Mean Voltage Research Articles

Comparison of voltage maps using OCTARAY catheter and PENTARAY catheter.

Recently, a new OCTARAY® mapping catheter was commercially launched. The catheter is designed to enable high-density mapping and precise signal recording via 48 small electrodes arranged on eight radiating splines. The purpose of this study was to compare bipolar voltage and low-voltage-area size, and mapping efficacy between the OCTARAY catheter and the PENTARAY® catheter METHODS: Twelve consecutive patients who underwent initial and second ablations for persistent atrial fibrillation within 2 years were considered for enrollment. Voltage mapping was performed twice, first during the initial ablation using the PENTARY catheter and second during the second ablation using the OCTARAY Long 3-3-3-3-3 (L3) catheter. Mean voltage with the OCTARAY-L3 catheter (1.64±0.57mV) was 32.3% greater than that with the PENTARAY catheter (1.24±0.46mV, p<.0001) in total left atrium. Low-voltage-area (<0.50mV) size with the OCTARAY-L3 catheter was smaller than that with the PENTARAY catheter (6.9±9.7vs. 11.4±13.0cm2 , p<.0001). The OCTARAY-L3 catheter demonstrated greater efficacy than the PENTARAY catheter in terms of shorter mapping time (606±99vs. 782±211s, p=.008) and more mapping points (3,026±838vs. 781±342 points, p<.0001). The OCTARAY catheter demonstrated higher voltage recordings, narrower low-voltage areas, and a more efficacious mapping procedure than the PENTARAY catheter.

The impact of sick sinus syndrome on flow velocity of the left atrial appendage in patients with atrial fibrillation

Abstract Background Sick sinus syndrome (SSS) itself has been suspected as one of potential embolic stroke sources, however, the mechanism remains unclear. Reduced flow velocity of left atrial appendage (LAAFV) plays a major role in thrombus formation in patients with atrial fibrillation (AF). We evaluated the contribution of SSS to LAAFV in patients with AF. Methods We studied 153 consecutive patients (age 69±10, 100 males, 79 paroxysmal AF, CHADS2 score 1.6±1.2) who underwent catheter ablation (CA) for AF at our hospital and our college of medicine. All patients enrolled in this study underwent transesophageal echocardiography (TEE) and transthoracic echocardiography prior to CA. LA global mean voltage and LA activation time were also measured using High-density LA mapping during CA. Clinical characteristics and laboratory data was obtained before CA for AF. SSS was defined as sinus arrest with 3 seconds or more by Holter ECG, or pacemaker implantation due to SSS. Results Reduced LAAFV was associated with old age (R²=0.0783, P=0.0005), female (R²=0.0260, P=0.0285), non-paroxysmal AF (R²=0.1403, P&amp;lt;0.0001), hypertension (R²=0.0226, P=0.0338), history of congestive heart failure (R²=0.0890, P=0.0007), high CHADS2 score (R²=0.1248, P&amp;lt;0.0001), high level of BNP (R²=0.2054, P&amp;lt;0.0001), AF rhythm during TEE (R²=0.1577, P&amp;lt;0.0001), low LV ejection fraction (R²=0.0255, P=0.0488), large LA diameter (R²=0.1544, P&amp;lt;0.0001), high E wave (R²=0.1168, P&amp;lt;0.0001), low LA global mean voltage (R²=0.1775, P&amp;lt;0.0001), long LA activation time (R²=0.1383, P&amp;lt;0.0001) and SSS (n=29, R²=0.0957, P=0.0002). On multiple linear regression analysis, SSS, AF rhythm during TEE, BNP, female was independently related to reduced LAAFV (Table). Conclusion SSS itself might be related to reduced LAAFV in patients with AF.Table

The Josephson junction as a quantum engine

We treat the Cooper pairs in the superconducting electrodes of a Josephson junction (JJ) as an open system, coupled via Andreev scattering to external baths of electrons. The disequilibrium between the baths generates the direct-current bias applied to the JJ. In the weak-coupling limit we obtain a Markovian master equation that provides a simple dynamical description consistent with the main features of the JJ, including the form of the current–voltage characteristic, its hysteresis, and the appearance under periodic voltage driving of discrete Shapiro steps. For small dissipation, our model also exhibits a self-oscillation of the JJ’s electrical dipole with frequency around mean voltage V. This self-oscillation, associated with ‘hidden attractors’ of the nonlinear equations of motion, explains the observed production of monochromatic radiation with frequency Ω and its harmonics. We argue that this picture of the JJ as a quantum engine resolves open questions about the Josephson effect as an irreversible process and could open new perspectives in quantum thermodynamics and in the theory of dynamical systems.

BIOLOGICAL PROFILE OF LOCALLY GROWN BANANA CULTIVARS AND THE CAPABILITY OF THEIR PSEUDOSTEM SAP AS AN ALTERNATIVE ELECTROLYTE FOR WET CELL

This study used the qualitative and quantitative experimental research design to establish the biological profile of the banana cultivars and the capability of their pseudostem sap as an alternative electrolyte for wet cell. Data were gathered by collecting banana sap and placing it in a 12-volt wet cell battery and observed at different time intervals. Mean, ANOVA, Duncan’s Multiple Range Test, LSD and pairwise comparison were used to determine significant differences between potential voltage and time interval. Bungulan, Lakatan, and Morado are derived from Musa Acuminata, while the Bulkan, Dippig, and Tordan are from the species of Musa Acuminata x Musa balbisiana. However, each cultivar is a member of a separate group, including the AABB, Cavendish subgroup of the AAA, AA, AAA, ABB, and AAB Group. The pH of the substrate is neutral, while the pH of newly harvested pseudostem sap turns acidic after 4 weeks of storage. The effects of the treatments, time interval, and their interactions produced a highly significant difference. The positive and negative control, and the six cultivars are statistically and significantly different from one another while Bungulan, Morado and Tordan cultivars are statistically the same. Week 1 had the highest voltage recorded and statistically the same mean voltages as in Weeks 2 and 4 with the lowest voltage seen in Week 3.The interaction of the sulfuric acid, distilled water, cultivars, and time interval yielded different voltage and are not statistically comparable. The pseudostem sap of the different banana cultivars contained in a 12-volt wet cell battery can lit the 5, 10 and 15-watts LED bulbs until the fourth week of storage.Using the pairwise comparisons, the treatments are statistically the same with one another. Hence, the banana pseudostem sap can be used as an alternative electrolyte for wet cell.

Effect of asymmetric proof mass and size-dependency in flexoelectric nanoharvester subjected to base and restraint forces

The piezoelectric and flexoelectric techniques are of great interest among the scientific fraternity, especially for the design of vibration-based micro/nano energy harvesters. The development of such energy harvesters in the micro/nanoscale has a huge potential, mostly in wireless networks and IoT-based applications. The present work thus formulates novel nanostructure-based analytical models of energy harvesters with asymmetric proof mass considering nonlocal flexoelectricity, geometrical nonlinearity, mid-plane stretching, harmonic base, and axially restraint forces. Using non-classical Euler-Bernoulli nanobeam and Hamilton’s principle, governing differential equation of motion has been derived. Analytical solutions have been obtained to compute the eigenfrequencies and subsequent modes of vibration concerning various systems’ physical and geometric variables. Nonlinear steady-state voltage and power characteristics thereafter have been investigated and studied their local stability and bifurcation for primary and sub-harmonic resonant conditions. The influences of performance factors associated with asymmetrically proof mass, nonlocal elasticity, and time-dependent base and restraint forces on the nonlinear voltage and power output using frequency characteristics criterion. These results have been validated with the findings using COMSOL-2D, and interestingly, mean voltage and power responses from linear models are found to be highly consistent with findings in COMSOL 2D. The present outcome shows how the asymmetric proof mass and nanoscale effect create disparities in harvesting energy performance and, simultaneously, how important their role is to avoid any undesirable structural instability. The present studies together can strengthen the significance of size-dependency and asymmetric proof mass while designing a nanoscale generator in the presence of harmonic excitation.

Harvesting Energy through Piezoelectric Tiles: A Comparative Study of Wood, Porcelain, and Ceramic Tiles

This study investigated the feasibility of using piezoelectric tiles in harvesting energy from the footsteps of people. The piezoelectric tiles were made of three materials, namely wood, porcelain, and ceramic tiles, where five piezoelectric plates were attached to each corner and center of individual tiles. A voltmeter was then attached to the piezoelectric tile system to determine the voltage output when people step on the tiles. Study findings revealed that the wood tile produced a mean voltage of 0.711V, the porcelain tile, 0.698V, and the ceramic tile, 1.018V. Analysis of variance results showed that there were significant voltage output differences among the three tiles, and the post-hoc analysis revealed that the voltage outputs of wood and porcelain tiles were comparable with one another, while the voltage output of ceramic tiles was the greatest among the three. The study concluded that the mechanical energy coming from the footsteps could be harvested using the piezoelectric tile, where mechanical energy could be converted into an electrical source. Furthermore, the researchers recommended having a wider variety of sample tiles to see the difference between the tiles and have a wider variety of data that could establish the positive results of this study.

Short-Circuit Protection Schemes for LVDC Microgrids Based on the Combination of Hybrid Circuit Breakers and Mechanical Breakers

In recent years, low-voltage direct current (LVDC) microgrids are becoming more attractive because they represent a solution to integrate renewable sources, storage, and electronic loads bringing some advantages in comparison with traditional AC grids. However, the protection of such a network involves many challenges, especially in the case of LVDC microgrids with more than one feeder and multiple energy sources. Indeed, the traditional protection breakers used for an AC grid cannot isolate the faults and protect the components of a DC grid, while the use of solid-state circuit breakers increases energy losses. This paper deals with the analysis and design of the protection schemes for LVDC microgrids through the combination of mechanical circuit breakers and hybrid circuit breakers. This solution has the advantage of energy loss reduction but introduces further issues due to the slow transition times of the mechanical circuit breakers. Thus, a completely decentralized control system capable of overcoming the fast fault-clearing time, cost-effectiveness, and selectivity issues is designed to protect from pole-to-pole faults. The proposed control strategy is compared with a centralized protection scheme available in the literature through numerical simulation. The two algorithms show similar performances, with a mean voltage dip duration of less than 30 ms and a maximum voltage dip duration of about 100 ms in the most severe fault condition, but the proposed solution is more reliable and flexible since it does not depend on the communication system.

A hybrid analytical and numerical model for cross-over and performance decay in a unit cell vanadium redox flow battery

Developing an accurate and efficient model for cross-over is critical for improving the long-term performance of redox flow batteries (RFBs). This work presents a hybrid analytical and numerical model that combines a two-dimensional analytical solution to the active species, a one-dimensional analytical model for cross-over mechanisms, and a zero-dimensional numerical model for outlet concentrations of reactants. By comparing with experiment over 41 cycles (ca. 144 h), the model reported a mean voltage difference of 0.0089 V, mean time difference of 14 s per cycle (of 3.5 h), maximum relative difference for capacity and energy of 1.34% and 1.63%, respectively. The predicted mean concentrations for V2+, V3+, and VO2+ in membrane are 65% ∼ 77% of measured values from the literature. Upon validation, the model reproduced behaviors in electrolyte imbalance similar to those observed in experiments and numerical models, and revealed the control of cross-over, self-discharge, stoichiometry of side reactions, and Coulombic efficiency on electrolyte imbalance. The model also demonstrates excellent computational efficiency for simulating 41 cycles (around 37,000 points) within 3 ∼ 4 s. The demonstrated efficiency and accuracy for predicting cross-over and its impacts on voltage, capacity&energy decay, membrane concentrations, and electrolyte imbalance makes it a reliable tool for optimizing RFBs’ long-term performance.

High-Precision Dead-Time Intellectual Property Core and Its Compensation for Inverters

In the inverter circuit, there exists a specific on-off time in each power transistor. As such, to prevent a short circuit of the two switch devices on the upper and lower bridge arms, a specific dead time must be set in the pulse width modulation (PWM) and the sinusoidal pulse width modulation (SPWM) signals. In this paper, an intellectual property (IP) core that can introduce a high-precision dead time of arbitrary length into PWM or SPWM signals of the inverter is designed to increase the precision, convenience and generalization of dead time control, resulting in a boosted control accuracy of up to 10 ns. Moreover, the added Avalon bus enables IP cores to be accessed by the field programmable gate array (FPGA) processor in a standard manner and multiple IP cores of the same class can be easily incorporated. In addition, an application for setting and compensating for dead time in a three-phase inverter based on system on programmable chip (SOPC) technology is presented. With the Nios II CPU as its core, the system adopts the mean voltage compensation method to calculate the compensation voltage, and performs dead-time compensation in a feed-forward manner. The three dead-time IP cores are controlled by Avalon bus. These allow the dead time of three groups of power transistors to be accurately controlled and flexibly adjusted. The system also features the master computer communication function while boasting the advantages of flexible control, high precision and low cost.

EEG Analysis for Images Encode and Retrieval under White Noise Stimulation

Utilization of an EEG machine aids researchers in detecting the brain responses and states during provided stimulation. The EEG comes with multiple electrode channels for recording the electrical activity of the brain. This work aims to discover the brain responses under stimulation of white noise during images encoding and retrieving using the EEG machine. The motivation of this research is because limited previous works determine the association between memory encoding and retrieving process based on EEG analysis. Twenty college students participated in this experimental work. They were required to remember the images in two different conditions: control/silent and exposure to white noise with two task difficulties: easy and difficult phases. The EEG was recorded during the remembering and recalling period for data acquisition. The obtained raw EEG dataset was imported to .txt format for further processing. The Butterworth bandpass filter with a frequency range of 4 to 45 Hz was applied to filter the low and high noise components in the EEG signal. Next, the mean of de-noise EEG voltage was obtained to select the most affected channels. It was found that the Fp1, Fp2, F7, and F3 channels achieved the highest mean voltage that higher than 5 μV. Therefore, these channels were selected for extraction of relative rhythm power to investigate the effect of white noise on memory performance. The findings showed that the alpha, gamma, beta, and theta activities were highly found during the encoding and retrieving process when participants were exposed to white noise. These brain rhythms were related to participants' attentional level, information processing and calm state during the assessment. The behavioral data showed that the participants successfully remembered the images more when exposed to white noise compared to the control condition with percentage differences of 21% and 33% for easy and difficult phases due to the stochastic resonance effect and activation of brain rhythms.

The omnipolar mapping technology-a new mapping tool to overcome "bipolar blindness" resulting in true high-density maps.

Omnipolar mapping (OT) is a novel tool to acquire omnipolar signals for electro-anatomical mapping, displaying true voltage and real-time wavefront direction and speed independent of catheter orientation. The aim was to analyze previously performed left atrial (LA) and left ventricular (LV) maps for differences using automated OT vs. standard bipolar settings (SD) and HD wave (HDW) algorithm. Previously obtained SD and HDW maps of the LA and LV using a 16-electrode, grid-shaped catheter were retrospectively analyzed by applying automated OT, comparing voltage, point density, pulmonary vein (PV) gaps, and LV scar area. In this analysis, 135 maps of 45 consecutive patients (30 treated for LA, 15 for LV arrhythmia) were included. Atrial maps revealed significantly higher point densities using OT (21471) vs. SD (6682) or HDW (12189, p < 0.001). Mean voltage was significantly higher using OT (0.75 mV) vs. SD (0.61 mV) or HDW (0.64 mV, p < 0.001). OT maps detected significantly more PV gaps per patient vs. SD (4 vs. 2), p = 0.001. In LV maps, OT revealed significantly higher point densities (25951) vs. SD (8582) and HDW (17071), p < 0.001. Mean voltage was significantly higher for OT (1.49 mV) vs. SD (1.19 mV) and HDW (1.2 mV), p < 0.001. Detected scar area was significantly smaller using OT (25.3%) vs. SD (33.9%, p < 0.001). OT mapping leads to significantly different substrate display, map density, voltage, detection of PV gaps, and scar size, compared to SD and HDW in LA and LV procedures. Successful CA might be facilitated due to true HD maps.

The Omnipolar Mapping Technology - a new mapping tool to overcome bipolar blindness resulting in true high-density maps

Abstract Funding Acknowledgements Type of funding sources: None. Background Mapping, using the novel omnipolar technology (OT) obtains omnipolar signals displaying true voltage, real-time wavefront direction and speed, independent of catheter orientation and external reference. Employment of OT potentially overcomes so called "bipolar blindness" (conventional bipolar electroanatomic mapping). Hence, OT potentially improves substrate assessment, comprehension of tachycardia mechanisms and gap detection after previous catheter ablation (CA). Purpose Purposes of our study was to analyze previously performed left atrial (LA) and left ventricular (LV) maps for differences using automated OT vs. SD vs. the previously published HD Wave (HDW) algorithm. Methods Maps of patients undergoing CA for atrial or ventricular arrhythmia were initially acquired using HDW settings in conjunction with the Advisor HD Grid mapping catheter. These maps were then analyzed retrospectively applying the automated OT algorithm vs. SD vs. HDW. to reveal differences in voltage and point density. Additionally, detection of pulmonary vein (PV) gaps and LV scar area was evaluated. Results In 45 consecutive patients 135 maps were analyzed. The study population undergoing CA consisted of: 30 (22.2%) patients undergoing repeated CA for recurrence of persistent atrial fibrillation (persAF)/left atrial tachycardia (AT) and 15 (11.1%) patients with ventricular tachycardia (VT) or premature ventricular contractions (PVC). Atrial maps revealed a significantly higher point density using OT (21471) vs. SD (6682) or HDW (12189, p&amp;lt;0.001). Mean voltage was significantly higher using OT (0.75mV) vs. SD (0.61mV) or HDW (0.64mV, p&amp;lt;0.001). OT maps detected significantly more PV gaps vs. SD (4 vs. 2, p=0.001). In LV maps, OT revealed a significantly higher point density (25951) vs. SD (8582) and HDW (17071), p&amp;lt;0.001. Mean voltage was significantly higher for OT (1.49mV) vs. SD (1.19mV) and HDW (1.2mV), p&amp;lt;0.001. Detected scar area was significantly smaller using OT (25.3%) vs. SD (33.9%, p&amp;lt;0.001). Conclusion Using OT results in a higher voltage and point density compared to SD and HDW. Therefore displayed scar extend is significantly smaller in atrial and ventricular maps. Also, more PV gaps were detected using OT. The OT algorithm potentially improves scar delineation, facilitates substrate characterization, and may improve procedural outcome.

Systematic identification of low voltage-high frequency electrogram zones at sites of left atrial reentrant tachycardia termination

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Abbott Laboratories Background Localization of the critical isthmus of conduction of LAMRT circuits within scar tissue is challenging (Panel A). Low voltage (LV) has been used as a marker for the arrhythmic substrate. However, voltage amplitudes due to near field (NF) vs. far-field (FF) electrogram (EGM) components are not clearly differentiated. The peak frequency (PF) associated with bipolar EGM’s is a novel parameter which may distinguish them (Panel B). Purpose To compare the ability of LV vs. LVHF to discriminate the LAMRT termination region Methods Bipolar voltage and activation maps were generated with a 16-pole grid catheter (Advisor HD Grid) during LAMRT (Panels A,C). Peak frequency maps were retrospectively computed (Panels B,D). LAMRT’s were included if acute termination could be achieved by focal RF lesion set restricted to a boundary &amp;lt;1.5cm diameter. The left atrial (LA) mapped surface was sub-regioned into the termination (T-ZONE) and non-termination (NT-ZONE) zones. The T-ZONE surface was centered about the site of termination and was allowed to extend to a rectangular kernel &amp;gt;0.5cm and &amp;lt;1.5cm across perpendicular axes, with the NT-ZONE encompassing the remainder of the mapped surface area (SA). Sensitivity (SE) and specificity (SP) of discrimination of the T-ZONE vs. NT-ZONE was measured according to the %T-ZONE vs. %NT-ZONE SA occupied at LV thresholds ranging from 0.1-1.0mV in increments of 0.1mV (Panel E). In addition to LV, LVHF at peak frequency cutoffs of 150Hz (LVHF150), 200Hz (LVHF200), 250Hz (LVHF250) and 300Hz (LVHF300) were also assessed for T-ZONE discrimination (Panels F,G). Results Of 16 consecutive patients with 24 ATs prospectively enrolled, 13 LAMRT’s from 13 patients met the termination criteria for inclusion. LAMRT termination consisted of a mean of 2.85±2.82 focal RF lesions. The T-ZONE occupied a mean SA of 0.82±0.30cm2 (41±19 EGM points) vs. 158.6±42.2cm2 (2967±1227 points) for the NT-ZONE. While the mean voltage from the T-ZONE was significantly lower vs. the NT-Zone (0.12±0.05mV vs. 0.60±0.28mV respectively), mean T-ZONE peak frequency of the was significantly higher vs. the NT-ZONE (345±76Hz vs. 255±34Hz). The maximum EGM duration in the T-ZONE was 172±63ms. ROC discrimination of the T-ZONE resulted in AUC’s of 0.69- LV, 0.76- LVHF150, 0.80- LVHF200, 0.81- LVHF250 and 0.76- LVHF300. LVHF200 and LVHF250 yielded the best improvements in AUC vs. LV unconstrained by high PF (11.3% and 12.2% respectively)(Panel G). LVHF200 with a cutoff of 0.2mV yielded a balanced SE/SP of 0.86/0.83 respectively, while LVHF250 with a cutoff of 0.3mV yielded a balanced SE/SP of 0.85/0.84. Conclusion During AT, systematic identification of EGM regions of high frequency within low voltage can significantly improve discrimination of the site of AT. termination, beyond.

The relationship between high dominant frequency and low voltage areas in patients with atrial fibrillation: digital twin study

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): a grant [2022R1I1A1A0106342211] from the Basic Science Research Program run by the National Research Foundation of Korea (NRF) which is funded by the Ministry of Science, ICT &amp; Future Planning (MSIP) Background It has been suggested that the high dominant frequency (DF) site plays an atrial fibrillation (AF) driver, but its relationship with the atrial substrate voltage map (Vm) in the entire chamber AF map has yet to be studied. We explored the relationship between the DF site during AF and Vm in the entire chamber maps by applying the human left atrial (LA) electroanatomical map (EAM) to the digital twin AF map. Methods We acquired LA substrate Vm (at sinus rhythm, &amp;gt;800 points bipolar electrograms) of 110 patients with persistent AF (male 72.7%, 58.7±9.8 years old) who underwent AF catheter ablation. We applied EAM to digital twins (0.4 million nodes), reflecting anatomy, histology, and electrophysiology. We evaluated the highest 10% DF areas for 6 sec after inducing virtual AF. The correlation between the highest 10% DF and the low Vm areas (&amp;lt;0.2mV) was evaluated in the LA region of 10 segments. Results The mean voltage of the entire LA area was 1.96±0.85 mV (2.19±0.82 mV extra-PV area, 1.33±0.93 mV PV area) in 110 patients. The correlation between low Vm and high DF areas was not significant in the entire LA (r=0.106, p&amp;lt;0.001), extra-PV (r=0.157, p&amp;lt;0.001), and PV (r=0.079, p=0.097) areas. In the LA 10 segment regional analysis, 72 patients (65.5%) showed the co-localization of the highest DF in the region with the lowest Vm, and 14 patients (12.7%) had the lowest Vm segment in the region with the highest DF. The mean voltage where high DF appeared was 0.69±1.35 mV, and the mean voltage of the region where high DF did not appear was 0.59±1.15 mV (p=0.171). Conclusion High DF site, a parameter representing a localized focal source, had statistically significant but very poor correlations with LA extra-PV voltage substrate in patients with persistent AF.

Identification of the fossa ovalis by voltage mapping using a high-density mapping catheter

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Transseptal puncture (TP) is routinely performed under fluoroscopy and/or echocardiography guidance. Additional methods to localize the fossa ovalis (FO) may decrease radiation exposure, as well as periprocedural risk. In the recent years, high-density mapping (HDM) catheters have been used for mapping and ablation of left atrial (LA) arrhythmias. Purpose The aim of this study is to determine whether a HDM catheter can reliably identify the specific FO electrogram (EGM) patterns. Methods During atrial fibrillation (AF) ablation, a voltage map of the right-sided atrial septum was created using a HDM catheter (Pentaray, Biosense Webster, USA, spacing 2-6-2 mm). The location of the FO was identified by transesophageal echocardiogram and fluoroscopy guidance prior to TP. At the end of the procedure, a 3D phantom was created during catheter retrieval from the left to the right atrium through the TP. Post ablation analysis was done to evaluate whether the HDM catheter was able to record EGM characteristics of the FO. Results Fifteen patients were included (male 63%, mean age 61.2±11.7 y. o.); 80% of the cases were in sinus rhythm, 53% had a normal LA size, and the mean CHADS2-VA2SC score was 1.5 ± 1.6. One patent fossa ovalis and one septal pouch of the left atrium were seen. In all patients, an area of low voltage could be identified in the vicinity of the transseptal puncture. In 74%, the location of transseptal puncture was inside of the area of low voltage. The mean voltage value of this area was 0.6 ± 0.3 mV, whereas the mean voltage value of the myocardium surrounding the "low voltage area" was 4.3 ± 2.1 mV (P&amp;lt;0.01). The surface of the low voltage could be best demarcated using a scale from 0.05 -1.5 mV with an area measured at 3.8 ± 2.6 cm2 [Figure 1]. At other voltage scales, the FO surface demonstrated smaller areas of low voltage (scale/surface [mV/cm2] : 0.05-0.5/ 0.8 ± 1.3; 0.05-1.0/2.2 ± 1.8; 0.5-1.0/2.3±1.6). In 63%, fractionated potentials were recorded in the area of the FO [Figure 1]. Conclusions Based on its EGM characteristics, the fossa ovalis can be accurately localized with a high-density mapping catheter. This finding will certainly help to implement radiation free procedure particularly when echocardiographic modalities are not available. Figure 1: Mapping of the region of the fossa ovalis with a high density mapping catheter revealed an area of low voltage with fractionnated electrogram. Fossa ovalis was identified by transseptal puncture. TP: phantom of the catheters, CS: coronary sinus, H: His, IVC: inferior vena cava, SVC: superior vena cava, * fractionnated electrogram

Anatomical and electrophysiological factors involved in atrial cardiomyopathy identify remodeling discrepancies between paroxysmal and persistent atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Progressive atrial fibrotic remodeling has been reported to be associated with atrial cardiomyopathy and the transition from paroxysmal to persistent atrial fibrillation(AF). We sought to identify the anatomical and electrophysiological factors involved in atrial remodeling that promote AF persistency. Methods Consecutive patients with paroxysmal(n=134) or persistent(n=136) AF who presented for their first AF ablation procedure were included. Patients underwent high-definition mapping (1835 ± 421 sites/map) during sinus rhythm and were randomized to training and validation sets for model development and evaluation. A total of 62 parameters from both electro-anatomical left atrial(LA) mapping and non-invasive baseline data were extracted encompassing four main categories: (1)LA size, (2)extent of low-voltage-substrate(LVS), (3)LA voltages and (4)bi-atrial conduction time as identified by the duration of amplified P-wave(APWD) in a digital 12-lead-ECG. Least absolute shrinkage and selection operator(LASSO) and logistic regression were performed to identify the factors that are most relevant to AF persistency in each category alone and all categories combined. The performance of the developed models for diagnosis of AF persistency was validated regarding discrimination, calibration and clinical usefulness. Results In training and validation sets, APWD (threshold 151ms), LA volume (threshold 94ml), bipolar LVS area &amp;lt;1.0 mV (threshold 4.55cm2) and LA global mean voltage (GMV, threshold 1.66mV) were identified as best determinants for AF persistency in the respective category. Moreover, APWD (AUC 0.851 and 0.801) and LA volume (AUC 0.788 and 0.741) achieved better discrimination than LVS extent (AUC 0.783 and 0.682) and GMV (AUC 0.751 and 0.707). The integrated model (combining APWD and LAV, which were identified after selection among all 62 parameters) yielded the best discrimination performance between AF types (AUC 0.876 in training set and 0.830 in validation set). The calibration performance and clinical usefulness were also superior in APWD and LAV. Conclusion Among 62 electro-anatomical parameters, we identified APWD, LA volume, LVS extent and mean LA voltage as the four determinant electrophysiological and anatomical factors that are most indicative for AF persistency. Notably, the combination of APWD with LA volume enabled discrimination between paroxysmal and persistent AF with high accuracy, emphasizing their importance as underlying substrate of persistent AF.

Progression and regression in the left atrial substrate in patients with atrial fibrillation: the PROGRESS-AF study

Abstract Funding Acknowledgements Type of funding sources: None. Background Progression or regression of the atrial substrate in atrial fibrillation (AF) has been demonstrated in animal models and human right atrial maps. Dynamic changes over time of the left atrial (LA) substrate in patients with AF have not been evaluated in detail yet. Purpose To evaluate changes of the LA substrate between first and redo AF ablation procedures. Methods In our prospective single center observational study, consecutive patients undergoing first and redo AF ablation during sinus rhythm were included. The LA was divided into anterior, septal, lateral and inferior regions. The veins and posterior segments were excluded from the analysis. In each segment median voltages and area % of spontaneous low voltage zone (LVZ) of the LA (&amp;lt;0.5 mV) were measured and compared between first and second procedure in each patient. Progression/Regression was diagnosed if a significant concordant decrease/increase in the median voltage in at least two regions was observed, respectively. Results In the first procedure 34.055 (1.216 points/patient) and in the second 76.958 (2.748 points/patient) points were analyzed in 28 patients (age: 61.2±9.5 years, 39% female, 39% persistent AF). The time between first and second procedure was 1.2 (0.4-2.3) years. Eleven (39%) patients had spontaneous &amp;gt;5% LVZ at both first and second procedure (p=1). In 17 (60%) patients progression was identified; in 5 patients in all 4 segments, in 8 in 3 and in 4 in 2. In the Progression group the total mean LA voltage (1.28±1.30 vs. 0.76±0.71 mV, p&amp;lt;0.001) and the regional mean voltage in all atrial regions decreased significantly: anterior: 0.80±0.76 vs. 0.52±0.51, p&amp;lt;0.001; septal: 1.04±0.94 vs. 0.68±0.57,p&amp;lt;0.001; lateral: 1.71±1.60 vs. 1.04±1.01, p&amp;lt;0.001; and inferior 1.69±1.58 vs. 0.80±0.62, p&amp;lt;0.001. The % LVZ increased not significantly: 6.3±9.5% vs. 9.8±10.1%, p=0.3. In 11 (40%) patients regression was observed (in 3 patients in 3 regions and in 8 in 2). In the Regression group the total mean LA voltage (1.47±1.35 vs. 1.89±1.56, p&amp;lt;0.001) and the regional mean voltage in all but one atrial regions increased significantly: anterior: 1.60±1.55 vs. 1.84±1.58, p=0.001; lateral: 1.59±1.26 vs. 2.59±1.81, p&amp;lt;0.001; inferior: 1.29±1.10 vs. 1.84±1.33, p&amp;lt;0.001; and septal: 1.36±1.43 vs. 1.25±1.18, p=0.06. The % LVZ decreased not significantly (8.6±9.5% vs. 4.1±10.1%, p=0.1). There was no significant difference in any baseline clinical or echocardiographic parameter between the Progression and Regression group. Conclusions Our preliminary study is the first to report bidirectional dynamic properties of the LA substrate with concordant either progressive or regressive changes of atrial voltage in different atrial regions outside of the PVs following AF ablation. A better understanding of the dynamic changes of the LA substrate could help to differentiate between patients with reversible and despite ablation therapy progressive irreversible atrial structural remodeling.

Pattern of EEG voltage and oscillations under stimulation of Mozart’s music and white noise for visual learning process

The focus on behavioural data as a prominent indicator for evaluating the effect of stimulation on human cognitive function neglects the understanding of the body’s physiological responses. Another remain limitation is the physiological features usually analyzed from learning encode databases. Hence, the current research objectively investigates the correlation of EEG voltage and oscillations pattern from visual learning encoding and recognition stages under stimulation of various circumstances based on EEG patterns with behavioural data. The acquired EEG signal from visual assessment under no-audio and audio circumstances was processed using the Daubhecies wavelet function. The most affected EEG channels were identified according to the peak mean voltage from each electrode channel. The statistical features of mean, standard deviation, peak amplitude, and relative power were obtained from brain rhythms. The evaluation showed that the most affected EEG channel was at the Fp2 electrode with a voltage of about 0.1 V. It was related to the state of subjects that were required to identify the symbol and position of provided assessment. Most EEG features gained the highest value for recognition than the encoding stage, especially the relative power showed a statistically significant value with a p-value < 0.05. This revealed that brain oscillations were higher during recognition than encoding because the brain needed to work hard to retrieve the stored visual information. The behavioural data were parallel and in line with EEG rhythms pattern, where the highest brain oscillation led to better visual score performance. Throughout the evaluation, it was found that the EEG voltage and rhythms pattern during encoding were correlated with recognition and behavioural data.

PO-03-119 ATRIAL SUBSTRATE CAN BE ASSESSED DURING PACING INSTEAD OF SINUS RHYTHM? – ADVANTAGE AND LIMITATION OF SINUS-NODE PACING MAP-

Atrial pacing (AP) is frequently used instead of sinus rhythm (SR) during substrate mapping to save time with stable pacing rhythm. However, the effect of pacing on atrial substrates such as activation, voltages and frequency of electrograms has not been systematically examined. We aimed to elucidate the advantage and limitation of AP-map. In patients who underwent catheter ablation for atrial fibrillation, atrial substrate maps of left atrium were created after the ablation during SR, AP with the cycle length of 300ms (AP300) and AP with the cycle length of 600ms (AP600) with a HD grid catheter using the Ensite X mapping system. AP was performed from high right atrium around sinus node with a spot catheter. Mapping time, the number of acquired electrograms points, mean omnipolar voltage of electrograms, and mean peak frequency of electrograms were compared among created maps. The pattern of activation in left atrium was also analyzed in each map. A total of 60 left atrium maps were created in 20 patients. The summary of the results is shown in the figure. The figure also exhibits voltage maps and peak frequency maps during SR, AP600, and AP300 of a representative case. When compared with during SR, mapping time was significantly reduced and mean voltage and mean peak frequency of electrograms significantly decreased during AP600. Moreover, mapping time was much shorter and mean peak-frequency of electrograms was much lower during AP300. The number of acquired electrogram points was significantly higher during AP300 compared with SR. Mean voltage of electrograms became significantly lower during AP300 compared with SR. Left atrial activation pattern during SR and that during AP were almost the same (Each wave front collided around the 4 o’clock or 5 o’clock of mitral annulus in all maps). Although AP-map allowed us to acquire higher-resolution maps in shorter time without changing activation pattern, amplitude and frequency of electrograms may be reduced as the cycle length of AP becomes shorter.

PO-02-003 IDENTIFICATION OF AREAS OF ANISOTROPIC CONDUCTION USING OMNIPOLAR TECHNOLOGY TO PREDICT FIRST-PASS ISOLATION AND RECONNECTION OF THE POSTERIOR WALL

Posterior wall isolation (PWI) can be a useful adjunct to pulmonary vein isolation (PVI) for the management of persistent atrial fibrillation (AF). Successful isolation of the posterior wall is challenging, with first-pass isolation rates under 40%. Difficulties in achieving block may be due to inability to create transmural lesions due to complex posterior wall architecture from septopulmonary (SPB) and septoatrial (SAB) bundle insertion. Activation mapping using omnipolar technology (OT) may allow identification of areas of anisotropic conduction that represent atrial fiber and bundle insertion points to target for additional ablation. Correlate areas of anisotropy to first-pass isolation of the posterior wall and determine whether anisotropy can predict sites requiring additional ablation to achieve bidirectional block We retrospectively analyzed patients with persistent AF who underwent first-time PVI with PWI from November 2020 to December 2022 at a single tertiary referral center with using the EnSite X mapping system with OT (Abbott, IL). Demographic and procedural information was collected. The posterior wall was divided into 6 regions and areas of anisotropy, defined as an abrupt pivot or collision in OT vectors, along with mean and maximum bipolar voltage were recorded. Areas requiring additional ablation to achieve bidirectional block were recorded. 17 patients were included in our cohort, of which 5 had first-pass isolation (29%). Final isolation of the posterior wall was achieved in all cases. There were no significant differences in patient demographics. Total ablation times were significantly less in the first-pass group (2174 versus 1721 seconds, p = 0.035). Anisotropic areas were present in 80% of first-pass cases versus 75% of cases without first-pass. While overall PW voltage was similar in both groups, voltage at sites of anisotropy was significantly higher in patients without first-pass (6.8 vs 2.6, p = 0.024). In patients without first-pass, reconnection was at site of anisotropy in 50% of cases with mean bipolar voltage 7.4mV. Activation mapping using OT may help identify areas of anisotropic conduction that are common sites of epicardial connections. Targeting these areas with additional ablation may improve rates of first-pass isolation and reduce rates of chronic reconnection. Further investigation and a larger cohort is needed to validate the predictive utility of OT.