Ablation Efficiency Research Articles

Study on the mechanism of thrombus ablation in vitro by burst-mode femtosecond laser.

The burst-mode femtosecond laser has the potential to be a novel thrombus removal technique. This paper proposed to investigate the mechanism of thrombus ablation in vitro by burst-mode femtosecond laser. A simulation model of the interaction between femtosecond laser and thrombus was established. An in vitro thrombus model was prepared. Combined with the high-speed galvanometer and femtosecond laser, the ablation experiments in vitro were performed. The experimental results showed that the ablative threshold was 0.27 times and the efficiency was about 1.4 times of burst-mode femtosecond laser as those of traditional mode femtosecond laser. These phenomena were related to the residual temperature and free electrons on the thrombus surface, which confirmed the simulating results and had relationship with incubation effects. The high ablative efficiency and safety of burst-mode femtosecond laser for thrombus ablation were verified, which may help to achieve the femtosecond pulse output through flexible fiber easily and stably. The burst-mode femtosecond laser represents an important technological advancement of the method in terms of endovascular treatment with femtosecond laser.

Er:YAG laser brainsurgerywithvascularspecificcoagulation.

Erbium:yttrium-aluminum-garnet (Er:YAG) laser ablation can effectively resect water-bearing tissues. Application of Er:YAG resection in neurosurgery is complicated by unpredictable bleeding in surgical field. Recently, an integrated theranostic system combining a dual-wavelength laser surgery system using a thulium (Tm) fiber-laser for coagulation and Er:YAG for resection, combined with optical coherence tomography (OCT) guidance was demonstrated for the in vivo resection of tumor tissue. However, lateral thermal spread in the range of 100s of micrometers is common due to lack of vascular specificity using a Tm fiber-laser for coagulation. In this study, a vascular specific ytterbium (Yb) fiber-laser is utilized for enhanced photocoagulation during in vivo neurosurgery improving the precision of Er:YAG tissue resection with minimal lateral thermal spread. Mice underwent stereotactic laser surgery with the proposed Yb/Er:YAG dual wavelength vascular specific neurosurgery in vivo. AnOCTsystem (wavelength range 1310 ± 70 nm) and OCT derived angiography images were used to record cortical images to confirm the coagulation of blood vessels and guide subsequent Er:YAG resection steps. After the laser surgery, mice were killed, and histological analysis was carried out using hematoxylin and eosin staining and Nissl staining to compare the lateral thermal spread with our previously reported Tm/Er:YAG neurosurgery where a continuous wave Tm fiber-laser was used for coagulation. Coagulation scheme using a Yb fiber-laser allowed stoppage of blood flow in disparately sized blood vessels encountered in the mice brain. Histological analysis of murine brain slices post Yb/Er:YAG laser surgery yielded lower thermal spread compared withTm/Er:YAG laser surgery, maximizing the efficiency in both hemostasis (blood flow stoppage) and maximizing tissue ablation efficiency with minimal residual thermal damage zone. In this study, a vascular specific coagulation scheme with Yb/Er:YAG dual-wavelength surgery is presented for neurosurgery. Additionally, Yb/Er:YAG study results are compared with that of a tissue coagulation approach in Tm/Er:YAG surgery previously reported to highlight improved coagulation, reduced nonspecific thermal damage and limited lateral thermal spread. Experimental results suggest that the developed dual-wavelength laser system can effectively resect neural tissues with high localization, minimal lateral thermal spread at the micrometer level while maintaining a bloodless surgical field.

Micromachining of Alumina Using a High-Power Ultrashort-Pulsed Laser.

We report on a comprehensive study of laser ablation and micromachining of alumina using a high-power 1030 nm ultrashort-pulsed laser. By varying laser power up to 150 W, pulse duration between 900 fs and 10 ps, repetition rates between 200 kHz and 800 kHz), spatial pulse overlap between 70% and 80% and a layer-wise rotation of the scan direction, the ablation efficiency, ablation rate and surface roughness are determined and discussed with respect to an efficient and optimized process strategy. As a result, the combination of a high pulse repetition rate of 800 kHz and the longest evaluated pulse duration of 10 ps leads to the highest ablation efficiency of 0.76 mm/(W*min). However, the highest ablation rate of up to 57 mm/min is achieved at a smaller repetition rate of 200 kHz and the shortest evaluated pulse duration of 900 fs. The surface roughness is predominantly affected by the applied laser fluence. The application of a high repetition rate leads to a small surface roughness Ra below 2 m even for the usage of 150 W laser power. By an interlayer rotation of the scan path, optimization of the ablation characteristics can be achieved, while an interlayer rotation of 90 leads to increasing the ablation rate, the application of a rotation angle of 11 minimizes the surface roughness. The evaluation by scanning electron microscopy shows the formation of thin melt films on the surface but also reveals a minimized heat affected zone for the in-depth modification. Overall, the results of this study pave the way for high-power ultrashort-pulsed lasers to efficient, high-quality micromachining of ceramics.

Impacts of laser pulse width and target thickness on laser micro-propulsion performance

In order to optimize the laser ablation performance of a micro-thruster with 1U dimensions, which employs a micro semiconductor laser, the impacts of pulse width and glycidyl azide polymer (GAP) thickness on thrust performance were researched. The results showed that with a GAP thickness of 200 μm, the single-pulse impulse (I) increased gradually with the increase in the laser pulse width from 50 to 800 μs, while the specific impulse (I sp), impulse coupling coefficient (C m) and ablation efficiency (η) all reached optimal values with a 200 μs pulse width. It is worth noting that the optimal pulse width is identical to the ignition delay time. Both C m and η peaked with a pulse width of 200 μs, reaching 242.22 μN W−1 and 35.4%, respectively. With the increase in GAP thickness, I and C m increased gradually. GAP of different thicknesses corresponded to different optimal laser pulse widths. Under a certain laser pulse width, the optimal GAP thickness should be the most vertical thickness of the ablation pit, and the various propulsion performance parameters at this time were also optimal. With the current laser parameters, the optimal GAP thickness was approximately 150 μm, I sp was approximately 322.22 s, and η was approximately 34.94%.

MHz burst mode processing as a tool for achieving removal rates scalability in ultrashort laser micro-machining

The average power of ultrashort laser source has been increasing continuously and, therefore, solutions are required to employ fully these technology advances for improving the ablation efficiency in laser micro-processing. The use of burst mode processing is one of the solutions that has attracted a significant research and industrial interest in the past decade. A novel empirical methodology is proposed and implemented in this research to assess the MHz burst mode impact on the specific removal rate (SRR) and processing efficiency in ultrashort laser micro-machining. Especially, the capability of the MHz burst mode processing is investigated to scale up SRRs achievable on copper and stainless steel while utilising fully the available maximum pulse energy and average laser power. The results showed that the MHz burst mode offer a significant SRR scalability potential that can be attributed to beneficial near optimum fluence level and other side effects such as heat accumulation. Also, it is evidenced from the obtained results that the surface quality attained with the burst mode processing was comparable to that achieved with the single-pulse processing and even better at some specific process settings. Thus, the obtained SRR improvements were not in expense of the surface quality and the MHz bust mode processing represents a promising solution to employ fully the constantly increasing average power in ultrashort laser processing operations.

UV-Femtosecond-Laser Structuring of Cyclic Olefin Copolymer.

We report on the laser ablation of cyclic olefin copolymer using an amplified ultrashort pulsed laser in the ultraviolet spectral range. In addition to a high ablation depth per laser-structured layer up to 74 m at a fluence of 22 J cm, an excellent mean roughness of laser-patterned surfaces down to 0.5 m is demonstrated. Furthermore, with increasing fluence, increasing ablation efficiencies up to mm3 W−1 min−1 are determined. Regarding the quality of the ablation, we observed steep ablation flanks and low debris formation, though for fluences above 10.5 J cm the formation of troughs was observed, being attributed to multiple reflections on the ablation flanks. For comparison, laser ablation was performed under identical conditions with an infrared laser wavelength. The results highlight that UV ablation exhibits significant advantages in terms of ablation efficiency, surface roughness and quality. Moreover, our results show that a larger UV focus spot accelerates the ablation process with comparable quality, paving the way for high-power UV ultrashort pulsed lasers towards an efficient and qualitative tool for the laser machining of cyclic olefin copolymer. The production of complex microfluidics further underlines the suitability of this type of laser.

Modification of dental enamel, dentin by an ultra-fast femtosecond laser irradiation: A systematic review

ObjectiveTo assess literature for the effectiveness and impact of femtosecond (fs) laser irradiation for surface processing of enamel and dentine. Materials and methodsThis systematic review followed PRISMA guidelines. Criteria for inclusion and exclusion were established, and searches undertaken in the PubMed/MEDLINE, Embase and, Scopus databases for articles published in English over a period of the last 25 years. In-vivo studies were excluded. Analysis explored the effects of varying laser parameters including the ablation threshold, ablation rate, relative ablation efficiency and the influence of laser processing parameters, such as the laser scanning speed, on purported surface changes and presumed thermal effects on dental enamel and dentin that arise directly as a result of fs laser irradiation. ResultsEleven articles that met the inclusion criteria reported that fs laser pulses can progressively remove (i.e., ablate) dental enamel and dentin with an acceptable precision and accuracy, with little or no observed thermal effects. These reported the use of an ultra-fast fs lasers employing different wavelengths, pulse durations and irradiation parameters, such as the output power and the pulse repetition rates. The chemical composition of enamel and dentin was found not to be significantly altered by an fs laser treatment. ConclusionSignificant efforts are still required to optimise fs laser parameters for precise and selective ablation of dental tissue and dentine to enable minimally invasive restorative procedures.

Ultrasound-guided percutaneous microwave ablation for uterine fibroids: mid-term local treatment efficiency and associated influencing factors.

To investigate the mid-term local treatment efficiency of ultrasound-guided percutaneous microwave ablation (MWA) for uterine fibroids (UFs) and the associated influencing factors. From July 2020 to October 2021, a total of 28 patients with 52 UFs who had undergone ultrasound-guided MWA were retrospectively included in this study. Pre-treatment clinical characteristics, conventional ultrasound and contrast-enhanced ultrasound (CEUS) features were analyzed to explore their correlation with volume reduction ratios (VRRs) of sufficient ablation (i.e. a VRR of at least 50% at the 3 month follow-up). The patients were assessed at 1-, 3-, 6 month follow-up after MWA treatment and the assessment included VRR, adverse events, uterine fibroid symptom (UFS) and quality of life (QoL) scores, and clinical symptoms. The procedures of percutaneous MWA for UFs were tolerated well and no major complications occurred in all patients. At the 1-, 3-, 6 month follow-up, the median VRRs of UFs were 30.1%, 46.9%, and 65.8%, respectively. At the 3 month follow-up, 44.4% of fibroids obtained sufficient ablation while the remaining 55.6% obtained partial ablation (i.e. a VRR of <50%). Non-enhancing area during the early phase (i.e. within 30 s after injecting contrast agent) on pre-treatment CEUS was present in 22.2% UFs, which was associated with sufficient ablation at the 3 month follow-up (p < 0.05). In addition, the relevant clinical symptoms of all patients were alleviated or removed. The UFS and QoL score after MWA decreased significantly in comparison with those after MWA (p = 0.04 and p = 0.057, respectively), indicating a remarkable improvement of clinical symptom and QoL. Ultrasound-guided MWA is an effective and safe method to treat patients with UFs. Non-enhancing area during the early phase on pretreatment CEUS is associated with mid-term local treatment efficiency, which might be used to predict treatment outcome. Non-enhancing area during the early phase on pretreatment CEUS is an important factor associated with mid-term local treatment efficiency. This is the first study finding that CEUS feature can be used as a marker for the prediction of mid-term local treatment response.

US/MR Bimodal Imaging-Guided Bio-Targeting Synergistic Agent for Tumor Therapy.

PurposeBreast cancer is detrimental to the health of women due to the difficulty of early diagnosis and unsatisfactory therapeutic efficacy of available breast cancer therapies. High intensity focused ultrasound (HIFU) ablation is a new method for the treatment of breast tumors, but there is a problem of low ablation efficiency. Therefore, the improvement of HIFU efficiency to combat breast cancer is immediately needed. This study aimed to describe a novel anaerobic bacteria-mediated nanoplatform, comprising synergistic HIFU therapy for breast cancer under guidance of ultrasound (US) and magnetic resonance (MR) bimodal imaging.MethodsThe PFH@CL/Fe3O4 nanoparticles (NPs) (Perfluorohexane (PFH) and superparamagnetic iron oxides (SPIO, Fe3O4) with cationic lipid (CL) NPs) were synthesized using the thin membrane hydration method. The novel nanoplatform Bifidobacterium bifidum-mediated PFH@CL/Fe3O4 NPs were constructed by electrostatic adsorption. Thereafter, US and MR bimodal imaging ability of B. bifidum-mediated PFH@CL/Fe3O4 NPs was evaluated in vitro and in vivo. Finally, the efficacy of HIFU ablation based on B. bifidum-PFH@CL/Fe3O4 NPs was studied.ResultsB. bifidum combined with PFH@CL/Fe3O4 NPs by electrostatic adsorption and enhanced the tumor targeting ability of PFH@CL/Fe3O4 NPs. US and MR bimodal imaging clearly displayed the distribution of the bio-targeting nanoplatform in vivo. It was conducive for accurate and effective guidance of HIFU synergistic treatment of tumors. Furthermore, PFH@CL/Fe3O4 NPs could form microbubbles by acoustic droplet evaporation and promote efficiency of HIFU ablation under guidance of bimodal imaging.ConclusionA bio-targeting nanoplatform with high stability and good physicochemical properties was constructed. The HIFU synergistic agent achieved early precision imaging of tumors and promoted therapeutic effect, monitored by US and MR bimodal imaging during the treatment process.

Catheter ablation for atrial fibrillation - standard of care and future perspectives

Atrial fibrillation is the most frequent cardiac arrhythmia in adults. For symptomatic atrial fibrillation, catheter ablation has proven to be an effective and safe treatment that is superior to antiarrhythmic drug treatment regarding quality of life and maintenance of normal sinus rhythm. Moreover, there is increasing evidence that early rhythm control and catheter ablation can be of prognostic benefit. Especially heart failure patients with impaired left ventricular systolic function seem to benefit from rhythm control therapy by catheter ablation. Furthermore, technological innovations such as novel single-shot devices, contact force mapping, the concept of high-power-short-duration (HPSD) ablation and implementation of electroporation (pulsed field ablation) offer the prospect of further improving ablation efficiency and safety. This review provides an overview of current standards of care as well as future trends in atrial fibrillation catheter ablation techniques.

Hybrid ablation procedure for the treatment of nonparoxysmal atrial fibrillation: A systematic review and meta-analysis.

Hybrid ablation combines the advantages of surgical and catheter ablation. Many studies have explored the efficiency and safety of hybrid ablation in patients with nonparoxysmal AF. We systematically searched for prospective controlled trials that compared hybrid ablation with catheter/surgical ablation in PubMed, Web of Science, Wiley Library, and CNKI. Our main assessment indicators included maintenance of sinus rhythm (SR) without antiarrhythmic drugs for more than 12 months, major adverse events (MAEs), procedure time and fluoroscopy time. Of 1214 identified studies, five were eligible and were included in our analysis (N=451 participants). The pooled results showed that hybrid ablation was more effective in maintaining SR than a single procedure (surgical ablation or catheter ablation) (OR=2.52, 95% confidence interval [CI]: 1.63-3.89, p<.001). Little significant heterogeneity was revealed (p=.32 for heterogeneity, I2 =14%). More MAEs occurred in the hybrid group than in the single procedure group (OR=7.47, 95% CI: 1.90-29.41, p=.004; I2 =0%). Two trials reported the procedure and fluoroscopy times, and the procedure time for hybrid ablation was significantly longer than that of a single procedure (mean difference=107.42, 95% CI: 88.62 to 126.22, p<.001; I2 =82%). There was no significant difference in fluoroscopy time between the 2 groups (mean difference=-1.00, 95% CI: -5.37 to 3.36, p=.65; I2 =12%). Hybrid ablation was more effective than catheter ablation and was as effective as surgical ablation in patients with nonparoxysmal AF. Meanwhile, hybrid ablation, especially concomitant hybrid ablation, increases the incidence of MAEs and prolongs the procedure time.

Reducing thermal damage to adjacent normal tissue with dual thermo-responsive polymer via thermo-induced phase transition for precise photothermal theranosis

Photothermal therapy has been extensively studied to improve the light-to-heat efficiency for tumor ablation, but could cause severe damage to adjacent healthy tissue due to the thermal transfer, the random distribution of photothermal agents (PTAs), or combination hereof. Herein, we solve this dilemma with a material design strategy to develop a P(AAm-co-AN)-b-P(NIPAM-co-DMAa)-b-P(AAm-co-AN) ABA triblock copolymer by RAFT polymerization, which exhibits both UCST and LCST dual thermo-responsive behaviors in aqueous solution. The P(AAm-co-AN) block with appropriate AN content allows to finely tune its UCST to ∼ 43°C, which can effectively co-assemble with camptothecin (CPT) and Cy7-TCF, a near-infrared (NIR) PTA, realizing the photo-activated “on-demand” release of CPT and Cy7-TCF. The LCST of P(NIPAM-co-DMAa) segment is adjusted to ∼ 53°C by varying DMAa content, enabling an irreversible sol-to-gel transition. The heat transfer in hydrogel and heat dissipation at the interface of hydrogel-adjacent tissue are limited, resulting in selectively cell killing in tumor, with little hyperthermia in adjacent tissues. Moreover, the hydrogel continues to release CPT to enhance the synergistic efficacy of PTT with chemotherapy. These results suggest that dual thermo-responsive polymer can contribute PTT with high selectivity and negligible side effects for precise medicine. Statement of SignificancePhotothermal therapy exploits the susceptibility of tumor cells toward external light-induced hyperthermia, but can cause severe damage to adjacent healthy tissue due to thermal transfer, random distribution of photothermal agents (PTAs), or combination hereof. Here, we solve this dilemma by developing a P(AAm-co-AN)-b-P(NIPAM-co-DMAa)-b-P(AAm-co-AN) triblock copolymer with UCST and LCST dual thermo-responsive behaviors, realizing the sequential micelle-unimer-hydrogel phase transitions. The polymer can effectively encapsulate PTA/drug, achieve long systemic circulation, accumulate in tumor through EPR effect, regulate drug release by controlling tumor temperature above UCST via irradiation, and finally exhibit a sol-gel transition, eradicating the heat transfer to adjacent tissue. This represents a practicable strategy to guide the design of next-generation polymeric vector that can contribute PTT with negligible side effects.

Microwave Reduced Graphene Oxide as Efficient NIR Photothermal Agent

Current study reports the enhanced cancer cells photothermal ablation efficiency of Microwave Reduced Graphene Oxide (MRGO). Reduction of chemically exfoliated graphene oxide has been carried out using a microwave (700W for 5 minutes). The produced MRGO have been characterized with TEM, SEM, XRD, FTIR, RAMAN, AFM and UV-Vis spectroscopy. MRGO nano size sheets with average lateral dimension ~200nm, exhibited higher NIR absorption efficiency, in comparison to Graphene Oxide (GO). Photothermal efficacy (at optimized NIR laser 808 nm, power of 5.0W/cm2 for 5 min) of MRGO have been tested against human alveolar epithelial carcinoma cell (A549) and human colorectal carcinoma cells (HCT116). As a result, a significant decrease in cell viability by 84% and 80% for A549 and HCT116 cell lines respectively has been estimated. No significant toxicity has been observed with MRGO (in absence of NIR treatment) at the concentrations well above the doses needed for photothermal heating against the same cancer cells. Our study introduces MRGO as a biocompatible and efficient photothermal agent.

Synthesis and optical characteristics of silver nanoparticles produced by laser ablation of metal in liquid

The process of silver ablation in water by high-power laser pulses (λ = 1064 nm, τ = 20 ns) in the power density range from 2.6 ⋅ 108 to 5.5 ⋅ 108 W/cm2 has been investigated. The dependences of the ablation efficiency and the size distribution of silver nanoparticles on the power density of laser radiation and on the duration of synthesis have been determined. It was found that the resulting nanoparticles have a multimodal size distribution, in which three fractions with average sizes of 5; 50 and more than 100 nm can be distinguished. Particles with a diameter of more than 100 nm are formed as a result of the removal of the liquid-droplet phase directly from the target surface due to the hydrodynamic mechanism, particles 5 and 50 nm in size are formed due to condensation at different stages of cooling of the vapor-plasma formation. The proportion of these fractions in the silver sol is determined by the effective density of the laser power on the target surface. It is shown that pulsed laser irradiation of a sol of silver nanoparticles after the completion of the synthesis process makes it possible to significantly narrow the particle size distribution and increase the stability of the resulting suspension. It was found that the synthesised silver nanoparticles deposited on a silicon substrate can effectively enhance the Raman signal of human serum albumin.

The Efficiency of Ablation of Metals by Scanning Beam of Pulsed Irradiation with Nanosecond-Range Fiber Yb:YAG Laser

The Efficiency of Ablation of Metals by Scanning Beam of Pulsed Irradiation with Nanosecond-Range Fiber Yb:YAG Laser

Interface Adhesion Property and Laser Ablation Performance of GAP-PET Double-Layer Tape with Plasma Treatment.

In the field of laser ablation micro-propulsion, the property of double-layer tape has significant impact on the propulsion performance. In this paper, low temperature plasma was used to treat the surface of polyethylene terephthalate (PET) to improve its adhesion with energetic polymer. The PET surface pre- and post-plasma treatment was characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), and the enhancement mechanism of the interface adhesion was discussed. In addition, the ablation performance of the double-layer tape after the plasma treatment was studied. The results showed that the plasma etching effect increased the root mean square roughness of the PET surface from 1.74 nm to 19.10 nm. In addition, after the plasma treatment, the number of C–OH/COOH bonds and O=C–O bonds increased, which also greatly improved the adhesion between the PET and energetic polymers. In the optimization of the ablation performance, the optimal laser pulse width was about 200 μs. The optimal values of the specific impulse (Isp), impulse coupling coefficient (Cm), and ablation efficiency (η) were 390.65 s, 250.82 μN/W, and 48.01%, respectively. The optimization of the adhesion of the double-layer tape and the ablation performance lay the foundation for the engineering application of laser ablation micro-thrusters.

First human experience with catheter ablation using dipole charge density mapping integrated in robotics in the management of atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Remote magnetic navigation (RMN) guided catheter ablation (CA) previously demonstrated high efficiency and efficacy in atrial fibrillation (AF) ablation. Heretofore, only the CARTO 3D mapping system was integrated in the RMN system. Recently, a novel high-resolution non-contact mapping system (AcQMap) can be used in combination with the RMN robotic system (AcQMap-RMN). Purpose To assess efficiency, efficacy and safety of dipole charge density mapping in RMN guided ablation procedures for AF. Methods All patients undergoing pulmonary vein isolation (PVI) or redo-PVI using the AcQMap-RMN system were analyzed. The AcQMap identifies different activation patterns such as focal firing, rotational activity, and localized irregular activation for substrate ablation. Procedural efficiency was characterized by procedure time, total ablation time and radiation doses. Efficacy data were based on 12-month follow up and number of redo procedures. Procedural safety was evaluated by intra- and post-procedural complications. Results A number of 71 consecutive patients were included in the study (47 male, 24 female, mean age 60.8±9.9, 49 redo, 22 de novo). Twenty-four patients had paroxysmal (PAF), 47 had persistent AF (persAF). After completing PVI, 42 patients underwent AcQMap based substrate ablation. Twenty-four patients converted to atrial tachycardia/flutter during the ablation. The mean procedure time was 170.5±43.3 min, mean ablation time 1749.6±950.7 s, mean radiation dose was 207.0 (IQR 128.5 - 349.5) mGy. In the PAF group, radiation doses (128.5 vs 256.0 mGy, p=0.00) and application numbers (21.1 vs 37.0, p=0.00) were lower, ablation times were shorter (1312.5 vs 1919.3 s, p=0.02) compared to the persAF patient group. Two patients in the PAF group, and 9 patients in the persAF group had documented recurrence at the 6-month follow-up visits. In the PAF group, 23 patients were AF-free (95.8%), in the persAF group, 34 patients were AF-free at the end of the 12-month follow-up period (72.3%). Six patients had a redo procedure. Two patients were documented with hematoma, as minor post-procedural complication (2.8%). Conclusion AcQMap-RMN integration provides high acute and long-term success rates, improved efficiency and low complication rates in paroxysmal and persistent AF ablation.

A novel dipole charge density mapping system integrated in robotics offers advantages for ablation of atrial tachycardias: first-in-human experience

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation (CA) for atrial tachycardia (AT) and atrial flutter (AFL) offers favorable acute and long-term outcomes. Until recently, mapping of AT/AFL was only possible with sequential mapping methods using manually controlled catheters. Even by implementing multielectrode mapping, some limitations exist during mapping of short-lived arrhythmias and ATs with unstable CL. Remote magnetic navigation (RMN) with its atraumatic catheter design has superior safety profile and excellent accuracy. Recently, a novel high-resolution mapping system (AcQMap) can be used in combination with RMN (AcQMap-RMN). Purpose To assess the feasibility, safety and efficacy of AcQMap-RMN guided ablation in the management of complex ATs. Methods All patients undergoing CA for AT/AFL using AcQMap-RMN were included. The AcQMap system utilizes two different types of mapping: Single Position Map (SMP) and SuperMap, allowing mapping of both non-sustained and sustained ATs. Procedural efficiency was characterized by procedure time, total ablation time and radiation doses. Acute success was defined by arrhythmia source elimination. Efficacy data are based on 12-month follow up and number of redo procedures. Procedural safety was evaluated by intra- and post-procedural complications. Results A total number of 76 patients were referred for CA with AT/AFL (mean age 59.0±13.2), including 3 patients with inappropriate sinus tachycardia and 73 patients with AT/AFL. Out of 73 patients, 8 had perinodal AT. From the remaining 65 patients, 38 had de novo, 22 had post-PVI, and 5 patients had post-MAZE AT/AFL. Twenty-nine patients had short-lived ATs and were mapped exclusively by SPM. The mean procedure time was 175.9±61.4 min, mean ablation time 964.0 (IQR 422.0-1693.0) s, and mean radiation dose was 152.0(IQR 86.7-294.0) mGy. Acute success was documented in 70 procedures (92.1%). From de novo AT/AF patients 4 (10.5%), from post-PVI and post-MAZE AT/AFL patients 3 had recurrence at the end of the follow-up period (11.1%). Four patients had redo procedure. Three patients had post-procedural complications including 2 patients with groin hematoma and 1 patient with transient ischemic attack. Conclusion AcQMap-RMN integration offers improved efficiency, high success and low complication rates in complex AT ablation.

Efficient Water-Assisted Glass Cutting with 355 nm Picosecond Laser Pulses.

In this study, the cutting of borosilicate glass plates in ambient air and water with a 355 nm wavelength picosecond laser was carried out. Low (2.1–2.75 W) and high (15.5 W) average laser power cutting regimes were studied. Thorough attention was paid to the effect of the hatch distance on the cutting quality and characteristic strength of glass strips cut in both environments. At optimal cutting parameters, ablation efficiency and cutting rates were the highest but cut sidewalls were covered with periodically recurring ridges. Transition to smaller hatch values improved the cut sidewall quality by suppressing the ridge formation, but negatively affected the ablation efficiency and overall strength of glass strips. Glass strips cut in water in the low-laser-power regime had the highest characteristic strength of 117.6 and 107.3 MPa for the front and back sides, respectively. Cutting in a high-laser-power regime was only carried out in water. At 15.5 W, the ablation efficiency and effective cutting speed per incident laser power increased by 16% and 22%, respectively, compared with cutting in water in a low-laser-power regime.

Long-term study on electrophysiological characteristics and catheter ablation of idiopathic ventricular arrhythmias originating from the left ventricular posterior papillary muscles guided by intracardiac ultrasound.

BackgroundThis study aimed to investigate the electrophysiological characteristics of idiopathic ventricular arrhythmias (VAs) originating from the left ventricular posterior papillary muscles (LPPM) and explore the efficiency of catheter ablation using three‐dimensional intracardiac ultrasound technology.MethodsTwenty‐seven cases of premature ventricular contraction/ventricular tachycardia (PVC/VT) originating from the left ventricular posterior papillary muscles were recorded from July 2015 to June 2019 in the Central Hospital of Shengli Oil Field and the First Affiliated Hospital of Zhengzhou University. Electrophysiological mapping and radiofrequency catheter ablation (RFCA) were performed using three‐dimensional intracardiac ultrasound technology. The characteristics of the body surface and intracavity electrocardiogram were analyzed. All cases were followed up for 24 months after the operation.ResultsThe VAs of all 27 cases were successfully eliminated by catheter ablation. QRS complexes were observed with a right bundle branch block (RBBB) pattern and a steep slope in the initial segment. Lead I appeared with an Rs pattern, and inferior leads (lead II, III, and aVF) were usually with an S wave. The lead aVR appeared with a qR pattern, while the R wave was commonly found in aVL. The main wave in leads V1‐V3 was positive but negative in V5 and V6.ConclusionVentricular arrhythmias originating from the left ventricular posterior papillary muscles have similar electrophysiological characteristics. The origin site was accurately located using three‐dimensional intracardiac ultrasound technology. Catheter ablation effectively eliminated VAs.