Catheter ablation for atrial fibrillation: indications and future perspective.

Recent advances in techniques, technologies and proven superiority over anti-arrhythmic drugs have made catheter ablation the cornerstone of management for atrial fibrillation (AF), which has shown a steady increase in prevalence in the ageing population worldwide. The aim of therapeutic interventions is to achieve stable sinus rhythm that would improve the quality of life and reduce the risk of AF-associated complications. Pulmonary veins (PVs) were first described as the source of initiation of ectopic triggers driving AF, which led to the establishment of PV isolation (PVI) as the most widely practiced procedure to treat AF. Antral PVI is still recognized as the stand-alone ablation strategy for newly diagnosed paroxysmal AF (PAF). However, in non-PAF patients, PVI seems to be inadequate and several adjunctive strategies, including ablation of left atrial posterior wall and non-PV triggers, AF mapping and ablation of rotors and drivers, ethanol infusion of vein of Marshall and renal denervation, etc. have been reported with mixed results. Recent trials have also documented the benefits of early rhythm control in preventing cardiovascular events in addition to slowing the progression of PAF to more persistent forms. Similarly, very late relapse of the arrhythmia after successful PVI has drawn attention to the critical role of non-PV triggers and highlighted their relevance as potential ablation targets during repeat procedures. Ablation technology is also under constant evolution with the introduction of non-thermal energy sources and new tools to create durable lesions. This review summarizes the indications, advancements, and future perspective of AF ablation.

Pulsed Field Ablation for the Treatment of Atrial Fibrillation: PULSED AF Pivotal Trial.

BACKGROUND: Pulsed field ablation uses electrical pulses to cause nonthermal irreversible electroporation and induce cardiac cell death. Pulsed field ablation may have effectiveness comparable to traditional catheter ablation while preventing thermally mediated complications. METHODS: The PULSED AF pivotal study (Pulsed Field Ablation to Irreversibly Electroporate Tissue and Treat AF) was a prospective, global, multicenter, nonrandomized, paired single-arm study in which patients with paroxysmal (n=150) or persistent (n=150) symptomatic atrial fibrillation (AF) refractory to class I or III antiarrhythmic drugs were treated with pulsed field ablation. All patients were monitored for 1 year using weekly and symptomatic transtelephonic monitoring; 3-, 6-, and 12-month ECGs; and 6- and 12-month 24-hour Holter monitoring. The primary effectiveness end point was freedom from a composite of acute procedural failure, arrhythmia recurrence, or antiarrhythmic escalation through 12 months, excluding a 3-month blanking period to allow recovery from the procedure. The primary safety end point was freedom from a composite of serious procedure- and device-related adverse events. Kaplan-Meier methods were used to evaluate the primary end points. RESULTS: Pulsed field ablation was shown to be effective at 1 year in 66.2% (95% CI, 57.9 to 73.2) of patients with paroxysmal AF and 55.1% (95% CI, 46.7 to 62.7) of patients with persistent AF. The primary safety end point occurred in 1 patient (0.7%; 95% CI, 0.1 to 4.6) in both the paroxysmal and persistent AF cohorts. CONCLUSIONS: PULSED AF demonstrated a low rate of primary safety adverse events (0.7%) and provided effectiveness consistent with established ablation technologies using a novel irreversible electroporation energy to treat patients with AF. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT04198701.

Pulsed-field ablation: an alternative ablative method for gastric electrophysiological intervention.

Pulsed-field ablation (PFA) is an emerging ablative technology that has been used successfully to eliminate cardiac arrhythmias. As a nonthermal technique, it has significant benefits over traditional radiofrequency ablation with improved target tissue specificity and reduced risk of adverse events during cardiac applications. We investigated whether PFA is safe for use in the stomach and whether it could modulate gastric slow waves. Female weaner pigs were fasted overnight before anesthesia was induced using tiletamine hydrochloride (50 mg·mL-1) and zolazepam hydrochloride (50 mg·mL-1) and maintained with propofol (Diprivan 2%, 0.2-0.4 mg·kg-1·min-1). Pulsed-field ablation was performed on their gastric serosa in vivo. Adjacent point lesions (n = 2-4) were used to create a linear injury using bipolar pulsed-field ablation consisting of 40 pulses (10 Hz frequency, 0.1 ms pulse width, 1,000 V amplitude). High-resolution electrical mapping defined baseline and postablation gastric slow-wave patterns. A validated five-point scale was used to evaluate tissue damage in hematoxylin and eosin-stained images. Results indicated that PFA successfully induced complete conduction blocks in all cases, with lesions through the entire thickness of the gastric muscle layers. Consistent postablation slow-wave patterns emerged immediately following ablation and persisted over the study period. Pulsed-field ablation induces rapid conduction blocks as a tool to modulate slow-wave patterns, indicating it may be suitable as an alternative to radiofrequency ablation.NEW & NOTEWORTHY Results show that pulsed-field ablation can serve as a gastric slow-wave intervention by preventing slow-wave propagation across the lesion site. Stable conduction blocks were established immediately following energy delivery, faster than previous examples of radiofrequency gastric ablation. Pulsed-field ablation may be an alternative for gastric slow-wave intervention, and further functional and posthealing studies are now warranted.

Recent Advancements in Electroporation Technologies: From Bench to Clinic.

Over the past decade, the increased adoption of electroporation-based technologies has led to an expansion of clinical research initiatives. Electroporation has been utilized in molecular biology for mammalian and bacterial transfection; for food sanitation; and in therapeutic settings to increase drug uptake, for gene therapy, and to eliminate cancerous tissues. We begin this article by discussing the biophysics required for understanding the concepts behind the cell permeation phenomenon that is electroporation. We then review nano- and microscale single-cell electroporation technologies before scaling up to emerging in vivo applications.

Myocardial injury and inflammation following pulsed-field ablation and very high-power short-duration ablation for atrial fibrillation.

INTRODUCTION: Pulmonary vein isolation (PVI) using radiofrequency ablation (RFA) is an established treatment strategy for atrial fibrillation (AF). To improve PVI efficacy and safety, high-power short-duration (HPSD) ablation and pulsed-field ablation (PFA) were recently introduced into clinical practice. This study aimed to determine the extent of myocardial injury and systemic inflammation following PFA, HPSD, and standard RFA using established biomarkers. METHODS: We included 179 patients with paroxysmal AF receiving first-time PVI with different ablation technologies: standard RFA (30-40 W/20-30 s, n = 52), power-controlled HPSD (70 W/5-7 s, n = 60), temperature-controlled HPSD (90 W/4 s, n = 32), and PFA (biphasic, bipolar waveform, n = 35). High-sensitivity cardiac troponin T (hs-cTnT), creatine kinase (CK), CK MB isoform (CK-MB), and white blood cell (WBC) count were determined before and after ablation. RESULTS: Baseline characteristics were well-balanced between groups (age 63.1 ± 10.3 years, 61.5% male). Postablation hs-cTnT release was significantly higher with PFA (1469.3 ± 495.0 ng/L), HPSD-70W (1322.3 ± 510.6 ng/L), and HPSD-90W (1441.2 ± 409.9 ng/L) than with standard RFA (1045.9 ± 369.7 ng/L; p < .001). CK and CK-MB release was increased with PFA by 3.4-fold and 5.8-fold, respectively, as compared to standard RFA (p < .001). PFA was associated with the lowest elevation in WBC (Δ1.5 ± 1.5 × 109 /L), as compared to standard RFA (Δ3.8 ± 2.5 × 109 /L, p < .001), HPSD-70W (Δ2.7 ± 1.7 × 109 /L, p = .037), and HPSD-90W (Δ3.6 ± 2.5 × 109 /L, p < .001). CONCLUSION: Among the four investigated ablation technologies, PFA was associated with the highest myocardial injury and the lowest inflammatory reaction.

A zero-exchange approach for left atrial access in pulmonary vein isolation with pulsed field ablation.

INTRODUCTION: Pulsed field ablation (PFA) has emerged as an innovative technique for pulmonary vein isolation (PVI). Typically, a transeptal puncture (TSP) with a standard sheath precedes a switch to the larger diameter sheath in the left atrium. This study aimed to describe the safety and feasibility of direct TSP using the large diameter Faradrive sheath before performing PVI with PFA. METHODS: We prospectively enrolled 166 consecutive patients with paroxysmal or persistent atrial fibrillation (AF) undergoing PVI with PFA at our institution. TSP was performed in all cases with transesophageal echocardiography guidance, using the Faradrive sheath and a 98 cm matched Brockenbrough needle. The primary endpoint was the occurrence of pericardial tamponade during or within the first 48 h after the procedure. The secondary endpoint was the occurrence of any major complication. RESULTS: All 166 patients were included into the final analysis (44% female): 64% of patients had paroxysmal AF and 36% persistent AF (68 ± 11 years old, median CHA2DS2Vasc Score 3, median left atrial volume index 31). The median duration of the procedure was 60 min, median time to TSP was 15 min, and the median fluoroscopy dose was 595 cGy × cm2. The primary endpoint occurred in one patient: a non-TSP related pericardial tamponade, which was managed with pericardial puncture. CONCLUSION: Direct TSP with skipping sheath exchange using the large diameter Faradrive sheath for PVI with PFA was safe, feasible, and reduced costs in all patients. Large scale studies and registries are needed to verify this workflow.

Electroporation saves the day again: Pulsed-field ablation for phrenic nerve-sparing in right atrial tachycardia.

INTRODUCTION: Pulsed-field ablation (PFA) is a novel nonthermal energy that shows unique features that can be of use beyond pulmonary vein ablation, like tissue selectivity or proximity rather than contact dependency. METHODS AND RESULTS: We report three cases of right focal atrial tachycardias arising from the superior cavoatrial junction and the crista terminalis, in close relationship with the phrenic nerve, effectively ablated using a commercially available PFA catheter designed for pulmonary vein isolation without collateral damage. CONCLUSION: PFA can be useful for treating right atrial tachycardias involving sites near the phrenic nerve, avoiding the need for complex nerve-sparing strategies.

Pulsed field ablation technology for pulmonary vein and left atrial posterior wall isolation in patients with persistent atrial fibrillation.

INTRODUCTION: Limited data exist on pulsed-field ablation (PFA) in patients with persistent atrial fibrillation (PeAF) undergoing left atrial posterior wall isolation (LAPWI). METHODS: The Advanced TecHnologies For SuccEssful AblatioN of AF in Clinical Practice (ATHENA) prospective registry included consecutive patients referred for PeAF catheter ablation at 9 Italian centers, treated with the FARAPULSETM-PFA system. The primary efficacy and safety study endpoints were the acute LAPWI rate, freedom from arrhythmic recurrences and the incidence of major periprocedural complications. Patients undergoing pulmonary vein isolation (PVI) alone, PWI + LAPWI and redo procedures were compared. RESULTS: Among 249 patients, 21.7% had long-standing PeAF, 79.5% were male; mean age was 63 ± 9 years. LAPWI was performed in 57.6% of cases, with 15.3% being redo procedures. Median skin-to-skin times (PVI-only 68 [60-90] vs. PVI + LAPWI 70 [59-88] mins) did not differ between groups. 45.8% LAPWI cases were approached with a 3D-mapping system, and 37.3% with intracardiac echocardiography. LAPWI was achieved in all patients by means of PFA alone, in 88.8% cases at first pass. LAPWI was validated either by an Ultrahigh-density mapping system or by recording electrical activity + pacing maneuvers. No major complications occurred, while 2.4% minor complications were detected. During a median follow-up of 273 [191-379] days, 41 patients (16.5%) experienced an arrhythmic recurrence after the 90-day blanking period, with a mean time to recurrence of 223 ± 100 days and no differences among ablation strategies. CONCLUSION: LAPWI with PFA demonstrates feasibility, rapidity, and safety in real-world practice, offering a viable alternative for PeAF patients. LAPWI is achievable even with a fluoroscopy-only method and does not significantly extend overall procedural times.

Ablation of epicardial ventricular focus through coronary sinus using pulsed-field ablation. A case report.

INTRODUCTION: With the entry of pulsed-field ablation (PFA) into electrophysiology, new possibilities for ablation of different substrates such as epicardial foci of premature ventricular contractions (PVCs) from coronary venous system (CVS) have been opened. METHODS: This article focuses on a case of a 27-year-old patient with frequent monomorphic PVCs of epicardial origin, treated by radiofrequency ablation, followed by PFA. RESULTS: After unsuccessful focus ablation through CVS with RFA, successful ablations from the same region with PFA were achieved. CONCLUSION: This is the first described case of successful ablation of epicardial PVCs using PFA, which we hope will help in defining indications for this novel technology and enhance quality of treatment for patients with different arrhythmias.

Comparison of efficiency of PFA catheter designs by computer modeling.

INTRODUCTION: Various catheter designs are appearing for Pulsed Field Ablation (PFA). It is unclear if they differ in terms of safety and efficiency. PFA studies have reported hemolysis, kidney injury, high troponin, among other side effects. METHODS: Using a CT-derived computer model, we compared catheter designs using two metrics: (1) efficiency: power delivered to an atrial wall target, expressed as a percent of total generator power; and (2) safety: electric current to achieve 90% transmurality (since more energy causes more collateral effects), as well as the corresponding electrode current density (ECD), a heat and bubble metric. The following catheter designs were compared: penta-spline basket, Nitinol spheres (focal 9 mm and large 1-shot), circular, balloon, and flex-circuit. Target was a 6 × 47 mm circumferential segment of atrial wall at LPV antrum. Transmurality was defined as percent of target having >600 volts per centimeter (V/cm) electric field needed for electroporation. RESULTS: Efficiency was 0.9, 1.4, 2.7, 5.9, 10, and 12% for the large 1-shot and 9 mm Nitinol spheres, penta-spline, circular, flex spline, and balloon catheters, respectively. Regarding safety, currents for 90% transmurality were 70, 39,36,12.5, 5.3, and 4 Amps for the same respective catheters, with less being safer. ECD was 124, 25, 74, 83, 41, and 31 A/cm2, respectively. CONCLUSION: Computer models demonstrated a remarkable range in efficiency among catheters studied. Those having less atrial blood exposure had the highest efficiencies, with factors of up to 13X more efficiency compared to exposed ones. Higher efficiency designs have less collateral current and are safer. Confirmatory in-vivo studies are required.

Local calcium chloride infusion after pulsed field ablation enhances acute efficacy of cardiac electroporation.

INTRODUCTION: Pulsed field ablation (PFA) has emerged as an innovative therapy for cardiac arrhythmias. Drawing parallels with PFA's application in solid tumors, calcium chloride (CaCl2) as an adjuvant therapy, known as calcium electroporation, may amplify PFA's apoptotic effects. We propose that PFA in the atrium could enhance calcium uptake through PFA-created pores, thereby increasing ablation efficacy even at reduced power levels by exploiting PFA's permeabilization effects. METHODS: We conducted in vivo ablations on the atria of seven pigs using low PFA power (250 V, 20 µs for 50 pulses at 200 ms intervals). Post-PFA, we randomly administered an infusion of either 200 mg/2 ml CaCl2 (calcium group) or saline (control) directly to the ablation site via the catheter tip. We evaluated reduction in electrogram voltage amplitude, electrocardiography (ECG) parameters, ablation lesion parameters, and histology after PFA. RESULTS: Nineteen lesions from control and calcium groups were examined. Control lesions showed no voltage decrease post-PFA, whereas calcium-treated lesions exhibited a significant voltage reduction. Gross pathology indicated marked differences in maximum lesion surface diameter, depth, and volume between the lesion groups. Histologically, calcium group lesions were characterized by a more severe acute PFA response with contraction band necrosis, myocytolysis and nuclear pyknosis in adjacent myocardium, in addition to microhemorrhages. CONCLUSION: Infusing calcium chloride locally after PFA markedly improves the immediate efficacy of electroporation in porcine atria. This study suggests that calcium electroporation could bolster PFA outcomes without higher energy levels, potentially diminishing associated risks. These preliminary findings warrant further research into the long-term efficacy and potential clinical application of calcium electroporation in PFA.

Prediction of major intravascular hemolysis during pulsed electric field ablation of atrial fibrillation using a pentaspline catheter.

INTRODUCTION: Pulsed electric field (PEF) has emerged as a promising energy source for catheter ablation of atrial fibrillation (AF). However, data regarding the in-vivo effect of PEF energy on erythrocytes during AF ablation procedures are scarce. This study aimed to quantify the impact of PEF energy on erythrocyte damage during AF ablation by assessing specific hemolytic biomarkers. METHODS: A total of 60 patients (age: 68 years, males: 72%, serum creatinine: 91 µmol/L) with AF underwent catheter ablation of AF using PEF energy delivered by a multipolar pentaspline Farawave catheter (Farapulse, Boston Scientific, Inc.). Ablation beyond pulmonary vein isolation was performed at the operator's discretion. Peripheral venous blood was sampled for assessing the plasma levels of free hemoglobin (fHb), direct (conjugated) bilirubin, lactate dehydrogenase (LDH), and creatinine before, immediately after the ablation, and on the next day. RESULTS: Following the PEF ablation with duration of [median (interquartile range)] 75 (58, 95) min, with 74 (52, 92) applications and PVI only in 27% of patients, fHb, LDH, and direct bilirubin significantly increased, from 40 (18, 65) to 493 (327, 848) mg/L, from 3.1 (2.6, 3.6) to 6.8 (5.0, 7.9) µkat/L, and from 12 (9, 17) to 28 (16, 44) µmol/L, respectively (all p < .0001). A strong linear correlation was found between the peak fHb and the number of PEF applications (R = 0.81, p < .001). The major hemolysis (defined as fHb >500 mg/L) was predicted by the number of PEF applications with the corresponding area under the receiver operating characteristic curve of 0.934. The optimum cut-off value of >74 PEF applications predicted the major hemolysis with 89% sensitivity and 87% specificity. CONCLUSION: Catheter ablation of AF using PEF energy delivered from a pentaspline catheter is associated with significant intravascular hemolysis. More than 74 PEF applications frequently resulted in major hemolysis. However, the critical amount of PEF energy that may cause kidney injury in susceptible patients remains to be investigated.

Safety and effectiveness of additional left atrial posterior wall ablation using pulsed field ablation for persistent and long-standing persistent atrial fibrillation patients.

INTRODUCTION: The unique safety profile of pulsed field ablation (PFA) has made pulmonary vein isolation (PVI) + left atrial posterior wall (LAPW) ablation promising for treating persistent atrial fibrillation (PerAF). The goal of this study was to assess long-term freedom from atrial fibrillation, atrial flutter, and atrial tachycardia (AF/AFL/AT), as well as the safety and feasibility of LAPW PFA using multipolar, pentaspline Farawave catheter. METHODS: Retrospective observational study at a single institution. Data for 94 patients were collected from a prespecified intraprocedural registry. The long-term AF/AFL/AT recurrence assessment was based on an analysis of medical history; 24-h Holter ECGs at 3, 6, and 12 months postablation; and 12-lead ECGs recorded during symptomatic episodes or visits. RESULTS: Half of the patients had ls-PerAF, and half had a history of catheter ablation-mostly RF PVI. The acute ablation success rate was 100%, and the primary safety outcome was observed in 2 patients. Fifty patients experienced AF/AFL/AT recurrence (54.3%). An increase in LAPW low-voltage areas and AF classification were associated with arrhythmia recurrence. After a median follow-up of 13 months, the Kaplan‒Meier estimated median time free of AF/AFL/AT after a single procedure was 14.7 months. CONCLUSION: PFA PVI + PWA had the best outcome in perAF patients without extensive LA fibrosis. AF recurrence was paroxysmal in significant part of the cohort. The addition of PWA to PVI using multipolar PFA was safe and did not significantly influence the transpired ablation time.

Catheter-tissue contact optimizes pulsed electric field ablation with a large area focal catheter.

INTRODUCTION: Pulsed electric field (PEF) ablation relies on the intersection of a critical voltage gradient with tissue to cause cell death. Field-based lesion formation with PEF technologies may still depend on catheter-tissue contact (CTC). The purpose of this study was to assess the impact of CTC on PEF lesion formation with an investigational large area focal (LAF) catheter in a preclinical model. METHODS: PEF ablation via a 10-spline LAF catheter was used to create discrete right ventricle (RV) lesions and atrial lesion sets in 10 swine (eight acute, two chronic). Local impedance (LI) was used to assess CTC. Lesions were assigned to three cohorts using LI above baseline: no tissue contact (NTC: ≤∆10 Ω, close proximity to tissue), low tissue contact (LTC: ∆11-29 Ω), and high tissue contact (HTC: ≥∆30 Ω). Acute animals were infused with triphenyl tetrazolium chloride (TTC) and killed ≥2 h post-treatment. Chronic animals were remapped 30 days post-index procedure and stained with infused TTC. RESULTS: Mean (± SD) RV treatment sizes between LTC (n = 14) and HTC (n = 17) lesions were not significantly different (depth: 5.65 ± 1.96 vs. 5.68 ± 2.05 mm, p = .999; width: 15.68 ± 5.22 vs. 16.98 ± 4.45 mm, p = .737), while mean treatment size for NTC lesions (n = 6) was significantly smaller (1.67 ± 1.16 mm depth, 5.97 ± 4.48 mm width, p < .05). For atrial lesion sets, acute and chronic conduction block were achieved with both LTC (N = 7) and HTC (N = 6), and NTC resulted in gaps. CONCLUSIONS: PEF ablation with a specialized LAF catheter in a swine model is dependent on CTC. LI as an indicator of CTC may aid in the creation of consistent transmural lesions in PEF ablation.

Impact of pulsed field ablation on intraluminal esophageal temperature.

INTRODUCTION: Atrio-esophageal fistula after esophageal thermal injury (ETI) is one of the most devastating complications of available energy sources for atrial fibrillation (AF) ablation. Pulsed field ablation (PFA) uses electroporation as a new energy source for catheter ablation with promising periprocedural safety advantages over existing methods due to its unique myocardial tissue sensitivity. In preclinical animal studies, a dose-dependent esophageal temperature rise has been reported. In the TESO-PFA registry intraluminal esophageal temperature (TESO) changes in a clinical setting are evaluated. METHODS: Consecutive symptomatic AF patients (62 years, 67% male, 61% paroxysmal AF, CHA2 DS2 Vasc Score 2) underwent first-time PFA and were prospectively enrolled into our registry. Eight pulse trains (2 kV/2.5 s, bipolar, biphasic, x4 basket/flower configuration each) were delivered to each pulmonary vein (PV). Two extra pulse trains per PV in flower configuration were added for wide antral circumferential ablation. Continuous intraluminal esophageal temperature (TESO) was monitored with a 12-pole temperature probe. RESULTS: Median TESO change was statistically significant and increased by 0.8 ± 0.6°C, p < .001. A TESO increase ≥ 1°C was observed in 10/43 (23%) patients. The highest TESO measured was 40.3°C. The largest TESO difference (∆TESO) was 3.7°C. All patients remained asymptomatic considering possible ETI. No atrio-esophageal fistula was reported on follow-up. CONCLUSION: A small but significant intraluminal esophageal temperature rise can be observed in most patients during PFA. TESO rise over 40°C is rare. The clinical implications of the observed findings need to be further evaluated.

Pulsed-field ablation does not induce esophageal and periesophageal injury-A new esophageal safety paradigm in catheter ablation of atrial fibrillation.

INTRODUCTION: Esophageal injury is one of the most serious complications of pulmonary vein isolation (PVI) with thermic energy sources. Better tissue selectivity of primarily non-thermic pulsed field ablation (PFA) may eliminate collateral injury, particularly the risk of atrio-esophageal fistula (AEF). OBJECTIVE: To compare the incidence of any (peri)-esophageal injury following PVI using PFA to thermic energy sources. METHODS: Using endoscopy, endoscopic ultrasound, and electrogastrography before and after PVI, esophageal and periesophageal injury (mucosal lesions, food retention, periesophageal edema, or vagal nerve injury) were assessed following PFA and radiofrequency (RF)- or cryoballoon (CB)-PVI. RESULTS: Between December 2022 and February 2023, 20 patients (67 ± 10 years, 53% male) undergoing PFA (Farapulse, Boston Scientific) for atrial fibrillation (AF) were studied and compared with a previous cohort of 57 patients who underwent thermic PVI (CB: n = 33; RF: n = 24). Following PFA-PVI, none of the patients had mucosal lesions, food retention, or ablation-induced vagal nerve injury; four patients showed periesophageal edema. Following thermic ablation, 33/57 patients (58%) showed esophageal and/or periesophageal injury (CB: 21/33 [64%], RF: 12/24 [50%]), in detail 4/57 mucosal lesions, 18/57 food retention, 17/57 vagal nerve injury, and 20/52 edema. Midterm success rates were similar for all energy sources. CONCLUSION: In contrast to thermic ablation tools, PFA is not associated with relevant esophageal and periesophageal injury, and might, therefore, reduce or eliminate the risk of potentially lethal AEF in interventional treatment of AF. The etiology of ablation-induced periesophageal edema is unknown but has not been shown to be related to lesion progression.

Pulsed-field versus cryoballoon ablation for atrial fibrillation-Impact of energy source on sedation and analgesia requirement.

INTRODUCTION: Pulsed field ablation (PFA) represents a novel, nonthermal energy modality that can be applied for single-shot pulmonary vein isolation (PVI) in atrial fibrillation (AF). Comparative data with regard to deep sedation to established single-shot modalities such as cryoballoon (CB) ablation are scarce. The aim of this study was to compare a deep sedation protocol in patients receiving PVI with either PFA or CB. METHODS: Prospective, consecutive AF patients undergoing PVI with a pentaspline PFA catheter were compared to a retrospective CB-PVI cohort of the same timeframe. Study endpoints were the requirements of analgesics, cardiorespiratory stability, and sedation-associated complications. RESULTS: A total of 100 PVI patients were included (PFA n = 50, CB n = 50, mean age 66 ± 10.6, 61% male patients, 65% paroxysmal AF). Requirement of propofol, midazolam, and sufentanyl was significantly higher in the PFA group compared to CB [propofol 0.14 ± 0.04 mg/kg/min in PFA vs. 0.11 ± 0.04 mg/kg/min in CB (p = .001); midazolam 0.00086 ± 0.0004 mg/kg/min in PFA vs. 0.0006295 ± 0.0003 mg/kg/min in CB (p = .002) and sufentanyl 0.0013 ± 0.0007 µg/kg/min in PFA vs. 0.0008 ± 0.0004 µg/kg/min in CB (p < .0001)]. Sedation-associated complications did not differ between both groups (PFA n = 1/50 mild aspiration pneumonia, CB n = 0/50, p > .99). Nonsedation-associated complications (PFA: n = 2/50, 4%, CB: n = 1/50, 2%, p > .99) and procedure times (PFA 75 ± 31, CB 84 ± 32 min, p = .18) did not differ between groups. CONCLUSIONS: PFA is associated with higher sedation and especially analgesia requirements. However, the safety of deep sedation does not differ to CB ablation.

VARIPULSE: A step-by-step guide to pulmonary vein isolation.

INTRODUCTION: The VARIPULSE™ variable-loop circular catheter (VLCC) is a bidirectional, multielectrode catheter that can perform electrophysiological mapping and deliver pulsed field energy through the TRUPULSE™ Generator for the treatment of atrial fibrillation. This ablation system, including the CARTO 3™ three-dimensional electroanatomical mapping system, represents a fully integrated system. METHODS: Pulsed field ablation (PFA) is a novel, primarily cardiac tissue-selective ablation technology with a minimal thermal effect, potentially eliminating the collateral tissue damage associated with radiofrequency ablation or cryoablation. Integration of a mapping system may lead to shorter fluoroscopy times and improve the usability of the system, allowing tracking of energy density and placement to confirm no areas around the vein are left untreated. RESULTS: This step-by-step review covers patient selection, mapping, the step-by-step ablation workflow, details on catheter repositioning and ensuring contact, considerations for ablation of specific anatomical variations, and discussion of ablation without fluoroscopy based on our initial clinical experience. CONCLUSIONS: The VLCC is part of the fully integrated PFA system designed for pulmonary vein isolation, using mapping to guide catheter placement and lesion set creation. The current workflow, which is based on our initial clinical experience, may be further refined as the PFA system is used in real-world settings.

Ventricular tachycardia ablation with pentaspline pulsed field technology in two patients with ischemic cardiomyopathy.

INTRODUCTION: Due to its unique features, pulsed field ablation (PFA) could potentially overcome some limitations of current radiofrequency (RF) ventricular tachycardia (VT) ablation. However, data on the use of PFA in this setting are currently scarce. METHODS: Two patients with ischemic cardiomyopathy and previously failed RF VT ablations were treated with PFA. RESULTS: A total of 18 bipolar applications (case1) and seven bipolar applications (case2) were delivered to the infero-lateral and infero-septal areas (case1) and to the apical lateral left ventricular (LV) wall (case2), placing the catheter adjacent to the LV wall in the flower configuration. A rapid cessation of VT and restoration of sinus rhythm were observed during PFA delivery in both cases. Further applications were delivered to achieve complete elimination of late potentials. In case 1, during the in-hospital stay, ECG monitoring did not show VT recurrences. Six-month follow-up was uneventful, with no VT recurrences at ICD interrogation. In case 2, due to postdischarge VT recurrences, a second RF procedure was scheduled 1 month later. The voltage map performed in sinus rhythm showed a low-voltage zone located at the anterolateral wall, near the previous ablation site. Numerous late potentials were recorded. At the 6-month follow-up, no further VT recurrences were documented after RF redo ablation. CONCLUSION: While the speed of application and potential transmural effect can facilitate the ablation of large diseased endocardial areas, early loss of contact due to difficult pentaspline catheter manipulation in the LV could lead to insufficient contact force and, consequently, inadequate energy penetration.

Are "Carbon Dots" Always Carbon Dots? Evidence for their Supramolecular Nature from Structural and Dynamic Studies in Solution and in the Pure Solid.

A model for the morphology (size, shape, and crystallinity) of carbon dots (CDs) in the solid state consistent with the observed photoluminescence in solution is proposed herein. Overwhelming evidence has been collected that links the data coming from solid-state analysis (high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS)) to that of solution (pulsed-field gradient (PFG)-NMR spectroscopy, time-resolved fluorescence anisotropy (TRFA), and steady-state/time-resolved fluorescence), allowing the establishment of an overall structural model for CDs. According to this model, the so-called carbon dots, observed under HRTEM imaging, are in fact supramolecular organized structures dynamically assembled from small to medium-sized molecular species when the solvent is removed to give the solid form. In this way, the imaged nanoparticles (TEM/AFM) are not covalently bound entities formed during the synthetic process, but instead supramolecular entities formed by noncovalent interactions. These particles, if at all present in solution, have the form of loose associations of relatively small molecules. This study was conducted on CDs obtained from the hydrothermal carbonization (HTC) of a biomass waste (olive wet pomace).