Mapping System Research Articles

Hybrid convergent ablation: an evaluation of left atrial electroanatomical voltage maps

Abstract Background Hybrid convergent ablation is an effective, emerging treatment for persistent atrial fibrillation (AF) (1). Minimally invasive surgical epicardial left atrial (LA) ablation is performed via a subxiphoid incision to ablate the posterior wall, within the limits of the pericardial reflections, before endocardial catheter ablation is performed primarily to complete pulmonary vein isolation. The overall aim is to create durable, transmural posterior wall ablation to target potential drivers that may sustain persistent AF. Purpose We evaluated electroanatomical maps obtained during endocardial ablation to determine the site and extent of LA posterior wall scar following epicardial ablation and whether this determines outcome in patients undergoing convergent ablation. Methods Patients who underwent Convergent ablation at a single UK cardiac centre (2012-2019) using CARTO-3 mapping system for endocardial ablation were included. Patients who had previous AF ablation were excluded. Low-voltage areas (LVAs) were manually measured using the CARTO-3 system and defined as areas <0.5mV on bipolar voltage maps (pulmonary veins were excluded). Scar location was classified by evaluating for presence and amount of LVA in each quadrant of the posterior LA wall. AF recurrence was evaluated at 12 months post-procedure. SPSS (v. 27) was used for statistical analysis. Results Of the 32 patients included, 7 patients experienced AF recurrence within 12 months post-procedure (21.9%). The average amount of posterior wall LVA following convergent ablation was 54.1% of posterior wall area and 5.8% of total left atrial area, neither of which were associated with 12-month AF recurrence (see Table 1). The presence and extent of LVAs in the upper quadrants were heterogeneous amongst patients and did not relate to AF recurrence. All patients displayed LVAs in the lower quadrants post-epicardial ablation, with the majority having LVAs occupying more than 50% of these quadrants. 96.8% had LVA on the inferior LA surface. In total, 75% of patients had a significant amount of LVA (defined as LVA occupying >50% of the quadrant area) in both lower posterior wall quadrants (see Figure 1) and this feature was associated with lower AF recurrence on multivariable Cox regression analysis (see Table 1). Conclusions Extensive scar was observed in the LA posterior wall in patients following epicardial convergent ablation. The presence of such scar, particularly in the lower regions of the posterior wall, may influence outcomes and be associated with reduced AF recurrence.Table 1Figure 1

Integration of electro-anatomical maps in the planning phase of stereotactic arrhythmia radioablation for refractory ventricular tachycardia

Abstract Introduction Despite the efficacy of stereotactic arrhythmia radioablation (STAR) for the treatment of refractory ventricular tachycardia (VT), the planning phase to precisely delineate the arrhythmogenic substrate still suffers from limitations due to the incompatibility of data formats between 3D electro-anatomical mapping systems (EAM) and STAR planning software (CyberKnife). Purpose Within the STOPSTORM European consortium, we present a workflow to integrate all 3D EAM data (e.g. voltage, activation time, anatomical tags) into the STAR planning software using the open source software Slicer3D to improve targeting of the arrhythmogenic substrate. Method Two protocols were compared retrospectively. Protocol 1 (STAR gold-standard) comprised the manual contouring of the clinical target volume (CTV) on planning 4D-CAT SCAN drawn side-by-side using EAM (Carto3, Biosense Webster) screen-shots and diagnostic reports. Protocol 2 comprised semiautomatic segmentation of CTV on planning 4D-CAT SCAN using imported EAMs annotated with landmarks for VT target delimitation. The semiautomatic segmentation of CTVs included three steps: (1) semiautomatic segmentation of ventricular myocardium (VM), the blood-pool of the concerned ventricle and at least two additional cardiac cavities; (2) 3D alignment of EAM with the segmented cavities; and (3), 3D delineation of CTV identified as the transmural section of VM segment surrounding the EAM’s VT target delimited by the annotated landmarks. The volume overlap (Dice coefficient) and the absolute difference of the CTVs obtained with the two protocols were compared. Both measurements were expressed in percentage as follows: Dice coefficient 0% means no overlap and 100% complete overlap; absolute difference of volumes 0% means no difference and 100% means that one CTV was twice the size of the CTV generated by the other protocol. Results Both protocols were applied to four patients (65.5 ± 8.5 yo) with refractory VT successfully treated with STAR. Figure 1 shows an example (Patient 1) of the CTV contouring using the CARTO EAMs aligned with the CT images in Slicer3D. Figure 2 illustrates significant mismatch between the segmented CTVs of the two protocols. The median volume overlap of the CTVs was 44%, while the median volume absolute difference was 35%. Table 1 reports detailed results. Conclusion Our study reveals a high variability of CTV delineation for STAR using two different protocols. The intraprocedural assignment of anatomical landmarks for VT target delimitation on EAM appears promising to improve CTV delineation. Further research is needed to evaluate the correlation between STAR outcome and CTV delineation accuracy.

Catheter ablation for atypical atrial flutter: characterization and recurrence predictors

Abstract Background Atypical atrial flutter (AFLA) is a macro-reentrant atrial tachycardia not using the cavotricuspid isthmus. Due to recent innovations in technology, catheter ablation has emerged as the most viable option to treat AFLA. Data related to electrophysiologic characteristics and predictor prognostic factors is limited. Purpose Our study aimed to analyze long-term outcomes after catheter ablation and to identify predictors for atrial arrhythmia (AA) recurrence (documented atrial fibrillation (AF), atrial tachycardia, or atrial flutter). Methods We performed a retrospective single-center review of all consecutive patients treated for AFLA ablation in our center from October 2008 to July 2022. All patients underwent radiofrequency ablation with a 3D mapping system. Results From 64 patients (mean age 61.0 ± 11.28 years, 60.9% male and mean follow-up period (FUP) 58.5 ± 47.79 months) 32 (50.0%) had history of previous catheter ablation (35.9% PVI), 14 (21.9%) previous cardiac surgery and 18 (28.1%) corresponded to AFLA not related to ablation or previous cardiac surgery. Most patients (79.7%) had paroxysmal AFLA, 50% concomitant AF, 50% were on anthyarrhytmic drugs (AAD) and 35.9% underwent previous electrical cardioversion (ECV). Mean left ventricular ejection fraction was 55.1 ± 10.44%, 25 (39.1%) patients had moderate to severe left atrial (LA) dilatation and 11 (17.2%) right atrial (RA) dilatation. Low-voltage areas (LVA) were identified in 38 (59.4%) patients. A total of 81 AFLA were present or induced (1.3 ± 0.74 AFLA per patient) and in 7 (10.9%) patients an atrial arrhythmia was not induced. The LA was involved in 70.3% and the RA in 29­.7%. The location of the circuit is described in the table 1 as well as ablation details. Acute procedural success was achieved in 87.5%. AA recurrence occurred in 32.8% at 1 year, 35.9% at 2 years and 40.6% at FUP (14.1 ± 41.41 months after ablation), for which 3.1% had re-ablation (17.0 ± 23.99 months after index ablation), 5 (7.8%) ECV and 15 (23.4%) maintained or initiated AAD. 10 (15.6%) went to the emergency department (ED) due to AA (mean time since ablation until the first ED visit 31.4 ± 69.07 months). One patient had an ischemic stroke and 6 patients cardiovascular (CV) hospitalization. There were 5 non-CV deaths and there were no CV deaths. Female gender was an independent predictor of AA recurrence (15 (60.0%) vs 11 (31.4%), hazard ratio (HR): 3.496 [95% CI: 1.761 – 200.000], p=0.046) as well as moderate or severe LA dilatation (14 (51.9%) vs 3 (17.6%), HR 3.257 [95%CI 1.715 – 38.462], p=0.033). The presence of fibrosis or the ablation strategy were not associated with recurrence. Conclusion AFLA most frequently originated in the LA, LVA were frequent, as well as the presence of structural changes and previous ablation or cardiac surgery. In our cohort study, female gender and the severity of LA dilatation were independent predictors of AA recurrence.

Conduction time around the mitral valve annulus could predict the incidence of peri-mitral atrial tachycardia

Abstract Background Empirical ablation for mitral isthmus (MI) for AF patient is sometimes challenging for its complex anatomy and wall thickness. It would be helpful in determining the ablation strategies if it could be predicted in advance that peri-mitral atrial tachycardia (PMAT) would occur. Using 3D mapping, a method to confirm MI block has been reported using E-PMCT (estimated peri-mitral conduction time: the doubling the time between coronary sinus (CS) pacing and the wave-front collision at the opposite side of the mitral annulus). Purpose We investigated whether E-PMCT correlated with cycle length of PMAT and was involved in the establishment of PMAT. Methods We retrospectively investigated the AF patients who were created the LA map during CS pacing with multipolar mapping catheter which could measure E-PMCT after pulmonary vein isolation. Amon these cases, 1) PMAT was observed spontaneously or induced (PMAT group, N=25, 68.6±10.9 years old, male 15) and none of the AT occurred by the provocation test and during follow up (no-AT group, N=53, 65.2 years old , male 38) were analyzed. In these group, we evaluated the relationships between E-PMCT and tachycardia circuit of PMAT. Results E-PMCT was significantly longer in PMAT group than non-AT group(216.5±30ms vs 166.7ms, p<0.005). Strong positive correlation was observed between cycle length of PMAT and E-PMCT (Person’s r=0.85, p<0.001). PMAT was non induced in patients with E-PMCT less than 176ms. According to the ROC curve, AUC for the detection of the non-AT group was 0.908 (95% CI 0.843-0.974, sensitivity 91.7%, specificity 81.1%) with the cut off value E-PMCT less than 180ms. The slow conduction during CS pacing were consistent with slow conduction during PMAT in this study. Although left atrial diameter, ejection faction, type of AF(paroxysmal or not), low voltage area in the left atrium and mitral annulus size in 3D mapping system was also different between PMAT group and non-AT group in the univariate analysis, E-PMAT was strongest predicter of occurrence of PMAT in multivariate analysis. Conclusion E-PMCT obtained after PVI could predict the non-inducibility of PMAT and was helpful to decision making for ablation strategy.

The zero fluoroscopic approach to avnrt ablation significantly reduces radiation without compromising safety, efficacy or procedure time compared to a conventional or minimal fluoroscopic approach

Abstract Introduction In 2020, we showed that ablation of AVNRT (induced under conventional fluroscopy) with a 3D electro-anatomical mapping system (EAMS) (minimal X-RAY group) significantly reduces radiation exposure without compromising safety, efficacy and procedure time compared to a procedure performed entirely under conventional fluoroscopy (X-RAY group). Purpose The objective of this study was to determine whether the direct use of EAMS in selected patients with a high probability of induction of AVNRT could reduce radiation exposure to near zero without compromising the safety, efficacy and duration of the procedure (EAMS group) Methods We compare the 136 patients in the X-RAY group, the 141 patients in the minimal X-RAY group with 39 patients included in the EAMS group (included between July 2020 and December 2022). All procedures were performed at a single centre in Belgium using the same 3D electroanatomical mapping system. In the EAMS group, fluoroscopy had to be used to guide catheter progression for only 5 patients. We compared radiation dose, acute success, complication rates and procedure duration. Results AVNRT induction was achieved in 38 of 39 patients in the EAMS group. Only one patient was not inducible, but the slow pathway ablation was performed on the basis of the arrythmic ECG recording which was highly suggestive of AVNRT; the success of the ablation could therefore not be validated acutely. Radiation dose in the EAMS group was significantly lower compared to the minimal X-RAY group and X-RAY group (8,5 vs 1179 and 2686 mgray.cm2, p <0,0001) and fluroscopic time was obviously shorter (0,02 vs 2,5 and 8,6 minutes, p<0,0001). Procedural time (74,3 vs 70 and 69 mon, p = NS) and success rate (97,5% vs 99 and 98%, p = NS) were not significantly different in the three groups. No serious complications were observed in any group. No minimal complication were reported in the zero-fluoroscopy group. Conclusion AVRNT catheter ablation using a zero-fluoroscopic approach with EAMS significantly reduces radiation exposure without compromising safety, efficacy or procedure time.

The efficacy of ultra-high-density mapping guided partial antral ablation for pulmonary vein isolation in atrial fibrillation patients

BackgroundThe muscular discontinuities or lack of myocardial extensions around the pulmonary veins (PVs) antrum were previously reported. The objective of our study was to compare the efficacy of a partial antral ablation for PV isolation (PVI) using ultra-high density (UHD) mapping with a conventional wide antral circumferential ablation (WACA) in atrial fibrillation (AF) patients.MethodsA total of 119 patients medical records who received catheter ablation for AF in our hospital were analyzed. In one group of patients, detailed activation mapping of each PV was performed using a UHD mapping system. Each PV antral segment’s activation pattern was classified into “directly-activated from the LA” or “passively-activated from an adjacent PV segment” patterns. The ablation applications were performed at the directly-activated PV antral segment only for the PVI when the PV had “passively-activated segments” (partial antral ablation; PA-UHD group). Another patient group received a conventional WACA for the PVI (WACA group).ResultsSixty patients received partial antral ablation (PA-UHD), and age/sex-matched 59 patients received WACA. In the PA-UHD group, passively-activated segments were observed in 58.3% of all PV segments. The success rate of a partial antral ablation for the PVI in PVs with passively-activated segments was 85%. The 1-year atrial tachyarrhythmia recurrence did not differ between the PA-UHD and WACA groups.ConclusionsOur study revealed the presence of passively-activated PV segments, which could potentially indicate muscular discontinuity at the PV-LA junction. In most PVs with passively-activated segments, PVI was successfully achieved by ablation with only directly-activated segments. The 1-year recurrence rate of atrial tachyarrhythmia in PA-UHD group was comparable to that observed in the WACA group.

Cardioneuroablation for symptomatic bradyarrhythmia: for whom it fails?

Abstract Background Cardioneuroablation (CNA) has been proposed as a new therapeutic approach in selected patients with symptomatic functional bradyarrhythmia including recurrent neurally-mediated syncope. Purpose In patients after CNA, we investigated the potential predictors of the recurrence of clinically significant bradyarrhythmia. Methods A retrospective study included 187 consecutive patients (age: 40±12 years; 57 % of males; predominant AV nodal phenotype of the disorder in 37 % of patients; post-atropine sinus rate acceleration by 72±31 %) who underwent their first CNA at our centre from 2014 to 2022 and were followed for the minimum of 3 months. Biatrial radiofrequency ablation was performed under general anaesthesia by irrigated-tip catheter at empirical sites of ganglionated plexi (GP) with the navigation by 3D electroanatomic mapping system and intracardiac echocardiography. Anterior right GP and posteromedial left GP were always targeted to modulate the innervation of both sinoatrial and atrioventricular nodes, irrespective of the clinical manifestation of the disease. The loss of responsiveness of both nodes to extracardiac vagus nerve stimulation (frequently bilateral) was the procedural endpoint. The association of baseline, procedural, and early follow-up characteristics with the recurrence of clinically significant bradyarrhythmia was analyzed. Results CNA with the procedural duration of 154±32 min and radiofrequency time of 14±7 min resulted acutely in sinus rate acceleration by 27±13 bpm, shortening of AH interval by 16±28 ms, an increase of Wenckebach point by 26±28 bpm, shortening of AV node effective refractory period by 114±128 ms, and sinus node recovery time by 462±867 ms. At the 3-month visit, the sinus rate was still significantly higher (83±14 bpm) than at baseline (61±13 bpm); with acceleration by 23±14 bpm. During a median follow up of 33 months (IQR: 18-48 months), recurrence of clinically significant bradyarrhythmia was documented in 18 (10 %) patients. Re-CNA was performed in 11 patients and was scheduled in 3 patients. In 6 (3 %) patients, a pacemaker was finally implanted. Compared to the rest of the population, patients with bradyarrhythmia recurrence were non-significantly younger (36±12 vs. 40±12 years, P=0.16) and had non-significantly less acceleration of sinus rate at the 3-month post-CNA visit (by 18±11 vs. 23±13 bpm, P=0.10) suggesting a trend to more pronounced reinnervation of the sinus node. Conclusion Long-term clinical efficacy of CNA is reasonably high. We did not identify practically useful predictors of CNA failure. This investigation was significantly limited by the low rate of clinical events.

Need an endomyocardial biopsy? Call your electrophysiology team

Abstract Introduction With significant advances in targeted chemotherapeutic options for soft tissue tumours, obtaining a tissue diagnosis is more important than ever. Primary and secondary cardiac tumours are rare [1] and endomyocardial biopsy of these tumours has been sparsely reported [2-9]. Advanced tools in cardiac electrophysiology happen to lend themselves well to cardiac tumour biopsy. Our electrophysiology (EP) guided endomyocardial biopsy (EMB) service includes electrophysiologists, cardio-oncology specialists, cardiac imaging specialists, oncologists, and pathologists. For the last 9 years all targeted endomyocardial biopsies in our tertiary institution have been undertaken by our EP guided EMB service with extensive experience in electroanatomical mapping (EAM), visualisable sheaths and integrated intracardiac echography (ICE). We report the findings. Methods We performed a retrospective review of all cases referred to the EP guided endomyocardial biopsy service at our centre and identified those with attempts to biopsy a cardiac mass. We describe the incorporation of advanced electrophysiology techniques utilised by the service. Specifically, the use of intracardiac echocardiography integrated into an electro-anatomical mapping system and bioptome delivery via a visualisable, deflectable sheath. This allows for the real time 3D visualisation of the target mass, surrounding anatomy and position of the bioptome during biopsy. Results Of 38 patients who underwent targeted biopsy at our centre, a total of 8 patients (5 female; mean ± SD age 54 ± 21 years) were referred for cardiac tumour biopsy, undergoing a total of 9 procedures (mean ± SD duration 116 ± 21 mins). Table 1 details the patient’s pertinent history and underlying pathology, the tumour site, possible alternative biopsy sites, a summary of techniques and technologies utilised and the eventual diagnosis. In 100% of cases, tissue was sampled from the desired location, though in two patients the histological result was inconclusive due the retrieval of necrotic tissue or fibrotic tissue only. This translated into a definitive histopathological diagnosis in 75% of patients. One patient experienced a transient right bundle branch block during the procedure, in all others the procedures were uncomplicated. Image 1 exemplifies some of the cases with pre-procedure imaging results and intra-procedural views from both ICE and the EAM. Conclusion In this study, our approach to utilising the combination of intracardiac echocardiography integrated into an electro-anatomical mapping system and bioptome delivery via a visualisable, deflectable sheath appears safe, and provides unparalleled accuracy in endomyocardial sampling of cardiac tumours.Table 1Image 1

Catheter ablation of atrial fibrillation: three-dimensional transesophageal echocardiography versus magnetic resonance imaging for pre-interventioal pulmonary vein imaging (8-year follow-up)

Abstract Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug-refractory atrial fibrillation (AF). However, it is still challenging because of the high degree of variability of the pulmonary vein (PV) anatomy. Three-dimensional transesophageal echocardiography (TEE) is a promising new technique for cardiac imaging. Therefore, we have evaluated the usefulness of 3-D TEE for analysing the left atrial anatomy prior to an ablation procedure in comparison to magnetic resonance imaging (MRI). Methods In 240 patients, 3-D TEE and cardiac MRI were performed immediately prior to an ablation procedure (paroxysmal AF: 110 patients, persistent AF: 130 patients). The image quality provided by 3-D TEE and by cardiac MRI was compared in all patients. Two different ablation strategies were used. In patients with paroxysmal AF, the cryoablation technique was used. In the other patients, a circumferential pulmonary vein ablation was performed using a three-dimensional mapping system. Results A 3-D TEE and a cardiac MRI could be performed successfully in all patients prior to the ablation procedure. Several variations of the PV anatomy could be visualized precisely by 3-D TEE and cardiac MRI (e.g. accessory PVs, common PV ostia, varying diameter of the left atrial appendage and its distance to the left superior PV). The image quality was good in the majority of patients even if AF with rapid ventricular response was present during the examination. The image quality provided by 3-D TEE was acceptable in 230/240 patients (95.8 %). The TEE findings correlated well with the PV angiographies performed using cardiac MRI. There was a good correlation with regard to the diameter of the PV ostia assessed by these two imaging techniques. All ablation procedures could be performed successfully (mean number of completely isolated PVs: 3.9 (cryo group), 3.9 (radiofrequency catheter ablation group)). At 96-month follow-up, 64.6 % of all patients were free from an arrhythmia recurrence (cryo group: 70.0 %, Carto group: 60.0 %). There were no major complications. Conclusions AF ablation procedures can be performed safely and effectively based on prior 3-D TEE imaging. The image quality was acceptable in the vast majority of patients.

Abstract 18656: Characterization of Pulmonary Vein Reconnection in Repeat Procedures After After Initial Cryoballoon Ablation Identified With High Density Mapping

Introduction: Catheter ablation of atrial fibrillation using the cryoballoon has become an alternate strategy to radiofrequency for pulmonary vein isolation (PVI). Both techniques, however, can result in pulmonary vein reconnection and the need for recurrent ablations. Objective: To study the incidence and specific location of pulmonary vein reconnection in patients with prior cryoballoon ablation for atrial fibrillation Methods: Retrospective analysis of patients that underwent radiofrequency ablation following a single initial cryoballoon PVI ablation was performed. Twenty patients were studied, all of whom underwent repeat ablation using radiofrequency with a mapping system (Rhythmia, Boston Scientific). A gap was defined as entrance conduction from the LA into the PV as suggested by the activation map. Results: Patients had an average of a 20 month period of normal sinus rhythm after initial ablation. A total of 48 gaps were identified in 18/20 patients (2.4 gaps per patient). The most common site of PV-LA conduction reconnection was at the superior pulmonary veins, specifically on the anterior portions. 60% (12/20) of patients had noted reconnection sites at the left superior pulmonary vein. All but one of these patients had gaps on the anterior surface of the vein. 75% (15/20) of patients were identified as having reconnection sites at the right superior pulmonary vein. All of these patients had gaps on the anterior surface of the vein. Less commonly, the left and right inferior veins each had 40% (8/20) patients with reconnection at these areas, with no consistent surface as the main site of reconnection. Further, 85% (17/20) patients had procedural ablation beyond only pulmonary vein re-isolation, owing primarily to the occurrence of atypical atrial flutters or atrial tachycardias that were seen during the repeat procedure itself Conclusion: Cryoballoon ablation is a successful technique for PVI in AF patients. However, reconnection of these sites is possible. Our analysis shows that the most common sites are at the anterior surface of the superior pulmonary veins. This could portend a potential drawback to be cognizant of during these initial procedures. Further analysis with a larger patient population will be necessary

Abstract 11895: Efficacy of Maintaining Mean Aortic Pressure by Percutaneous Left Ventricular Assist Device for Hemodynamic Support in Ventricular Tachycardia Ablation - Relation to Cycle Length

Introduction: Percutaneous left ventricular assist device (pLVAD) has been used to maintain mean aortic pressure (MAP) during ventricular tachycardia (VT) ablation (ABL) and is a class II recommendation. We sought to assess the ability of pLVAD to maintain MAP and its relationship to VT cycle length (CL). Methods: All patients who underwent CA for VT with pLVAD support within a 3-year period were included. Type of pLVAD was determined by operator. Insertion of device was performed under fluoroscopy via femoral arterial sheath. Acute ablation success was defined as absence of inducible VT at end of procedure. Results: A total of 9 patients were included. Most patients had ischemic cardiomyopathy (Table 1); pLVAD was inserted prophylactically in 66.67% of patients and for refractory VT/VF storm in 22.2%. One patient was had critical AS and underwent balloon valvuloplasty prior to VT ablation. Impella CP was used in 78%, and Impella 2.5 in 22%, mean cardiac output was 2.9 + 0.5 L at mean P flow rate 7.3 + 1.3. CARTO was used in 89% and ESI Navx in 11% for electroanatomic/activation mapping. There were no instances of electromagnetic interference, despite the use of magnetic mapping system in all cases (CARTO in 8, Stereotaxis in 1). Mean PCWP was 17.88 + 10.12 pre-ablation vs 23.57 + 8.30 post-ablation (p=ns). There were 24 VTs, 42% were sustained, with a mean CL 342 + 80 msec, ranging from 223 to 558 msec. Mean MAP pre-ablation was 67.44 + 12.85 mmHg vs 61.86 + 13.27 post-ablation with absent negative correlation to VT CL (p=ns). There was no difference in MAP between VT Cl > 300 msec vs < 300 msec: 66 + 11 vs 59 + 14 mm Hg, (p=ns). Mean dose of phenylephrine was 452 mcg. pLVAD was removed at the end of procedure, there were no femoral site complications. Conclusions: pLVAD utilization maintains stable MAP even with faster VT cycle length in patients undergoing VT ABL under general anesthesia obviating need for high dose pressor support.

City-scale continual neural semantic mapping with three-layer sampling and panoptic representation

Neural implicit representations are drawing much attention from the robotics community recently, as they are expressive, continuous and compact. However, city-scale continual implicit dense mapping based on sparse LiDAR input is still an under-explored challenge. To this end, we successfully build a city-scale continual neural mapping system with a panoptic representation that consists of environment-level and instance-level modeling. Given a stream of sparse LiDAR point cloud, it maintains a model that maps 3D coordinates to signed distance field (SDF) values. To address the difficulty of representing geometric information at different levels in city-scale space, we propose a tailored three-layer sampling strategy to sample the global, local and near-surface domains dynamically. Meanwhile, to realize high fidelity mapping of instance under incomplete observation, category-specific prior is introduced to better model the geometric details. We evaluate on the public SemanticKITTI [1] dataset and demonstrate the significance of the newly proposed three-layer sampling strategy and panoptic representation, using both quantitative and qualitative results. Codes and model will be publicly available.

Abstract 17847: Typical Right Atrial Flutter Ablation Using Subclavian Venous Access in Patients With Interrupted or Occluded Inferior Vena Cava

Introduction: Ablation for typical atrial flutter (AFL) traditionally involves vascular access from the femoral vein to facilitate advancing catheters through the Inferior Vena Cava (IVC) to the right atrium (RA). In patients with interrupted or occluded IVC, this procedure is challenging to perform. We report a case series of typical right AFL ablation using subclavian access in interrupted or occluded IVC. Cases: A 63-year-old female with typical AFL refractory to medical therapy was referred for radiofrequency ablation (RFA). She had a history of surgically corrected atrial septal defect at age 4 years with known IVC interruption draining into RA via an azygous venous extension. Another case involved a 41-year-old male with quadriplegia and typical AFL who underwent an attempted RFA from femoral access that was aborted due to massive thrombosis of IVC. Decision making: In both cases, two sheaths were placed into the left subclavian venous system using ultrasound guidance. A coronary sinus catheter and irrigated tip ablation catheter were advanced into the coronary sinus and RA respectively. Additionally, in the second case, an intracardiac echocardiography probe was inserted via separate venous access. Using the electroanatomic mapping system, entrainment and activation mapping confirmed a tricuspid isthmus-dependent AFL. RFA was performed using an open irrigated RFA catheter in a linear fashion resulting in the termination of the tachycardia to sinus rhythm. In the first case, ablation extended from the tricuspid annulus to the os of the hepatic vein at the 06:00 position. Post ablation, hemostasis was achieved using a suture-mediated closure device. At follow-up, both patients were asymptomatic without evidence of AFL on extended-duration cardiac monitoring. Conclusion: In patients with interrupted or occluded IVC, the subclavian veins can be accessed for mapping and ablation of typical AFL when traditional femoral venous access is challenging.

Abstract 16588: Electrophysiology Procedural Access and Growth in Remote Geographies Using Novel Remote Mapping and Clinical Support Software

Introduction: COVID-19 redefined workflows in the field of electrophysiology (EP). The geographic paucity of experienced clinical mapping support was a crucial issue that limited the worldwide adoption of complex ablation procedures. Hypothesis: To ascertain the feasibility of utilizing a novel software for remote mapping and clinical support for all spectrums of cardiac ablation procedures in a remote geography. Methods: Ablation procedures performed at Metromed International Cardiac Centre (MICC); India were included in this early feasibility analysis (EFA). All procedures were performed by a single EP operator. Remote clinical support was provided by an EP physician (primary operator's sibling) in the US. Mapping was performed by an experienced mapper from a remote location 400 miles away from MICC. The mapping system utilized was Ensite Precision with SJM Connect software. Results: 360 contiguous ablation procedures from 2020 to 2023 were included in this EFA and compared to procedures performed between 2017 to 2019. The SJM Connect software allows remote access to the Ensite console via a secured connection. It requires the operator to be granted access to the console via a permission request. The software then allows the remote operator to access the system as view-only or complete control of the console providing full remote support. Communication occurs between the remote user and the console via a chat and voice call. There was an overall increase by three times in the total number of ablations performed after using the remote system. There was also an increase in different types of complex ablation procedures performed. Conclusions: This EFA demonstrates the safety and efficacy of using remote clinical support and mapping for ablation procedures. It opens a world of possibilities including the expansion of ablation technology to all corners of the world with experienced clinical mapping support connecting the EP community on a worldwide platform.

Abstract 18177: Novel Pre-Operative Non-Invasive Computational 12-Lead ECG Mapping to Facilitate Surgical Ablation of Ventricular Arrhythmias

Background: In patients undergoing cardiac surgery who have ventricular arrhythmias (VAs) such as VT, VF, or PVCs, concurrent surgical ablation is an attractive therapeutic strategy. However, electrophysiologic mapping systems are not routinely available in the OR and it may be difficult to localize the VA origin. We developed a workflow incorporating novel 12-lead ECG computational model-based mapping to localize VAs. Hypothesis: We hypothesized that use of pre-operative computational ECG mapping can help guide surgical ablation of VAs in patients undergoing cardiac surgery. Methods: Patients undergoing cardiac surgery with pre-existing VT, VF or PVCs were enrolled with informed consent. A standard 12-lead ECG of the VA was recorded in the clinic or during non-invasive programmed stimulation in the EP lab. ECG mapping localized the VA and visualized on a 3D model. During circulatory arrest, surgical ablation was performed using either cryoablation or irrigated RF ablation probe. Follow-up was performed with event monitors or ICD monitoring. Results: A total of 7 patients (mean age 55±15 years, female 29%, EF 31%±20%) were enrolled (Table). Surgical indications included mitral annuloplasty (Pt 1), pulmonary thromboendoarterectomy + CABG (Pt 2), coronary artery unroofing (Pt 3), left ventricular assist device (Pt 4-6, Fig 1), and CABG (Pt 7). In this cohort, 5 PVCs, 3 monomorphic VT and 1 VF morphologies were localized using ECG mapping and surgically ablated at time of cardiac surgery. There was a 100% (18 to 0) decrease in VT/VF episodes and 97.2 ± 0.03% reduction in PVC burden at median 9.5 month (IQR 3.7-29.5) follow-up. No intra- or post-operative complications occurred. Conclusions: This case series illustrates feasibility and excellent efficacy of a novel preoperative ECG mapping workflow using a forward-solution algorithm to guide successful and safe concomitant ventricular arrhythmia ablation during cardiac surgery.

Tree species classification on images from airborne mobile mapping using ML.NET

ABSTRACT Deep learning is a powerful tool for automating the process of recognizing and classifying objects in images. In this study, we used ML.NET, a popular open-source machine learning framework, to develop a model for identifying tree species in images obtained from airborne mobile mapping. These high-resolution images can be used to create detailed maps of the landscape. They can also be analyzed and processed to extract information about visual features, including tree species recognition. The deep learning model was trained using ML.NET to classify two tree species based on the combination of airborne mobile mapping images. Our approach yielded impressive results, with a maximum classification accuracy of 93.9%. This demonstrates the effectiveness of combining imagery sources with deep learning tools in ML.NET for efficient and accurate tree species classification. This study highlights the potential of the ML.NET framework for automating object classification and can provide valuable insights and information for forestry management and conservation efforts. The primary objective of this research was to evaluate the effectiveness of an approach for identifying tree species through a model generated using a combination of ortho and oblique images captured by a mobile mapping system.

Contracting on average iterated function systems by metric change

We study contraction conditions for an iterated function system (IFS) of continuous maps on a metric space which are chosen randomly, identically and independently. We investigate metric changes, preserving the topological structure of the space, which turn the IFS into one which is contracting on average. For the particular case of a system of C 1-diffeomorphisms of the circle which is proximal and does not have a probability measure simultaneously invariant by every map, we derive an equivalent metric which contracts on average and conclude that it carries a unique stationary probability measure. Here we strongly use local contraction properties established by Malicet in 2017, which then imply that the IFS has a negative random Lyapunov exponent and generalizes a result by Baxendale.

A novel approach to typical atrioventricular nodal reentrant tachycardia with high-resolution mapping using the CARTO 3 cardiac mapping system.

We hypothesized that high-resolution activation mapping during sinus rhythm (SR) in Koch's triangle (KT) can be used to describe the most delayed atrial potential around the atrioventricular node and evaluated whether ablation targeting of this potential is safe and effective for the treatment of patients with typical atrioventricular nodal reentrant tachycardia (AVNRT). We conducted a prospective, non-randomized, observational study using high-resolution activation mapping from the sinus node to KT with a PENTARAY or OCTARAY catheter using the CARTO 3 cardiac mapping system (Biosense Webster) during SR in 62 consecutive patients (22 men; age [mean ± standard deviation] = 55 ± 14 years) treated for typical AVNRT at our institution from August 2021 to March 2023. In all cases, the most delayed atrial potential was observed near the His potential within KT. Ablation targeting of this potential helped successfully treat each case of AVNRT, with a junctional rhythm observed at the ablation site. Initial ablation was deemed successful in 55/62 patients (89%); in the remaining seven patients, lesion expansion resolved AVNRT. One procedural complication occurred, namely, a transient atrioventricular block lasting 45 s. One patient experienced a transient tachycardic episode by the 1-month follow-up, but no further episodes were noted up to the 1-year follow-up. Activation mapping at KT during SR with the high-resolution CARTO system clearly revealed the most delayed atrial potential near the His potential within KT. Targeting this potential was a safe and effective treatment method for patients with typical AVNRT in our study.

Power grid fault event reasoning based on entity extraction model of knowledge map

In the initial construction process of smart grid dispatching control system in power grid dispatching control center, because different subsystems are in decentralized development, independent operation and independent management, it is easy to reduce data interconnection, which leads to difficulties in data sharing and restricts the information level of the system. The data is multi-source, and the data format is inconsistent, resulting in the application problems that the data can not be shared, accessed, managed, analyzed and mined in real time among different subsystems. In order to solve the problems of data sharing and mining, this paper constructs a knowledge map entity extraction model to study the power grid fault events. Based on the knowledge map theory, the structured and unstructured data related to power grid dispatching are processed to improve the application efficiency of data. Cleaning the preprocessed data to obtain the corresponding entity value and attribute value. The knowledge extraction model of power grid fault event reasoning knowledge mapping is constructed, and the power grid fault event reasoning knowledge edge mapping system is designed to extract the relationship between events and complete data storage. The experimental results show that the text prediction degree of the proposed model is high, which can reach more than 95; The accuracy is 96.71%, the recall rate is 94.88%, and the F1 value is 9.27%. This proves the feasibility of this study, in order to provide data and theoretical support for intelligent management and real-time dispatching of power grid.

Electrographic flow mapping of persistent atrial fibrillation: intra- and inter-procedure reproducibility in the absence of 'ground truth'.

Validating mapping systems that identify atrial fibrillation (AF) sources (focal/rotational activity) is confounded by the absence of ground truth. A key concern of prior mapping technologies is spatiotemporal instability, manifesting as poor map reproducibility. Electrographic flow (EGF) employs a novel algorithm that visualizes atrial electrical wavefront propagation to identify putative AF sources. We analysed both intra- (3 min) and inter- (>3 months) procedure EGF map reproducibility. In 23 persistent AF patients, after pulmonary vein isolation (PVI), EGF maps were generated from 3 serial 1 min recordings using a 64-electrode basket mapping catheter (triplets) at right and left atrial locations. Source prevalence from map triplets was compared between recordings. Per protocol, 12 patients returned for 3-month remapping (1 non-inducible): index procedure post-PVI EGF maps were compared with initial EGF remapping at 3-month redo. Intra-procedure reproducibility: analysing 224 map triplets (111 right atrium, 113 left atrium) revealed a high degree of map consistency with minimal min-to-min shifts: 97 triplets (43%), exact match of leading sources on all 3 maps; 95 triplets (42%), leading source within 1 electrode space on 2 of 3 maps; and 32 triplets (14%), chaotic leading source pattern. Average deviation in source prevalence over 60 s was low (6.4%). Inter-procedure reproducibility: spatiotemporal stability of EGF mapping >3 months was seen in 16 of 18 (89%) sources mapped in 12 patients with (re)inducible AF. Electrographic flow mapping generates reproducible intra- and inter-procedural maps, providing rationale for randomized clinical trials targeting these putative AF sources.