scholarly journals Considerations for Thermal Injury Analysis for RF Ablation Devices

2010 ◽  
Vol 4 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Isaac A. Chang
Keyword(s):  
Thermal Injury ◽  
Tissue Injury ◽  
Recursive Algorithm ◽  
Geometric Model ◽  
Volume Measurement ◽  
Lesion Size ◽  
Voltage Source ◽  
Lesion Volume ◽  
The Impact

Background: The estimation of lesion size is an integral part of treatment planning for the clinical applications of radiofrequency ablation. However, to date, studies have not directly evaluated the impact of different computational estimation techniques for predicting lesion size. In this study, we focus on three common methods used for predicting tissue injury: (1) iso-temperature contours, (2) Cumulative equivalent minutes, (3) Arrhenius based thermal injury. Methods: We created a geometric model of a multi-tyne ablation electrode and simulated thermal and tissue injury profiles that result from three calculation methods after 15 minutes exposure to a constant RF voltage source. A hybrid finite element technique was used to calculate temperature and tissue injury. Time-temperature curves were used in the assessment of iso-temperature thresholds and the method of cumulative equivalent minutes. An Arrhenius-based formulation was used to calculate sequential and recursive thermal injury to tissues. Results: The data demonstrate that while iso-temperature and cumulative equivalent minute contours are similar in shape, these two methodologies grossly over-estimate the amount of tissue injury when compared to recursive thermal injury calculations, which have previously been shown to correlate closely with in vitro pathologic lesion volume measurement. In addition, Arrhenius calculations that do not use a recursive algorithm result in a significant underestimation of lesion volume. The data also demonstrate that lesion width and depth are inadequate means of characterizing treatment volume for multi-tine ablation devices. Conclusions: Recursive thermal injury remains the most physiologically relevant means of computationally estimating lesion size for hepatic tumor applications. Iso-thermal and cumulative equivalent minute approaches may produce significant errors in the estimation of lesion size.

1322Impact of system impedance in ablation-index guided lesion formation in an in vitro model

EP Europace ◽  
2020 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
C Lozano-Granero ◽  
J Moreno Planas ◽  
R Matia Frances ◽  
A Hernandez Madrid ◽  
I Sanchez Perez ◽  
...  
Keyword(s):  
Contact Force ◽  
Lesion Size ◽  
Lesion Volume ◽  
Application Time ◽  
Lesion Formation ◽  
Running Water ◽  
High Impedance ◽  
Ablation Index ◽  
The Impact

Abstract Funding Acknowledgements Beca de la Sección de Electrofisiología y Arritmias para formación en investigación post-residencia en centros españoles INTRODUCTION Ablation Index and Lesion Size Index are novel markers of ablation lesion quality that incorporate power (W), contact force (CF), and time (T) in a weighted formula to accurately estimate lesion size. While LSI includes system impedance (I) in the formula, this parameter is not considered for AI calculation. PURPOSE The aim of our study was to analyse the impact of I in lesion formation. METHODS Radiofrequency (RF) lesions were created on porcine myocardial slabs by using an open-tip irrigated catheter with real-time monitoring of CF (a TactiCath™ Quartz Contact Force Ablation Catheter for LSI-guided lesions and a ThermoCool® SmartTouch® Catheter for AI-guided lesions). Catheters were mounted in an articulated arm and manually maneuvered over a platform placed within a tank filled with either a low impedance medium (saline solution) or a high impedance medium (running water) with a heating pump to produce non-pulsatile flow directed perpendicularly to the myocardium surface at a rate of 5 l/min and a temperature of 37ºC. For each catheter and medium, ten lesions were performed with a CF of 20 grams and a W of 25, 30, 35 and 40 watts aiming at a LSI of 5 or a AI of 400 (recommended targets for posterior wall pulmonary vein isolation for each index). After RF delivery, the myocardium was cross-sectioned at the level of each lesion and its blanched zone was measured with a dial calliper with a 0.1 mm resolution (image, panel A). Lesion volume was calculated using width and depth, according to a validated formula (image, panel B). RESULTS No difference in application time was noted in the AI-guided lesions depending on the medium (23.8 ± 1.6s, 17.2 ± 1.4s, 13.7 ± 0.8s and 12.2 ± 0.7s for 25W, 30W, 35W and 40W, respectively) while a significant reduction in application time was noted in the LSI-guided lesions performed in a low I medium (93.8 ± 6.6 ohms; 17.9 ± 1.9s, 11.3 ± 3.7s, 9.1 ± 0.9s and 7.3 ± 0.5s for 25W, 30W, 35W and 40W) compared with those performed in a high impedance medium (132.4 ± 6.6 ohms; 27.3 ± 1.4s, 17.9 ± 2.5s, 15.5 ± 1.4 and 13 ± 1.2 for the same programmed W (p < 0.0001 for all comparisons). Both catheters showed differences in lesion size according to the I, with lower lesion volumes in the low I medium and higher lesion volumes in the high I medium. Although globally smaller in size, higher lesion volumes were noted in the AI-guided lesions compared to LSI-guided lesions in a low I medium (image, panel C). On the contrary, a better performance of the LSI-guided lesions was observed in the high I medium (image, panel D). CONCLUSIONS System impedance affected lesion size both in LSI-guided an AI-guided ablation lesions, with smaller lesions seen in a lower I medium. Further studies are needed to assess the clinical relevance of this findings in an in-vivo scenario. Abstract Figure.

scholarly journals Modeling traumatic brain injury combined with hemorrhagic shock in rats: Neurological assessment and PET imaging with 18F-fluorodeoxyglucaric acid

2021 ◽  
Author(s):  
Hibah O Awwad ◽  
Andria Hedrick ◽  
Alex Mdzinarishvili ◽  
Hailey Houson ◽  
Kelly Standifer ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Hemorrhagic Shock ◽  
Tissue Injury ◽  
Brain Lesion ◽  
Lesion Size ◽  
Neurological Deficits ◽  
Lesion Volume ◽  
Sprague Dawley ◽  
The Impact

Traumatic brain injury (TBI)is a major cause of death and disability worldwide. Hemorrhagic shock (HS) aggravates tissue injury and complicates TBI recovery. We studied the combined insult of mild TBI and HS and investigated the impact of varying loss of blood volume on neurologic deficit and brain lesion volume. A novel positron emission tomography (PET) technique was employed to monitor tissue injury. Male Sprague Dawley rats received mTBI by controlled cortical impact (CCI) followed by withdrawal of 0%, 30-40%, 45%, or 50% of blood (mTBI, mTBI+HS≤40%, mTBI+HS45%, and mTBI+HS50%, respectively). Neurological deficit (mNSS= 5.6, 7.6, and 12.3) and mortality (2/12, 2/6, and 7/12) were higher in mTBI+HS≤40%, mTBI+HS45%, and mTBI+HS50%, than in mTBI alone rats (no death; mNSS=3.3). Histologic lesion size increased 3.5-fold in mTBI+HS50% compared to mTBI alone and the infarct-avid PET agent 18F-fluorodeoxyglucaric acid (FGA) proportionately detected tissue necrosis in mTBI+HS50% rats. Based on these results, we conclude that HS aggravates mTBI-induced neurological deficits, tissue injury and mortality. PET using 18F-FGA as an imaging marker can detect the extent of injury in a non-invasive manner.

scholarly journals A Dual Role for Nitric Oxide in NMDA-Mediated Toxicity in vivo

1995 ◽  
Vol 15 (6) ◽  
pp. 904-913 ◽  
Author(s):  
Mordecai Y.-T. Globus ◽  
Ricardo Prado ◽  
J. Sanchez-Ramos ◽  
Weizhao Zhao ◽  
W. Dalton Dietrich ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Injection Site ◽  
Treated Group ◽  
Lesion Size ◽  
Lesion Volume ◽  
Excitotoxic Damage ◽  
Peripheral Areas ◽  
Oxide Synthase

Nitric oxide has been implicated in N-methyl-d-aspartate (NMDA)-mediated damage in vitro; however, its role in excitotoxic damage in vivo is not clear. In the present study we evaluated the histopathological and hemodynamic consequences of intrastriatal injections of various doses of NMDA and determined the effects of nitric oxide synthase inhibition on these changes. NMDA was injected into the striatum at doses of 50, 150, and 300 nmol with or without Nω-nitro-l-arginine methyl ester (L-NAME; 100 μg, locally). Three days following injections histopathological assessment was performed by morphometric analysis of the lesion area in multiple sections taken from the anterior to the posterior borders of the lesion. In animals injected with 150 and 300 nmol of NMDA (±L-NAME), local CBF (lCBF) was determined 30 min following injections using 14C-iodoantipyrine autoradiography. All NMDA-treated animals showed a well-demarcated lesion extending beyond the injection site. The volume of the lesion correlated significantly with the NMDA dose injected. The effects of L-NAME on lesion size were dependent on the dose of the NMDA. The lesion induced by 50 nmol of NMDA was not affected by L-NAME. With a dose of 150 nmol of NMDA, L-NAME induced a 43% increase in lesion volume. In contrast, a 38% decrease in lesion size was observed in animals treated with 300 nmol of NMDA combined with L-NAME. At a dose of 150 nmol, NMDA induced a significant elevation in lCBF, which was restricted to regions close to the injection site including the center areas of the anterior and middle striatum. The increase in lCBF observed with 150 nmol of NMDA was significantly attenuated in the NMDA + L-NAME-treated group. The lCBF changes induced by 300 nmol of NMDA were not significantly different from those in the 150-nmol group; however, the extent of the regions involved was larger. The increases in lCBF were observed in all striatal regions including the central and peripheral areas. L-NAME did not have a significant effect on the lCBF changes induced by NMDA at a dose of 300 nmol. These data suggest that in vivo the involvement of nitric oxide in NMDA toxicity depends on the NMDA dose and on the participation of hemodynamic mechanisms secondary to NMDA exposure.

scholarly journals Seasonal Variation in Host Susceptibility to Fusarium Canker in Young Almond Trees

Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 772-779
Author(s):  
Abigail J. Stack ◽  
Meera Madra ◽  
Thomas R. Gordon ◽  
Richard M. Bostock
Keyword(s):  
Cold Storage ◽  
Fusarium Species ◽  
Lesion Size ◽  
Host Susceptibility ◽  
Seasonal Effect ◽  
Canker Disease ◽  
Almond Trees ◽  
Bare Root ◽  
The Impact

Loss of water that reduces the relative water content (RWC) of bark can occur during processing, cold storage, and planting of bare-root stone fruit trees. In California nurseries and newly planted orchards, this stress can predispose young almond trees (Prunus dulcis) to a canker disease caused primarily by Fusarium species. While reduced bark RWC contributes to disease development, anecdotal observations suggest a seasonal effect on host physiology may also influence disease severity. We evaluated the effect of season and the impact of drying and reduced RWC on susceptibility of almond branch segments excised from orchard trees (cv. Nonpareil) to Fusarium acuminatum, Fusarium avenaceum, Fusarium brachygibbosum, and Fusarium californicum sp. nov. With lesion size as the criterion, excised inoculated branch segments were most susceptible in spring, of intermediate susceptibility during winter dormancy, and least susceptible during summer and fall. Consistent with an earlier study, branches with RWC between 80 and 85% yielded lesions that were significantly larger than lesions from branches with bark that was above or below that range. However, the effect of reduced bark moisture on lesion size was only apparent in the spring. These results affirm the importance of avoiding conditions that diminish moisture status in bare-root almond trees in Fusarium canker disease management, especially during transport and planting operations in the spring, a period of high physiological vulnerability. California nurseries apply fungicides to bare-root trees prior to cold storage to reduce “mold” growth. Of eight fungicides currently registered for use on almond trees, fludioxonil (Scholar), fluopyram/trifloxystrobin (Luna Sensation), and fluxapyroxad/pyraclostrobin (Merivon) were most inhibitory to in vitro mycelial growth of F. acuminatum, F. avenaceum, and F. brachygibbosum. However, our almond branch disease assay did not demonstrate preventive or curative fungicide action against infections by F. acuminatum or F. avenaceum.

scholarly journals Modulation of the extrinsic cell death signaling pathway by viral Flip induces acute-death mediated liver failure

2019 ◽  
Vol 10 (12) ◽  
Author(s):  
Miriam Bittel ◽  
Andreas E. Kremer ◽  
Michael Stürzl ◽  
Stefan Wirtz ◽  
Iris Stolzer ◽  
...  
Keyword(s):  
Cell Death ◽  
Viral Infections ◽  
Tissue Injury ◽  
Multiple Organ ◽  
Severe Liver ◽  
Transgenic Expression ◽  
Effector Caspase ◽  
The Impact

AbstractDuring viral infections viruses express molecules that interfere with the host-cell death machinery and thus inhibit cell death responses. For example the viral FLIP (vFLIP) encoded by Kaposi’s sarcoma-associated herpesvirus interacts and inhibits the central cell death effector, Caspase-8. In order to analyze the impact of anti-apoptotic viral proteins, like vFlip, on liver physiology in vivo, mice expressing vFlip constitutively in hepatocytes (vFlipAlbCre+) were generated. Transgenic expression of vFlip caused severe liver tissue injury accompanied by massive hepatocellular necrosis and inflammation that finally culminated in early postnatal death of mice. On a molecular level, hepatocellular death was mediated by RIPK1-MLKL necroptosis driven by an autocrine TNF production. The loss of hepatocytes was accompanied by impaired bile acid production and disruption of the bile duct structure with impact on the liver-gut axis. Notably, embryonic development and tissue homeostasis were unaffected by vFlip expression. In summary our data uncovered that transgenic expression of vFlip can cause severe liver injury in mice, culminating in multiple organ insufficiency and death. These results demonstrate that viral cell death regulatory molecules exhibit different facets of activities beyond the inhibition of cell death that may merit more sophisticated in vitro and in vivo analysis.

Impact of power and contact force in ablation-index guided radiofrequency lesions in an in vitro model

EP Europace ◽  
2021 ◽  
Vol 23 (Supplement_3) ◽  
Author(s):  
C Lozano-Granero ◽  
E Franco Diez ◽  
R Matia Frances ◽  
A Hernandez-Madrid ◽  
I Sanchez Perez ◽  
...  
Keyword(s):  
Contact Force ◽  
Lesion Size ◽  
Public Institution ◽  
Lesion Volume ◽  
Lesion Depth ◽  
Lower Index ◽  
Ablation Index ◽  
Radiofrequency Lesions ◽  
Size And Morphology

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Electrophisiology Section of the Spanish Society of Cardiology Introduction. Lesion Size Index (LSI) and Ablation Index (AI) are markers of lesion quality that incorporate power, contact force (CF), and time in a weighted formula to estimate lesion size. Although accurate predicting lesion depth in-vitro, their precision in lesion size estimation has not been well established for certain power and CF settings. Purpose. We conducted an experimental ex-vivo study to analyse the effect of power and CF in size and morphology of ablation lesions in a porcine heart model. Methods. 24 sets of 10 perpendicular epicardial radiofrequency applications were performed with two commercially available catheters (TactiCath, Sensor Enabled; and SmartTouch) on porcine left ventricle submerged in 37ºC saline, combining different power (25, 30, 35, 40, 50 and 60W) and CF (10 and 20g) settings, and aiming at a lower (LSI/AI of 5/400) or higher (LSI/AI of 6/550) index. After each application, lesions were cross-sectioned and measured. Results. 480 lesions were performed. For a given target index and CF, significant differences in lesion volume and depth with different power settings were observed with both catheters. Regarding lesion volume, statistically significant differences were observed with all CF and LSI targets with TactiCath, except for 10 g and LSI 5 (10 g and LSI 5, p = 0.4134; 10 g and LSI 6, p < 0.0001; 20 g and LSI 5, p < 0.0001; 20 g and LSI 6, p < 0.0001). The same occurred for SmartTouch, showing statistically significant differences with all CF and AI targets, except for 20 g and AI 550 (10 g and AI 400, p = 0.0001; 10 g and AI 550, p < 0.0001; 20 g and AI 400, p < 0.0001; 20 g and AI 550, p = 0.001). Similar differences could be found in lesion depth with each catheter. Globally, lesions performed with 50 and 60W were significantly smaller and shallower than those performed with 35 or 40W (figure). Regarding CF, catheters behaved differently: lesions performed with 10g were smaller and shallower than those performed with 20g with Tacticath, while being bigger and deeper with SmartTouch. In a side-by-side comparison, lesions performed with TactiCath were smaller and shallower than those performed with SmartTouch when applying a lower CF of 10g, both when targeting a lower index objective (volume: 41.8 ± 54.3mm3 vs 158.3 ± 33.2mm3, p < 0.0001; depth: 2 ± 1.7mm vs 4.6 ± 0.5mm, p < 0.0001) or a higher index objective (volume: 103.1 ± 56.5mm3 vs 280 ± 54mm3, p < 0.0001; depth: 4 ± 1.1mm vs 5.8 ± 0.5mm, p < 0.0001). However, lesions with TactiCath were bigger and deeper when applying a higher CF of 20g aiming at a lower index objective (volume: 123.8 ± 39.9mm3 vs 89.7 ± 29.4mm3, p < 0.0001; depth: 4 ± 0.8mm3 vs 3.6 ± 0.5mm, p < 0.0001). No statistically significant difference was observed when applying a higher CF of 20g aiming at a higher index objective. Conclusions. Size and morphology of index-guided radiofrequency lesions varied significantly with different power and CF settings, highlighting the importance of achieving a good CF in any ablation procedure. Abstract Figure. Box-plot of lesion volume

The Predominant microRNAs in β-cell Clusters for Insulin Regulation and Diabetic Control

2020 ◽  
Vol 21 (7) ◽  
pp. 722-734
Author(s):  
Adele Soltani ◽  
Arefeh Jafarian ◽  
Abdolamir Allameh
Keyword(s):  
Mirna Expression ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Diabetic Control ◽  
In Vitro Proliferation ◽  
Cell Functions ◽  
Mirna Expression Profiles ◽  
Multiple Processes ◽  
The Impact

micro (mi)-RNAs are vital regulators of multiple processes including insulin signaling pathways and glucose metabolism. Pancreatic β-cells function is dependent on some miRNAs and their target mRNA, which together form a complex regulative network. Several miRNAs are known to be directly involved in β-cells functions such as insulin expression and secretion. These small RNAs may also play significant roles in the fate of β-cells such as proliferation, differentiation, survival and apoptosis. Among the miRNAs, miR-7, miR-9, miR-375, miR-130 and miR-124 are of particular interest due to being highly expressed in these cells. Under diabetic conditions, although no specific miRNA profile has been noticed, the expression of some miRNAs and their target mRNAs are altered by posttranscriptional mechanisms, exerting diverse signs in the pathobiology of various diabetic complications. The aim of this review article is to discuss miRNAs involved in the process of stem cells differentiation into β-cells, resulting in enhanced β-cell functions with respect to diabetic disorders. This paper will also look into the impact of miRNA expression patterns on in vitro proliferation and differentiation of β-cells. The efficacy of the computational genomics and biochemical analysis to link the changes in miRNA expression profiles of stem cell-derived β-cells to therapeutically relevant outputs will be discussed as well.

Healing effects of curcumin nanoparticles in deep tissue injury mouse model.

2020 ◽  
Vol 18 ◽  
Author(s):  
Zirui Zhang ◽  
Shangcong Han ◽  
Panpan Liu ◽  
Xu Yang ◽  
Jing Han ◽  
...  
Keyword(s):  
Wound Healing ◽  
Mrna Expression ◽  
Tissue Injury ◽  
Inflammatory Cells ◽  
Pcr Analysis ◽  
Protective Effects ◽  
Deep Tissue ◽  
Deep Tissue Injury

Background: Chronic inflammation and lack of angiogenesis are the important pathological mechanisms in deep tissue injury (DTI). Curcumin is a well-known anti-inflammatory and antioxidant agent. However, curcumin is unstable under acidic and alkaline conditions, and can be rapidly metabolized and excreted in the bile, which shortens its bioactivity and efficacy. Objective: This study aimed to prepare curcumin-loaded poly (lactic-co-glycolic acid) nanoparticles (CPNPs) and to elucidate the protective effects and underlying mechanisms of wound healing in DTI models. Methods: CPNPs were evaluated for particle size, biocompatibility, in vitro drug release and their effect on in vivo wound healing. Results : The results of in vivo wound closure analysis revealed that CPNP treatments significantly improved wound contraction rates (p<0.01) at a faster rate than other three treatment groups. H&E staining revealed that CPNP treatments resulted in complete epithelialization and thick granulation tissue formation, whereas control groups resulted in a lack of compact epithelialization and persistence of inflammatory cells within the wound sites. Quantitative real-time PCR analysis showed that treatment with CPNPs suppressed IL-6 and TNF-α mRNA expression, and up-regulated TGF-β, VEGF-A and IL-10 mRNA expression. Western blot analysis showed up-regulated protein expression of TGF-β, VEGF-A and phosphorylatedSTAT3. Conclusion: Our results showed that CPNPs enhanced wound healing in DTI models, through modulation of the JAK2/STAT3 signalling pathway and subsequent upregulation of pro-healing factors.

The Impact of Antioxidants from the Diet on Breast Cancer Cells Monitored by Raman Microspectroscopy

2018 ◽  
Vol 16 (2) ◽  
pp. 127-137
Author(s):  
Paula Sofia Coutinho Medeiros ◽  
Ana Lúcia Marques Batista de Carvalho ◽  
Cristina Ruano ◽  
Juan Carlos Otero ◽  
Maria Paula Matos Marques
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Cell Line ◽  
Breast Cancer Cells ◽  
Triple Negative ◽  
Breast Adenocarcinoma ◽  
Coumaric Acid ◽  
Human Breast ◽  
The Impact

Background: The impact of the ubiquitous dietary phenolic compound p-coumaric acid on human breast cancer cells was assessed, through a multidisciplinary approach: Combined biological assays for cytotoxicity evaluation and biochemical profiling by Raman microspectroscopic analysis in cells. </P><P> Methods: Para-coumaric acid was shown to exert in vitro chemoprotective and antitumor activities, depending on the concentration and cell line probed: a significant anti-invasive ability was detected for the triple-negative MDA-MB-231 cells, while a high pro-oxidant effect was found for the estrogen- dependent MCF-7 cells. A striking cell selectivity was obtained, with a more noticeable outcome on the triple-negative MDA-MB-231 cell line. Results: The main impact on the cellular biochemical profile was verified to be on proteins and lipids, thus justifying the compound´s anti-invasive effect and chemoprotective ability. Conclusion: p-Coumaric acid was thus shown to be a promising chemoprotective/chemotherapeutic agent, particularly against the low prognosis triple-negative human breast adenocarcinoma.

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