Ablation Efficiency Research Articles

An in vitro and in vivo study on extracorporeal transducer optimization for high-intensity focused ultrasound to improve the safety and efficacy of breast tumor ablation

Objective To observe the characteristics of a new extracorporeal high intensity focused ultrasound transducer, titled Haifu system JCQ-B, and to compare its safety and efficacy for breast ablation with the standard Haifu system JC transducer. Materials and methods Ox liver with pig skin and pork ribs were prepared in a semi-sphere shape, served as in vitro acoustic model. The udders of female goats were used as in vivo acoustic model. Both in vitro and in vivo models were ablated by either JCQ-B or JC transducer. The morphology of biological focal region (BFR), the coagulative necrosis volume, and the temperature increase were observed and compared. Results The BFR morphology of JCQ-B transducer was circular both in vitro and in vivo, with a length-width ratio close to one. Under the same sonication parameters (sonication power, time and depth in tissue), coagulation necrosis volume caused by JCQ-B transducer was larger than that caused by JC transducer both in vitro and in vivo. The increase in temperature in the near and far acoustic pathways with JCQ-B transducer was significantly lower than that of JC transducer in vitro. After receiving high sonication energy during in vivo experimentation, there were no complications observed after the ablation of JCQ-B transducer, while small skin damage was observed after the ablation of JC transducer. Conclusions The JCQ-B transducer improved the safety and efficacy of treatment by optimizing BFR morphology and ablation efficiency, which could be applied in the treatment of breast tumor.

Thulium Fiber Laser vs Pulse-Modulated Holmium MOSES Laser in Flexible Ureteroscopy for the Management of Kidney Stones: A Single-Center Retrospective Analysis.

Introduction and Objective: The study's primary objective was to compare the laser efficiency and clinical outcomes of two widely used systems, the holmium MOSES laser and the thulium fiber laser (TFL), in managing kidney stones. The secondary outcomes were to evaluate the impact of stone composition on laser efficacy. Methods: We conducted a retrospective review of patients who underwent flexible ureteroscopy (f-URS) for solitary renal calculi between December 2020 and August 2022 at our institution and had a 3-month postoperative CT scan. Patient demographics and stone parameters were recorded, including stone site, size, volume, and density. Intraoperative data were collected and analyzed, including total operative time, ureteroscopy time, lasing time, technique, total energy delivered, and stone composition. All patients underwent a CT scan at 3 months follow-up. We recorded the presence of residual stones and the percentage of stone volume reduction. Ablation efficiency was calculated by dividing the energy utilized (J) by the stone volume (mm3). The ablation speed was calculated by dividing the stone volume (mm3) by the lasing time (seconds). Patients with a stone size <4 mm were deemed stone-free. Results: The MOSES and TFL groups comprised 62 and 49 patients, respectively. There were no significant differences between groups for baseline patient demographics or stone characteristics. The two modalities had comparable total energy, laser time, efficacy, and ablation speeds. No differences were detected in stone-free rates or complications between both groups. When dealing with calcium phosphate stones, we observed that the lasing time was significantly shorter with MOSES than TFL (7.95 vs 10.85 minutes, respectively [p = 0.01]). Conclusions: MOSES and TFL laser systems had comparable efficacy for lithotripsy of renal calculi during f-URS; however, calcium phosphate stones had a longer lasing time with TFL. REB Number: 100210.

High-security automatic path planning of radiofrequency ablation for liver tumors

Background and objectiveRadiofrequency ablation (RFA) is an effective method for the treatment of liver tumors. Preoperative path planning, which plays a crucial role in RFA treatment, requires doctors to have significant experience and ability. Specifically, correct and highly active preoperative path planning should ensure the safety of the whole puncturing process, complete ablation of tumors and minimal damage to healthy tissues. MethodsIn this paper, a high-security automatic multiple puncture path planning method for liver tumors is proposed, in which the optimization of the ablation number, puncture number, target positions and puncture point positions subject to comprehensive clinical constraints are studied. In particular, both the safety of the puncture path and the distribution of ablation ellipsoids are taken into consideration.The influence of each constraint on the safety of the whole puncturing process is discussed in detail. On this basis, the efficiency of the planning method is obviously improved by simplifying the computational data and optimized variables. In addition, the performance and adaptability of the proposed method to large and small tumors are compared and summarized. ResultsThe proposed method is evaluated on 10 liver tumors of various geometric characteristics from 7 cases. The test results show that the average path planning time and average ablation efficiency are 41.4 s and 60.19%, respectively. For tumors of different sizes, the planning results obtained from the proposed method have similar healthy tissue coverage. Through the clinical evaluation of doctors, the planning results meet the needs of RFA for liver tumors. ConclusionsThe proposed method can provide reasonable puncture paths in RFA planning, which is beneficial to ensure the safety and efficiency of liver tumor ablation.

LMAP-18 ADAPTING LASER INTERSTITIAL THERMAL THERAPY (LITT) FOR TREATMENT OF INTRACRANIAL LESIONS IN CANINES

Abstract Malignant gliomas are devastating intracranial tumors with dismal prognoses that impose unique therapeutic challenges. Treatment options include surgical resection, radiation, and chemotherapy, but efficacy is limited and carries associated morbidity. Promise persists for newer modalities, such as immune-based platforms, but the blood-brain barrier (BBB) restricts intracranial therapeutic access, limiting success. Laser interstitial thermal therapy (LITT) is a minimally invasive surgical intervention permitting thermal ablation of brain tumors and other intracranial lesions. During LITT, a laser probe is stereotactically introduced through a small skull burr hole into the lesion. Continuous MRI is used to conduct real-time temperature monitoring via software-based calculation of cumulative thermal dosage zones. LITT is not only capable of ablating neoplastic tissue, but can also open the BBB in peritumoral regions, and thus may synergize with other emerging therapies. We adapted a commercially available LITT system (Monteris Medical) for use in dogs with intracranial lesions. Canine cadavers were used to optimize LITT procedures before employing this platform in live dogs. Our approach consists of 1. obtaining volumetric, T1-weighted, MRI studies to plan trajectories to intracranial targets, 2. fixing canine patients to a surgical bed and registering them for surface matching to a volume rendered image, 3. using an integrated instrument holder (Varioguide, Brainlab) to guide drilling of 4.5 mm skull burr holes for placement of self-tapping titanium “mini-bolts” (Monteris Medical), and 4. introducing the laser catheter probe through the mini-bolts for lesion ablation in the MRI suite. This method allows for rigid stereotaxy, successful neuronavigation, and a minimally invasive approach. We have successfully performed LITT on four canine patients with spontaneously occurring intracranial gliomas and plan to treat additional canine patients with intracranial lesions. Future studies will explore combination therapeutic platforms, including immunotherapy and gold nanoparticles to improve the efficiency and specificity of tumor ablation.

Ablation and surface structuring of nitride ceramics induced by picosecond laser pulses

In this work, the picosecond laser ablation process of aluminium nitride (AlN) and silicon nitride (Si3N4) ceramics is studied. The laser irradiation is performed by a Nd:YAG laser system that generates pulses with a duration of 10 ps and operates at the wavelengths of 266 nm, 355 nm, 532 nm, and 1064 nm. The ablation phenomena characterization is based on analyses of the ablation depth, the surface morphology and the chemical changes induced by the laser radiation. The dependences are studied of these characteristics on the processing parameters, namely, the laser wavelength, fluence and number of applied pulses, and the ambient pressure. The results presented concern the drilling geometry and the tracks formed when the sample is moving with respect to the laser beam. The ablation efficiencies in terms of ablation depth per incident fluence and per pulse are also discussed. It is found that the laser treatment results in a variety of micro- and nanostructures on the surface of the material. Ripple structure formation is observed in both ceramics, which are of different type with respect to the period and orientation. The ablation mechanisms are considered and evidence is provided that in picosecond regime decomposition of the ceramics could takes place with aluminium or silicon formation on the surface. The paper offers novel data on the fundamental picture of picosecond laser-matter interaction that can be useful in ceramic surface structuring and in designing methods for fabricating complex composite materials.

Enhanced thermal ablation via an acoustic vortex with a large focal region

Focused ultrasound ablation provides a truly noninvasive tumor treatment option with clinically proven feasibility and safety. However, the frequently required long treatment duration hinders its clinical applicability. In this work, we compared the thermal ablation induced by conventional focused ultrasound (cFUS), split-focus ultrasound (sFUS), and acoustic vortex (AV) in tissue phantoms containing phase-change nanodroplets and mouse tumors. The results indicated that AV could substantially enhance the thermal ablation efficiency compared with cFUS, which was attributed to the larger focal region in the former. Additionally, the ablation region appeared as a unique cylindrical area with a smaller length-to-width ratio in AV than that in cFUS. Though the efficiency could also be improved in sFUS compared with cFUS, the ablation region was irregular and non-ablated tissues were present. Furthermore, in vivo experiments demonstrated that the tumor volume decreased faster and the mice survived longer after AV treatment compared with cFUS. The cavitation activity was also found to be more intense in AV ablation. The proposed method may solve the general issue of low efficiency often observed in cFUS ablation and further promote the development of other ultrasound treatments.

Investigation of Ablation Efficiency of Stainless Steel Using Pulsed Lasers in Burst Mode

Due to its high corrosion resistance and mechanical properties, stainless steel is commonly used in various industrial applications. Although different types of stainless steel are similar in their chemical composition, they can differ significantly in their thermal diffusivity. This property is relevant in the ability of a material to conduct heat and thus, in laser processing. In this frame, this study compares the ablation efficiency and characteristics of polished stainless steel samples of the alloys AISI 304, AISI 420, and AISI 316Ti. They are irradiated with single ultrashort pulses having pulse durations between 250 fs and 10 ps as well as using GHz burst modii. The goal is to investigate the differences in both the ablation threshold and the ablation rate to improve the ablation efficiency. The results show that shorter pulse durations lead to a more efficient ablation process. On the other hand, GHz bursts are found to be, in general, less efficient. In addition, there is a significant difference in the surface morphology depending on the process parameters. The differences in the thermal diffusivity do not significantly influence the ablation threshold fluence but surface morphology and the ablation rate.

Controlled pyrolysis of epoxy through highly silicone-branched structures to construct a compact porous char layer for ablation resistant coatings

Excellent mechanical and adhesive properties make epoxy an ideal coating, but speedy pyrolysis rate, excessive gas products, and low residual char lead to low ablation efficiency, limiting the application in long-time thermal protection environments. In this paper, through branching structure design including pre-curing and alcohol exchange reactions, highly silicon-branched epoxy resins with different degrees of branching and silicon contents were synthesized. And the synthesis of highly silicone-branched epoxy resins with different branching degrees was verified by FTIR and viscosity curves. Through the analysis of thermal stability and pyrolysis history, the influence of the branched structure and content of silicone on the ablation mechanism of epoxy resin was investigated in detail. With 90 phr addition, the char residue increased to 42.3 %, and the release of pyrolysis products including a variety of flammable products was significantly inhibited. Furthermore, under a torch test of 160 kW/m2, due to the deposition mechanism in the gas and liquid phases of degradation products, a compact porous char was constructed during the ablation. The linear ablative rate of EP-3M@90P was reduced by more than 60 %, and the maximum value of back-surface temperature decreased by 48 °C compared to EP. Besides, the silicone-branched epoxy resin exhibits excellent mechanical properties, and the impact strength of EP-3M@90P nearly doubled compared to EP. Predictably, the design of silicone-branched structures to achieve control of the degradation history of epoxy resins provides a superior method for the preparation of high-strength and high-toughness thermal protective coatings.

Comparison between nanosecond and femtosecond laser pulses for the removal of spray paint from granite surfaces

We investigated the removal of spray paint from heritage granite surfaces using a nanosecond pulse laser and compared the results, in terms of the effectiveness of treatment and preservation of the stone surface from potential damage, with results obtained using a femtosecond pulse laser. We show that, with the nanosecond laser, the ablation threshold of the stone was measured at 0.5 J·cm-2, but it was only possible to remove certain types of spray paints, such as blue and green paints, at a higher fluence of 0.9 J·cm-2. To remove other types of paints, such as red and yellow, it was necessary to increase even further the laser fluence to 1.5 J·cm-2, well above the ablation threshold of the stone. In this case, damage was induced in the minerals, such as melting of biotite, and a general roughening of the other minerals’ surfaces was observed. Despite nanosecond pulse lasers being more widespread for cleaning purposes, we demonstrate that femtosecond pulse lasers allowed better effectiveness in removing various colours of paint, without leaving residues, while keeping the laser energy below the damage threshold of the underlying stone, allowing complete preservation of the substrate, and avoiding the melting of the most sensitive mineral grains (particularly biotite). We determined the ablation efficiency of spray paint using the femtosecond pulse laser and found a maximum ablation regime centered around 6.2 J·cm-2, at 8.36 mm3·(min·W)-1. This study highlights the benefits of using a laser with femtosecond pulses instead of longer pulse durations (nanosecond range) for the preservation and maintenance of heritage stone.

GaAs ablation with ultrashort laser pulses in ambient air and water environments

Water-assisted ultrashort laser pulse processing of semiconductor materials is a promising technique to diminish heat accumulation and improve process quality. In this study, we investigate femtosecond laser ablation of deep trenches in GaAs, an important optoelectronic material, using water and ambient air environments at different laser processing regimes. We perform a comprehensive analysis of ablated trenches, including surface morphological analysis, atomic-resolution transmission electron microscopy imaging, elemental mapping, photoluminescence, and Raman spectroscopy. The findings demonstrate that GaAs ablation efficiency is enhanced in a water environment while heat-accumulation-related damage is reduced. Raman spectroscopy reveals a decrease in the broad feature associated with amorphous GaAs surface layers during water-assisted laser processing, suggesting that a higher material quality in deep trenches can be achieved using a water environment.

A High‐Precision, Low‐Voltage Pulsed Field Ablation Device with Capability of Minimally Invasive Surgery

AbstractPulsed field ablation is a novel approach to treating 33.5 million patients with atrial fibrillation and offers a tissue‐specific advantage over conventional radiofrequency ablation and cryoablation. However, for complex structural targets in the heart, current electrodes often damage non‐target areas due to inaccurate ablation and have to employ electrical pulses with amplitudes of several kilovolts. Herein, materials and designs of a catheter‐integrated microelectrode and sensors that can be used for high‐precision and low‐voltage pulsed field ablation through minimally invasive operation on a large animal model, is reported. The device with a new electrode configuration supports point‐by‐point ablation with a width of 3.8 mm (≈1/10 that of a typical ablation electrode) for individual lesions at the voltage of 300 V (an order of magnitude reduction compared to the current state‐of‐the‐art). More impressively, the integrated catheter allows for pulsed field ablation on the large animal heart through minimally invasive surgery and blocks the electrical conduction pathway on the heart, which is the key to treating atrial fibrillation. This catheter‐integrated device will enhance the efficiency and safety of pulsed field ablation, especially for complex cardiac structures, thus facilitating its move to the clinic.

Microwave-Assisted Chemical Ablation (MA-CA): A Novel Microwave-Assisted Tissue Ablation Procedure—Preliminary Assessment of Efficiency

Microwave (MW) ablation is becoming a routine technology in the interventional radiology field. A new approach combining MW ablation and chemical ablation is developed in this paper. The rationale for the development of this Microwave-Assisted Chemical Ablation (MA-CA) technology was to improve the utility of thermal ablation as a minimally invasive treatment for cancer. The experimental conditions for ex vivo bovine liver samples were: A—100 W (120 s) with no addition of ethanol; B—100 W (30 s), wait (60 s) (no power), and 100 W (90 s) with no addition of ethanol; C—100 W (30 s), wait (60 s), 100 W (30 s), and 100 W (60 s) with the addition of 5 mL ethanol; and D—100 W (30 s), wait (60 s), 100 W (30 s), 0 W (30 s) with the addition of 2.5 mL ethanol, and 100 W (60 s) with the addition of 5 mL ethanol (12,000 Joules Total). The results showed that with the use of ethanol, the ablation zone was enlarged and revealed improved sphericity. This novel combination has greater advantages than either technology individually. The objective is to increase the precision and efficiency of MW ablation and to broaden the range of tissues and pathologies that can be treated using this new approach, and to validate the benefits that arise from combining the advantages of MW and chemical ablation in a relevant setting.

Study of GHz-Burst Femtosecond Laser Micro-Punching of 4H-SiC Wafers

The micromaching of silicon carbide using femtosecond laser pulses is becoming an important field of research. High-repetition-rate sub-pulse trains, so-called pulse bursts, are a particularly promising route towards completely new process regimes. We report on the results of micro-punching n-type 4H-silicon carbide wafers using GHz pulse burst in order to systematically investigate the influence of the temporal energy distribution on laser processing. Pulse-burst experiments are performed at a laser wavelength of λ= 1030 nm using a single GHz burst containing a varying number of pulses and then compared with standard single femtosecond pulse exposures. The pulse energy is swept across the ablation threshold. For each set of parameters, the micromachining efficiency is evaluated in terms of ablation efficiency and burr characteristics. Scanning electron micrographs provide qualitative information about the machining quality. The characteristics of the laser modification are discussed in relation to an increase in the number of pulses in a burst envelope and to an increase in pulse energy. We observe that, compared to a single pulse, a GHz burst comprised of 10 lower-energy pulses leads to an increase in the ablation rate by a factor of ≤ 10.

Effect of pulse parameters on ablation efficiency in dual-frequency HIFU therapy

High-intensity focused ultrasound (HIFU) has now been widely used to ablate various benign and malignant tumors. But it is still critical to increase the ablation efficiency in many clinical applications. Dual-frequency HIFU has been proven to be more efficient in ablation, but the principle on selecting the pulse parameters in this method remains to be explored. In this study, the in vitro lesion areas under different pulse repetition frequencies (PRFs), duty ratios, and frequency differences were compared, cavitation activity was also monitored during HIFU exposure. The results showed that different pulse parameters caused different types of lesions. In HIFU therapy, those pulse parameters that maximize the thermal effect, reduce heat dissipation and generate sufficient cavitation activities should be considered. But the method of evaluating or predicting the damage by using the cavitation dose is only applicable to mechanical damage.

Side Chain Engineering of Amphiphilic Conjugated Polymer Nanoparticles for Biofilm Ablation

AbstractBiofilm recalcitrance, which enables bacteria to survive deep within the body under antimicrobial treatment, leading to persistent infections by reducing the penetration of antimicrobials, remains a major challenge in the antibacterial field. Conjugated polymer‐based nanoparticles with near‐infrared (NIR) photo responsiveness have emerged as a promising class of photothermal agents for biofilm ablation. However, the development of CPNs has been limited due to dissociation of the nanoparticles synthesized through nanoprecipitation. In this study, surface‐functionalized amphiphilic conjugated polymer‐based nanoparticles with photothermal conversion capacity for pH‐responsive targeting of bacteria are developed. The pH‐sensitive properties of the nanoparticles promote their adhesion to negatively charged bacterial surfaces, resulting in accumulation in biofilms. This accumulation enhances the ablation efficiency of biofilms under the synergistic photothermal effect. The method of constructing functional amphiphilic conjugated polymer‐based nanoparticles is simple to operate and can be used universally, providing a potential design option for biocompatible light‐responsive nanoparticles for in vivo applications.

Inverse dependence of heat accumulation on pulse duration in laser surface processing with ultrashort pulses

Laser pulse duration is one of the important parameters that is able to dramatically change ablation efficiency. Shorter laser pulse duration leads to deeper transport of absorbed energy in subsurface material layers. Ultra-fast and non-equilibrium processes are able to remarkably affect residual energy, which is accumulated in the deeper subsurface layers after ablation. On the other hand, undesirably high heat accumulation leads to material overheating with surface oxidation, appearance of liquid phase and, as a result, low processing quality. In this paper, the influence of laser pulse duration on the heat accumulation value was experimentally evaluated for the first time. Heat accumulation was measured with a highly sensitive fast infrared detector. The results were presented in comparison with surface structure analysis, material ablation rate and optical reflectivity. Unexpected inverse dependence of heat accumulation on laser pulse duration was detected. An optimal laser pulse duration near 1 ps corresponds to the maximum heat accumulation value and also highest ablation efficiency in contrast to longer laser pulses. The same optimal pulse duration value was detected for low frequency (250 kHz) and for high frequency (1 MHz) laser surface processing regimes. The maximum heat accumulation value was expected at the longest laser pulses. The results are discussed from the point of view of the two-temperature model.

The effects of catheter choice on accessory pathway mapping efficiency

Abstract Funding Acknowledgements: Type of funding sources: None. Recent studies have assessed the use of a novel high density (HD) mapping catheter in pediatric patients, finding that the catheter is safe and effective in this population. However, there is a lack of understanding on use patterns of HD mapping technologies in this population and how these patterns affect intraprocedural workflows. The objective of this analysis was to assess the role of mapping catheter choice on the efficiency of accessory pathway localization and ablation in patients with structurally normal hearts treated in a pediatric EP setting. Acute data from 61 accessory pathway ablation cases in patients treated in a pediatric EP setting were prospectively collected from 14 hospitals in 6 countries in Europe and the US. Choice of mapping tools and strategy was left to physician discretion. Procedure data such as map collection duration and statistics were compared across three mapping catheter choices: Ablation Catheter (AC) (n=42), Linear Catheter (LC) (n=9), and HD Grid Catheter (HDC) (n=10). Of the 61 procedures, 16 cases were patients aged 0-12 years (26%), 34 aged 13-17 years (56%), and 5 aged 18+ years (18%). Distribution of catheter use was similar across age groups with HDC use of 13%, 15%, and 27%, respectively. Pathway location did not correlate with catheter choice. There was 0% incidence of congenital heart disease. Mean mapping times in the AC, LC, and HDC groups were 20.6±15.8, 18.8±12.9, and 14.2±13.8 minutes, respectively; differences in mapping times were not statistically significant but trended lower with higher density mapping. The mean number of mapping points used in each group was 44±46, 101±62, and 1521±908 points, respectively (p&amp;lt;.01). Ablation was attempted in 57 (93%) of cases with 100% acute success eliminating accessory pathway conduction. Ablation time was analyzed in patients receiving RF ablation (93% of treated; n=53); mean RF time was 526s in the AC group, 369s in the LC group, and 367s in the HDC group; differences were not statistically significant (p&amp;gt;.05). All groups had similar ablation target technique distributions including timing map and signal morphology. Mean procedure time was 2:11 (h:mm) in the AC group, 1:56 in the LC group, and 1:44 in the HDC group; differences were not statistically significant. Analysis of this cohort of pathways in a pediatric setting shows multipolar catheters may provide more mapping information in shorter times. RF ablation and procedure times also trend shorter in procedures with HD Grid used for mapping, regardless of anatomic location of pathway. Further analysis in a larger cohort may be warranted to validate these findings and explore use of open window mapping described elsewhere.

High efficacy single catheter standardized workflow for radiofrequency ablation of atrial fibrillation in the high-power short-duration era

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Dr. Valeriano and Dr. Fabbricatore have been supported by a research grant provided by the Cardiopath PhD program (University of Naples Federico II) Background Recent developments in radiofrequency (RF) ablation technologies have improved the efficacy of pulmonary vein isolation (PVI). The combination of the ablation index, lesion tags, and optimized inter-lesion distance (CLOSE protocol) has further reduced the incidence of gaps along the ablation lines. This high acute success rate challenged the use of conventional circular mapping catheters and prompted a single catheter-approach ablation strategy. Modulating the relationship between resistive and conductive heating, high-power short-duration (HPSD) ablation technology can potentially increase lesion-to-lesion consistency. A novel catheter with optimized temperature control and microelectrodes has been recently designed to further improve workflow efficiency. Purpose: This study aimed to assess the efficacy and efficiency of HPSD ablation in a standardized single-catheter workflow for PVI. Methods: Data on consecutive AF ablations performed with HPSD catheter from December 2020 to December 2021 at a single tertiary-care center were prospectively collected. The workflow consisted of a procedure sequence including single transeptal access with a bidirectional steerable sheath, 3D modeling with 3D rotational angiography, assessment of PV potentials with microelectrodes in each vein (figure 1), followed by radiofrequency encircling of the PVs using a high-power setting of 50W in a temperature- and flow-controlled mode with CLOSE-guided protocol. Isolation was validated by reassessing the previously observed PV potentials and by pacing within the lesion set. Results: A total of 73 consecutive AF patients (67% paroxysmal, 33% persistent) were included. All patients received PVI, 15 underwent additional cavotricuspid isthmus ablation and 6 received additional treatments (table 1). Mean procedure time was 68±27 min with minimal fluoroscopy time and dose (3.2±2.1 min; 4.7±3.9 Gycm2). Complications were infrequent with 1 cardiac tamponade and 1 pericarditis. First-pass isolation was achieved in 91% of the circles and validation by microelectrodes successfully identified the residual gaps with 100% of acute procedural success. In a selected cohort of 20 patients with paroxysmal AF undergoing PVI-only procedure performed by an expert operator, the ablation time was 22.8±5.1 min with a skin-to-skin time of 47.3±7.1 min (table 2). The median follow-up duration was 397 days (IQR: 367-462). AT/AF free survival rate was 90% at 12 months. Conclusions: HPSD ablation using a standardized single-catheter workflow improved the procedural efficiency of PVI and resulted in a high rate of first-pass isolation with a low recurrence rate at 12-month follow-up.

The role of atrial electro-mechanical coupling as predictor of catheter ablation efficiency: EPs and clinicians working together

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial fibrillation (AF) results in electrical and structural remodeling of the atria, and the extent of remodeling has already been found to be associated with higher AF recurrence rate after catheter ablation (CA). Recently, a novel echocardiographic parameter derived from tissue Doppler imaging (TDI), called PA-TDI, has been introduced to assess the total atrial activation time, as a non-invasive surrogate of fibrosis and atrial cardiomyopathy. The aim of the study was to investigate the role of PA-TDI interval as predictor of AF ablation efficacy. Methods Consecutive patients with persistent or paroxysmal symptomatic AF referred to our Center to perform radiofrequency ablation or cryoablation procedures were prospectively enrolled. In these patients, a complete transthoracic echocardiographic examination was performed before and after the ablation procedure, including assessment of the PA-TDI interval. Results From October 2018 to May 2020, 221 consecutive patients (mean age 61 ± 9 years, 74% male, mean BMI 26.5 ± 3.6, mean Ejection Fraction 61 ± 6%) symptomatic for AF, undergoing the procedure ablation (first procedure or re-do) were enrolled. Out of the blanking period, 25% of patients experienced recurrence of arrhythmia during follow-up (mean 16 months). Compared to patients who did not relapse, patients with AF recurrence have a generally longer post-procedural PA-TDI interval (139.6 ± 22.1 msec vs 153.9 ± 33 msec, respectively). In the multivariable analysis only post-procedure PA-TDI and re-do interventions were found to be independent predictors of AF recurrence. A PA-TDI cut-off&amp;gt;144msec identifies patients at risk of post ablation AF recurrence with sensitivity 58.7% and specificity 73.5% (AUC 0.697). Conclusions The PA-TDI interval is an independent predictor of AF recurrence after catheter ablation. This echocardiographic parameter is easily obtainable, low-cost, reproducible, and accessible even in peripheral centers.

A heuristic method for rapid and automatic radiofrequency ablation planning of liver tumors.

Preprocedural planning is a key step in radiofrequency ablation (RFA) treatment for liver tumors, which is a complex task with multiple constraints and relies heavily on the personal experience of interventional radiologists, and existing optimization-based automatic RFA planning methods are very time-consuming. In this paper, we aim to develop a heuristic RFA planning method to rapidly and automatically make a clinically acceptable RFA plan. First, the insertion direction is heuristically initialized based on tumor long axis. Then, the 3D RFA planning is divided into insertion path planning and ablation position planning, which are further simplified into 2D by projections along two orthogonal directions. Here, a heuristic algorithm based on regular arrangement and step-wise adjustment is proposed to implement the 2D planning tasks. Experiments are conducted on patients with liver tumors of different sizes and shapes from multicenter to evaluate the proposed method. The proposed method automatically generated clinically acceptable RFA plans within 3min for all cases in the test set and the clinical validation set. All RFA plans of our method achieve 100% treatment zone coverage without damaging the vital organs. Compared with the optimization-based method, the proposed method reduces the planning time by dozens of times while generating RFA plans with similar ablation efficiency. The proposed method demonstrates a new way to rapidly and automatically generate clinically acceptable RFA plans with multiple clinical constraints. The plans of our method are consistent with the clinical actual plans on almost all cases, which demonstrates the effectiveness of the proposed method and can help reduce the burden on clinicians.