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Background: Characterizing atrial fibrillation (AF) substrate can guide ablation strategies.
Objective: A novel parameter, peak frequency (PF), was evaluated in its ability to characterize the substrate in AF.
Methods: Patients undergoing persistent AF ablation were included. Patients had omnipolar voltage (OV) and PF maps in AF and bipolar voltage (BV) maps in sinus rhythm (SR) at pacing intervals of 600 and 250 ms. PF was evaluated at sites of fixed remodeling (low voltage zones [LVZs] across all maps), functional remodeling (LVZs in AF OV and SR BV 250 ms maps) and non-LVZs. was defined as the highest frequency detected in the electrogram.
Results: In 40 patients, the average voltage in AF OV maps differed significantly from that in SR BV 600 ms maps (0.49±0.76 mV in AF OV vs 1.12±0.97 mV SR BV 600 ms; <.001) but not SR BV 250 ms maps (0.49±0.76 mV in AF OV vs 0.52±0.84 mV SR BV 250 ms; =.10). PFs of ≥244 and ≤214 Hz were predictive of non-LVZs (odds ratio [OR] 3.91; <.001) with an area under the curve (AUC) of 0.71 and of fixed remodeling (OR 17.67; <.001) with an AUC of 0.90, respectively. A PF between 215 and 236 Hz was predictive of functional remodeling (OR 2.83; 95% confidence interval 2.71-2.95; <.001) with an AUC of 0.76. A majority of LVZs identified only in AF OV maps exhibited PF compatible with that seen in non-LVZs, suggesting that PF analysis can pinpoint potential overestimations of LVZs.
Conclusion: PF can effectively discern between sites of fixed remodeling, functional remodeling, and potential overestimations of LVZs. PF may thereby aid in better characterization of the substrate in AF.
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http://dx.doi.org/10.1016/j.hroo.2024.12.011 | DOI Listing |
iScience
September 2025
Energy Conversion Research Center, Electrical Materials Research Division, Korea Electrotechnology Research Institute, Changwon, Gyeongsangnam-do 51543, Republic of Korea.
Indoor photovoltaics (IPVs) are small and not optimized for versatile environments, making them environmentally sensitive. To expand the application of energy-harvesting photovoltaics, overcoming the current problems and mismatch loss is important. In this study, we found that IPVs are sensitive to changes in current density under low illuminance, and we introduced a protocol to reveal the modules resulting in the smallest standard deviation using current maps.
View Article and Find Full Text PDFJ Cardiovasc Electrophysiol
September 2025
Demoulas Center for Cardiac Arrhythmias, Massachusetts General Hospital, Boston, Massachusetts, USA.
Introduction: Fluoroless mapping and ablation using a Pentaspline pulsed field ablation catheter has many advantages. This can be achieved using a "tripolar configuration," which enables high-quality electroanatomical maps, improves the ability to localize electrograms (EGMs), and minimizes the use of additional mapping catheters compared to the standard bipolar configuration. We aimed to evaluate the benefits of using a tripolar configuration in fluoroless atrial fibrillation ablation compared to the standard bipolar configuration.
View Article and Find Full Text PDFEES Solar
August 2025
Institute of Computational Physics, Zurich University of Applied Sciences (ZHAW) 8400 Winterthur Switzerland
The current density-voltage (-) curve of perovskite solar cells (PSCs) commonly depends on the voltage scanning rate and direction, due to the presence of mobile ionic charges which screen the electric field, lowering the total driving force for charge extraction. In this study, experimental data and drift-diffusion simulations are combined to provide new insights into scan rate dependent - curves, focusing on triple mesoscopic carbon-based PSCs (CPSCs), which show a distinct current overshoot ('bump') in the backward scan which had not been fully explained until now. Additionally, the thickness optimisation problem in CPSCs is shown to be governed by the ionic distribution, which determines the ability to collect charge photogenerated in the ZrO layer.
View Article and Find Full Text PDFInsights Imaging
August 2025
Department of Cardiology, University Heart Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Objectives: This study aimed to assess the feasibility of left ventricular myocardial characterization in patients with ventricular arrhythmias using late enhancement (LE) photon-counting detector computed tomography (PCD-CT) scans, in comparison with invasive endocardial electroanatomical mapping (EAM).
Materials And Methods: This single-center retrospective observational study included 20 patients (mean age 64 ± 8 years, 4 female) who underwent PCD-CT prior to 3D endocardial uni- and bipolar EAM and radiofrequency catheter ablation (RFCA) between May 2022 and February 2024. Sixteen patients (80%) had cardiac implantable electronic devices.
Microsc Microanal
July 2025
Department of Materials Engineering, University of British Columbia, 309-6350 Stores Road, Vancouver, BC V6T 1Z4, Canada.
Compact direct electron detectors are becoming increasingly popular in electron microscopy applications including electron backscatter diffraction, as they offer an opportunity for low cost and accessible microstructural analysis. In this work, we explore how one of these commercial devices based on the Timepix chip can be optimized to obtain high-quality data quickly and easily, through careful systematic analysis of a variety of samples, including: semiconductor silicon, commercially pure nickel, a dual phase titanium-molybdenum alloy, and a silicon carbide ceramic matrix composite. Our findings provide strategies for very fast collection of orientation maps, including at low voltage (5-10 keV) and low beam current conditions.
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