean±SD. Results Sixty-two consecutive pts undergoing RF catheter ablation of AF from the CHARISMA registry were included A total of 4619 ablation spots performed around PVs were analyzed (58% paroxysmal, 84% de novo, RF deliveries per pt=76±27, RF delivery time=9.1±5s, CF=12.3±8g). The majority of these were HP applications (n=4192, 91%). The mean LI was 158±17Ω prior to ablation and 138±14Ω after ablation (p&amp;lt;0.0001, absolute LI drop of 21.9±8Ω) with a LI drop rate equal to 4.4±3Ω/s. HP ablations had significantly shorter RF delivery times, 8.8±4s vs 12±7s (p&amp;lt;0.0001), larger LI drops (22.2±8Ω vs 19.3±9Ω, p&amp;lt;0.0001) and higher LI drop rates (4.5±3Ω/s vs 3.6±2Ω/s, p&amp;lt;0.0001) than SP, respectively. For both HP and SP settings, the magnitude of LI drop increased and RF delivery time decreased with increasing amounts of CF. The largest differences between HP and SP were found when CF was &amp;lt;15g (RF delivery time: 9±5s at HP vs 12.9±7s at SP, percentage of difference 26.3%, p&amp;lt;0.0001; LI drop: 21.2±8Ω at HP vs 18.6±9Ω, percentage of difference -14.3%, p&amp;lt;0.0001). No major complications occurred during the procedures. All PVs were successfully isolated. Conclusions This preliminary experience suggests that, HP ablation is effective and safe and resulting in shorter RF delivery times and larger LI drops than SP ablation.

Effect on sinus cycle length and atrioventricular node function after high-power short-duration versus conventional radiofrequency catheter ablation in paroxysmal atrial fibrillation

BackgroundThe efficacy and safety of high-power, short-duration (HPSD) radiofrequency catheter ablation for atrial fibrillation (AF) have been demonstrated in several studies. We aimed to evaluate and compare the effects of the conventional method and the HPSD method for AF ablation on the sinus and AV node function in patients with paroxysmal AF.MethodsThe medical records of patients with paroxysmal AF who underwent pulmonary vein isolation (PVI) were retrieved from a prospectively collected AF ablation registry at a large-sized tertiary center. The HPSD group (n = 41) was distinguished from the conventional ablation group (n = 198) in terms of the power (50 W vs. 20–40 W) and duration (6–10 s vs. 20–30 s) of radiofrequency energy delivery during PVI. Peri-procedural changes in cardiac autonomy were assessed in terms of the changes in sinus cycle length (SCL), block cycle length (BCL), and effective refractory period (ERP) of the atrioventricular node (AVN).ResultsThe SCL, BCL, and ERP of the AVN at baseline and post-ablation were not significantly different between the conventional ablation group and the HPSD group. Shortening of the SCL, BCL, and ERP of the AVN was observed immediately after AF ablation in both groups. One-year recurrence of AF/atrial flutter (35.1% vs. 20.3%; P = 0.011) and atrial flutter (13.8% vs. 4.7%; P = 0.015) were higher in the HPSD group than in the conventional ablation group.ConclusionBoth the HPSD and the conventional ablation method resulted in post-ablation vagal modification as evidenced by the shortening of SCL, BCL, and ERP of the AVN. One-year recurrence of atrial flutter and AF/atrial flutter was higher in patients who underwent the HPSD method.

CA-537-01 ACUTE CHANGE OF CARDIAC AUTONOMIC REGULATIONS AFTER THERMAL AND NON-THERMAL PULMONARY VEIN ABLATION

Pulmonary vein isolation (PVI) by thermal energy (radiofrequency energy or cryoenergy) results in collateral ganglionic plexi ablation. On the contrary, pulsed electric field (PEF) energy presumably spares neural tissue. We investigated and compared the effect of PVI on parasympathetic input into the sinus node (SAN) and AV node (AVN) when four different ablation strategies were used. A study enrolled 49 patients who underwent PVI in general anesthesia (age: 57 ± 13 years, 71% males). In 17 patients, point-by-point radiofrequency energy delivery by the irritated-tip catheter was used for ablation while 7 patients were ablated using a second-generation cryoballoon catheter. In 7 patients, PEF energy was delivered using a single-shot Farawave catheter (Boston Scientific) while 18 patients were ablated using Sphere9 lattice-tip catheter (Affera, Inc.); both subgroups with manufacturer-specific PEF settings. Before and after PVI, the responsiveness of the SAN and AVN was assessed by extracardiac vagal nerve stimulation (ECVS) via a diagnostic catheter in the right internal jugular vein. Five-second stimulation trains were delivered with a frequency of 50 Hz, pulse width of 0.05 ms, and output of 1 V/kg (<70V) both in sinus rhythm and during atrial pacing. Substantial reduction of response to ECVS was arbitrarily defined as a maximum induced pause of <1.5 seconds. At baseline, physiological response to ECVS (long sinus arrest and/or AV block) was demonstrated. After PVI, a substantial reduction of SAN response was observed in 21/24 (88%) patients after thermal PVI and 7/25 (25%) patients after non-thermal PVI (P = 0.0001). Similarly, a substantial reduction of AVN response was observed in 21/24 (88%) patients after thermal PVI and 9/25 (36%) patients after non-thermal PVI (P = 0.0003). The Figure shows on the continuous scale the post-PVI pauses in sinus rhythm (maximum P-P interval) and atrial pacing (maximum R-R interval) induced by ECVS. Vagal responses of SAN and AVN are preserved in most AF patients after non-thermal PVI. This contrasts with the much stronger effect of thermal PVI. Whether this may influence the clinical outcome of AF ablation procedures remains to be investigated in future studies.

Efficacy of Endoscopic and Surgical Treatments for Gastroesophageal Reflux Disease: A Systematic Review and Network Meta-Analysis.

Although various endoscopic and surgical procedures are available for the treatment of gastroesophageal reflux disease (GERD), the comparative efficacy of these treatments has not been fully elucidated. This study aimed to comprehensively evaluate the efficacy of various endoscopic and surgical treatments for GERD. All relevant randomized controlled trials published through August 2021 that compared the efficacy of endoscopic and surgical GERD treatments, including radiofrequency energy delivery, endoscopic plication, reinforcement of the lower esophageal sphincter (LES), and surgical fundoplication, were searched. A network meta-analysis was performed to analyze treatment outcomes, including the requirement of proton pump inhibitor (PPI) continuation and GERD-health-related quality of life questionnaire score (GERD-HRQL). As such, 25 studies with 2854 patients were included in the analysis. Endoscopic plication, reinforcement of the LES, and surgical fundoplication were effective in reducing the requirement of PPI continuation compared to PPI therapy (pooled risk ratio (RR) (95% confidence interval [CI]): endoscopic plication, 0.34 (0.21–0.56); reinforcement of LES, 0.32 (0.16–0.63), and surgical fundoplication, 0.16 (0.06–0.42)). Radiofrequency energy delivery tended to reduce the requirement of PPI continuation compared to PPI therapy (RR (95% CI): 0.55 (0.25–1.18)). In terms of GERD-HRQL, all endoscopic and surgical treatments were superior to PPI therapy. In conclusion, all endoscopic or surgical treatments, except radiofrequency energy delivery, were effective for discontinuation of PPI medication, especially surgical fundoplication. Quality of life, measured by GERD-HRQL, also improved in patients who underwent endoscopic or surgical treatment compared to those who received PPI therapy.

High-Frequency, Low-Tidal-Volume Mechanical Ventilation Safely Improves Catheter Stability and Procedural Efficiency During Radiofrequency Ablation of Atrial Fibrillation

High-Frequency, Low-Tidal-Volume Mechanical Ventilation Safely Improves Catheter Stability and Procedural Efficiency During Radiofrequency Ablation of Atrial Fibrillation

Targeted cluster ablation of non-CTI-dependent atrial arrhythmias in congenital heart disease using ultrahigh-definition mapping.

Ablation of atrial arrhythmias in patients with congenital heart disease (CHD) has markedly improved with advanced mapping systems. However, recurrence rates remain high. The linear ablation strategy is not uncommonly practiced necessitating prolonged ablation times. We report the outcomes of adopting a strategy of minimal, cluster delivery of radiofrequency (RF) energy at critical substrates identified by ultrahigh-definition mapping for atrial arrhythmias in patients with CHD. Non-cavotricuspid isthmus (non-CTI) atrial tachycardias were ablated with a targeted ablation cluster technique (TACT) using an ultrahigh-density mapping system combined with multielectrode monitoring and endpoint determination in preference to linear ablation. The arrhythmia substrates, RF times, and acute- and medium-term success rates were studied. Fifty-eight tachycardias were mapped and ablated in 42 procedures: 34 non-CTIs and 24 CTIs. A targeted ablation cluster was performed for non-CTI tachycardias, with a median ablation time of 3.1 min. In 53% of non-CTI tachycardias, arrhythmia termination was achieved with ≤2 RF applications. After a mean follow-up of 23.6 months, 27 (80%) patients were free of recurrent atrial arrhythmias. One of 34 targeted non-CTI tachycardia recurred, with a final success rate of 91%. Linear ablation was performed for CTI flutters with a median ablation time of 6.8 min (vs. non-CTIs, p = .006). Three of 21 tachycardias recurred due to reconnection of the ablation line but the final success rate was 100%. The TACT approach for non-CTI atrial arrhythmias in congenital patients as guided by theultrahigh-density mapping is an effective method with short ablation times and excellent medium-term outcomes.