Density Maps Research Articles

Electrophysiological assessment of atrial tachycardia substrates in patients with repaired tetralogy of Fallot

Abstract Introduction Adults with repaired tetralogy of Fallot (rToF) are most often referred to Adult Congenital Heart Disease centers for atrial tachycardia (AT) and radiofrequency catheter ablation (RFCA) is often required. A systematic evaluation of the mechanisms and recurrences of arrhythmias in these patients is lacking. Methods 28 patients with rToF referred for catheter ablation to the Interventional Electrophysiology Unit of our center between January 2013 and January 2023 were evaluated. Pts underwent electrophysiologic study (EPS) with 3D electroanatomic high density mapping. Evaluation of right atrial bipolar voltage and activation mapping of the AT was performed. Intra-atrial re-entrant tachycardias (IART), focal AT (FAT), other. Activation mapping was performed to identify the critical isthmus for IART. FATs were localized according to the earliest unipolar signal. Whenever possible, all the induced tachycardias were treated besides the arrhythmia which represented the clinical indication to EPS. RFCA was aimed at the earliest activation point for FAT and at the critical isthmus for IART, anchoring lesion to fixed obstacles (valve annuli or atriotomy scar). All patients provided written informed consent for participating in the study. Results Among 28 adult (age 47±13 years) patients (females n=14, 50%), 53 AT were documented: 34 (64%) IART, 11 (21%) FAT and 8 (15%) atrial fibrillation (AF). Mean tachycardia cycle length (excluding AF) was 307±95 ms. At least 2 ATs were induced in 12 pts during index EPS. Among IARTs, incisional IART (IARTinc, atriotomy and superior and inferior vena cava orifices, SVC and IVC, respectively) was the prevalent critical part of the circuit (n=22, 52%), while CTI was the second mechanism (n=20, 48%). In three pts, due to non-inducibility, a pre-emptive lesion set comprising in one case CTI and in two cases CTI+SVC-atriotomy-IVC line was performed. 2 patient underwent scheduled pulmonary veins isolation and CTI ablation. Among FAT, in 3 cases the AT was mapped in the coronary sinus, in two at the tricuspid annulus, in the remaining at the crista terminalis, at the right appendage base, at the posterolateral incision scar or between atriotomy and SVC. In 6 patients AF was induced but not ablated. During a median follow up of 23 months (interquartile range, 6-37) recurrence occurred in 8 pts (18% of pts, 15% of tachycardias). Patients with recurrences were younger (43±7 vs. 48±17 y, p=0.04); no differences were found according to critical isthmus location (4 CTI and 4 IARTinc, 50%, p=ns). Conclusions Among rToF pts with AT, IART is the prevalent mechanism and atriotomy scar is the prevalent critical isthmus. FAT location is much more variable. Atrial fibrillation burden is not negligible. Long-term freedom from AT in this clinical setting is encouraging.

A novel method to identify critical isthmus of right atrial reentrant tachycardia; Functional substrate mapping characteristics during sinus rhythm

Abstract Background Right atrial tachycardia (AT) is a frequent rhythm disorder in patients with atrial scar mainly due to surgical incisions or congenital heart diseases. Despite the mounting evidence about AT mechanisms and types, data is scarce regarding the conduction properties as well as functional characteristics of atrial substrate during sinus rhythm that has role in the maintenance of the tachycardia. Purpose We sought to evaluate the relationship between the functional substrate mapping (FSM) characteristics of right atrium and the critical isthmus (CI) of re-entrant ATs in patients with underlying atrial scar. Methods Among patients with the history of right AT who underwent catheter ablation with 3-D mapping were retrospectively enrolled. Voltage map and isochronal late activation mapping (ILAM) were created during sinus / paced rhythm using multielectrode catheters to detect deceleration zones (DZ). Subsequently AT was induced with programmed stimulation and activation mapping was performed to detect CI of the tachycardia. Atrial tachyarrhythmia (ATa) recurrence was defined as detection of atrial fibrillation or AT (≥ 30 s) during the follow-up. Results A total of 24 patients [mean age: 46 ±15, gender: 13 (54 %) female] with right AT were included. A total of 37 ATs were mapped [16 (43.2%); localized reentry, 21 (56.7%), macroreentry]. Atrial low voltage zones comprised 23.3 ± 13.0 % of total right atrium. The mean value of bipolar voltage, EGM duration and conduction velocity during sinus rhythm corresponding to CI of ATs were 0.18 ± 0.10 mV, 121.7 ± 29.4 ms, 0.06 ± 0.04 m/s and, respectively. Total number of DZs per chamber was 1.1 ± 0.3, which were all located in the low-voltage zone (<0.5 mV) detected by high density mapping. All CIs of non- cavo-tricuspid-isthmus (CTI) dependent reentry were colocalized with DZs detected during FSM. The positive predictive value of DZs to detect CI of inducible ATs is 80.8%. During the mean follow-up of 11.7 ± 8.1 months, freedom from ATa was 87.5%. Conclusion Although, CTI-dependent macroreentry is the most common mechanism in patients with RA scar, our findings demonstrated the relevance of FSM to predict non-CTI dependent ATs. Conduction slowing manifested as DZs with continuous-fragmented signal morphology may guide to tailor ablation strategy in case of underlying RA scar.

Local impedance drop as a predictor of sucessful pulmonary vein isolation

Abstract 1. Introduction Pulmonary vein isolation (PVI) is the cornerstone of AF treatment. An accurate estimation of the lesion size and a optimal evaluation of the catheter-myocardium coupling is crucial for achieving an effective and safe radiofrequency (RF) ablation. A few studies have suggested that local impedance (LI) drop is a better predictor than general impedance drop in terms of lesion size, electrical coupling and therefore acute PVI success. An open-irrigated ablation catheter designed to measure contact force (CF) and LI drop while applying RF has been recently developed. 2. Purpose The aim of this study is to evaluate if conduction GAPS are located in certain areas and if LI drop can predict the presence of conduction gaps in each of these segments. 3. Methods Observational prospective study including 55 consecutive patients who underwent PVI. The RF lesions were delivered with 30 W (posterior wall) or 35 W (anterior wall) for a maximum of 30 seg with a CF > 5 g. The applications were stopped if a LI of 35 Ohm was reached on the posterior wall or 40 Ohm on the anterior wall. PVs were divided into seven segments and ablation tags were assigned to a segment according to their anatomical position (figure 1) We categorized the tags included in each segment as successful or not according to the presence of conduction gaps detected with an Ultrahigh density mapping catheter once the WACA was completed. At the same time lesion by lesion were studied regardless of the segment where it was located. 4. Results We analyzed 4002 lesion tags of 55 patients who underwent PVI. 53 Gaps were found in 19/55 (34.5%) left WACA and 16/54 (29,6%) right WACA and were localized predominantly in three PVI segments (L1, L6 and R3) 34(54.85%) vs 19 (35,8%) (L2-L5, L7, R1-R2, R4-R7) (p<0.001) (figure 1). They were mainly circumscribed to anterior segments in left PVs and posterior-superior segment in right PVs (figure1). When examining lesions independently of their location we found a significant difference in LI drop among successful and unsuccessful lesions (24.22±8.31 vs 15.67±7.85) Ohm, p<0.001). In the same line when studying lesions in those segments with > 10% of GAPS (L1, L6 R1 and R3) LI drop was greater in successful lesion tags: L1 25.2 ± 5.35 vs 16.8 ± 5.17 (p<0.001), L6 25.2±5.7 vs 16±5.48 (p<0.001), R1 27.9±4.78 vs 17.1±5.73 (p=0.03) and R3 18.5±5.4 vs 10.7±2.49 (p<0.001). 5. Conclusions Gaps were located predominantly in anterior segments in left PVs and posterior-superior segment in right PVs. A low LI drop was an excellent predictor of conduction gaps, and it performs well regardless of the segment where it was analyzedFig. 1

Focal pulsed field ablation in complex cases of atrial tachycardia - feasibility, outcome and safety of a novel technology

Abstract Introduction The importance of pulsed-field ablation (PFA) is rising in the field of catheter ablation. Nevertheless, the use of a single-shot devices is limited to pulmonary vein isolation (PVI). Thus, significance of technologies implementing point-by-point PFA is growing. A commercially available system uses radiofrequency (RF) catheters in combination with a PFA-generator. Data on the use is sparse, especially for treating atrial tachycardia (AT). The aim of this study was to evaluate feasibility, safety and mid-term outcomes of point-by-point PFA in complex cases of AT. Methods All consecutive patients treated with a focal PFA-catheter (N = 34) suffering from AT were included. A high density map was created in all patients. Established RF catheters were employed as PFA catheters with the PFA generator. Except for the ablation generator, the standard setting at our clinic for ablation of AT was not changed. In case of sinus rhythm at the beginning, burst stimulation was performed in order to induce the clinical AT. Acute procedure success was defined as creation of ablation lesions preventing the mechanism of the clinical tachycardia and/or non-inducibility of the clinical AT. Outcome and safety was evaluated during the hospital stay and visits at our outpatient clinic, including 7d-Holter-ECG. Results In all 34 included patients, acute procedure success was achieved. Baseline characteristics are listed in table 1. In average, patients had 1,21 ± 0,88 ablations before, 67,6% of patients had linear lesions in the past. Mean procedure duration was 102,7 ± 30,3 min, the LA dwell time was 75,0 ± 24,7 min (table 2). Any desired lesion set was accomplished (pulmonary vein isolation, linear lesions or ablation of focal AT/localized reentry) with the focal PFA technology. Linear lesions were ablated in 32 (94,1%) patients, while a pulmonary vein isolation was performed in 12 patients (35,3%). Ablation of localized reentries was necessary in two patients (5,9%). In total, 51 linear lesions were created: 27 anterior lines, 18 roof lines, 5 CTI-lines and one posterior box; bidirectional block was proven in all cases. Furthermore, three patients suffered a macro-reentry due to reconnected pulmonary veins. The site of termination of the tachycardia is shown in Figure 1. No procedure-related minor or major complications occurred (no groin complications, no stroke, no pericardial tamponade). After a mean follow-up of 179,4 ± 107,8 days, 8 patients (23,5%) suffered a recurrence of any atrial arrhythmia. Conclusion Applying focal PFA with well-known radiofrequency ablation catheters is safe and efficient, also in cases of atrial tachycardia. The integration of the new system into clinical practice is feasible and did not prolong the procedures. Acute procedure success was achieved in all cases. For further evaluation of efficacy and safety, a control group of patients treated with radiofrequency or a randomized trial is needed.

Characterization of conduction recovery and atrial electrophysiological properties after pulmonary vein isolation using pulsed field ablation

Abstract Background Pulsed field ablation (PFA) is a relatively new technology for isolation of pulmonary veins in patients with atrial fibrillation (AF). Data addressing reasons for recurrent atrial fibrillation despite primarily successful pulmonary vein isolation (PVI) using PFA are scarce, due to an up to date limited number of patients treated this way. Objective The aim of this study was to analyze electrophysiological characteristics of reconduction and / or left atrial substrate of patients referred to our center for Re-Do procedures for recurrent AF after an initial PVI using PFA. Methods 90 patients (mean age 66±9 years, 69 male (77%)) had been treated in our center from November 2021 to July 2023 with PVI using PFA. 9 (10%) of these patients were referred for Re-Do procedures. These were performed by radiofrequency ablation (RFA) using Carto system including high density mapping and high power / short duration (HPSD) ablation. We analyzed location of PV reconnection and low voltage areas (LVA) in the left atria. Results 7 out of 9 patients (77%) presented with reconnections of pulmonary veins. In one patient a single vein showed reconduction (RSPV), in 5 patients 2 veins were conducting (1x LSPV, 3x LIPV, 1 left sided common os (LCo), 1x RSPV, 3x RIPV). None of the patients showed 3 or 4 reconnected veins. Areas of reconduction in each vein were: LSPV 1x ridge, 1x posterior; LIPV 1x posterior, 1x anterior and posterior; LCo 1x posterior, RSPV 1x anterior, 2x carina, 1x anterior and posterior; RIPV 1x complete, 2x carina. In 7 patients a fibrotic atrial cardiomyopathy (FACM) was diagnosed via high density mapping of LVA’s. In 2 of these patients all 4 pulmonary veins were chronically isolated after the initial PVI. All patients except one (very small anterior LVA) with FACM ≥1 were treated with additional linear or encircling lesions according to the individual extent of the fibrotic areas. 2 patients had no LVA’s detectable. In one of those 2 patients 2 veins had reconnected. The other patient had chronically isolated veins (no proof of dormant conduction with adenosine) and no detectable non-PV-triggers under isoprenaline. Conclusion In the population of patients undergoing PVI using PFA in our center, only 10% had clinically relevant recurrences leading to the necessity of a Re-Do procedure. Most patients (77%) in this setting had reconnections of pulmonary veins. There is a tendency of posterior reconnections of the left pulmonary veins and reconnections of the carina of the right pulmonary veins, but the number of patients is too small to clearly define predilection sites that have to be paid attention to when using PFA. Additionally, left atrial substrate is an important problem in patients with recurrent AF despite primarily successful PVI and has to be considered and thoroughly addressed in Re-Do procedures.Reconnection of LSPV and anterior LVAAblation of RSPV and LSPV (posterior)

Localization of ganglionated plexi by high density mapping: an atropine-response analysis

Abstract Introduction Growing interest has emerged around cardiac autonomic nervous system driven by ablation approaches for the treatment of neurally-mediated syncope (NMS). Ganglionated-plexi (GPs) located in the epicardial fat pads are the main target of ablative therapies, but little is known about the finest method to track their location from the endocardium. Most current techniques rely on empirical research of signal fragmentation and/or vagal response at anatomical landmarks. A poor accuracy in targeting GPs may lead to the risk of incomplete or over-extensive ablation. Purpose We analyzed the atrial electrograms (EGMs) in healty subjects and their response to atropine to describe physiological fragmentation and the relationship with vagal output. Methods Study partecipants were selected from young patients without structural heart desease who underwent electrophysiological study (EPS) for standard indications. High-density mapping of right atrium was performed before and after administration of 2 mg atropine at the end of the planned procedure. Offline analyses were performed comparing the two maps of each patient focusing on the fragmentation of the atrial EGMs. Results The study cohort comprised 10 patients (mean age of 39±11 years, 6 males). The indication for EPS was: supraventricular tachycardia (SVT) ablation in 9 patients, syncope in 1 patient. High density three-dimensional electro-anatomic maps (EAM) were all obtained with a multipolar catheter during sinus rhythm (number of points: 8794±937 in basal maps and 9007±1296 after atropine, p=0,87). The response to atropine was documented by an increase in heart rate (mean increase 59 ± 19% of basal cycle length). All basal maps showed a similar pattern of fragmentation in the posterior-septal wall reflecting the anatomical distribution of right GPs. In particular, three main stations were identified in the supero-, mid- and infero-posterior regions. Fragmentation of EGMs was found to progress from the edge to the core of each area. After administration of atropine, a reduction in fractionated area was observed in all patients. Filtering the maps according to a cut-off of fragmentation ≥ 6 peaks allowed identification of the nucleus with the highest degree of variation after atropine injection (mean basal area = 0,89 ± 0,81 cm2 ; mean atropine area = 0,44 ± 0,56 cm2 p<0,001). Conclusion Fragmentation of atrial electrograms is a dynamic property related to vagal output. High density mapping with a high pass filter of 6 peaks allows to identify the smallest vagal sensitive area in the anatomical stations of the GPs.

Clinical and electrophysiological characteristics and long term outcomes of catheter ablation for right and left atrial tachycardias

Abstract Background Atrial tachycardias (AT) are complex supraventricular tachycardias which are refractory to antiarrhythmic drugs that require catheter ablation. Purpose In this trial, we aimed to evaulate the outcomes of catheter ablation in patients with symptomatic atrial tachycardia, define the acute procedural success and the recurrence rates in long-term follow-up and determine the clinical and electrophysiological features that affect these outcomes. Methods A total of 666 [mean age: 55 ±16, gender: 344 (51.7%) female] symptomatic patients with AT were enrolled. Prior catheter or surgical ablation history for ATa was present in 199 (29.9%) and 18 (2.7%) of these patients, respectively. Activation mapping was performed during tachycardia in all patients as well as entrainment mapping when needed. Voltage mapping were performed in sinus rhythm in both atriums, late potential mapping was also performed in some patients. Low voltage areas and signals with continuous-fragmented morphology were tagged. Results Macroreentry was the primary mechanism in right and left atrium (70.2% and 52.8%, respectively). Cavotricuspid isthmus (CTI) dependent macroreentry was the most frequent mechanism in right ATs and perimitral reentry and roof-dependent macroreentry were the most common mechanisms in left ATs. A total of 59 (7.5%) complications were observed in 780 procedures.(2.1% major and 5.5% minor) Acute procedural success was 95.9%. Freedom from ATa was 72.8 % during a mean follow-up of 39±23 months. Freedom from ATa after index procedure was 82.3% at 12 months and 75.9 % at 24 months. After multiple procedures, freedom from ATa was 90% at 12 months and 86% at 24 months during the follow-up. In multivariate Cox regression analysis, atrial fibrillation (AF) [(HR) 2.43, 95% c(CI) 1.78-3.30; p<0.001] , history of cardiac surgery [(HR) 1.68, 95% c(CI) 1.22-2.30; p=0.001] and moderate to severe tricuspid regurgitation [(HR) 1.47, 95% c(CI) 1.08-2.01; p=0.014] were significant predictors of ATa recurrence. Conclusion Our findings demonstrated that tailored catheter ablation of ATs especially guided by high density mapping has a high acute success rate and favourable long-term outcomes in patients with symptomatic AT episodes.

Conduction velocity-based functional substrate mapping during atrial fibrillation (AF) enhances identification of AF drivers compared to mapping during sinus rhythm

Abstract Background Conduction velocity (CV) heterogeneity is known to play a role in the initiation and maintenance of atrial fibrillation (AF) [1,2]. CV has been shown to decrease with cycle lengths (CLs) <600ms in low voltage areas (LVAs) [3,4], and with CLs <300ms in non-LVAs [4]. Yet, the impact of rhythm and CL on voltage-independent, CV-based atrial substrate mapping remains uncertain. Purpose This study evaluates CV differences based on mapping protocol and explores the relationship between CV and AF pathologic conduction patterns (PCPs) identified through global, non-contact, charge density mapping (CDM) [5]. Methods CDM was performed in twelve patients with persistent AF, presenting for de novo ablation. All mapping was performed prior to any ablation. Sinus rhythm (SR) CV was assessed during atrial pacing at two CLs (380ms and 800ms). To mitigate the impact of wavefront direction, pacing was performed at three sites: mid coronary sinus, left atrial appendage, and right atrial appendage. AF CV was determined from a 20-second continuous recording of global propagation. PCPs were identified as: focal firing (FF), rotational propagation (Localised Rotational Activation [LRA]), and pivoting propagation (Localised Irregular Activity [LIA]) [5]. Patients’ left atrial geometries consisted of approximately 3000 vertices, facilitating paired comparisons of spatial data. At each vertex, values for median CV dependent on mapping protocol and frequency of PCPs were utilised for analysis. Variables are presented as mean±standard deviation, median (interquartile range), and count (percentage) as appropriate. All analyses were performed using R (version 4.1.2). CV distributions were compared using the Analysis of Variance test. Results Mean age was 64±12 years, eight (67%) were male, median time since AF diagnosis was 3.1 (2-3.5) years, and median CHA2DS2-VASc score was 2 (2-4). Median CV across our cohort was significantly lower during AF than SR with either long or short CL pacing (0.37mm/ms vs 0.66mm/ms vs 0.61mm/ms, p<0.001). Histograms of CV vs left atrial surface area demonstrated similar distributions for both CLs. However, there was poor overlap with AF, which was prominently skewed towards slower CVs (Figure 1). Slower CVs during AF were associated with an increased frequency of PCPs (Figure 2), particularly FF with CVs <0.2mm/ms, and LRA and LIA with CVs <0.4mm/ms. This association was absent during SR. Conclusions Rhythm has a significant impact on CV-based functional substrate mapping. Slower CVs observed during AF likely result from the presence of CLs shorter than 300ms, which impact both LVA and non-LVA areas. Crucially, areas of slow CV during AF were associated with the location of PCPs. Mapping performed during AF may improve identification of areas where functional remodelling has preceded structural. Such areas, characterised by CV heterogeneity, may serve as promising targets for catheter ablation.Figure 1.Figure 2.

The role of high density mapping in cathether ablation of paroxysmal atrial fibrillation - preliminary results

Abstract Introduction Despite technical progress and numerous approaches in ablation strategies, long-term success in paroxysmal atrial fibrillation (PAF) treatment is still suboptimal. Non-transmural ablation lesions in antral isolation lines, causing late electrical reconnection between pulmonary veins (PVs) and left atrium (LA) could present one of the potenital issues for reduced effectiveness of radiofrequency cathether ablation (RFCA). Potentially, these lesions can be identified with high-density (HD) mapping as low voltage, fragmented electrocardiograms (LFEGMs) representing gaps in antral isolation lines. Purpose To compare the long-term pulmonary vein isolation (PVI) durability of two PVI verification methods (circumferential vs high-density mapping catheter) after catheter ablation of PAF. Methods Thirty-three patients with PAF were prospectively randomized to PVI verification by either circumferential mapping catheter (CM group) or HD mapping catheter (HD group). Patients in both groups underwent PVI according to the CLOSE protocol with PVI verification after a 30 minute waiting period. Additionally, in the HD group antral ablation lines were mapped to search for LFEGMs that were defined as fragmented signals (at least 3 deflections) and/or conduction to the LA during stimulation on the ablation line (10 mA at 1 msec) and/or voltage amplitude above 0.1 mV. If LFEGMs were found, additional ablations were performed until electrical inactivity was confirmed with the HD catheter. To monitor AF reccurence 6-day continuous holter ECG was performed after 3, 6, and 12 months after the initial procedure. Arrhythmia recurrence was defined as any atrial tachyarrhythmia lasting more than 30 seconds. Patients also underwent a mandatory second procedure 12 months after the initial PVI, during which HD re-mapping was performed to test durability of PVI and absence of conducting gaps in antral isolation lines. Results There were 16 patients in the CM group and 17 patients in the HD group. Baseline characteristics (gender, age, body mass index, LA volume index, left ventricular ejection fraction, CHA2DS2VASc score) did not significantly differ between the groups. Procedural characteristic are summarized in Table 1. There were significantly more isolated PVs at the remapping procedure in the HD group compared to the CM group (91.2% (62/68) vs 75.0% (48/64); P=0.021). There were also significantly more patients with all PVs durably isolated in the HD group (82.4% (14/17) vs 37.5% (6/16); P=0.008). However, arrhythmia recurrence rate was similiar between the CM and HD group (43.8% (7/16) vs 35.3% (6/17); P=0.640). Conclusion HD mapping improved PVI durability after 12 months compared to standard CM verification. However, lower number of isolated PVs in the HD group did not have an impact on arrhythmia reccurence.

Tackling of challenging accessory pathways utilizing open window mapping, does it add benefit?

Abstract Introduction 3D electroanatomical mapping is beneficial in accessory pathway ablation for better delineation of the anatomy, less procedure and fluro time, it depends on point-by-point mapping to identify the connection sites of the accessory pathway (AP) to the atria or ventricle, or the site of the AP potential. However, this approach requires an accurate interpretation of the local electrograms. In contrast, open window mapping (OWM) doesn’t need to differentiate the signals site of origin, it is based on an automatic annotation process in which the signals with the highest -dV/dt are annotated at each obtained point irrespective of the cardiac chamber. (1) Few reports describe the additional benefit of such technique in patients with complex congenital heart diseases. (2) Purpose To present our centre experience in using OWM technique in addition to early meets late (EML) algorism in accessory pathway ablation especially in patients with complex congenital heart disease or previous failed ablation trials. Methods We reviewed patients who underwent AVRT ablation at our centre from August 2022 to August 2023 with emphasis on cases mapped using OWM & EML techniques using high density mapping catheters. Demographic data, clinical presentation, resting & tachycardia ECGs, and Echo reports were examined thoroughly, additionally, we revised the 3D maps, ablation details, fluro dose, and outcomes of the procedures. Results Over one year, among 74 patients underwent AVRT ablation, open window mapping was used in 4 patients with manifest preexcitation (Rt posteroseptal in 3 of them & Rt free wall in one patient). Among the four patients: 3 were pediatrics, youngest was 5 years old, 19 Kg, 2 patients had previous failed ablation trials, their Echo reports revealed severe form of Ebstein anomaly with large ASD in the first patient, case 2 had single ventricle physiology with bidirectional Glenn while the two other patients had structurally normal heart (Table). The mapping using the OW & EML techniques confirmed the site of AP breakthrough conduction at Rt posteroseptal area in 3 of them and Rt posterolateral area in the remaining one, ablation resulted in immediate loss of preexcitation with no recurrence in all patients. Average fluro dose was 0.1 Gy which is significantly lower than the average dose in the remaining AVRT cases. Over median follow up period of 9 months, there were no recurrence of the accessory pathways & no complications. Conclusion Open window mapping technique is highly beneficial for accurate & fast mapping of accessory pathways especially in those with complex congenital heart where AP ablation remains considerably more challenging. OWM also added benefit in redo cases as the previous ablation trials hampered manual EGM interpretation. Finally, most of our cases were pediatrics where using high density mapping catheters and contact force ablation catheters appears to be safe and effective.Demographic, ECG, Echo & procedure data3D map & Echo in patient 2

Peak frequency mapping usefulness and utilization for typical AVNRT ablation

Abstract Background Accurate identification of slow pathway for the AVNRT ablation is important to achieve successful result and avoid complications mainly AV nodal block. There were some developments to produce precise image to locate this such as identify low voltage bridge (LVB) using electro-anatomical mapping and visualization of direct slow pathway capture (DCSP). The peak frequency (PF) associated with bipolar EGMs is a novel parameter which may serve to distinguish near filed (NF) from far field (FF) electrocardiogram (EGM) components. This technique can be used to differentiate sub-components derived from high density mapping. Previous study suggested this mapping appears to assist in substrate differentiation, pathway localization, and contact assessment. However, this approach has been never evaluated clinically in AVNRT ablation Objective This study conducted to evaluate the usefulness and utilization of the peak frequency mapping to identify the slow pathway location. Method The study conducted in November to December 2023 where twenty consecutive patients with common AVNRT were included in the study. Regular bipolar voltage and activation maps were generated with a regular 4 mm tip catheter. Following this, peak frequency maps (PF) were computed online prior ablation and displayed on the activation map with shadowed areas where PF was <200 Hz (figure, left panel). Focal radiofrequency application (RFa) was directed to the areas of late activation (figure, left panel) and low frequency (figure, right panel) (LA-LF). Successful ablation reached if junctional rhythm was recorded during RFa and AVNRT was no longer inducible afterwards. Results Twenty patients (48 ±15 years, 75% female) were enrolled in the study. A late activation low frequency area of 0.92±0.48 cm2 was found in 18 of them. This study revealed that there was a difference between PF in the slow pathway area compared to the adjacent area where the mean PF at the slow pathway area was 175.5 ± 37.1 Hz (analysis per patient) and 170.1 ± 48.10 Hz (analysis per recording site) which was lower and differed significantly than the PF recorded at the adjacent atrial area (279.71 ± 28.11 Hz per patient, 279.91 ± 69.47 Hz per recording site) (P<0.0001). Following the mapping, RFa were successfully applied at these late activation low-frequency (LA-LF) area induced junctional rhythm in 17 patients. AVNRT was no longer inducible after the ablation in all 17 patients. Additional RFa were often given to reinforce the result (11 ± 9 RFa, 4.03 ± 3.35 min RFa time). Conclusion The peak frequency mapping could be performed to map the slow nodal pathway which is often located in an area of late activation and low frequency.

Catheter ablation of premature ventricle complex from multiples site of origin guided by an ultra-high density mapping system in a single-center

Abstract Background Frequent premature ventricle complex (PVC) could induce cardiomyopathy in some patient. PVC ablation by radiofrequency (RF) is a well-stablished procedure in high density PVC patients and results are consistent and robust in literature, with somewhat differing success rates reported. Catheter ablation of radiofrequency guided by ultra-high density mapping systems (UHDMS), enable a much more accurate reconstruction of the site of origin (SOO). Furthermore, we obtained this anatomic recreation with the analysis of a few number of beats. The UHDMS have demonstrated to be feasible and safe in a wide range / large spectrum of arrhythmic substrates, however, there is lack of evidence of its usefulness in the ablation of PVC. Purpose To determine the safety and utility, both in the acute phase and in the short-medium term, of employing a UHDMS in PVC catheter ablation in a retrospective cohort of patients treated at a single centre. Methods Catheter ablation procedures guided by an UHDMS carried out from July 2015 to January 2021 in a single-center of Spain were retrospectively included. The primary outcomes analyzed were: acute success rate, short-medium success rate (6-month efficacy after ablation), and complication rate related to the procedure. Results One hundred and two procedures, corresponding to 92 patients (mean age 59 ± 14 years, 63% male, 74% without cardiomyopathy, mean LVEF of 60%), were analyzed. The acute success rate was 93%. According the SOO, the lowest acute success rate was PVC from epicardial level (LV Summit) (75%). At 6-month follow-up after the first procedure, the short-medium success rate was up to 84% (no recurrence of the PVC ablated). There were three acute complications related to the procedure (complication rate 2,94%). In 19% (21 out 102) of the procedures, at least two arrhythmic substrates were successfully ablated in a single intervention. Conclusion Catheter ablation guided by an UHDMS showed an excellent safety profile in PVC ablation procedures. Beyond this minor complication rate, this type of technique has improved acute and short-term success rates. This allows us to assert that this type of technique grants a very high success rate and improves previously results. Last but not least, this new approach was useful and accurate in complex patients, providing good results in ablation procedures of two or more arrhythmic substrates without altering the safety profile.

Surviving Tidal Tails Around the Milky Way Bulge Globular Cluster NGC 6355

We present results of the analysis of a set of images obtained in the field of the Milky Way bulge globular cluster NGC 6355 using the Dark Energy Camera, which is attached to the 4 m Blanco telescope of the Cerro-Tololo Interamerican Observatory. We dealt with a heavy differential absorption across the observed field, a crowded field star population, and the superposition of field stars on to the cluster color–magnitude diagram main features to produce an intrinsic cluster stars density map. The resulting stellar density map reveals the presence of an extended envelope, a tidal tail, and scattered debris; the tidal tails pointing toward the Milky Way center. Such extra-tidal overdensities, detected above the mean star field density, resulted to be between four and six times larger that the local star field density fluctuation. They have also been recently generated by two independent studies which performed numerical simulations of synthetic tidal tails of Milky Way globular clusters. These results contrast with previous theoretical speculations about the possibility to detect tidal tails of globular clusters with chaotic orbits because they would be washed out after they were generated.

Histology-Based Radiomics for [18F]FDG PET Identifies Tissue Heterogeneity in Pancreatic Cancer.

Radiomics features can reveal hidden patterns in a tumor but usually lack an underlying biologic rationale. In this work, we aimed to investigate whether there is a correlation between radiomics features extracted from [18F]FDG PET images and histologic expression patterns of a glycolytic marker, monocarboxylate transporter-4 (MCT4), in pancreatic cancer. Methods: A cohort of pancreatic ductal adenocarcinoma patients (n = 29) for whom both tumor cross sections and [18F]FDG PET/CT scans were available was used to develop an [18F]FDG PET radiomics signature. By using immunohistochemistry for MCT4, we computed density maps of MCT4 expression and extracted pathomics features. Cluster analysis identified 2 subgroups with distinct MCT4 expression patterns. From corresponding [18F]FDG PET scans, radiomics features that associate with the predefined MCT4 subgroups were identified. Results: Complex heat map visualization showed that the MCT4-high/heterogeneous subgroup was correlating with a higher MCT4 expression level and local variation. This pattern linked to a specific [18F]FDG PET signature, characterized by a higher SUVmean and SUVmax and second-order radiomics features, correlating with local variation. This MCT4-based [18F]FDG PET signature of 7 radiomics features demonstrated prognostic value in an independent cohort of pancreatic cancer patients (n = 71) and identified patients with worse survival. Conclusion: Our cross-modal pipeline allows the development of PET scan signatures based on immunohistochemical analysis of markers of a particular biologic feature, here demonstrated on pancreatic cancer using intratumoral MCT4 expression levels to select [18F]FDG PET radiomics features. This study demonstrated the potential of radiomics scores to noninvasively capture intratumoral marker heterogeneity and identify a subset of pancreatic ductal adenocarcinoma patients with a poor prognosis.

Assessment of Potential Risks Related to Mass Movement Hazards along the Southern Escarpment of the Bamileke Plateau (West-Cameroon Highlands)

The South Escarpment of the Bamileke Plateaus (SEBP) is located on the CVL and is part of the WCH. It is subject to risks related to mass movements. This region has significant potential for agro-pastoral many activities. It is for this reason that the demographic explosion is important there. The population in place practices many activities and owns several assets. This is the essence of the vulnerability to mass movements in this region. This vulnerability is human and material. Assessing the risk of mass movement also requires an assessment of vulnerability. Field campaigns have made it possible to identify the various vulnerable sites. Falling rocks, landslides and subsidence are the main mass movements in the region. The mass movement density map and probable area map highlight these mass movements. By questioning the populations and using the documents, we estimated the losses. The population is estimated at around 195.181 inhabitants. The estimated loss of agro-pastoral activities is 62.251.150 FCFA or 115.455.96 USD. The ESPB is covered by approximately 279.0335 km of road. It is full of many homes and public buildings. The estimated loss of buildings and properties amounts to 2778509.700 FCFA or 5151001.33 USD. By questioning the populations and using the documents, we estimated the losses. The population is estimated at around 195,181 inhabitants. The estimated loss of agro-pastoral activities is 62.251.150 FCFA or 115.455.96 USD. The SEBP is covered by approximately 279.0335 km of road. It is full of many homes and public buildings. The estimated loss of buildings and properties amounts to 2778509.700 FCFA or 5151001.33 USD. By questioning the populations and using the documents, we estimated the losses. The population is estimated at around 195,181 inhabitants. The estimated loss of agro-pastoral activities is 62.251.150 FCFA or 115.455.96 USD. The SEBP is covered by approximately 279.0335 km of road. It is full of many homes and public buildings. The estimated loss of buildings and properties amounts to 2778509.700 FCFA or 5151001.33 USD

Soliton structures for the (3 + 1)-dimensional Painlevé integrable equation in fluid mediums

The (3 + 1)-dimensional Painlevé integrable equation are a class of nonlinear differential equations with special properties, which play an important role in nonlinear science and are of great significance in solving various practical problems, such as many important models in fields such as quantum mechanics, statistical physics, nonlinear optics, and celestial mechanics. In this work, we utilize the Hirota bilinear form and Mathematica software to formally obtain the interaction solution among lump wave, solitary wave and periodic wave, which has not yet appeared in other literature. Additionally, using the (G′/G)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(G'/G)$$\\end{document}-expansion method, we provide a rich set of exact solutions for the (3 + 1)-dimensional Painlevé integrable equation, which includes two functions with arbitrary values. This method is the first to be applied to the (3 + 1)-dimensional Painlevé integrable equation. By giving some 3D graphics and density maps, the dynamic properties are analyzed and demonstrated, which is beneficial for promoting understanding and application of the (3 + 1)-dimensional Painlevé integrable equation.

A clinical-radiomics nomogram based on spectral CT multi-parameter images for preoperative prediction of lymph node metastasis in colorectal cancer.

To develop a clinical-radiomics nomogram based on spectral CT multi-parameter images for predicting lymph node metastasis in colorectal cancer. A total of 76 patients with colorectal cancer and 156 lymph nodes were included. The clinical data of the patients were collected, including gender, age, tumor location and size, preoperative tumor markers, etc. Three sets of conventional images in the arterial, venous, and delayed phases were obtained, and six sets of spectral images were reconstructed using the arterial phase spectral data, including virtual monoenergetic images (40keV, 70keV, 100keV), iodine density maps, iodine no water maps, and virtual non-contrast images. Radiomics features of lymph nodes were extracted from the above images, respectively. Univariate analysis and least absolute shrinkage and selection operator (LASSO) regression were used to select features. A clinical model was constructed based on age and carcinoembryonic antigen (CEA) levels. The radiomics featuresselected were used to generate a composedradiomics signature (Com-RS). A nomogram was developed using age, CEA, and theCom-RS. The models' prediction efficiency, calibration, and clinical application value were evaluated by the area under the receiver operating characteristic curve (AUC), calibration curve, and decision curve analysis, respectively. The nomogram outperforms the clinical model and the Com-RS (AUC = 0.879, 0.824). It is well calibrated and has great clinical application value. This study developed a clinical-radiomics nomogram based on spectral CT multi-parameter images, which can be used as an effective tool for preoperative personalized prediction of lymph node metastasis in colorectal cancer.

On Task and in Sync: Examining the Relationship between Gaze Synchrony and Self-reported Attention During Video Lecture Learning

Successful learning depends on learners' ability to sustain attention, which is particularly challenging in online education due to limited teacher interaction. A potential indicator for attention is gaze synchrony, demonstrating predictive power for learning achievements in video-based learning in controlled experiments focusing on manipulating attention. This study (N=84) examines the relationship between gaze synchronization and self-reported attention of learners, using experience sampling, during realistic online video learning. Gaze synchrony was assessed through Kullback-Leibler Divergence of gaze density maps and MultiMatch algorithm scanpath comparisons. Results indicated significantly higher gaze synchronization in attentive participants for both measures and self-reported attention significantly predicted post-test scores. In contrast, synchrony measures did not correlate with learning outcomes. While supporting the hypothesis that attentive learners exhibit similar eye movements, the direct use of synchrony as an attention indicator poses challenges, requiring further research on the interplay of attention, gaze synchrony, and video content type.

Research on Rapeseed Seedling Counting Based on an Improved Density Estimation Method

The identification of seedling numbers is directly related to the acquisition of seedling information, such as survival rate and emergence rate. It indirectly affects detection efficiency and yield evaluation. Manual counting methods are time-consuming and laborious, and the accuracy is not high in complex backgrounds or high-density environments. It is challenging to achieve improved results using traditional target detection methods and improved methods. Therefore, this paper adopted the density estimation method and improved the population density counting network to obtain the rapeseed seedling counting network named BCNet. BCNet uses spatial attention and channel attention modules and enhances feature information and concatenation to improve the expressiveness of the entire feature map. In addition, BCNet uses a 1 × 1 convolutional layer for additional feature extraction and introduces the torch.abs function at the network output port. In this study, distribution experiments and seedling prediction were conducted. The results indicate that BCNet exhibits the smallest counting error compared to the CSRNet and the Bayesian algorithm. The MAE and MSE reach 3.40 and 4.99, respectively, with the highest counting accuracy. The distribution experiment and seedling prediction showed that, compared with the other density maps, the density response points corresponding to the characteristics of the seedling region were more prominent. The predicted number of the BCNet algorithm was closer to the actual number, verifying the feasibility of the improved method. This could provide a reference for the identification and counting of rapeseed seedlings.

Decreased inter-hemispheric cooperation in major depressive disorder and its association with neurotransmitter profiles

BackgroundInter-hemispheric cooperation is a prominent feature of the human brain, and previous neuroimaging studies have revealed aberrant inter-hemispheric cooperation patterns in patients with major depressive disorder (MDD). Typically, inter-hemispheric cooperation is examined by calculating the functional connectivity (FC) between each voxel in one hemisphere and its anatomical (structurally homotopic) counterpart in the opposite hemisphere. However, bilateral hemispheres are actually asymmetric in anatomy. MethodsIn the present study, we utilized connectivity between functionally homotopic voxels (CFH) to investigate abnormal inter-hemispheric cooperation in 96 MDD patients compared to 173 age- and sex-matched healthy controls (HCs). In addition, we analyzed the spatial correlations between abnormal CFH and the density maps of 13 neurotransmitter receptors and transporters. ResultsThe CFH values in bilateral orbital frontal gyri and bilateral postcentral gyri were abnormally decreased in patients with MDD. Furthermore, these CFH abnormalities were correlated with clinical symptoms. In addition, the abnormal CFH pattern in MDD patients was spatially correlated with the distribution pattern of 5-HT1AR. Limitationsdrug effect; the cross-sectional research design precludes causal inferences; the neurotransmitter atlases selected were constructed from healthy individuals rather than MDD patients. ConclusionThese findings characterized the abnormal inter-hemispheric cooperation in MDD using a novel method and the underlying neurotransmitter mechanism, which promotes our understanding of the pathophysiology of depression.