3D Mapping Research Articles

Use of an AI-powered visualization platform to support precision clinical decision-making in patients with breast cancer undergoing neoadjuvant chemotherapy.

e12618 Background: Chemotherapy to reduce cancer burden and tumor size ("downstaging") is widely used in neoadjuvant treatment of early-stage breast cancer (ESBC) and can have a dramatic impact on selection of further treatment courses, including surgery. The resulting decision-making process between physicians and cancer patients requires detailed and effective communication of the patient's disease status, and clear presentation of this information in Tumor Board settings. Artificial intelligence (AI) -powered visualization platforms offer the potential to aid in evaluating breast tumor location and morphology, and accordingly optimize treatment. Additionally, these tools offer enhanced communication with patients regarding future treatment options, particularly serving as clinical decision support (CDS) tools. Methods: We assessed the performance of an AI platform that employs dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to render three-dimensional (3D) visualizations of breast tumors and 5 additional chest tissues on an independent validation dataset comprise of 100 ESBC cases with ground-truth tumor labels vetted by 2 breast-specialized radiologists. The platform provides 3D depictions of the tumor and its multi-tissue context, as well as functionalities for quantifying tumor morphology, tumor-to-landmark structure distances, excision volumes, and approximate surgical margins. We subsequently evaluated the tool's utility in a real-world setting to understand how the tool impacts clinical decision-making and patient communication, specifically around surgical planning in the context of neoadjuvant chemotherapy (NACT). Results: The platform generated accurate 3D tumor maps, as evidenced by a median Dice score of 75.6% and a median Hausdorff distances of 15.1 mm relative to the radiologist validation set. The automatic longest tumor dimension calculations were linearly correlated with radiologist direct measurements (Pearson correlation coefficient = 0.78) and had a median absolute difference of 6.3 mm. We found strong overlap between the platform’s ground-truth convex hulls, as shown by a median Dice score of 81.5%. When used by a skilled breast-specialized surgeon, the tool enabled rapid and intuitive patient-physician communication of the location and extent of disease, and potential degrees of downstaging to breast-conserving surgery. Conclusions: Detailed 3D tumor and surrounding multi-tissue depictions offer both qualitative and quantitative comprehension of cancer topology and may aid in formulating an optimal treatment approach for breast cancer treatment. We show that detailed depictions enhance communication between physicians and patients and may aid in streamlining decision-making.

Multi-Parametric Molecular Imaging of the Brain Using Optimized Multi-TE Subspace MRSI.

To develop a novel multi-TE MR spectroscopic imaging (MRSI) approach to enable label-free, simultaneous, high-resolution mapping of several molecules and their biophysical parameters in the brain. The proposed method uniquely integrated an augmented molecular-component-specific subspace model for multi-TE 1H-MRSI signals, an estimation-theoretic experiment optimization (nonuniform TE selection) for molecule separation and parameter estimation, a physics-driven subspace learning strategy for spatiospectral reconstruction and molecular quantification, and a new accelerated multi-TE MRSI acquisition for generating high-resolution data in clinically relevant times. Numerical studies, phantom and in vivo experiments were conducted to validate the optimized experiment design and demonstrate the imaging capability offered by the proposed method. The proposed TE optimization improved estimation of metabolites, neurotransmitters and their T2's over conventional TE choices, e.g., reducing variances of neurotransmitter concentration by ∼ 40% and metabolite T2 by ∼ 60%. Simultaneous metabolite and neurotransmitter mapping of the brain can be achieved at a nominal resolution of 3.4 × 3.4 × 6.4 mm 3. High-resolution, 3D metabolite T2 mapping was made possible for the first time. The translational potential of the proposed method was demonstrated by mapping biochemical abnormality in a post-traumatic epilepsy (PTE) patient. The feasibility for high-resolution mapping of metabolites/neurotransmitters and metabolite T2's within clinically relevant time was demonstrated. We expect our method to offer richer information for revealing and understanding metabolic alterations in neurological diseases. A novel multi-TE MRSI approach was presented that enhanced the technological capability of multi-parametric molecular imaging of the brain. The proposed method presents new technology development and application opportunities for providing richer molecular level information to uncover and comprehend metabolic changes relevant in various neurological applications.

A Survey of Designs for Combined 2D+3D Visual Representations.

We examine visual representations of data that make use of combinations of both 2D and 3D data mappings. Combining 2D and 3D representations is a common technique that allows viewers to understand multiple facets of the data with which they are interacting. While 3D representations focus on the spatial character of the data or the dedicated 3D data mapping, 2D representations often show abstract data properties and take advantage of the unique benefits of mapping to a plane. Many systems have used unique combinations of both types of data mappings effectively. Yet there are no systematic reviews of the methods in linking 2D and 3D representations. We systematically survey the relationships between 2D and 3D visual representations in major visualization publications-IEEE VIS, IEEE TVCG, and EuroVis-from 2012 to 2022. We closely examined 105 articles where 2D and 3D representations are connected visually, interactively, or through animation. These approaches are designed based on their visual environment, the relationships between their visual representations, and their possible layouts. Through our analysis, we introduce a design space as well as provide design guidelines for effectively linking 2D and 3D visual representations.

N$^{3}$-Mapping: Normal Guided Neural Non-Projective Signed Distance Fields for Large-Scale 3D Mapping

N$^{3}$-Mapping: Normal Guided Neural Non-Projective Signed Distance Fields for Large-Scale 3D Mapping

INSIHGT: A scalable and homogeneous 3D multiplexed molecular mapping platform for spatial biology and precision medicine.

e15180 Background: The dynamic interplay between cancer cells and their microenvironment is a determinant of disease evolution and response to treatment. However, the current state of three-dimensional (3D) tumor microenvironment analysis is hindered by inadequate penetration of antibodies into thick tissue sections, leading to a substantial gap in acquiring unbiased, precise 3D multiplexed immunohistochemistry (IHC) images. Methods: We developed INSIHGT to surmount these limitations by enabling multi-round, multiplexed 3D IHC in standard formalin-fixed tissues. This fully automatable, fast-track method requires a simple series of chemical cocktail exchanges, translating to a tissue-to-image time of 6 days for 1 cm³ samples and as little as 6 hours for biopsy specimens. INSIHGT offers a scalable and efficient solution for detailed 3D spatial mapping of cancerous cells and their interactions within their native context. Results: 3D IHC with INSIHGT shows ideal penetration homogeneity, which quantitatively matches reference signals in 1cm3 samples. We further validated INSIHGT with 309 commercially available primary antibodies and is compatible with simultaneous fluorescent in situ hybridization (FISH) to detect RNA transcripts or DNA chromosomal abnormalities. Notably, the quality of post-INSIHGT traditional histological analyses, such as H&E and standard IHC, was not altered. We demonstrated a 3D mapping of over 20 markers in a 1 mm-thick tumor sample across seven INSIHGT cycles, and an atlas of multiple tumour samples with 3D IHC & H&E. The large datasets seamlessly integrates with single-cell segmentation and analysis workflows, yielding comprehensive maps that elucidate protein expression, cell morphology, spatial positioning, and potential cell-cell interactions. Conclusions: INSIHGT provides an unparalleled level of visualization and analytical detail concerning the spatial dynamics within the tumor microenvironment at a single-cell resolution. As a transformative next generation histopathology platform, it can uncover new structural and molecular details within clinical specimens, accelerating biomarker discovery and novel diagnostic assays development, thereby enriching the field of tumor biology and propelling the progress of personalized oncology treatments.

Investigating microplastics and nanoplastics released from food bag ziplock using SEM and Raman imaging

Microplastic contamination is a concern in our daily lives, such as being released from self-sealing ziplock (sliderless zipper) plastic bags that are commonly used for food storage. That is because during the closure and opening process, due to friction and deformation, the male rim inserting into or separating from the female rim can release debris as micro- and nanoplastics (MNP). Herein, we initially observed the released debris using scanning electron microscopy (SEM). Subsequently, Raman imaging was employed to directly visualise the debris, either scratched on the rim surface or fallen down from the rim, from molecular spectrum perspective. Raman imaging analyses MNP from hundreds to thousands of spectra rather than from a single spectrum or peak, enhancing the signal-to-noise ratio statistically and providing morphological information for quantification. The confocal Raman-based mapping of MNP may be susceptible to be false images, which can be improved through terrain 3D mapping. Additionally, the weak signal of nanoplastics can be enhanced by reducing scanning pixel size and deconvoluting with surface-fitting algorithm. Consequently, we estimated that approximately 5(±3) MNP per millimetre along the ziplock length may be released during each closure/opening process. Given the use of these plastic bags for food storage, this level of contamination is concerning, warranting careful risk assessment alongside other potential MNP sources of plastic items used in our kitchens. Overall, Raman imaging can be effectively analyse MNP and more broadly nanomaterials, with help of algorithms and SEM.

Two‐Photon Excited Magneto‐Photoluminescence in Exciplex Material for 3D Mapping of Magnetic Field

AbstractTwo‐photon excited fluorescence materials with sufficient responsiveness to magnetic field are essential for applications such as 3D mapping of magnetic field distributions based on magneto‐optical effect. In this study, a two‐photon excited magneto‐photoluminescence (MPL) in the intermolecular exciplex of 1,1‐bis[(di‐4‐tolylamino)phenyl]cyclohexane and tris(2,4,6‐trimethyl‐3‐(pyridin‐3‐yl)phenyl)borane (TAPC:3TPYMB) is observed. This MPL can be attributed to the promotion of delocalization of excitons in the exciplex under two‐photon excitation, resulting in a weakened spin‐exchange interaction and thereby enhancing the magnetic field‐sensitive spin conversion process. The temperature‐dependent MPL further validates the strong correlation between the delocalization of excitons in the exciplex and the enhanced MPL observed during temperature variation. Combining the penetration capability and magneto‐optical effect of two‐photon excited fluorescence in TAPC:3TPYMB exciplex, a novel magnetic sensor suitable for 3D mapping of magnetic field distributions is further developed. The present work not only enhances the understanding of the magneto‐optical coupling mechanism but also opens up opportunities for the application of molecular materials in opto‐spintronic devices.

Mapping Hydrogen Positions along the Proton Transfer Pathway in an Organic Crystal by Computational X-ray Spectra.

Understanding proton transfer (PT) dynamics in condensed phases is crucial in chemistry. We computed a 2D map of N 1s X-ray photoelectron/absorption spectroscopy (XPS/XAS) for an organic donor-acceptor salt crystal against two varying N-H distances to track proton motions. Our results provide a continuous spectroscopic mapping of O-H···N↔O-··· H+-N processes via hydrogen bonds at both nitrogens, demonstrating the sensitivity of N 1s transient XPS/XAS to hydrogen positions and PT. By reducing the O-H length at N1 by only 0.2 Å, we achieved excellent theory-experiment agreement in both XPS and XAS. Our study highlights the challenge in refining proton positions in experimental crystal structures by periodic geometry optimizations and proposes an alternative scaled snapshot protocol as a more effective approach. This work provides valuable insights into X-ray spectra for correlated PT dynamics in complex crystals, benefiting future experimental studies.

Media Pembelajaran Miniatur Peta Kontur 3D bagi Siswa SMK Teknik Geospasial

The geospatial engineering skills program is a program that focuses on understanding surveying and mapping techniques. At SMK Negeri 1 Singosari in Cartography lessons for class X, learning uses conventional media and 2D printed maps, so efforts are needed to encourage active participation of students. This research aims to develop fun learning media for class X Geospatial Engineering students at SMK Negeri 1 Singosari. The research model applied in developing 3D contour map learning media is Research and Development. The research and development model is carried out using the ADDIE model. The resulting product is a miniature 3D contour map for class X cartography learning in Geospatial Engineering. The contour chosen in this media is the contour of the Mount Bromo area. This miniature 3D contour map media can be accessed using barcodes on Google Earth. The results of the assessment by material experts, media experts, small group and large group students showed a very good category. The learning media developed has advantages and disadvantages. The advantages of learning media are that it includes learning objectives, is equipped with access to the Google Earth application, and is equipped with guidelines on how to read 3D contour maps. Meanwhile, the weakness of this learning media is that it is large.

A Dynamic Visual SLAM System Incorporating Object Tracking for UAVs

The capability of unmanned aerial vehicles (UAVs) to capture and utilize dynamic object information assumes critical significance for decision making and scene understanding. This paper presents a method for UAV relative positioning and target tracking based on a visual simultaneousocalization and mapping (SLAM) framework. By integrating an object detection neural network into the SLAM framework, this method can detect moving objects and effectively reconstruct the 3D map of the environment from image sequences. For multiple object tracking tasks, we combine the region matching of semantic detection boxes and the point matching of the optical flow method to perform dynamic object association. This joint association strategy can prevent trackingoss due to the small proportion of the object in the whole image sequence. To address the problem ofacking scale information in the visual SLAM system, we recover the altitude data based on a RANSAC-based plane estimation approach. The proposed method is tested on both the self-created UAV dataset and the KITTI dataset to evaluate its performance. The results demonstrate the robustness and effectiveness of the solution in facilitating UAV flights.

Left atrial posterior wall isolation during catheter ablation with the pulsed field ablation in patients with persistent atrial fibrillation

Abstract Background Few data are available on pulsed-field ablation (PFA) targeting left atrial posterior wall (LAPW) in persistent atrial fibrillation (PeAF) patients. Purpose We sought to explore the role of PFA in persistent AF patients beyond pulmonary vein isolation (PVI), extending the lesion set to obtain LAPW isolation. Methods We enrolled consecutive patients referred for persistent AF catheter ablation using the Farapulse PFA system at nine Italian centers. Complete 3D mapping was performed before and immediately after LAPW isolation to validate our workflow in all cases. To analyze lesions' formation and residual gaps, the line around each pair of PVs was divided into 7 distinct sections in accordance with the literature, while the roof line, the floor line, and the two longitudinal posterior wall lines were equally divided into three parts. The PW was overall divided into nine regions. This scheme has been illustrated in Figure 1, Panel A. Results Fifty patients meeting inclusion criteria were included. PVI was achieved in all 202 (100%) PVs (1 patient exhibited a left common trunk, 2 patients exhibited a right middle cardiac PV). One-hundred ninety-eight (98.0%) PVs were acutely isolated on first pass, as confirmed by both entrance and exit block on subsequent 3D-mapping with the mapping catheter. A total of 7 PV gaps were detected through 3D mapping: 4 at the RSPV, 2 at the RIPV and 1 at the LSPV. When considering LAPWI, overall LAPW ablated area was 20.0±6 cm2 with lesions being deployed with the PFA catheter maneuvered in the flower configuration from one LAPW area to another. First-pass roof area (sectors #1 to #3) block was achieved in 44 (88%), first-pass floor area (sectors #7 to #9) block in 43 (86%) and inner-area (sectors #3 to #6) block in 45 (90%). A total of 23 residual LAPW activity gaps were detected through validation using high-output pacing and 3D mapping. Remapping examples has been reported in Figure 1, panel B-C-D. Evaluation of individual segments of the LAPW via signals’ assessment from the PFA splines demonstrated an accuracy of 94.9% (437 out of 450 sectors), compared to the results of subsequent high-output pacing and 3D mapping. Following PFA consolidation in these areas, LAPW isolation was successfully achieved in all cases (100%) using PFA alone, with no need for radiofrequency touch-ups. No major procedure-related adverse events were reported. Conclusion A structured workflow with the novel Farapulse PFA system allowed for a reliable, safe, and fast LAPW isolation, as confirmed by ultra-high-density 3D mapping.

Temporal stability of local cycle length and duty cycle distribution during atrial fibrillation

Abstract Appropriate targets for catheter ablation of atrial fibrillation (AFib) beyond pulmonary vein isolation (PVI) are still controversially discussed. Since available parameters to analyze the vulnerable substrate are very limited, there is the need to define and understand tailored features. Mapping during AFib can be particularly challenging due to its non-repetitive nature. Amongst others, temporal stability despite changing activation sequences is an essential requirement for features applied to AFib maps. The local cycle length (CL) and duty cycle (DC) offer novel measures to characterize the atrial substrate during AFib. This study aims at providing first insights into the temporal stability of CL and DC during AFib in order to assess the suitability of both features for the characterization of the individual substrate and tailor ablation strategies in future. In patients with recurrent AFib after PVI, two high-resolution 3D electro-anatomical maps were recorded sequentially during AFib before any ablation. Intracardiac electrograms (EGMs) were preprocessed to improve local signal quality and far field suppression. EGMs were recorded with a multipolar, basket-shaped high-density mapping catheter. Local CL and DC distribution were visualized using scatter plots and histograms. CL quantifies the time between subsequent local activations, DC quantifies the fraction of CL with local EGM activity, and the confidence (conf) feature quantifies the spatiotemporal consistency of EGM morphology. Only recordings with conf > 0.6 are analyzed. Feature calculation is based on a weighted conglomerate of all acquisitions within a series of beats. Adjustable CL and DC thresholds allow highlighting regions within the 3D map for individual spatial analysis. Both the global distributions and the local occurrence of CL and DC were compared in order to assess temporal stability. Four patients (2x paroxysmal AFib, 2x persistent AFib) were enrolled. All subjects underwent repeat ablation after PVI due to recurrence of AFib. Table 1 summarizes mapping parameters for both AFib maps in individual patients. Despite differences in mapping time and the number of EGMs, CL and DC histograms were significantly similar when comparing maps within one patient. For individually selected ranges of CL and DC in the upper left corner of the scatter plot (short CL and high DC), localization of corresponding areas was comparable in both 3D maps. An example is shown for patient I in the left and central column of the figure. CL and DC distributions were temporally stable features for all patients in this study cohort. Localization of EGMs of given CL and DC range within the 3D maps were comparable but not identical for arbitrarily selected ranges. CL and DC can therefore be considered valid features for substrate characterization during AFib. Further studies will need to investigate how ablation strategies can be derived from individual CL and DC distributions.

Standardized regionalization of the atria for 3D cardiac imaging, electroanatomical mapping and computational modeling. A multidisciplinary consensus of the PersonalizeAF consortium

Abstract Background 3D imaging and high-resolution electroanatomical mapping have become an integral part of cardiac electrophysiology and the management of patients with arrhythmias. With further technological advances the significance of these modalities continues to grow. However, to perform regional quantitative analyses and intra- and inter-individual, as well as cross-modality comparisons, a universal definition of atrial regions and their boundaries is required. While for the left ventricle there is already an established standardized regionalization (AHA 18-segment model), there is no consensus for the regionalization of the atria. Purpose Here we propose standardized left and right atrial segments based on anatomical, electrophysiological and clinical considerations, with precise definition of regional boundaries allowing for reproducible and automated regionalization. Methods and results In a multidisciplinary task force of the European PersonalizeAF consortium involving cardiologists and cardiac electrophysiologists, as well as specialists in cardiac imaging and computational modeling we developed a standardized regionalization dividing the left atrium into eight, and the right atrium into seven segments (15-segment bi-atrial model) (Fig. 1A). As a proof-of-principle, two software algorithms for automatic regionalization of 3D atrial geometries based on the standardized 15-segment bi-atrial model were developed independently by different working groups of the PersonalizeAF consortium – one based on a commercially available software, the other being open-source. The algorithm based on the commercial software obtains the 15-segment bi-atrial model by dividing the surface mesh in the defined regions along geodesics using the Fast Marching Method (Fig. 1C). For the open-source solution, a publicly available semi-automatic bi-atrial division pipeline was developed: In this algorithm, after standardizing the surface mesh by remeshing and clipping the pulmonary veins, the orifices are annotated automatically. Based on these anatomical landmarks, the boundaries of each region are inferred by calculating geodesics using Dijkstra’s algorithm. Both algorithms were able to annotate the regions with high accuracy and very good agreement as indicated by interrater reliability testing (kappa >0.9), in geometries derived from 50 patients and 2 imaging modalities (CT and MRI), thus demonstrating the universal applicability and reproducibility of the standardized segments. Conclusion We propose a standardized regionalization of the cardiac atria for 3D cardiac imaging, electroanatomical mapping and computational modeling, based on anatomical, electrophysiological and clinical considerations. The reproducibility and universal applicability of this 15-segment bi-atrial model was demonstrated by two independently developed software algorithms for automatic regionalization.

Clinical accuracy of a 3-dimensional multielectrode non-invasive ECG mapping vest in premature ventricular contraction ablation procedures

Abstract Background Invasive 3D mapping is the current gold standard in determining premature ventricular contraction (PVC) localization. However, given its invasive nature, unawareness of PVC origin beforehand may lead to prolonged procedure times and increased complications risk. Purpose In this study, we compared the diagnostic accuracy of a non-invasive 3-dimensional mapping ECG vest (MECGV) with invasive 3D mapping and ablation successful points as a reference. We also evaluated 12-lead ECG based pre-procedural PVC localization accuracy of 2 expert operators blinded to clinical findings. Methods In 15 consecutive adult patients between the ages of 35 to 69 (male n: 9, median age: 48), MECGV and subsequently a 3D mapping with uneventful successful PVC RF catheter ablation were performed and included in the study. PVC localization estimations of MECGV method and the EP experts' locatization predictions were compared separately with invasive 3D ablation results using the Cohen's kappa method and with the help of a 16-segmentation model we created for the ease of the analyses . Results Results were presented on Table-1. MECGV was found to be highly compatible (Cohen's kappa 0.968, p<0.001) with the RF ablation results. However operators assessments were found to be less coherent with invasive 3D mapping (Operator 1 Cohen's kappa 0.571, p 0.033, Operator 2 Cohen's kappa 0.618, p: 0.019, respectively). MECGV accuracy was %87 in pinpointing the PVC focus. The only 2 localizations that MECGV failed were on the septal aspects of the heart (Picture-2 Failure of defining the focus on LVOT septal instead of RVOT septal) Conclusion MECGV method seems to be highly compatible with invasive 3D mapping techniques in detection of PVC localization and bests EP expert estimates in this regard. However, it also seem to have some pitfalls especially on septal aspects of the heart.Table-1 and segmentation schemePicture-1

Digital health in the electrophysiological lab: Initial experience, safety and feasibility using remote support for arrhythmia ablation-Results of REMOTE-VA study

Abstract Background In most electrophysiology (EP) labs, electroanatomical mapping (EAM) systems are operated on site by qualified staff or field technical engineers (FTE). Due to lack of skilled personnel, the FTE usually must travel between different hospitals and procedures must be planned in advance. Ablation of ventricular arrhythmias (VA) represents the most complex procedure in the field. The use of remote support (RS) to guide complex EP procedures has the potential to increase flexibility, reduce travel times and maximise healthcare resources. Purpose To evaluate the safety and feasibility of RS as compared to on-site support guided catheter ablation procedures for VA. Methods All patients undergoing ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation using remote support were included. The electronical system of the hospital was searched for 30 days postprocedural emergency department (ED) visits, unplanned ambulatory presentations, and readmissions. RS guided three-dimensional (3D) mapping was achieved by connecting the EAM software with an integrated audio-visual solution for remote support. Internet connection-based headphones and high-resolution cameras ensured the communication between the operator and the FTE, who worked exclusively from home office. The control group consisted of an equal number of patients matched for the type of procedure and undergoing on-site guided procedures. All ablations were performed using high density 3D mapping, as per institutional standard. Results Between October 2022 and October 2023, a total of 25 patients underwent VT (32%) or PVC ablation in our centre using RS and were compared to 25 patients undergoing the same procedures under on-site guidance. In the RS group one patient underwent epicardial VT ablation and another one bipolar ablation for VT Storm. The demographic data were similar between the groups. The median procedure time was 120 (93, 143) minutes in the RS group and 112 (95, 138) minutes in the control group (p=0.95), while the fluoroscopy time was 11.4 (7.0, 14.0) and 7.26 (5.0, 10.9) minutes respectively (p=0.08). The procedural success was achieved in 96% procedures in the RS group and in 100% in the control group. No technical issues or changes to on-site support were reported. One minor intraprocedural complication was noted among the control patients, while 24% of the patients in each group developed minor complications until discharge. Two patients in the RS group and one in the control group had ED visits, while only one patient in the control group had an unplanned ambulatory presentation. One unplanned readmission was reported in the control group (Table 1). Conclusions Even in the most complex procedures including epicardial ablation, the use of RS was feasible and safe in this single centre study. This approach has the potential to increase the feasibility in case of emergency procedures, reduce travel times, and maximise healthcare resources.

A role for Local Impedance in CF guided PVI: initial results from the LOCALIZE CF Trial

Abstract Background Contact force catheters (CF) in combination with high-resolution 3D mapping are the gold standard for treatment of complex arrhythmias. Stable CF and catheter position increase both the safety and effectiveness of energy delivery. To date, local impedance (LI) is the only established parameter for real-time measure of lesion quality. Other methods tend to use surrogate parameters. Catheter ablation may be further improved by combining CF and LI. Purpose LOCALIZE CF assessed the utility of LI in addition to CF in predicting lesion durability during RF PVI procedures for paroxysmal atrial fibrillation (PAF). Methods LOCALIZE CF is an international, multicenter non-randomized trial consisting of an index PVI and invasive redo mapping procedure at 3 months. Patients (pts) with PAF underwent de novo PVI using a combined CF/LI catheter and 3D mapping system. Operators could use CF but were blinded to LI. Power settings and ablation duration were at operator discretion. PVI was performed with point-by-point circumferential ablation. The procedural endpoint was confirmation of entry block for all pulmonary veins (PV) after a 20-minute wait. Secondary endpoints included: safety events, procedural characteristics, and the correlation between LI-values and gaps. Gaps at 3-month remap were analysed by anatomical segment (8/ipsilateral PVI circle, 16/pt). Results This study enrolled 60 pts across 4 European centers, 54 pts completed 3-month remap. On average, pts (25% female) were 61 years of age, BMI 27kg/m2, LVEF 64%, LA diameter 38mm, and CHA2DS2-VASc score 1. High-power (40-45W) short duration was used by 3 of 4 sites (32 patients), with standard power (<40W) in the remainder. First pass isolation, assessed after 20min wait, was achieved in 73% of pts. Acute isolation of all PVs was achieved in all pts. At the 3-month re-map procedure, 92 of 845 segments were found to be reconnected. 3,980 point-to-point index ablations were analysed with respect to gap vs blocked segments. The median CF in gap segments was 11g compared to 13.9g in blocked segments (p<0.0001). Gap segments had significantly lower median LI drop (13Ω) than blocked segments (19Ω; p<0.001). In multivariate analysis, lesion spacing, CF and LI drop all independently predicted block. In ROC curve analysis (>9.5g CF, >20Ω LI), a model including all 3 factors had a significantly greater area under the curve than spacing and CF alone (p<0.0001). Conclusions Real-time measurements such as LI and CF are important for improving the quality and durability of ablations. While CF represents the stability of the catheter, LI reflects real-time lesion formation. The combination of both is important and may improve ablation and avoid gaps. This study suggests that CF >9.5g and LI drop >20Ω are predictors of durable lesion. Thus, LI, when used alongside CF, potentially offers a distinctive measure of ablation effectiveness, complementing the data provided by CF.

Is the conventional deployment of electrode catheters appropriate to diagnose the circuit of atypical atrioventricular nodal reentrant tachycardia? -New insights into the retrograde slow pathways-

Abstract During atypical atrioventricular nodal reentrant tachycardia (AVNRT), the earliest atrial activation site following retrograde slow pathway conduction is either at the exit of the left inferior extension (LIE) in the coronary sinus (CS) or that of the right inferior extension (RIE) on the tricuspid annulus (TA). In an EP study, LIE can be detected by the CS catheter, but absence of catheters at the RIE can lead to it being missed. Aim To evaluate the electrophysiological characteristics of the retrograde slow pathway. Methods We assessed patients with atypical AVNRT using electro-anatomical 3D mapping. Results Among 14 patients (9 females, age 59±17), with a total of 18 atypical AVNRTs (15 fast/slow and 3 slow/slow), 4 patients had LIE, 6 had RIE, and 4 had both. The LIE exits were inside the CS, while those of RIE were on the posterior TA. During AVNRT or ventricular pacing, the local electrogram of RIE preceded that of the CS ostium and HBE by 24±12 and 34±12 ms respectively. Examination of activation times at the CS ostium and HBE showed that the nearer to the exit of RIE they were, the earlier they were excited. Conclusion The retrograde slow pathway of atypical AVNRT can have an exit site at the LIE or RIE, or both. Accurate identification of inferior extensions of the AV node is critical for diagnosis and treatment. We recommend placing a catheter on the posterior TA or 3D mapping the area for RIE exit detection in atypical AVNRT patients.

Pulsed field ablation for complex resistant atrial tachycardia recurring after radiofrequency ablation of persistent atrial fibrillation

Abstract Background There is a limited knowledge on immediate and long-term efficacy of pulsed field ablation (PFA) for residual atrial tachycardia (AT) recurring after persistent atrial fibrillation ablation (AF). Purpose To present immediate and medium-term outcome of PFA (Farapulse) for complex AT recurring after ≥1 radiofrequency ablation (RFA) of primary (longstanding) persistent AF. Methods In 5/2022-10/2023, 81 patients (64±8 years, 19 females) underwent PFA for complex AT in 83 PFA procedures after prior RFA procedure(s); in first (n=21), second (n=33), third (n=23), fourth (n=5), or fifth (n=1) repeat ablation procedure, respectively. Mapping/ablation strategy was directed by the CS activation/entrainment to: 1) no 3D mapping and direct PFA in left atrium (n=67); 2) PFA directly after 3D LA mapping (n=9); 3) PFA following RFA after 3D LA mapping (n=7). AT sources were classified as macroreentry (MRAT) (perimitral, roof-dependent, typical flutter) or localized (LOCAT) in case of smaller reentry or ectopic origin. Results At the procedure onset, persistent AT was present in 58 patients, in the remaining cases AT (n=21) or AF (n=4) were induced. AF eventually occurred at some time of procedure in another 10 patients and was terminated by ablation at LA ridge/CS/LOM region 8x, LA posterior wall 3x, LUPV 1x, RUPV 1x, and RA low lateral wall 1x. Only MRAT, only LOCAT, or both AT types were found at 34 (41%), 35 (42%), and 14 (17%) procedures, respectively. A total of 125 ATs was identified (1, 2, and 3 ATs in 52, 20, and 11 patients). MRAT (n=60) included 32 perimitral ATs, 20 roof-dependent ATs, and 8 typical flutters. LOCAT (n=65) included RUPV source (n=1), LA extraPV sources (n=59), and RA sources (n=5). SR was restored with a 5±7 PFA applications at the site of AF source, total of PFA deliveries was 71±27, and procedure and fluoroscopy times were and 89±37 and 9±5 minutes, respectively. In the 7 patients with initial ineffective 6, 6, 11, 5, 18, 10, and 2 minutes of RFA, the AT was converted into SR by subsequent 1, 4, 1, 13, 4, 24, and 20 PFA applications. All ATs were terminated and noninducibility was achieved in 82 (99%) and 74 (89%) procedures, respectively. In 52 patients with >3 month follow-up, 46 (88%) patients remain in stable SR (41 / 79%) off AAD); 3 and 3 patients have paroxysmal or persistent AT. Conclusion PFA with catheter Farapulse can affect complex/epicardial AT sources resistant to RFA in prior or present ablation procedure; however, there is a certain discrepancy between high efficacy in AT terminating and medium-term clinical outcome.

Neural network for automatic ICD-EGMs matching in pace-mapping and ablation of ventricular arrhythmias

Abstract Background Mapping of the ventricular arrhythmias (VA) is often not possible due to the non-inducibility of the electrophysiological study (EPS). Since twelve-lead electrocardiograms (ECG) of the clinical ventricular tachycardia (VT) are also often not available, therefore stored implantable cardioverter-defibrillator (ICD) electrograms (EGMs) of the clinical VT are often the only documentation. The pace mapping matching to the stored ICD-EGM template of the clinical VT can help to identify the VT exit site. Automatic objective computing of similarity scores between EGMs is impossible because ICD programmer devices do not have any interface allowing the export of digital EGMs. Therefore, images can only be accessed for similarity by subjective eyeballing. The MatcherNet Siamese neural network takes a pair of EGM images and predicts their similarity. Purpose This study aimed to assess the feasibility of the automatic ICD-EGMs matching by MatcherNet neural network for pace mapping of VT/premature ventricular contraction (PVC) exit site. Methods Consecutive patients undergoing VT ablation or ablation of ventricular fibrillation, triggered by PVC were included in the study, if the clinical VT/PVC was not inducible during EPS but ICD-EGMs of clinical VT/PVC were stored in the device. Electro-anatomical mapping was performed to reveal substrates (low-voltage areas, abnormal potentials, DEEP-potentials, conduction crowding). Subsequently, the low-output pacing from various locations tagged on the 3D map of LV was performed, and the paced ICD-EGM images were stored from the ICD programmer device for offline analysis and calculation of the similarity. RF ablation was conducted based on the substrate map findings, including the area of the most remarkable similarity between paced ICD-EGMs and clinical ICD-EGM templates assessed by eyeballing. The ICD-EGMs similarity scores (Manhattan similarity and Pearson correlation) were predicted by MatcherNet for each pacing site offline and transferred to the 3D map for the assessment of similarity distribution (Figure 1). Results We included 7 patients with VA episodes registered and stored by their ICD. The clinical characteristics are presented in Table1. In all patients, we were able to find the sites of highest ICD-EGM similarity to the clinical template with gradual decrementing of the similarity score at the increasingly distant pacing areas. The site of the highest similarity was collocated with VT substrate and ablation areas in all patients. Abrupt change of the similarity score at the adjacent pacing sites was detected in the 2 cases, indicating the possible protected VT isthmus. After ablation procedure only one patient with DCM experienced VA recurrence. Conclusion This technology opens new possibilities for the utilization of ICD-EGMs during the pace mapping of ventricular tachycardia, especially in the cases of non-inducibility during electrophysiological study.Figure 1Table 1

Atrial functional mitral regurgitation as a marker of atrial remodeling and ablation outcomes in atrial fibrillation patients

Abstract Background Atrial fibrillation (AF) triggers a cascade of atrial remodeling processes, significantly impacting atrial function and the efficacy of ablation therapies. This remodeling fosters the development of atrial cardiomyopathy and atrial dilation, which is linked to the emergence of mitral regurgitation, paving the way for the concept of atrial functional mitral regurgitation (aFMR). Our study delves into the intricate relationship between aFMR and the electrical architecture of the atrium, specifically focusing on left atrial bipolar voltage and the prevalence and extent of low-voltage areas (LVAs) in AF patients. By exploring these associations, this research aims to deepen our understanding of the interplay between the atrial substrate alterations and the development of aFMR. Methods A total of 282 patients were enrolled, who had presented for a redo PVI procedure after experiencing AF recurrence following a previous PVI. All patients received echocardiography prior to the electrophysiological procedure. All procedures were performed using 3D mapping and radiofrequency ablation. Reconnected pulmonary veins were detected in all patients and were re-isolated. The voltage of the electroanatomical points was documented on each of the atrial walls. LVAs were calculated in selected HD maps. Patients were followed-up for one year after the blanking period. Results Our cohort comprised 282 patients, predominantly male (69.4%), with a mean age of 64 years. 56% of the patients presented with persistent AF. LA area was larger in patients with aFMR ≥ 1+ as compared to aFMR < 1+ (17.0 [14.6-19.7] vs 20.6 [16.6-24.7] cm2, p<0.001). We observed significant differences in left atrial voltage and LVA extent between patients with varying degrees of aFMR (Table 1). Upon further investigation Patients with aFMR = 1+ showed significantly lower atrial voltage compared with aFMR < 1+ yet no significant increase in LVAs area. Patients with aFMR = 2 exhibited lower average voltage amplitudes in all atrial regions and larger LVA in the posterior wall, atrial roof, and septum compared to their aFMR < 1+ counterparts. Notably, the recurrence of AF was significantly higher in the AFMR ≥ 1+ (59% vs 46% p=0.027) group within one year of follow-up. aFMR was associated with AF recurrence even after adjusting for sex, age and AF types (HR:1.517, 95% CI: 1.057-2.184, p=0.025). Conclusion The presence of aFMR in AF patients may serve as a marker of progressive atrial remodeling and the onset of left atrial cardiomyopathy, characterized by reduced atrial voltage and increased LVAs. Additionally, aFMR is linked to the outcomes of PVI, suggesting that aFMR should be considered in the decision-making process for AF therapy. Further research is needed to explore the potential reversibility of these changes.Left atrial voltage and low voltage area