Effect of applied voltage, duration and repetition frequency of RF pulses for pain relief on temperature spikes and electrical field: a computer modelling study

Ewertowska, Elzbieta; Mercadal, Borja; Muñoz, Víctor; Ivorra, Antoni; Trujillo, Macarena; Berjano, Enrique

doi:10.1080/02656736.2017.1323122

Cited by 24 publications

(38 citation statements)

References 33 publications

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“…The general electric behavior of any electrode is basically as follows: a voltage is uniformly set along the entire surface of the electrode, while both current density J and electric field E distributions are spatially non-uniform at the electrode surface, as they result from solving the Laplace equation (assuming electrical conductivity to be constant). This behavior has previously been correctly reproduced by mathematical models using numerical methods [7][8][9][10]. Since the numerical simulation has to be able to accurately reproduce the physical situation expressed by the partial differential equations that model the process, comparing their results with any existing benchmark analytical solutions would be one way of validating the numerical simulations.…”

Section: Introductionmentioning

confidence: 78%

Analytical Solution for Electrical Problem Forced by a Finite‐Length Needle Electrode: Implications in Electrostimulation

Romero‐Méndez

Pérez‐Gutiérrez

Oviedo-Tolentino

et al. 2019

Mathematical Problems in Engineering

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Needle electrodes, widely used in clinical procedures, are responsible for creating an electric field in the treated biological tissue. This is achieved by setting a constant voltage along the length of their metallic section. In accordance with Laplace’s equation, the electric field is spatially non-uniform around the electrode surface. Mathematical modelling can provide useful information on the spatial distribution of electrical fields. Indeed, exact solutions for the electrical problem are indispensable for validating numerical codes. All the analytical models developed to date to solve the needle electrode electrical problem have been one-dimensional models, which assumed an electrode of infinite length. We here propose the first analytical solution based on a two-dimensional model that considers the real length of the electrode in which the Laplace equation is solved through the method of separation of variables, dealing with the nonhomogeneous source term and boundary conditions by Green’s functions. On assuming a needle electrode of given length, the problem combines boundary conditions on the electrode boundary (of the first and second kind). Since this rules out using the Sturm-Liouville Theorem, the problem is decomposed into two different problems and the principle of superposition is used. The solution obtained can reproduce a reasonable electric field around the electrode, especially the edge effect characterized by an extremely high gradient around the electrode tip.

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Section: Introductionmentioning

confidence: 78%

Analytical Solution for Electrical Problem Forced by a Finite‐Length Needle Electrode: Implications in Electrostimulation

Romero‐Méndez

Pérez‐Gutiérrez

Oviedo-Tolentino

et al. 2019

Mathematical Problems in Engineering

Self Cite

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“…As mentioned earlier, a parametric study has been conducted with the applied voltage of 45 V for two different scenarios, (a) with a fixed pulse frequency of 2 Hz and different durations, viz., 10 ms, 20 ms, 30 ms, 40 ms and 50 ms, respectively, and (b) with a fixed pulse duration of 20 ms and different frequencies, viz., 1 Hz, 2 Hz, 6 Hz and 10 Hz, respectively. Importantly, the combination of 2 Hz frequency and 20 ms RF pulse duration is widely used in clinical practices with the applied voltage of 45 V during the pulsed RFA procedure [14,19]. In what follows, we will explore different aspects of altering the critical input parameters, viz., duration and frequency of the RF pulses, during the pulsed RFA procedure and compare the results with the standard protocol (45 V-20 ms-2 Hz).…”

Section: Resultsmentioning

confidence: 99%

“…1 shows the two-dimensional axisymmetric computational domain considered in the present study that comprises of the muscle tissue with a single needle RF electrode. The dimensions of this domain have been chosen consistently with those available in the literature (e.g., [19]). The pulsed RFA has been performed utilizing a 22gauge needle electrode with the active tip length of 10 mm.…”

Section: Methodsmentioning

confidence: 99%

“…The pulsed RFA has been performed utilizing a 22gauge needle electrode with the active tip length of 10 mm. The considered thermo-electric properties in the present study at the frequency range of 500 kHz are given in Table 1 [11,[19][20].…”

Section: Methodsmentioning

confidence: 99%

“…where  (kg/m 3 ) is the density, c (J/kg/K) is the specific heat capacity, k (W/m/K) is the thermal conductivity, b is the density of blood (1050 kg/m 3 ), cb is the specific heat capacity of blood (3617 J/kg/K), ωb is the blood perfusion rate within the tissue (6.35×10 -4 s -1 ), Qp (W/m 3 ) is the ionic heat generated during RFA and is computed using Equation 2 above, Qm (W/m 3 ) is the metabolic heat generation that has been neglected due to its insignificant contribution during RFA [19], Tb is the blood temperature (37 ᴏ C), T is the unknown tissue temperature to be computed from Equation 5 and t (s) is the duration of the pulsed RFA procedure.…”

Section: Governing Equationsmentioning

confidence: 99%

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Computational Science – ICCS 2019

2019

Lecture Notes in Computer Science

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In this paper, a parametric study has been conducted to evaluate the effects of frequency and duration of the short burst pulses during pulsed radiofrequency ablation (RFA) in treating chronic pain. Affecting the brain and nervous system, this disease remains one of the major challenges in neuroscience and clinical practice. A two-dimensional axisymmetric RFA model has been developed in which a single needle radiofrequency electrode has been inserted. A finite-element-based coupled thermo-electric analysis has been carried out utilizing the simplified Maxwell's equations and the Pennes bioheat transfer equation to compute the electric field and temperature distributions within the computational domain. Comparative studies have been carried out between the continuous and pulsed RFA to highlight the significance of pulsed RFA in chronic pain treatment. The frequencies and durations of short burst RF pulses have been varied from 1 Hz to 10 Hz and from 10 ms to 50 ms, respectively. Such values are most commonly applied in clinical practices for mitigation of chronic pain. By reporting such critical input characteristics as temperature distributions for different frequencies and durations of the RF pulses, this computational study aims at providing the first-hand accurate quantitative information to the clinicians on possible consequences in those cases where these characteristics are varied during the pulsed RFA procedure. The results demonstrate that the efficacy of pulsed RFA is significantly dependent on the duration and frequency of the RF pulses.

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Bioinformatics and Biomedical Engineering

2019

Lecture Notes in Computer Science

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The present study aims at evaluating the effects of target nerve location from the bone tissue during continuous radiofrequency ablation (RFA) for chronic pain relief. A generalized three-dimensional heterogeneous computational model comprising of muscle, bone and target nerve has been considered. The continuous RFA has been performed through the monopolar needle electrode placed parallel to the target nerve. Finite-element-based coupled thermoelectric analysis has been conducted to predict the electric field and temperature distributions as well as the lesion volume attained during continuous RFA application. The quasi-static approximation of the Maxwell's equations has been used to compute the electric field distribution and the Pennes bioheat equation has been used to model the heat transfer phenomenon during RFA of the target nerve. The electrical and thermo-physical properties considered in the present numerical study have been acquired from the well-characterized values available in the literature. The protocol of the RFA procedure has been adopted from the United States Food and Drug Administration (FDA) approved commercial devices available in the market and reported in the previous clinical studies. Temperature-dependent electrical conductivity along with the piecewise model of blood perfusion have been considered to correlate with the in-vivo scenarios. The numerical simulation results, presented in this work, reveal a strong dependence of lesion volume on the target nerve location from the considered bone. It is expected that the findings of this study would assist in providing a priori critical information to the clinical practitioners for enhancing the success rate of continuous RFA technique in addressing the chronic pain problems of bones.

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Effect of applied voltage, duration and repetition frequency of RF pulses for pain relief on temperature spikes and electrical field: a computer modelling study

Abstract: For the same delivered energy, the new protocol significantly increases the magnitude of the applied electric field, which may be the reason why it is clinically more effective in achieving pain relief.

Cited by 24 publications

References 33 publications

Analytical Solution for Electrical Problem Forced by a Finite‐Length Needle Electrode: Implications in Electrostimulation

Analytical Solution for Electrical Problem Forced by a Finite‐Length Needle Electrode: Implications in Electrostimulation

Computational Science – ICCS 2019

Bioinformatics and Biomedical Engineering

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