Ablation Line Research Articles

Mitral isthmus line: anatomical aspects relevant to linear catheter ablation

Atrial Fibrillation (AF) is a common cardiac arrhythmia for which Pulmonary Vein (PV) isolation remains a mainstay treatment. Several linear ablation lines have been suggested to improve the efficacy of PV isolation. The mitral isthmus line/region lies between the left inferior PV and mitral valve annulus within the left atrium and used for targeting non-PV triggers during AF. Unfavorable anatomy along this line leads to incomplete ablation and recurrence of AF. The aim of this study is to provide anatomical data of mitral isthmus region and its implications for linear catheter ablation procedure. Total fifty formalin-fixed cadaveric hearts were examined. The mitral isthmus line was evaluated for its length, shape and presence of any structures. The mitral isthmus line length was not uniform with ranges between 21.05-34.62 mm (mean- 28.55 ± 3.12 mm). In 40% of studied hearts, a high amount of anatomic heterogeneity was present in this region, with undesirable structures like crevices (28%) and diverticula (12%). These structures had thinner walls compared to the surrounding atrial wall. The mitral isthmus line had concave shape in majority of cases (98%). This study concludes that a high amount of anatomical variability and barriers are present in along the mitral isthmus line. This could make it difficult to achieve complete block during ablation with pertaining risks of complications. Individualized strategy for ablation after studying the local anatomy is suggested to improve procedural outcomes.

A tailored substrate-based approach using focal pulsed field catheter ablation in patients with atrial fibrillation and advanced atrial substrate: Procedural data and 6-months success rates.

Focal pulsed-field ablation (F-PFA) integrated in electroanatomical mapping (EAM) systems allows tailored lesion sets in patients with atrial fibrillation (AF). To determine feasibility, safety and 6-months outcome of F-PFA for a tailored substrate-based catheter ablation (CA) approach in patients with AF and advanced atrial substrate. Consecutive patients with AF and advanced atrial substrate treated by a F-PFA system (Cardiofocus) through contact-force sensing catheters integrated in EAM systems were prospectively enrolled. The tailored substrate-based CA approach included isolation of all pulmonary veins (PVI) with wide area circumferential ablation, posterior wall isolation (PWI), mitral anterior line and cavo-tricuspid isthmus (CTI) ablation, according to substrate. At 6 months, feasibility, arrhythmia recurrence and safety were evaluated. In 83 patients (33% female, indexed left atrial volume: 44±15ml/m2, 80% persistent AF or atrial flutter (AFl), 57% re-do procedures), successful de-novo PVI was performed in 36 patients and PV reisolation in 30 patients. Mitral anterior line was performed in 19 patients with atypical AFl or anterior low voltage areas; PWI was performed in 38 patients with low voltage areas or evoked delayed electrograms during premature atrial extrastimuli; CTI was performed in 24 patients with typical AFl. Median procedural and fluoroscopy times were 115 and 7 minutes, respectively. No complications occurred. At 6 months, arrhythmia recurrence occurred in 30/83 patients (21 AF; 9 atypical AFl). Tailored substrate-based F-PFA in patients with AF and advanced atrial substrate is safe and effective. Acute procedural success was 100% with 64% freedom from arrhythmias after 6 months.

First-in-human trial of atrial fibrillation ablation using real time tissue optical assessment to predict pulsed field lesion durability.

Loss of bipolar electrograms immediately after pulsed field ablation (PFA) makes lesion durability assessment challenging. The aim of this trial (NCT06700226) was to evaluate a novel ablation system that can optically predict lesion durability by detecting structural changes in the tissue during ablation. Patients with paroxysmal atrial fibrillation underwent pulmonary vein isolation (PVI) using PFA (AblaView®, MedLumics). Using polarization sensitive optical coherence reflectometry (PS-OCR), reflective characteristics of myocardial tissue and visualization of real-time contrast between healthy tissue and ablated tissue using a drop in tissue birefringence (BiR) was assessed. Wide antral PVI was performed using single point irrigated PFA (unipolar, 1800V, 3 trains, 21sec). Remapping was performed at 3 months. Primary efficacy outcome was the ability of PS-OCR to predict lesion durability at 3-month remapping. Serious adverse events were recorded. Ten patients were included. In total, 38/40 PVs could be isolated with the system. The mean drop of BiR was 17.3±11.5%. Dragging across the ablation lines showed a persistent drop in BiR. During the remap procedures (9/10 patients), 15 PVs (41.7%) were found to be electrically reconnected. The mean loss of BiR during the index ablation for durable lesions was 20.9%, while only 10.1% BiR loss was observed during the index ablation for reconnected areas (p<0.001). None of the points with ≥17% loss of birefringence was found to be reconnected. This first in human study supports the use of real-time drop in tissue BiR for lesion assessment during PFA delivery and its procedural safety.

A novel focal lattice-tip catheter toggling between pulsed field energy and radiofrequency for atrial arrhythmia ablation: Results from a real-world, multicenter registry.

A novel focal lattice-tip catheter allowing the delivery of either pulsed field (PF) or radiofrequency (RF) energy has recently received regulatory approval. The technology features a proprietary 3-dimensional electroanatomic mapping system. We describe the first real-world and multicenter experience. Consecutive AF patients undergoing first-time or redo atrial tachyarrhythmia ablation with the Affera system were prospectively enrolled at 3 different centers. PF was the only energy source allowed when ablating the posterior left atrium; anterior applications were performed with either RF (PF/RF strategy) or PF (PF/PF strategy) on the basis of the operator's preference. The primary efficacy end point included acute electrical isolation of pulmonary veins and posterior wall or bidirectional block in case of linear lesions. The study included 130 patients (mean age, 67 ± 10 years; 63.8% [n = 83] male; 61.5% [n = 80] nonparoxysmal AF; 55.4% first-time AF ablation). First-time pulmonary vein isolation was performed in 72 patients: RF/PF in 13 (18.1%) patients and PF/PF in the remaining 59 (81.9%); first-pass isolation for pulmonary vein and posterior wall was achieved in 100% of cases. A total of 289 ablation lines were performed (roof line, 91 patients; inferior line, 83 patients; anterior mitral line, 32 patients; posterior mitral line, 45 patients; cavotricuspid isthmus line, 38 patients). First-pass isolation and primary efficacy end point were 96.2% (roof line, 100%; inferior line, 100%; anterior mitral line, 96.9%; posterior mitral line, 84.4%; cavotricuspid isthmus, 92.1%) and 100%, respectively. We had 2 (1.5%) major complications: 1 ST-segment elevation at the inferolateral leads requiring intracoronary administration of nitrate and 1 complete atrioventricular block. Catheter ablation with a novel 9-mm lattice-tip catheter confirmed high efficacy and safety in a real-world scenario.

Linear Ablation Using a Contact Force-Sensing Catheter in Ablation for Persistent Atrial Fibrillation: A Prospective Randomized Trial.

Background/Objectives: Pulmonary vein isolation (PVI) using radiofrequency catheter ablation with contact force (CF)-sensing technology has improved long-term outcomes in patients with atrial fibrillation. This prospective randomized study aimed to assess the efficacy and safety of CF-sensing technology for additional left atrial (LA) linear ablation of persistent AF (PerAF). Methods: After PVI, anteromitral (AM) line and roof line ablation were performed using a CF-sensing catheter. Patients were randomly assigned to either the CF-sensing (CFS) group or the CF-blind control (Blind) group. The primary endpoint was atrial arrhythmia recurrence. LA late gadolinium enhancement (LA-LGE) MRI was conducted at baseline and 1-year follow-up for long-term lesion evaluation. Results: A total of 62 patients with drug-refractory PerAF were enrolled (mean age: 58 ± 10 years; 77% male). The success rates of AM and roof line block were 97% and 100% in the CFS group (n = 33) and 93% and 90% in the Blind group (n = 29). The time to achieve block was reduced in the CFS group (AM: 36 ± 22 vs. 48 ± 28 min, p = 0.068; roof: 19 ± 14 vs. 27 ± 15 min, p = 0.031). The maximum CF for safety endpoints was significantly lower in the CFS group (AM: 42 vs. 69 g, p < 0.001; roof: 33 vs. 49 g, p = 0.003). Full linear LA-LGE formation on 1-year MRI did not differ significantly between the groups (AM: 17 vs. 36%; roof; 29 vs. 24%, both p = NS). Kaplan-Meier estimates of AF/AT-free survival after ablation procedures were 63.6% in the CFS group and 58.6% in the Blind group (log-rank p = 0.837). Conclusions: In patients with PerAF, additional LA linear ablation following PVI using CF-sensing technology improved procedural safety and reduced the time needed to achieve conduction block. However, it did not significantly influence clinical outcomes or the formation of permanent full linear lesions.

Femtosecond laser ablation of nitrocellulose for spatio-temporal flow control in µPADs

Microfluidic paper-based analytical devices (μPADs) are gaining popularity due to their low cost and ease of use, but controlling fluid flow for more complex biochemical assays within these devices remains challenging. This study investigates femtosecond laser ablation of nitrocellulose (NC), a preferred material for µPADs, to create mechanically switchable barriers and flow controllers. We investigated NC ablation using single laser pulses and spatially overlapping pulses that generate lines. Single pulse ablation thresholds were determined for wavelengths of 1,030 nm, 515 nm and 343 nm. Line ablation characteristics were investigated as a function of the temporal and spatial pulse separation and laser wavelength. High aspect ratio grooves (up to 4.26) were achieved under specific conditions. These grooves can be used to define the spatial separation of the flow in separated microchannels or to form a barrier line perpendicular to the microchannel that can modulate the temporal behavior of the fluid flow. This barrier introduced an additional high flow resistance slowing down the flow or, if it was designed to cut through nitrocellulose at the entire depth, completely stopped the liquid flow. It was further shown that a barrier formed in this way could be switched by mechanically bending the µPAD at the barrier position. The femtosecond laser patterning method presented here provides precise spatio-temporal control not only for flow branching and multiplexing, but also for controlling flow speed and switching flow on and off within the same manufacturing process. Our results open up new possibilities for complex, multi-step assays on µPADs.

Comparative Study of Arctic Front Advance Pro and POLARx Cryoballoons for Linear Ablation of the Left Atrial Roof.

The effectiveness of cryoballoon ablation (CBA) of the left atrial (LA) roof in addition to pulmonary vein isolation (PVI) using a novel cryoballoon catheter, POLARx, remains unclear. This study compared the efficacy of LA roof line ablation and PVI using POLARx (Boston Scientific) or AFA-Pro (Medtronic) in 100 patients with persistent atrial fibrillation. The right superior pulmonary vein (PV) anchoring and raise-up techniques were consistently used for LA roof line ablation, and rapid right ventricular pacing was applied if the cryoballoon temperature did not reach -40°C. Complete conduction block at the LA roof could be obtained in all patients with POLARx and in 98.0% of patients with AFA-Pro. Rapid right ventricular pacing was needed in 64.0% of patients with AFA-Pro and in no patients with POLARx. During LA roof line ablation, the nadir cryoballoon temperature was significantly lower with POLARx than with AFA-Pro (right: -54.2°C±4.4°C vs. -46.0°C±5.4°C; central: -56.8°C±4.4°C vs. -45.7°C±4.8°C; left: -56.1°C±4.3°C vs. -46.1°C±5.7°C), and the cryoballoon temperature reached -40°C earlier with POLARx than with AFA-Pro (right: 30.8±7.4 s vs. 74.1±37.7 s; central: 28.2±5.2 s vs. 62.9±30.9 s; left: 29.8±5.8 s vs. 69.6±40.7 s). The nadir cryoballoon temperature with POLARx was approximately 10°C lower than with AFA-Pro, consistently dropping below -40°C during LA roof line CBA. Thus, a complete conduction block of the LA roof line can be easily accomplished using right superior PV anchoring and the raise-up techniques without the need for rapid right ventricular pacing with POLARx.

Influence of crystal orientation and incident plane on n-type 4H-SiC wafer slicing by using picosecond laser

Laser slicing has been considered as the most efficient technique for slicing SiC wafers with the advantages of small kerf width (loss) and crack, low roughness on cleaved surface, high quality and efficiency, etc. Here, laser slicing of n-type 4H-SiC was demonstrated by using a homemade 1064 nm picosecond laser combined with mechanical stretch stripping. The influence of laser processing along [11 2¯ 0] and [1 1¯ 00] crystal orientations on Si-face and C-face of n-type 4H-SiC, specifically on the internal laser ablation lines and cracks, the peeling tensile strength, and the surface roughness of the peeled surfaces was investigated. The semi-insulating 4H-SiC wafer laser slicing was conducted for comparison. Under the same laser conditions, laser slicing of semi-insulating 4H-SiC was easier than that of n-type. The laser modification quality along [1 1¯ 00] orientation was better than that along [11 2¯ 0] orientation for both the semi-insulating and n-type 4H-SiC and the reasons were explained. The results indicated that the optimal laser slicing scheme detailed laser scanning along [1 1¯ 00] orientation and incidence from the C-face. Finally, a 6-inch, 420.36 µm-thick n-type 4H-SiC wafer was successfully sliced.

Comparison of the ablative performance of silicone rubber‐based composites by analyzing a large number of samples

AbstractSilicone rubber‐based materials are important thermal protection materials for high‐temperature applications. In this work, a holistic analysis of silicone rubber‐based materials was conducted with an aim to comparatively study the ablative performance of different rubber matrices using the oxyacetylene flame. Six types of silicone rubber‐based composites were prepared in large quantities using a customized device, and the relationship between the ablative properties and influencing factors was elucidated, which was useful in guiding the design and preparation of flexible ablative materials for thermal protection purpose. The expansion and ceramicization of char layer, which was realized by introducing expandable graphite and alumina was found helpful in reducing line ablation rate. The increase in the thickness of char layer and the decrease in surface roughness indicated a successful implementation of the above strategy, which led to a significant decrease in line ablation rate and an increase in thermal insulation performance of the studied system. Moreover, a thermal ablative composite with excellent moldability after ablation process was prepared which showed a promising application as a reusable thermal protection material. This work provided guidelines for developing flexible thermal ablative composites, which can be targeted for practical applications in aerospace and fire protection sectors.

Preparation and performance of C/Ta4HfC5-SiC composite fabricated by PIP combined with RMI process

Based on self-made Ta4HfC5 precursor, C/Ta4HfC5-SiC composite material were prepared by precursor impregnation and pyrolysis (PIP) combined with reactive melting infiltration (RMI) process. The density and open porosity of C/Ta4HfC5-SiC composite material are 2.71 ± 0.73 g/cm3 and 7.07 ± 1.29 %, respectively. Pores are distributed at multiple levels, including primarily nanopores below 40 nm, micropores between 0.04 and 8.5 μm, and a small number of macropores between 10 and 285 μm. The Ta4HfC5 phase exists in two forms: dispersed particles in the matrix and a "layered interface" on the surface of fibers within the bundle. The average bending strength, elastic modulus and fracture toughness of C/Ta4HfC5-SiC composite are 84.24 ± 8.71 MPa, 16.13 ± 5.42 GPa and 3.62 ± 0.63 MPa m1/2, respectively, showing a clear brittle fracture mode during the test. The line ablation rate and mass ablation rate of 60 s assessed by the oxyacetylene flame were 7.20 ± 0.35 μm/s and 10.84 ± 0.84 mg/s, respectively. The oxidation products such as Ta2O5, HfO2, Ta(Hf)CxOy formed by Ta4HfC5 phase during ablation present as thicker oxide layers, forming the main anti-ablation components.

Efficacy of the peak frequency map for left atrial posterior wall isolation.

Complete isolation of the left atrial posterior wall (LAPW) is challenging owing to overlapping epicardial conduction. Peak frequency (PF) is a novel parameter that focuses on near- and far-field electrogram components. In this study, we aimed to determine whether transmural block completion is related to the ablation site PF. We analyzed 44 consecutive patients undergoing initial LAPW isolation (LAPWI) between June 2023 and February 2024. Pre-LAPWI and PF maps were obtained using an HD-Grid catheter. In 17 of the 44 patients (Group-1), LAPWI was performed conventionally. In the remaining 27 patients (Group-2), PF-guided LAPWI was applied based on Group-1 results. In Group-1, the left atrial (LA) roof and floor line success rates were 58.8% and 76.5%, respectively. The average PF value in the roof lines of patients with a completed block line was significantly higher than that of the remaining patients (286.6 ± 29.3 Hz vs. 236.1 ± 40.9 Hz, p = .012), but the floor lines were similar. In Group-2, relatively high PF values were targeted to achieve complete block of the LA roof and floor lines, following the results obtained in Group-1. The LA roof line success rates (92.6% vs. 58.8%, p = .007), total number of radiofrequency (RF) applications (22.7 ± 5.6 vs. 27.6 ± 8.5, p = .03), and procedural time (32.6 ± 18.3 vs. 47.9 ± 25.6 min, p = .03) differed between Group-1 and Group-2. Using a PF map for determining the optimal ablation line for LAPWI by RF catheter ablation is feasible.

Harmonizing lightweight and ablation resistance: Design and performance of multilayer composite insulation materials for solid rocket motors

AbstractThe realization of lightweight insulation materials is often accompanied by a decrease in ablation performance. Coordinating the contradiction between lightweight and ablation resistance is the key to the development of thermal protection technology. Addressing the need for high‐performance insulation materials within solid rocket motors (SRMs) combustion chambers, we designed three multilayer composite structural insulation materials and studied their properties. The results show that among these constructed multilayer composites, the bilayer structure exhibited the lowest density at a mere 0.72 g/cm3, marking a 27% reduction compared to the basic structure. Remarkably, the bilayer configuration demonstrated superior ablation resistance, showcasing a 25% decrease in the line ablation rate in contrast to the basic structure after oxygen‐acetylene test. This achievement embodies the successful harmonization of lightweight properties with ablation resistance. Furthermore, based on the performance and microstructure of the char layer, a further analysis revealed the enhancement mechanism of ablative performance by the multilayer composite structure. It was found that the synergistic effect of the compact/porous structure of the char layer grants the bilayer structure thermal insulation material optimal ablative performance. This work provides strong support for improving the performance of SRMs.Highlights Insulation materials with multilayer composite structures are designed. The materials exhibit both lightweight and superior ablation resistance. Compact/porous char layers enhance material ablation performance.

Multielectrode catheter-based pulsed field ablation of persistent and long-standing persistent atrial fibrillation.

Rhythm control of non-paroxysmal atrial fibrillation (AF) is significantly more challenging, as a result of arrhythmia perpetuation promoting atrial substrate changes and AF maintenance. We describe a tailored ablation strategy targeting multiple left atrial (LA) sites via a pentaspline pulsed field ablation (PFA) catheter in persistent AF sustained beyond 6 months (PerAF > 6 m) and long-standing persistent AF (LSPAF). The ablation protocol included the following stages: pulmonary vein antral and posterior wall isolation plus anterior roof line ablation (Stage 1); electrogram-guided substrate ablation (Stage 2); atrial tachyarrhythmia regionalization and ablation (Stage 3). Seventy-two [age:68 ± 10years, 61.1%males; AF history: 25 (18-45) months] patients with PerAF > 6 m (52.8%) and LSPAF (47.2%) underwent their first PFA via the FarapulseTM system. LA substrate ablation (Stage 1 and 2) led to AF termination in 95.8% of patients. AF organized into a left-sided atrial flutter (AFlu) in 46 (74.2%) patients. The PFA catheter was used to identify LA sites showing diastolic, low-voltage electrograms and entrainment from its splines was performed to confirm the pacing site was inside the AFlu circuit. Left AFlu termination was achieved in all cases via PFA delivery. Total procedural and LA dwell times were 112 ± 25 min and 59 ± 22 min, respectively. Major complications occurred in 2 (2.8%) patients. Single-procedure success rate was 74.6% after 14.9 ± 2.7 months of follow-up; AF-free survival was 89.2%. In our cohort, PFA-based AF substrate ablation led to AF termination in 95.8% of cases. Very favourable clinical outcomes were observed during >1 year of follow-up.

Synthesis of ZrB2-SiC-ZrC composite powders with core-shell structure via sol-gel molecular modulation

In this study, ZrB2-SiC-ZrC (ZSZ) composite powders with molar ratios C/(B + Zr + Si) = 1.5, 1.9 and 2.4 were obtained by sol-gel method and boro/carbothermal reduction reaction. Meanwhile, the impact of heat treatment temperature (1100 °C–1600 °C) and holding time (1 h–2.5 h) on the resulting powders were studied. The results showed that the ZSZ powder precursors were first completely converted to ZrO2, SiO2, B2O3 and pyrolytic carbon after heat treatment at 1200 °C under the optimized molar ratio (2.4) and holding time (2.5 h). Then, the transformed oxidation products and pyrolytic carbon were completely transformed into ZSZ composite powders after optimized heat treatment at 1500 °C. The synthesized ZSZ composite powders are characterized by the core-shell structure, in which ZSZ particles act as the inner core are encapsulated by the low-crystalline ZrB2 phase as the outer shell to form a core shell structure. The ZSZ composite ceramic materials prepared using the core-shell structural powders have excellent ablative properties in the range of 2000 °C, with the mass and line ablation rate of −3.5 × 10−4 g/cm3 and 2.39 × 10−3 mm/s, respectively.

Ceramic Matrix Composite Cyclic Ablation Behavior under Oxyacetylene Torch.

To study the ablation properties and differences of plain-woven SiC/SiC composites under single and cyclic ablation. The ablation test of plain-woven SiC/SiC composites was conducted under an oxyacetylene torch. The results indicate that the mass ablation rate of cyclic ablation is lower than that of single ablation, whereas the line ablation rate is higher. Macro-microstructural characterization revealed the presence of white oxide formed by silica on the surface of the ablation center region. The fibers in the central region of the ablation were ablated layer by layer, and the broken fiber bundles exhibited a spiky morphology with numerous silica particles attached. The oxide layer on the surface and the silica particles on the fibers, which are in the molten state formed in the high-temperature ablation environment, contribute to resisting ablation. Thermal shock during cyclic ablation also played a role in the ablation process. The thermal shock causes cracks in the fiber bundles and matrix of the SiC/SiC composites. This study helps to apply SiC/SiC composite to complex thermal shock environments.

Direct-to-catheter ablation versus second line catheter ablation for persistent atrial fibrillation: Effect on arrhythmia recurrence, AF burden, early left atrium remodeling and quality of life.

Catheter ablation has obtained class 1 indication in ablation of young, healthy patients with symptomatic paroxysmal atrial fibrillation (AF). Anti-arrhythmic drugs (AADs) remain first-line therapy before ablating persistent AF (PersAF). We sought to evaluate the efficacy of a direct-to-catheter ablation approach against catheter ablation post AADs in PersAF. In this DECAAF II subanalysis, patients were stratified into two subgroups: 'Direct-to-catheter' group comprising patients who had not received AADs prior to ablation, and'second-line ablation' group, comprising patients who had been on any AAD therapy at any time before ablation. Patients were followed over 18months. The primary outcome was AF recurrence. Secondary outcomes included AF burden, quality of life (QoL) that assessed by the AFSS and SF-36 scores, and changes in the left atrial volume index (LAVI) assessed by LGE-MRI scans. The analysis included 815 patients, with 279 classified as'direct-to-catheter' group and 536 classified as'Second-line ablation' group. The primary outcome was similar between both groups (44.8% vs 44.4%, p > 0.05), as was AF burden (20% vs 16%, p > 0.05). Early remodeling, reflected by LAVI reduction, was similar between the groups (9.1 [1.6-18.0] in the second-line ablation group and 9.5 [2.5-19.7] in the direct-to-catheter group, p > 0.05). QoL pre/post ablation was also similar (p > 0.05). On multivariate analysis, history of AAD was not predictive of AF recurrence(p > 0.05). Prior AAD therapy demonstrated minimal impact on atrial remodeling and QoL improvement, in addition to limited benefit on AF recurrence and burden post-ablation in patients with PersAF. Additional studies are warranted to explore the efficacy of catheter ablation as a first-line therapy in PersAF.

Mechanical property, oxidation resistance, and ceramization mechanism of MoSi2-SiB6 reinforced phenolic resin matrix composites

Ceramizable phenolic resin matrix composites have a significant potential for widespread applications in the field of aerospace ablation. However, due to the sharp decrease of mechanical properties at elevated temperatures, the composite fails to meet the requirements of thermal protection as well as load-bearing of aircraft in a wide temperature range. In this study, boron phenolic composites modified by MoSi2 and SiB6 with high strength in a wide temperature range are prepared. The flexural strength of composites after ablation within the temperature range of 800 °C to 1600 °C ranges from 48.07 to 82.49 MPa. In particular, a significant increase of 224.9% is obtained at 1400 °C with 6 wt% SiB6. The mass ablation rate and line ablation rate of the composites are increased to 0.054 g/s and 0.013 mm/s, respectively. The cooperation effect of oxygen consumption, carbon fixation, oxygen barrier, and liquid phase bonding produced by ceramization reactions involving SiB6, MoSi2, O2, and pyrolytic carbon at different temperatures, resulting in an improvement of the mechanical property and the oxidation resistance of the composite. These composites have a potential in long term thermal protection and load-bearing of new ablation materials.

Anisotropic conductive film (ACF) step-by-step line ablation using NIR, green, and DUV wavelengths femtosecond laser for Micro-LED display repair

Anisotropic conductive film (ACF) step-by-step line ablation using NIR, green, and DUV wavelengths femtosecond laser for Micro-LED display repair

Risk assessment of esophageal ulceration following left atrial radiofrequency linear ablation.

Esophageal safety following radiofrequency (RF) left atrial (LA) linear ablation has not been established. To determine the esophageal safety profile of LA linear RF lesions, we performed systematic esophagogastroduodenoscopy in all patients with intraesophageal temperature rise (ITR) ≥ 38.5°C. Between December 2021 and July 2023, a total of 200 consecutive patients with atrial tachyarrhythmia (ATA) underwent linear ablation with posterior dome (roof or floor) or posterior mitral isthmus line transection. Patients with ITR ≥ 38.5°C were scheduled for esophageal endoscopy ~3 weeks after ablation. Patient and ATA characteristics, procedural parameters, endoscopy findings and ablation lesion data were collected and analyzed. One hundred thirty-threeout of 200 (67%) patients showed ITR ≥ 38.5°C during LA linear ablation. ITR (with maximal temperature of 45.7°C) was more frequently observed during floor line ablation (82% of cases). ITR was less observed during roof line ablation (34%) and posterior mitral isthmus ablation (4%). Endoscopy, performed in 115 patients after 24 ± 10 days, showed esophageal ulceration in four patients (two patientsKansas City classification [KCC] 2a and two patients KCC 2b). No patient showed esophageal perforation or fistula. Temperature rise during LA linear ablation is frequent and ulceration risk exists, particularly when floor line is performed. Safety measures are needed to avoid potential severe complications like esophageal perforation and fistula.

Ablation Parameters Predicting Pulmonary Vein Reconnection after Very High-Power Short-Duration Pulmonary Vein Isolation.

Recurrences due to discontinuity in ablation lines are substantial after pulmonary vein isolation (PVI) with radiofrequency ablation for atrial fibrillation. Data are scarce regarding the durability predictors for very high-power short-duration (vHPSD, 90 W/4 s) ablation. A total of 20 patients were enrolled, who underwent 90 W PVI and a mandatory remapping procedure at 3 months. First-pass isolation (FPI) gaps, and acute pulmonary vein reconnection (PVR) sites were identified at the index procedure; and chronic PVR sites were identified at the repeated procedure. We analyzed parameters of ablation points (n = 1357), and evaluated their roles in predicting a composite endpoint of FPI gaps, acute and chronic PVR. In total, 45 initial ablation points corresponding to gaps in the ablation lines were analyzed. Parameters associated with gaps were interlesion distance (ILD), baseline generator impedance, mean current, total charge, and loss of catheter-tissue contact. The optimal ILD cut-off for predicting gaps was 3.5 mm anteriorly, and 4 mm posteriorly. Biophysical characteristics dependent on generator impedance could affect the efficacy of vHPSD PVI. The use of smaller ILDs is required for effective and durable PVI with vHPSD compared to the consensus targets with lower power ablation, and lower ILDs for anterior applications seem necessary compared to posterior points.