Circular Catheter Research Articles

Comparative Evaluation of Two Pulsed Field Ablation Systems for Atrial Fibrillation: Insights from Real-World Clinical Implementation and Short-Term Outcomes

Pulsed field ablation (PFA) is a safe and effective technology for catheter ablation of atrial fibrillation (AF). Multiple PFA-platforms for AF-ablation have been developed. However, evidence comparing the real-word implementation and performance of different PFA-systems is still limited. This study compares procedural and acute outcome parameters during implementation of the PFA-system employing a pentaspline PFA-catheter (FARAPULSE, Boston Scientific) and a platform using a circular PFA-catheter (PulseSelect, Medtronic). The first consecutive 40 patients treated with each PFA-system were included. Baseline characteristics, procedural parameters and short-term outcome regarding peri-procedural safety and efficacy were evaluated. The majority of patients showed paroxysmal AF, nearly a third of patients in both groups suffered from persistent AF. Overall procedural complication rates were not different between subgroups (circular catheter: 12.5%; pentaspline catheter 7.5%, P=.71), mainly minor (circular catheter: 10.0%; pentaspline catheter: 7.5%, P=1.00). There was no significant difference in median procedure duration (circular catheter: 42.0min; pentaspline catheter: 43.0min, P=.292), LA-dwell-time (circular catheter. 29.0min; pentaspline catheter: 31.0 min, P=.623) and fluoroscopy duration (circular catheter: 13.2 min; pentaspline catheter: 11.9 min, P=.132). With the pentaspline PFA-catheter no learning curve was observed regarding procedural parameters over the course of 40 procedures. With the circular PFA-catheter, there was a statistically significant decrease in LA-dwell-time and fluoroscopy duration comparing the first and last ten procedures. Both PFA-systems could be safely and rapidly implemented into clinical practice of an experienced center. Large-scale clinical trials are needed to compare long-term outcome between different PFA-systems currently introduced into clinical practice.

High density mapping accuracy and efficiency in atrial fibrillation: real-world outcomes from the SECURE registry

Abstract Background/Introduction A high-density (HD) mapping catheter is valuable for validating pulmonary vein isolation (PVI) and analysing arrhythmic substrates of the left atrium (LA) during atrial fibrillation (AF) ablation. Multiple HD mapping catheters are available for use in clinical practice. A novel octa-spline mapping catheter with a close internal unipolar reference electrode is now available and may improve mapping efficiencies and image resolutions (Figure). Purpose This study aims to report real-world experiences with different commercially available HD mapping catheters in AF ablation and compare mapping performance. Methods SECURE is an ongoing observational, prospective, post-marketing study collecting real-world data on ablation procedures performed per standard-of-care. At the time of data extraction (Nov. 2023), 16 sites across 8 countries had enrolled 2,366 patients (pts), with 12-month follow-up data available for 828 pts. The current analysis, which included consecutive pts undergoing AF ablation, evaluated mapping efficiency and procedural outcomes with 3 HD mapping catheters: circular catheter (CC), penta-spline catheter (PSC), and octa-spline catheter (OSC). Mapping data were analysed with a cloud-based data management and artificial intelligence-powered algorithm. Results Overall, 859 pts with AF (paroxysmal AF [PAF], n=465; persistent AF [PsAF], n=240; long-standing PsAF [LS PsAF], n=154) were included in this analysis. The CC, PSC, and OSC were used in 428, 210, and 221 pts, respectively. Procedures using the OSC had a significantly higher mean mapping area (31,989.9 mm2) than those performed with the CC (23,152.2 mm2; P<0.0001) and PSC (29,804.6 mm2; P=0.0027), as well as a >3-fold higher mean mapping rate (138.4 vs 20.8 and 43.4 points/min, respectively; both P<0.0001). The higher number of mapping points translated to a higher mean mapping density (OSC, 0.34 vs CC, 0.05 and PSC, 0.07 points/mm2; both P<0.0001), with more uniform point distribution and less interpolation. With the CC, PSC, and OSC, respectively, total mean procedure times (incl PVI + other targets) were 118.0, 118.7, and 165.1 min, (P<0.0001 for OSC vs. both CC and PSC) and mean pre-ablation mapping times were 25.2, 25.0, and 21.5 min (P<0.0004 for OSC vs. both CC and PSC). The improved mapping quality and efficiency with the OSC allowed to include specific ablation targets beyond PVI. Fewer PVI-only procedures were performed with the OSC (29.4%) versus the CC (62.1%) and PSC (54.8%), while ablation of the PVI+ other targets was more common with the OSC versus the CC and PSC, including the cavotricuspid isthmus (37.1% vs 17.3% and 16.7%), LA roof (42.5% vs 13.1% and 21.4%), and LA posterior wall (21.7% vs 10.5% and 16.2%). Results were overall consistent per AF type (Table). Conclusions By providing more accurate mapping, the OSC allows for improved analysis of the arrhythmic substrate, which may improve ablation outcomes for pts with PAF and PsAF.Figure 1

In vivo assessment of catheter-tissue contact using tissue proximity indication and its impact on cardiac lesion formation in pulsed field ablation

BackgroundNo evidence exists regarding whether tissue proximity indication (TPI), an impedance-based contact indicator, can improve in vivo lesion formation and durability during pulsed field ablation (PFA). ObjectiveThis in vivo study investigated the relationship between catheter-tissue contact and lesion formation. MethodsIn 5 porcine subjects, PFA applications were delivered at 35 atrial target sites using the VARIPULSE variable-loop circular catheter with the CARTO 3 mapping system. We compared acute ablative low-voltage zones (LVZs; <0.5 mV), chronic LVZs, and pathologic lesions between no/minimum contact (TPI-negative/flickering TPI-positive status) and consistent tissue contact (consistent TPI-positive status) for typical clinical scenarios and tissue tenting (TPI-positive status with electrodes extensively away from the 3-dimensional mapping surface) for safety margin. Ultrasound imaging also confirmed contact category assessments. ResultsAcute and chronic LVZs were significantly larger with consistent contact compared with no/minimum contact, including pathologic lesion length (36.0 ± 12.5 mm vs 17.4 ± 15.2 mm; P = .002) and maximum width (10.3 ± 2.7 mm vs 5.7 ± 5.1 mm; P = .035); results with tenting (length: 34.6 ± 11.7; width: 11.3 ± 1.9 mm) were comparable to consistent contact. Lesion transmurality was achieved in all lesions with consistent contact or tissue tenting but only in 54.5% with no/minimum contact (P = .001 for each). The TPI-based electrode contact distance, measured as the cumulative length of the multielectrode catheter tip positive for TPI, significantly correlated with lesion length, maximum width, and transmurality. ConclusionConsistent TPI-based contact during PFA was strongly associated with distinct chronic transmural lesions, emphasizing the importance of tissue contact in optimizing circumferential lesion formation with circular PFA catheters.

Application repetition and electrode-tissue contact result in deeper lesions using a pulsed-field ablation circular variable loop catheter.

Pulsed-field ablation (PFA) is a novel, myocardial-selective, non-thermal ablation modality used to target cardiac arrhythmias. Although prompt electrogram (EGM) signal disappearance is observed immediately after PFA application in the pulmonary veins, whether this finding results in adequate transmural lesions is unknown. The aim of this study is to check whether application repetition and catheter-tissue contact impact lesion formation during PFA. A circular loop PFA catheter was used to deliver repeated energy applications with various levels of contact force. A benchtop vegetal potato model and a beating heart ventricular myocardial model were utilized to evaluate the impact of application repetition, contact force, and catheter repositioning on contiguity and lesion depth. Lesion development occurred over 18 h in the vegetal model and over 6 h in the porcine model. Lesion formation was found to be dependent on application repetition and contact. In porcine ventricles, single and multiple stacked applications led to a lesion depth of 3.5 ± 0.7 and 4.4 ± 1.3 mm, respectively (P = 0.002). Furthermore, the greater the catheter-tissue contact, the more contiguous and deeper the lesions in the vegetal model (1.0 ± 0.9 mm with no contact vs. 5.4 ± 1.4 mm with 30 g of force; P = 0.0001). Pulsed-field ablation delivered via a circular catheter showed that both repetition and catheter contact led independently to deeper lesion formation. These findings indicate that endpoints for effective PFA are related more to PFA biophysics than to mere EGM attenuation.

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

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. 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. 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. 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.

Predictors of Success for Pulmonary Vein Isolation With Pulsed-field Ablation Using a Variable-loop Catheter With 3D Mapping Integration: Complete 12-month Outcomes From inspIRE.

We previously presented the safety and early efficacy of the inspIRE study (Study for Treatment of Paroxysmal Atrial Fibrillation [PAF] by Pulsed-field Ablation [PFA] System With Irreversible Electroporation [IRE]). With the study's conclusion, we report the outcomes of the full pivotal study cohort, with an additional analysis of predictors of success. InspIRE was a prospective, multicenter, single-arm clinical trial of drug-refractory paroxysmal atrial fibrillation. Pulmonary vein isolation was performed with a variable-loop circular catheter integrated with a 3-dimensional mapping system. Follow-up with 24-hour Holter was at 3, 6, and 12 months, as well as remote rhythm monitoring: weekly from 3 to 5 months, monthly from 6 to 12 months, and for symptoms. The primary effectiveness end point (PEE) was acute pulmonary vein isolation plus freedom from any atrial arrhythmia at 12 months. Additional subanalyses report predictors of PEE success. The patient cohort included 186 patients: aged 59±10 years, female 30%, and CHA2DS2-VASc 1.3±1.2. The previously reported primary adverse event rate was 0%. One serious procedure-related adverse event, urinary retention, was reported. The PEE was achieved in 75.6% (95% CI, 69.5%-81.8%). The clinical success of freedom from symptomatic recurrence was 81.7% (95% CI, 76.1%-87.2%). Simulating a monitoring method used in standard real-world practice (without protocol-driven remote rhythm monitoring), this translates to a freedom from all and symptomatic recurrence of 85.8% (95% CI, 80.8%-90.9%) or 94.0% (95% CI, 90.6%-97.5%), respectively. Multivariate analyses revealed that left ventricular ejection fraction ≥60% (adjusted odds ratio, 0.30) and patients receiving ≥48 PFA applications (adjusted odds ratio, 0.28) were independent predictors of PEE success. Moreover, PEE success was 79.2% in patients who received ≥12 PFA applications per vein compared with 57.1% in patients receiving fewer PFA applications. The inspIRE study confirms the safety and effectiveness of pulmonary vein isolation using the novel 3-dimensional mapping integrated circular loop catheter. An optimal number of PFA applications (≥48 total or ≥12 per vein) resulted in an improved 1-year success rate of ≈80%. URL: https://www.clinicaltrials.gov; Unique identifier: NCT04524364.

Atrial fibrillation ablation workflow optimization facilitated by high-power short-duration ablation and high-resolution mapping.

Pulmonary vein isolation (PVI) for catheter ablation of atrial fibrillation (AF) is a time-demanding procedure. High-power short-duration (HPSD) ablation protocols and high-density mapping catheters have recently been introduced to clinical practice. We investigated the impact of high-density mapping and HPSD ablation protocols on procedural timing, efficacy, and safety by comparing different standardized set-ups. Three electrophysiology (EP) laboratory set-ups were analysed: (i) circular catheter for mapping and HPSD ablation with 30/35 W guided by an ablation index (AI); (ii) pentaspline catheter for mapping an HPSD ablation with 50 W guided by an AI; and (iii) pentaspline catheter for mapping and HPSD ablation with 90 W over 4 s using a novel ablation catheter. All patients underwent PVI without additional left atrial ablation strategies. Procedural data and operating intervals in the EP laboratory were systematically analysed. Three hundred seven patients were analysed (30/35 W AI: n = 102, 50 W AI: n = 102, 90 W/4 s: n = 103). Skin-to-skin times [105.3 ± 22.7 (30/35 W AI) vs. 81.4 ± 21.3 (50 W AI) vs. 69.5 ± 12.2 (90 W/4 s) min, P ≤ 0.001] and total laboratory times (132.8 ± 42.1 vs. 107.4 ± 25.7 vs. 95.2 ± 14.0 min, P < 0.001) significantly differed among the study groups. Laboratory interval analysis revealed significant shortening of mapping and ablation times. Arrhythmia-free survival after 12 months was not different among the study groups (log-rank P = 0.96). The integration of high-density mapping and HPSD protocols into an institutional AF ablation process resulted in reduced procedure times without compromising safety or efficacy.

Treatment of atrial fibrillation with second-generation cryoballoon followed by contact-sensing radiofrequency catheter ablation for arrhythmia recurrences-results of a 5-year follow-up.

The aim of this study was to report the long-term follow-up results of cryoballoon (CB) ablation in patients with atrial fibrillation. All consecutive patients who underwent second-generation CB ablation from February 2015 to December 2017 were included in our study. In all procedures, we used a 28-mm CB placed via a single transseptal puncture guided by intracardiac ultrasound. A 20-mm octapolar intraluminal circular catheter was used for intracardiac recordings. A single 180-s freeze strategy was employed. Repeated procedures were performed with a 3D mapping system and radiofrequency catheters. A total of 126 patients (69.8% male, mean age 57 ± 11years), of which 77.0% had paroxysmal atrial fibrillation (PAF), were included in the study. After a 5-year period, 52.4% of patients were in sinus rhythm without AF recurrence, off antiarrhythmic drugs. A total of 61.9% of patients were free of AF recurrence when redo PVI procedures were performed. When accounting for redo pulmonary vein isolation and antiarrhythmic drugs, a total of 73.8% of the patients were without AF recurrence in long-term follow-up. The patients who underwent redo pulmonary vein isolation procedures had statistically significant lower rates of AF recurrence (p = 0.006). In patients with PAF, long-term success rates improved from 62.9 to 79.4% for patients who underwent the redo procedure (p = 0.020). In patients with persistent atrial fibrillation (PersAF), success rates went up from 41.4 to 55.1% for patients with single or repeated PVI procedure (p = 0.071). In the whole cohort, a total of 3 (2.4%) procedure-related major complications occurred which included persistent PNP, arterial pseudoaneurysm, and arteriovenous fistula. Our data suggest a favorable long-term safety and efficacy profile of second-generation CB ablation. In the mixed paroxysmal and persistent population, up to 73.8% of patients remained free of AF recurrence in the 5-year follow-up, when accounting for redo procedures and AADs. Only 2.4% of patients experienced major complications of the ablation procedure, none with permanent sequelae.

Initial clinical experience of atrial fibrillation ablation guided by a cryoballoon-compatible, magnetic-based circular catheter.

The circular catheter compatible with current cryoballoon system for atrial fibrillation (AF) ablation is exclusively sensed by impedance-based electro-anatomical mapping (EAM) system, limiting the accuracy of maps. We aim to investigate the feasibility and safety of a magnetic-based circular mapping catheter for AF ablation with cryoballoon. Nineteen consecutive patients who underwent pulmonary vein isolation (PVI) with cryoballoon for paroxysmal or persistent AF were included. EAMs of left atrium (LA) created by the LASSOSTAR™NAV catheter (Lassostar map) before and after PVI were compared to that generated by a high-density mapping catheter (Pentaray map) from different aspects including structural similarity, PV angle, LA posterior wall (LAPW) and low voltage areas (LVAs), and the amplitude of far field electrograms (FFEs) recorded by catheters. All patients had successful PVI without major complications. With similar mapping time and density, the LA volume calculated from the Pentaray map and Lassostar map were comparable. There were no significant differences in PV angle of all PVs and PW area (16.8 ± 3.2 vs. 17.1 ± 2.8, p = .516) between Pentaray map and Lassostar map. High structural similarity score was observed between two maps (0.783 in RAO/LAO view and 0.791 in PA view). Lassostar map detected lesser but not statistically significant extension of LVA (13.9% vs. 18.3%, p = .07). Amplitude of FFE was larger at the right superior PV on Lassostar map (0.21 ± 0.16 vs. 0.14 ± 0.11 mV, p = .041) compared to that on the Pentaray map. In our initial experience, PVI with cryoballoon and magnetic-based circular LASSOSTAR™NAV catheter was safe and effective based on the accurate LA geometry it created.

Comprehensive dose-response study of pulsed field ablation using a circular catheter compared with radiofrequency ablation for pulmonary vein isolation: A preclinical study.

Comprehensive dose-response study of pulsed field ablation using a circular catheter compared with radiofrequency ablation for pulmonary vein isolation: A preclinical study.

Determinants of acute irreversible electroporation lesion characteristics after pulsed field ablation: the role of voltage, contact, and adipose interference.

Pulsed field ablation (PFA) is a non-thermal ablative approach in which cardiomyocyte death is obtained through irreversible electroporation (IRE). Data correlating the biophysical characteristics of IRE and lesion characteristics are limited. The aim of this study was to assess the effect of different procedural parameters [voltage, number of cycles (NoCs), and contact] on lesion characteristics in a vegetal and animal model for IRE. Two hundred and four Russet potatoes were used. Pulsed field ablation lesions were delivered on 3 cm cored potato specimens using a multi-electrode circular catheter with its dedicated IRE generator. Different voltage (from 300 to 1200 V) and NoC (from 1 to 5×) protocols were used. The impact of 0.5 and 1 mm catheter-to-specimen distances was tested. A swine animal model was then used to validate the results observed in the vegetable model. The association between voltage, the NoCs, distance, and lesion depth was assessed through linear regression. An almost perfect linear association between lesion depth and voltage was observed (R2 = 0.95; P < 0.001). A similarly linear relationship was observed between the NoCs and the lesion depth (R2 = 0.73; P < 0.001). Compared with controls at full contact, a significant dampening on lesion depth was observed at 0.5 mm distance (1000 V 2×: 2.11 ± 0.12 vs. 0.36 ± 0.04, P < 0.001; 2.63 ± 0.10 vs. 0.43 ± 0.08, P < 0.001). No lesions were observed at 1.0 mm distance. In a vegetal and animal model for IRE assessment, PFA lesion characteristics were found to be strongly dependent on voltage settings and the NoCs, with a quasi-linear relationship. The lack of catheter contact was associated with a dampening in lesion depth.

PO-04-039 DIELECTRIC IMAGING-GUIDED ULTRA-LOW TEMPERATURE CRYOABLATION FOR ATRIAL FIBRILLATION

Ultra-low temperature cryoablation(ULTC) can be used to create transmural ablation lesions in the left atrium (LA). With a circular catheter configuration, this energy modality can be used to create continuous ablation lesions around the pulmonary veins(PVs). The same catheter configuration can be used to isolate the posterior wall(PW) by creating multiple overlapping circular ablation lesions. Isolation of the PVs and the PW can be assessed using pacing maneuvers. Three-dimensional voltage mapping may provide additional information on the extent of the ablation lesions. A recently introduced dielectric imaging-based mapping system can be used to generate voltage maps and to visualize the ULTC ablation catheter. To evaluate the feasibility of ULTC, guided by dielectric imaging-based electroanatomic mapping. Patients with atrial fibrillation were consented for catheter ablation with the iCLAS cryoablation system(Adagio Medical, Laguna Hills, USA). Ablation included isolation of the PV’s and LA PW if deemed necessary. The KODEX-EPD system(EPD Solutions, Best, the Netherlands) was used in conjunction with a circular mapping catheter to create pre- and postablation voltage maps. If the postablation voltage map revealed incomplete ablation lesions, additional energy applications were applied. Patients visited the outpatient clinic at 3 months post ablation. All patients were enrolled in a prospective registry study that was approved by the local ethics committee. Six patients (4 male, 4 persistent AF, age 66±7 years, LAVI 38±14ml/m2) were treated. The PVs were targeted in all patients, while the PW was targeted in 5 patients. A postablation voltage map was generated in 5 patients, which revealed incomplete PV isolation in 2 patients and incomplete PW isolation in 1 patient. Additional ablation in these patients resulted in acute electrical isolation of all targets. Isolation of the PVs was achieved using a median of 11[IQR:9-15] energy applications and 11[8.5-14] minutes of ablation. Isolation of the PW required 6[6-7] applications and 3[3-3.5] minutes of ablation energy. Total mapping time was 14.5[12.5-22.5] minutes, total fluoroscopy time was 16[12.5-18.5] minutes, and the total procedure time was 107.5[67.25-123.5] minutes. At 3 months follow up, only 1 patient had recurrence of atrial arrhythmia. Longer follow up is ongoing. Dielectric imaging-based electroanatomic mapping can be used to evaluate lesions of ULTC.

Pulsed-Field Ablation Using a Novel Ablation-Mapping Integrated System for Pulmonary Vein Isolation-A Preliminary Animal Study.

The purpose of this study is to evaluate the preliminary safety and effect of a pulsed electric field (PEF) ablation system. The pulmonary veins (PVs) and superior vena cava (SVC) were isolated with the pulsed field ablation (PFA) system, which included a PEF generator and an electrode. The effects of PFA were investigated in six porcines using a novel circular catheter with combined functions (mapping/ablation) designed to work with a cardiac mapping system. The PEF generator delivered a train of biphasic pulsed electric pulses with a high amplitude (800-2000 V) and short pulse duration. The voltage mapping, PVs and SVC potentials, ostial diameters, and phrenic nerve and esophagus viability data were collected 4 weeks later, after which the animals were subsequently euthanized for gross histopathology analysis. PFA 100% isolated the PVs and SVC with four applications with a mean pulse number of 100-150 pulses, causing no muscle convulsion. PFA does not cause PV stenosis or phrenic nerve dysfunction. Histological analysis confirmed 100% transmurally without any venous stenoses or phrenic injuries. Pathology follow-up showed that PFA had selectively ablated cardiomyocytes but spared blood vessels, the esophagus, and phrenic nerves; after ablation, the myocardial tissue showed homogeneous fibrosis. The PFA system is safe and feasible in the preliminary porcine model, which can effectively isolate PVs and SVCs. Transmural tissue damage can be achieved without phrenic palsy or stenosis.

In vivo porcine characterization of atrial lesion safety and efficacy utilizing a circular pulsed-field ablation catheter including assessment of collateral damage to adjacent tissue in supratherapeutic ablation applications.

IntroductionPulsed‐field ablation (PFA), an ablative method that causes cell death by irreversible electroporation, has potential safety advantages over radiofrequency ablation and cryoablation. Pulmonary vein (PV) isolation was performed in a porcine model to characterize safety and performance of a novel, fully‐integrated biphasic PFA system comprising a multi‐channel generator, variable loop circular catheter, and integrated PFA mapping software module.MethodsEight healthy porcine subjects were included. To evaluate safety, multiple ablations were performed, including sites not generally targeted for therapeutic ablation, such as the right inferior PV lumen, right superior PV ostium, and adjacent to the esophagus and phrenic nerve. To evaluate the efficacy, animals were recovered, followed for 30(±3) days, then re‐mapped. Gross pathological and histopathological examinations assessed procedural injuries, chronic thrombosis, tissue ablation, penetration depth, healing, and inflammatory response.ResultsAll eight animals survived follow‐up. PV narrowing was not observed acutely nor at follow‐up, even when ablation was performed deep to the PV ostium. No injury was seen grossly or histologically in adjacent structures. All PVs were durably isolated, confirmed by bidirectional block at re‐map procedure. Histological examination showed complete, transmural necrosis around the circumference of the ablated section of right PVs.ConclusionThis preclinical evaluation of a fully‐integrated PFA system demonstrated effective and durable ablation of cardiac tissue and PV isolation without collateral damage to adjacent structures, even when ablation was performed in more extreme settings than those used therapeutically. Histological staining confirmed complete transmural cell necrosis around the circumference of the PV ostium at 30 days.

PO-624-02 ELECTRIC CURRENTS IN PULSED FIELD ABLATION: IMPLICATIONS FOR CATHETER DESIGN, SAFETY AND EFFICACY

Various novel catheter designs are in development for Pulsed Field Ablation (PFA). It is unclear if they differ substantially in terms of safety and efficacy. We previously reported on circular catheters and balloons, but not on a nitinol cage sphere (9mm) nor a penta-spline basket-flower design.

PO-718-08 PREDICTING TISSUE CONDUCTANCE CHANGES AND ABLATION LESION PATTERNS USING A QUASI-DYNAMIC PULSED FIELD ELECTROPORATION NUMERICAL MODEL FOR CARDIAC ABLATION

Pulsed field ablation (PFA) is proposed as a useful modality in AF treatment, but factors determining the field distribution, and lesion transmurality and geometry have not been fully characterized. To understand the physics behind the tissue response to PSA, we propose a quasi-dynamic PFA model that can predict the tissue conductivity when electroporation equilibrium is achieved, and identify tissue regions that undergo fully irreversible electroporation (IRE) Model parameters include: tissue conductivity at baseline (0.2 S/m) and after complete electroporation (0.8 S/m), critical depth of the electric field for reversible electroporation (RE, 200 V/m and IRE, 450 V/m), and the applied pulsed voltage amplitude. The iterative model yields the steady-state solution with a tissue conductivity map, clearly identifying regions of IRE. The model employed a circular catheter with 9 - 3 mm electrodes fired sequentially using a 1500 V and 3000 V pulse. The steady-state IRE regions are shown (figure) with an estimated IRE lesion surface area and volume of 780 mm2 and 1411 mm3, respectively, at 1500 V, and 1178 mm2 and 2760 mm3, respectively, at 3000 V. Lesion discontinuity is observed at 5.0 mm depth with 1500 V and 7.2 mm with 3000 V. Transverse views through the lesions show maximum lesion depth at each voltage amplitude. The tissue conductivity profiles through predicted lesions show the formation of gaps in the lesion pattern. (Figure 1) The proposed quasi-dynamic model yields steady-state tissue conductivity maps, shows full IRE tissue regions, and confirms larger lesions with higher pulse amplitudes. Future work will predict time-based tissue response given specific pulse duration and delivery of sequential pulses and compare numerical and experimental results.

Safety and efficacy aspects of pulsed field ablation catheters as a function of electrode proximity to blood and energy delivery method.

BackgroundPulsed field ablation (PFA) is a promising technology based on electroporation. It is unclear if different catheter designs imply efficacy and safety differences.ObjectiveTo vary geometry, blood exposure, and energy delivery methods among 3 representative catheter designs, and then compare lesion transmurality, extra-atrial safety, and embolic risk.MethodsA computed tomography–derived computer model was used. Balloon, flexible-circuit splined, and circular catheters were placed near the left pulmonary veins. Four energy delivery methods were tested: multi-unipolar, sequential unipolar, interlaced, and wide interlaced. A posterior wall target was defined. Efficacy was defined as percent target with >600 V/cm. Safety aspects included aortic/esophageal electroporation damage and a bubble-generation surrogate (electrode current density), with 90% transmurality requirement.ResultsBalloon catheters had highest efficacy, followed by flexible polymer splined and circular catheters. On energy delivery methods, the multi-unipolar one was most efficacious, followed by interlaced bipolar and sequential-unipolar ones. Electroporation risks to aorta and esophagus were highest with multi-unipolar energy delivery. Bubble risk was lowest with balloon catheters.ConclusionComputer models show that catheters with electrodes on a balloon surface or on flexible circuit splines are about 4 times more efficacious than circular catheters with electrodes exposed to atrial blood. Multi-unipolar energy delivery methods have a higher risk of electroporating aortic and esophageal tissue, when compared to bipolar interlaced methods. Considering embolic risks, circular catheters had the highest bubble-generating potential. A balloon or flexible circuit splined system with a wide interlaced delivery method showed the best balance in efficacy and safety.

Acute safety and performance outcomes from the inspIRE trial using a novel pulsed field ablation system for the treatment of paroxysmal atrial fibrillation

Abstract Background/Introduction The inspIRE clinical trial was designed to assess the safety and efficacy of a fully integrated biphasic pulsed field ablation (PFA) system comprised of a multi-channel generator, variable decapolar irrigated loop circular catheter, and mapping system (Figure A) for the treatment of paroxysmal atrial fibrillation (PAF). Purpose Using this novel PFA system in a multicentre clinical trial, we present the initial feasibility of electrical pulmonary vein isolation (PVI), procedural performance, and acute safety results. Methods inspIRE is a prospective, non-randomized, multi-centre study, planned to enrol up to 550 patients. PVI is performed with the novel, variable loop circular catheter, compatible mapping system and generator. Acute procedural effectiveness (entrance block in all clinically targeted PVs post adenosine/isoproterenol challenge) and the incidence of primary adverse events (PAEs) were assessed. PAEs are defined as the occurrence of cardiac tamponade/perforation, myocardial infarction, stroke/cerebrovascular accident, thromboembolism, transient ischemic attack, permanent phrenic nerve paralysis, pulmonary edema, pericarditis, and any major vascular access complications within 7 days of the ablation procedure. Additionally, any incidence of procedure or device related death, atrio-esophageal fistula, or PV stenosis (related to the ablation procedure or study catheter) within the 12M follow-up period is classified as a PAE. Results A total of 35 PAF subjects (age 59.7±10.7 years, 54.3% male) were treated across 5 European sites by 6 operators. Acute procedural success was achieved in 100% of study subjects (Figure B) with zero incidence of PAEs. Mean total procedure time was 82.9±19.9 minutes with 27.0±11.9 minutes of PFA from first to last application. Average fluoroscopy use was 10.6±6.8 minutes and LA dwell time was 45.6±15.3 minutes. Conclusion Initial results of the inspIRE trial demonstrate the acute safety and effectiveness of the new integrated IRE circular catheter, mapping system and generator for PVI in PAF patients. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): inspIRE is a company-sponsored study funded by Biosense Webster, Inc. Figure 1. (A) PFA System; (B) PVI Voltage Map

B-PO03-212 USE OF A SENTINELTM CEREBRAL PROTECTION SYSTEM TO FACILITATE PULMONARY VEIN ISOLATION IN A PATIENT WITH LEFT ATRIAL MASS ARISING FROM THE SEPTUM SECONDUM

We report the use of a cerebral embolic protection device (CPD) to aid pulmonary vein isolation (PVI) in a patient with a left atrial (LA) mass on the interatrial septum. N/A N/A A 64-year-old female with symptomatic paroxysmal atrial fibrillation (AF) despite antiarrhythmics underwent catheter ablation (CA). However, intracardiac echo (ICE) showed a small (0.6 x 0.6 cm) mass of varying echogenecity on LA side (mid to inferior aspect) of the interatrial septum (Fig 1A) so procedure was aborted. Cardiac MRI could not adequately define the mass. Dofetilide was initiated but patient continued to have symptomatic AF with high burden. Given concern for mass disruption and embolization, surgical ablation vs CA using CPD was discussed, and patient chose the latter. A SentinelTM CPD was placed through right radial artery with filters placed in right brachiocephalic and left common carotid arteries (Fig 1B). Under ICE guidance, single transseptal catheterization was performed with a RF needle, slightly superior and posterior to the mass (Fig 1C). A circular catheter was used to create LA geometry and PVI was successfully performed using a TacticathTM ablation catheter. Mass was still noted on ICE post-ablation. CPD was removed and debris collected by the filter showed mainly fat tissue (Fig 1D), suggesting the mass is likely a small LA myxoma. No acute neurological complications were noted. At 1-month follow-up, patient was in sinus rhythm with no neurological deficits. To our knowledge, this is the first reported use of SentinelTM CPD to guide AF CA due to an LA mass and demonstrates the minimally invasive options for curative therapy of symptomatic AF.

Characterization of atrial lesion safety and efficacy utilizing a circular catheter and the IRE generator with an in vivo porcine model

Abstract Funding Acknowledgements Type of funding sources: Other. Main funding source(s): Biosense Webster, Inc. Introduction/Objectives: Pulsed field ablation (PFA) is a non-thermal ablative method that delivers high voltage, very-short duration pulses that cause pore formation in the cytoplasmic membrane and cell death. The tissue selectivity of PFA is expected to reduce the risk of collateral tissue injury compared to radiofrequency catheter ablation (RFCA), while maintaining effectiveness. The objective of this study was to perform pulmonary vein (PV) isolation in a porcine model to characterize the safety and performance of a novel, fully-integrated biphasic PFA system. The system is comprised of a multi-channel generator, a variable loop circular catheter, and an integrated irreversible electroporation (IRE) mapping software module. Methods The study evaluated safety and efficacy of IRE in 8 healthy swine. First, to evaluate safety, multiple ablations were performed at various cardiac structures, including within the lumen of the right pulmonary vein (RIPV), at the right superior pulmonary vein (RSPV) ostium, and adjacent to the esophagus. Second, to evaluate efficacy, animals were recovered and followed for 30 (±3) days, then re-mapped. Gross pathological and histopathological examinations were performed to assess for procedural injury, chronic thrombosis, tissue ablation, depth of penetration, healing, and level of inflammatory response. Results All 8 swine survived for the 30 (±3) day follow up (FU) period. There were no acute (day of procedure) incidents of pulmonary vein narrowing of &amp;gt;70%, nor at 30 d follow-up (FU), even when ablation was purposefully performed directly deep to the ostium of the vein. No injury was seen grossly or histologically in the adjacent esophagus. All PVs were durably isolated as confirmed by bidirectional block at the 30 (±3) day re-map procedure, and histological examination showed complete, transmural necrosis around the entire circumference of the ablated section of the right PVs [Figure]. Conclusion(s): This pre-clinical evaluation of a fully integrated PFA system demonstrated effective and durable ablation of cardiac tissue and PV isolation with no collateral damage to adjacent structures. Notably, histological staining confirmed complete transmural cell necrosis around the circumference of the ostial PV at 30 days. Abstract Figure. PVI maps (A) histology (B) and safety(C)