Comparison of DC and RF for lesioning white and grey matter

Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI), 2014

Radiofrequency electrical currents have a tendency to move toward the center of the bulk of biologic tissues. To evaluate the effect of the frequency of currents on their entrance and propagation pattern in biologic tissues. Three electrosurgical generators with 0.4, 1.5, and 3 MHz frequency outputs were studied. Current was applied using a metallic needle introduced into a piece of cow liver, with different amounts of energy delivered at multiple points. Cross-sections of the liver were then studied for tissue effect. The diameters of the coagulated areas at the deepest and most superficial parts were measured. The tendency of the currents for penetration in the deeper layers of tissue rather than in the superficial layers was assessed using the superficial diameter/deep diameter ratio. Diameter of coagulated area was larger around deeper parts than around superficial parts of the electrode. No correlation between frequency of current and the superficial/deep diameter ratio of the ...

Journal of Interventional Cardiac Electrophysiology, 2000

Sequences of energy application to multiple electrodes and a study of ablation duration with distal tip and multi-electrode ablations were explored with a radiofrequency controller that distributes energy from a generator to up to 4 electrodes with various duty cycles. In vitro ablations were performed on bovine left ventricle in circulating blood and lesions in goats were performed to verify the in vitro results. All of the ablation sequences with simultaneous electrode activation of contiguous electrodes resulted in deeper lesions than those created in sequence. There was also no scalloping of the lesion if contiguous electrodes were activated simultaneously. During all distal tip ablations, lesion volume and depth was greater after 3 minutes of energy delivery than after 1 minute, but did not increase from 3 minutes to 5 minutes. There was a significant increase in multi-electrode ablation lesion depth with each additional minute in the ablation cycle. The in vivo ablations verified these results at 120 and 300 second ablations. Pulsed energy distal tip ablations resulted in deeper lesions than continuous only if power amplitudes over 50W were employed. In conclusion, contiguous electrodes in simultaneous use create lesions that resemble one large lesion rather than two lesions positioned next to each other. Multi-electrode ablation lesions continue to grow at ablation durations of up to 5 minutes compared to distal tip lesions which reach steady-state between 1 and 3 minutes. Pulsed energy delivery to distal tips may result in deeper lesions than conventional if high powers are employed.

Journal of Cardiovascular Electrophysiology, 1998

Depth with Larger Electrode. Introduction: Increasing electrode size allows an increase in radiofrequency lesion depth. The purpose of this study was to examine the roles of added electrode cooling and electrode-tissue interface area in producing deeper lesions.

European Journal of Inflammation, 2011

0393-974X (2011) Copyright © by BIOLIFE, s.a.s. This publication and/or article is for individual use only and may not be further reproduced without written permission from the copyright holder. Unauthorized reproduction may result in financial and other penalties 89 (S) Electrosurgery is the application of an alternative electric current with a high voltage on a biological tissue with a thermal effect to achieve an incision or coagulation. The effect is related to the electrode type, contact area, electrode movement speed and tissue characteristics. The cut is due to the current passage though active and neutral electrodes and the coagulation occurs as a result of tissue atrophy or desiccation when their hating is sufficiently slow. Parameters assessment to obtain the desired results may be done manually or automatic (1). The electrosurgery is not cauterisation as the thermal effect given is not external (e.g. caused by an elevated temperature tool) but internal, caused from the cu...

Europace, 2005

During radiofrequency ablation of arrhythmias tissue heating and hence lesion size depend on electrode-tissue contact and cooling of the electrode tip caused by cavitary blood flow. These factors are unique and unknown for each catheter placement in the beating heart. A tool for assessing these factors prior to ablation may indicate the lesion size which will be obtained for any given catheter position. Radiofrequency ablation was performed in vitro on strips of left ventricular porcine myocardium during two different levels of convective cooling (0 or 0.1 m/s), two different contact pressures (10 or 30 g) and parallel or perpendicular electrode-tissue orientation using 7F 4 mm tip catheters. Prior to ablation the impedance rise (DeltaIMP) caused by the obtained contact and the temperature rise with a 0.6 W 5 s test pulse (DeltaT) were measured. Subsequently, during unchanged conditions, radiofrequency ablation was performed as either temperature-controlled, power-controlled or irrigated tip ablation and lesion size was determined. DeltaIMP increased significantly (P < 0.05) by improved contact, whereas it was not affected by convective cooling. DeltaT was significantly increased by increasing contact pressure (P < 0.05) and significantly decreased by increased cooling (P < 0.001). DeltaT was not systematically affected by electrode orientation. The product of DeltaT and DeltaIMP showed a significant correlation between the obtained lesion size and power output for temperature-controlled and between lesion size and tip temperature for power-controlled ablation (P < 0.001). Pre-ablation measurement of DeltaIMP and DeltaT can indicate the lesion size resulting after ablation in temperature-controlled, power-controlled and irrigated ablation in vitro, since DeltaT reflects cavitary cooling and to a smaller extent electrode-tissue contact, and DeltaIMP reflects only electrode-tissue contact.

Kibernetika i vyčislitelʹnaâ tehnika, 2021

Introduction. High-frequency electric welding of biological tissues is an effective method of treatment in surgery. This is an electrosurgical method that minimizes the possibility of the destructive effect of electric current on soft living tissues. The welding method is widely used in general surgery for joining soft tissues where a weld is created when a high frequency electric current is passed through the tissue. With this method, it is possible to carry out serious operations, such as welding of liver tissue, retina, resection of tumor tissue and many other operations. For operations in surgery, it is important to know the optimal parameters of HF-welding, such as welding temperature, mechanical stress on tissues, welding time and voltage. The purpose of the paper is to determinatethe optimal conditions for high-frequency welding of living tissues, such as welding temperature, mechanical stress on tissues, welding time and voltage. To determine these parameters, the liver tissue fusion was simulated in the Sinda and Comsol software. Results. As a result of modeling and research, model dependencies were obtained that determine the optimal parameters of high-frequency welding for performing surgical operations for resection and welding of liver tissue. In the place of direct contact of the electrodes with the tissue, the temperature does not exceed +70 ° C, and at a distance of 2 mm in the adjacent tissues does not exceed +50 ° C, which provides a tissue-preserving electrosurgical effect.

IEEE Transactions on Biomedical Engineering, 2000

Repeated pulsed electrical stimulation is used in a multitude of neural interfaces; damage resulting from such stimulation was studied as a function of pulse duration, electrode size, and number of pulses using a fluorescent assay on chick chorioallontoic membrane (CAM) in vivo and chick retina in vitro. Data from the chick model were verified by repeating some measurements on porcine retina in-vitro. The electrode size varied from 100 m to 1 mm, pulse duration from 6 s to 6 ms, and the number of pulses from 1 to 7500. The threshold current density for damage was independent of electrode size for diameters greater than 300 m, and scaled as 1 2 for electrodes smaller than 200 m. Damage threshold decreased with the number of pulses, dropping by a factor of 14 on the CAM and 7 on the retina as the number of pulses increased from 1 to 50, and remained constant for a higher numbers of pulses. The damage threshold current density on large electrodes scaled with pulse duration as approximately 1 0 5 , characteristic of electroporation. The threshold current density for repeated exposure on the retina varied between 0.061 A/cm 2 at 6 ms to 1.3 A/cm 2 at 6 s. The highest ratio of the damage threshold to the stimulation threshold in retinal ganglion cells occurred at pulse durations near chronaxie-around 1.3 ms.

Pain Practice, 2009

Pulsed radiofrequency (PRF) fields applied by an electrode to neural structures, such as the peripheral sensory nociceptor axons and dorsal root ganglion, are clinically effective in reducing pain and other neuropathic syndromes. However, a full understanding of the underlying mechanisms by which this occurs has not yet been clarified. In this study, PRF is applied to the afferent axons of the sciatic nerves of rats. A standard radiofrequency (RF) electrode and RF generator is used to apply the RF signal output to the sciatic nerve using standard PRF parameters that have been successfully used in clinical practice. The ultrastructure of the treated axons is observed after 10 days by electron microscopy. A control, sham application is simultaneously applied to the contralateral sciatic nerve to provide a statistical differential comparison. It is found that the internal ultrastructural components of the axons show microscopic damage after PRF exposure, including: abnormal membranes and morphology of mitochondria, and disruption and disorganization of microfilaments and microtubules. The damage appears to be more pronounced for C-fibers than for A-delta and A-beta fibers. The results are discussed in terms of internal electric field strengths and thermodynamic parameters.

Academic Radiology, 1996

We determined whether heat distribution along a radiofrequency (RF) electrode would be uniform when longer tip exposures are used and whether local temperature effects would influence the shape of induced tissue coagulation.

Romanian journal of morphology and embryology = Revue roumaine de morphologie et embryologie, 2015

The technical progress in the medical sector in the past decades has continuously driven the development of electrosurgical techniques. The controversies surrounding the superiority of a certain technique relative to another - electrocautery, laser and radiofrequency - have determined us to carry out a histopathological design with the aim of comparing the healing sort of the shallow wounds generated by the three types of electrosurgical devices. The experimental study has investigated the healing process inflicted by the electrosurgical devices mentioned beforehand on 12 Wistar albino rats. The wounds were inflicted under intravenous general anesthesia with Xylazine and Ketamine and were performed lateral to the spine region, using laser, radiofrequency and electric cautery. The histological samples harvested at one, three, five, and seven days were sent to pathological examination. We followed by comparison the evolution of the first two phases of the wound healing produced by the...