Multi-national survey on the methods, efficacy, and safety on the post-approval clinical use of pulsed field ablation (MANIFEST-PF).

AIMS Pulsed field ablation (PFA) is a novel atrial fibrillation (AF) ablation modality that has demonstrated preferential tissue ablation, including no oesophageal damage, in first-in-human clinical trials. In the MANIFEST-PF survey, we investigated the 'real world' performance of the only approved PFA catheter, including acute effectiveness and safety-in particular, rare oesophageal effects and other unforeseen PFA-related complications. METHODS AND RESULTS This retrospective survey included all 24 clinical centres using the pentaspline PFA catheter after regulatory approval. Institution-level data were obtained on patient characteristics, procedure parameters, acute efficacy, and adverse events. With an average of 73 patients treated per centre (range 7-291), full cohort included 1758 patients: mean age 61.6 years (range 19-92), female 34%, first-time ablation 94%, paroxysmal/persistent AF 58/35%. Most procedures employed deep sedation without intubation (82.1%), and 15.1% were discharged same day. Pulmonary vein isolation (PVI) was successful in 99.9% (range 98.9-100%). Procedure time was 65 min (38-215). There were no oesophageal complications or phrenic nerve injuries persisting past hospital discharge. Major complications (1.6%) were pericardial tamponade (0.97%) and stroke (0.4%); one stroke resulted in death (0.06%). Minor complications (3.9%) were primarily vascular (3.3%), but also included transient phrenic nerve paresis (0.46%), and TIA (0.11%). Rare complications included coronary artery spasm, haemoptysis, and dry cough persistent for 6 weeks (0.06% each). CONCLUSION In a large cohort of unselected patients, PFA was efficacious for PVI, and expressed a safety profile consistent with preferential tissue ablation. However, the frequency of 'generic' catheter complications (tamponade, stroke) underscores the need for improvement

Electroporation and its Relevance for Cardiac Catheter Ablation

Irreversible electroporation can be used as a nonthermal energy source to ablate tissue. Cardiac catheter ablation by irreversible electroporation may be a safe and effective alternative for thermal ablation techniques such as radiofrequency or cryoablation. Total applied current, not delivered power (watts), energy (joules), or voltage, is the parameter that most directly relates to the local voltage gradient that causes electroporation. Electroporation can be achieved with various modalities: direct current, alternating current, pulsed direct current, or any combination of these. Experimental cardiac and noncardiac studies have demonstrated tissue specificity with survival of arteries and nerves in large lesions. In addition, porcine data suggest that application inside a pulmonary vein does not lead to pulmonary vein stenosis and that the esophagus is remarkably insensitive to electroporation. Therefore, irreversible electroporation is a very promising technique for cardiac catheter ablation and especially for electrical pulmonary vein isolation

Epicardial Ablation: Prevention of Phrenic Nerve Damage by Pericardial Injection of Saline and the Use of a Steerable Sheath

Because of the close proximity of the phrenic nerve to the pericardium, phrenic nerve damage caused by epicardial ablation can easily occur. We report two cases of epicardial VT ablation where pericardial injection of saline, combined with the use of a steerable sheath, successfully prevents the phrenic nerve from being damaged

Balloon Catheter Position and its Relationship with Esophageal Temperature during Pulmonary Vein Isolation using High-Intensity Focused Ultrasound

Background: HIFU can achieve PVI, but severe esophageal complications have happened. We analyzed relative position of HIFU balloon catheter (BC) to esophageal temperature (ET) probe and correlated it to ET changes. Methods and Results: Before each ablation relative position of HIFU BC to ET probe was recorded in RAO 30° and LAO 40°. We compared ablations where ET at end of ablation was <38.5°C or ≥38.5°C and <40.0°C or ≥40.0°C. A total of 600 images from 311 ablations in 28 patients (18 male, age 63±7 years), were analyzed. ET ≥38.5°C was reached when distance from BC to ET probe was: <20 mm in LAO for RSPV and <29 mm in LAO for RIPV. For RIPV ET ≥38.5°C was reached when angle between BC and ET probe was significantly smaller in LAO and RAO. ET ≥40.0°C was reached when distance of BC to ET probe was: <20 mm in LAO for RIPV, <14 mm in RAO for RIPV, <18 mm in RAO for LIPV. ET increased to ≥40.0°C when distance from BC to ET probe was significantly longer in LAO for LIPV. For RIPV ET ≥40.0°C was reached when angle between BC and ET probe was significantly smaller in LAO. Conclusions: There is a relationship between distance/angle of HIFU BC to ET probe and ET: shorter distances and smaller angles can cause higher ET

In-vitro analysis of the origin and characteristics of gaseous micro-emboli during catheter electroporation ablation

Introduction: Recent studies demonstrated that irreversible electroporation (IRE) ablation may be an alternative method for thermal ablation for pulmonary vein isolation. Development of gaseous microemboli during catheter ablation might lead to asymptomatic ischemic events and is therefore an important research topic. Gas formation during arcing with direct current catheter ablation has been studied in the past, however not for nonarcing IRE-ablation. Objective: The aim of the present study was to visualize, quantify, and characterize gas formation during nonarcing millisecond IRE-pulses using a multielectrode circular catheter. Methods: In vitro, gas formation during IRE-pulses was studied using a high-speed imaging, direct volume measurements, and a bubble counter. Gas formation was compared between cathodal and anodal IRE-pulses and between a small and large catheter hoop diameter. Results: High-speed images showed the location and dynamics of gas formation during cathodal and anodal millisecond IRE-pulses. The direct volume measurements demonstrated a significantly larger volume for cathodal than for anodal IRE-pulses (P <.001), and no significant difference between small and large hoop diameters. A strong linear relationship was found between delivered charge and total gas volume (r = 0.99). Bubble counter measurements showed that cathodal IRE-pulses produced more and larger gas bubbles than anodal IRE-pulses. The ratio of total gas volume between cathodal and anodal IRE-pulses is different as predicted from electrolysis theory. Conclusion: In vitro, millisecond anodal IRE-pulses produce significantly less and smaller gas bubbles than millisecond cathodal IRE-pulses. In vivo experiments are required to investigate the clinical implication of these observations

Acute and Long-Term Effects of Full-Power Electroporation Ablation Directly on the Porcine Esophagus

BACKGROUND: Esophageal ulceration and fistula are complications of pulmonary vein isolation using thermal energy sources. Irreversible electroporation is a novel, nonthermal ablation modality for pulmonary vein isolation. A single 200 J application can create deep myocardial lesions. Acute and chronic effects of this new energy source on the esophagus are unknown. METHODS AND RESULTS: In 8 pigs (±70 kg), the suprasternal esophagus was surgically exposed. A linear suction device with a single 35-mm long and 6-mm wide protruding linear electrode inside a plastic suction cup was used for ablation. Single, nonarcing, nonbarotraumatic, cathodal 100 and 200 J applications were delivered at 2 different sites on the anterior esophageal adventitia. No proton-pump inhibitors were administered during follow-up. Esophagoscopy was performed at days 2 and 7. After euthanasia at day 60, the esophagus was evaluated visually and histologically. All ablations were uneventful. Esophagoscopy at day 2 showed small white densities in the ablated areas, which appeared to be small intraepithelial vesicles. No epithelial erythema, erosions, or ulcerations were seen. At day 7, all densities had disappeared, and all esophaguses appeared completely normalized. After euthanasia, there were no macroscopically visible lesions on the adventitia or epithelium. Histologically, a small scar was observed at the outer part of the muscular layer, whereas the mucosa and submucosa were normal. CONCLUSIONS: Esophageal architecture remains unaffected 2 months after irreversible electroporation, purposely targeting the adventitia. Irreversible electroporation seems to be a safe modality for catheter ablation near the esophagus

Novel method for electrode-tissue contact measurement with multi-electrode catheters

With multi-electrode catheters, measuring contact force (CF) on each electrode is technically challenging. Present electrical methods, like the electrical coupling index (ECI) may yield false positive values in pulmonary veins. We developed a novel method that measures electrode-interface resistance (IR) by applying a very local electrical field between neighbouring catheter electrodes while measuring voltage between each catheter electrode and a skin patch. The aim of this study was to evaluate the new IR method to measure electrode-tissue contact. In vitro, effects of remote high-impedance structures were studied. In addition, both ECI and IR were directly compared with true electrode-tissue CF. In five pigs, the influence of high-impedance pulmonary tissue on ECI and IR was investigated while navigating the free floating catheter into the caval veins. Inside the left atrium (LA), IR was directly compared with CF. Finally, multi-electrode IR measurements in the LA and inferior pulmonary vein (IPV) were compared. In vitro, IR is much less affected by remote high-impedance structures than ECI (3% vs. 32%). Both IR and ECI strongly relate to electrode-tissue CF (r2=0.84). In vivo, and in contrast to ECI, IR was not affected by nearby pulmonary tissue. Inside the LA, a strong relation between IR and CF was found. This finding was confirmed by simultaneous multi-electrode measurements in LA and IPV. Data of the present study suggest that electrode-tissue contact affects the IR while being highly insensitive to remote structures. This method facilitates electrode-tissue contact measurements with circular multi-electrode ablation catheters