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Irastorza RM, Maher T, Barkagan M, Liubasuskas R, Berjano E, d'Avila A. Anterior vs. posterior position of dispersive patch during radiofrequency catheter ablation: insights from in silico modelling. Europace 2023; 25:1135-1143. [PMID: 36635956 PMCID: PMC10062334 DOI: 10.1093/europace/euac277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 12/16/2022] [Indexed: 01/14/2023] Open
Abstract
AIMS To test the hypothesis that the dispersive patch (DP) location does not significantly affect the current distribution around the catheter tip during radiofrequency catheter ablation (RFCA) but may affect lesions size through differences in impedance due to factors far from the catheter tip. METHODS An in silico model of RFCA in the posterior left atrium and anterior right ventricle was created using anatomic measurements from patient thoracic computed tomography scans and tested the effect of anterior vs. posterior DP locations on baseline impedance, myocardial power delivery, radiofrequency current path, and predicted lesion size. RESULTS For posterior left atrium ablation, the baseline impedance, total current delivered, current distribution, and proportion of power delivered to the myocardium were all similar with both anterior and posterior DP locations, resulting in similar RFCA lesion sizes (< 0.2 mm difference). For anterior right ventricular (RV) ablation, an anterior DP location resulted in slightly higher proportion of power delivered to the myocardium and lower baseline impedance leading to slightly larger RFCA lesions (0.6 mm deeper and 0.8 mm wider). CONCLUSIONS An anterior vs. posterior DP location will not meaningfully affect RFCA for posterior left atrial ablation, and the slightly larger lesions predicted with anterior DP location for anterior RV ablation are of unclear clinical significance.
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Affiliation(s)
- Ramiro M Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina.,Departamento de Ingeniería Mecánica, Facultad Regional La Plata, Universidad Tecnológica Nacional, La Plata, Argentina
| | - Timothy Maher
- Division of Cardiovascular Medicine, Harvard-Thorndike Electrophysiology Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA
| | - Michael Barkagan
- Cardiology Division, Shamir Medical Center, Sackler school of Medicine, Tel Aviv University, Beer-Yakov, Israel
| | - Rokas Liubasuskas
- Department of Medicine, Salem Hospital, Tufts University School of Medicine, Salem, MA, USA
| | - Enrique Berjano
- BioMIT, Department of Electronic Engineering, Universitat Politècnica de València, Valencia, Spain
| | - Andre d'Avila
- Division of Cardiovascular Medicine, Harvard-Thorndike Electrophysiology Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA
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Moll X, Fondevila D, García-Arnas F, Burdio F, Trujillo M, Irastorza RM, Berjano E, Andaluz A. Comparison of two radiofrequency-based hemostatic devices: saline-linked bipolar vs. cooled-electrode monopolar. Int J Hyperthermia 2022; 39:1397-1407. [DOI: 10.1080/02656736.2022.2140840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Xavier Moll
- Departament de Medicina i Cirurgia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Barcelona, Spain
- Fundació Hospital Clínic Veterinari, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Dolors Fondevila
- Departament de Medicina i Cirurgia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Félix García-Arnas
- Departament de Medicina i Cirurgia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Fernando Burdio
- Department of Surgery, Division of Hepato-Biliary and Pancreatic Surgery, Hospital del Mar, Barcelona, Spain; Hospital del Mar Medical Research Institute (IMIM), Barcelona, Spain
| | - Macarena Trujillo
- Department of Applied Mathematics, BioMIT, Universitat Politècnica de València, Valencia, Spain
| | - Ramiro M. Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina
- Departamento de Ingeniería Mecánica, Universidad Tecnológica Nacional, Facultad Regional La Plata, La Plata, Argentina
| | - Enrique Berjano
- Department of Electronic Engineering, BioMIT, Universitat Politècnica de València, Valencia, Spain
| | - Anna Andaluz
- Departament de Medicina i Cirurgia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Barcelona, Spain
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González-Suárez A, Irastorza RM, Deane S, O'Brien B, O'Halloran M, Elahi A. Full torso and limited-domain computer models for epicardial pulsed electric field ablation. Comput Methods Programs Biomed 2022; 221:106886. [PMID: 35597202 DOI: 10.1016/j.cmpb.2022.106886] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 05/10/2022] [Accepted: 05/11/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVES Pulsed Electric Field (PEF) ablation has been proposed as a non-thermal energy to treat atrial fibrillation (AF) by ablation of ganglionated plexi using the epicardial approach. The electric field distribution at the target site (heart) and its surroundings has not yet been assessed previously, using epicardial ablation technique. Our objective was to develop computational models, incorporating the real anatomy of the heart and the patient's torso, to assess the electric field distribution when applying epicardial monopolar PEF. METHODS A novel 3D realistic full torso model was built with the multi-electrode ablation device placed on the epicardium and a dispersive pad on the patient's back to evaluate the electric field distribution. The 400 V/cm isoline was used to estimate the 'PEF-zone'. A 3D limited-domain model was also built including only the region of interest around the ablation device to assess its validity in comparison with the full torso model. RESULTS The electrical field is mainly limited to the target site (PEF-zone with lengths of 25.79 to 29.00 mm, depths of 5.98-7.02 mm and maximum widths of 8.75-10.57 mm) and is practically negligible in adjacent organs (<30 V/cm and <36 V/cm in oesophagus and lungs, respectively). The electrical currents ranged from 3.67 A to 7.44 A. The 3D limited-domain model provided a similar electric field distribution to those obtained from the 3D full torso models (differences < 0.5 mm in PEF-zone depth). CONCLUSIONS Computational results suggest that PEF-zone is very focused around the ablation catheter. Limited-domain models offer similar results in terms of PEF-zone size, reducing the complexity of the modelling.
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Affiliation(s)
- Ana González-Suárez
- Electrical and Electronic Engineering, National University of Ireland Galway, Ireland; Translational Medical Device Lab, National University of Ireland Galway, Ireland.
| | - Ramiro M Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina; Departamento de Ingeniería Mecánica, Universidad Tecnológica Nacional, Facultad Regional La Plata, La Plata, Argentina
| | - Stuart Deane
- AtriAN Medical Limited, Unit 204, NUIG Business Innovation Centre, Upper Newcastle, Galway, Ireland
| | - Barry O'Brien
- AtriAN Medical Limited, Unit 204, NUIG Business Innovation Centre, Upper Newcastle, Galway, Ireland
| | - Martin O'Halloran
- Electrical and Electronic Engineering, National University of Ireland Galway, Ireland; Translational Medical Device Lab, National University of Ireland Galway, Ireland
| | - Adnan Elahi
- Electrical and Electronic Engineering, National University of Ireland Galway, Ireland; Translational Medical Device Lab, National University of Ireland Galway, Ireland
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Aryana A, Irastorza RM, Berjano E, Cohen RJ, Kraus J, Haghighi-Mood A, Reddy VY, d'Avila A. Radiofrequency Ablation Using a Novel Insulated-Tip Ablation Catheter Can Create Uniform Lesions Comparable in Size to Conventional Irrigated Ablation Catheters While Using a Fraction of the Energy and Irrigation. J Cardiovasc Electrophysiol 2022; 33:1146-1156. [PMID: 35322477 PMCID: PMC9325397 DOI: 10.1111/jce.15461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 01/08/2022] [Accepted: 02/07/2022] [Indexed: 12/04/2022]
Abstract
Introduction During radiofrequency ablation (RFA) using conventional RFA catheters (RFC), ~90% of the energy dissipates into the bloodstream/surrounding tissue. We hypothesized that a novel insulated‐tip ablation catheter (SMT) capable of blocking the radiofrequency path may focus most of the energy into the targeted tissue while utilizing reduced power and irrigation. Methods This study evaluated the outcomes of RFA using SMT versus an RFC in silico, ex vivo, and in vivo. Radiofrequency applications were delivered over porcine myocardium (ex vivo) and porcine thigh muscle preparations superfused with heparinized blood (in vivo). Altogether, 274 radiofrequency applications were delivered using SMT (4–15 W, 2 or 20 ml/min) and 74 applications using RFC (30 W, 30 ml/min). Results RFA using SMT proved capable of directing 66.8% of the radiofrequency energy into the targeted tissue. Accordingly, low power–low irrigation RFA using SMT (8–12 W, 2 ml/min) yielded lesion sizes comparable with RFC, whereas high power–high irrigation (15 W, 20 ml/min) RFA with SMT yielded lesions larger than RFC (p < .05). Although SMT was associated with greater impedance drops ex vivo and in vivo, ablation using RFC was associated with increased charring/steam pop/tissue cavitation (p < .05). Lastly, lesions created with SMT were more homogeneous than RFC (p < .001). Conclusion Low power–low irrigation (8–12 W, 2 ml/min) RFA using the novel SMT ablation catheter can create more uniform, but comparable‐sized lesions as RFC with reduced charring/steam pop/tissue cavitation. High power–high irrigation (15 W, 20 ml/min) RFA with SMT yields lesions larger than RFC.
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Affiliation(s)
- Arash Aryana
- Mercy General Hospital and Dignity Health Heart and Vascular Institute, Sacramento, CA, USA
| | - Ramiro M Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina.,Instituto de Ingeniería y Agronomía, Universidad Nacional Arturo Jauretche, Florencio Varela, Argentina
| | - Enrique Berjano
- BioMIT, Department of Electronic Engineering Universitat Politècnica de València, Valencia, Spain
| | - Richard J Cohen
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | - Vivek Y Reddy
- Helmsley Cardiac Arrhythmia Service, Mount Sinai School of Medicine, New York, NY, USA
| | - André d'Avila
- Beth Israel Deaconess Medical Center, Boston, MA, USA
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González-Suárez A, Pérez JJ, Irastorza RM, D'Avila A, Berjano E. Computer modeling of radiofrequency cardiac ablation: 30 years of bioengineering research. Comput Methods Programs Biomed 2022; 214:106546. [PMID: 34844766 DOI: 10.1016/j.cmpb.2021.106546] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/08/2021] [Accepted: 11/15/2021] [Indexed: 06/13/2023]
Abstract
This review begins with a rationale of the importance of theoretical, mathematical and computational models for radiofrequency (RF) catheter ablation (RFCA). We then describe the historical context in which each model was developed, its contribution to the knowledge of the physics of RFCA and its implications for clinical practice. Next, we review the computer modeling studies intended to improve our knowledge of the biophysics of RFCA and those intended to explore new technologies. We describe the most important technical details of the implementation of mathematical models, including governing equations, tissue properties, boundary conditions, etc. We discuss the utility of lumped element models, which despite their simplicity are widely used by clinical researchers to provide a physical explanation of how RF power is absorbed in different tissues. Computer model verification and validation are also discussed in the context of RFCA. The article ends with a section on the current limitations, i.e. aspects not yet included in state-of-the-art RFCA computer modeling and on future work aimed at covering the current gaps.
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Affiliation(s)
- Ana González-Suárez
- Electrical and Electronic Engineering, National University of Ireland Galway, Ireland; Translational Medical Device Lab, National University of Ireland Galway, Ireland
| | - Juan J Pérez
- Department of Electronic Engineering, BioMIT, Universitat Politècnica de València, Valencia, Spain
| | - Ramiro M Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina; Instituto de Ingeniería y Agronomía, Universidad Nacional Arturo Jauretche, Florencio Varela, Argentina
| | - Andre D'Avila
- Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
| | - Enrique Berjano
- Department of Electronic Engineering, BioMIT, Universitat Politècnica de València, Valencia, Spain.
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Irastorza RM, Bovaira M, García-Vitoria C, Muñoz V, Berjano E. Effect of the relative position of electrode and stellate ganglion during thermal radiofrequency ablation: a simulation study. Int J Hyperthermia 2021; 38:1502-1511. [PMID: 34674597 DOI: 10.1080/02656736.2021.1974580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
PURPOSE Stellate ganglion (SG) block by thermal radiofrequency ablation (RFA) is frequently conducted as a therapeutic intervention for sympathetic-maintained and neuropathic pain syndromes. RFA's partial lack of effectiveness could be partly due to the ablation zone (AZ) not completely covering the SG section and therefore preventing the 'cutting' of the afferent pathways. Our objective was to build a theoretical model to conduct computer simulations to assess the effect of the electrode position relative to the SG. METHODS A three-dimensional model was built including the SG and adjacent tissues (vertebrae C7-T1-T2, trachea, carotid artery and vertebral artery). RFA (90-s, 80 °C) was simulated considering a 22 G-5 mm electrode. The AZ was computed using the 50 °C isotherm. RESULTS An electrode displacement of 2 mm in any direction from the optimal position (centered on the SG) meant that the AZ did not fully cover the SG section. Likewise, SG size considerably affected the RFA effectiveness since the AZ fully covered the section of small but not large SGs. CONCLUSIONS The findings suggest that the currently used SG RFA settings (i.e., 22 G-5 mm electrode, 90-s, 80 °C) may not be appropriate due to their inability to achieve an AZ that fully covers the SG cross section under certain circumstances, such as a large SG and non-optimal positioning of the RF electrode with respect to the SG center.
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Affiliation(s)
- Ramiro M Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina.,Instituto de Ingeniería y Agronomía, Universidad Nacional Arturo Jauretche, Florencio Varela, Argentina
| | - Maite Bovaira
- Department of Anesthesiology, Critical Care and Pain Management, Hospital Intermutual de Levante, Valencia, Spain
| | - Carles García-Vitoria
- Department of Anesthesiology, Critical Care and Pain Management, Hospital Intermutual de Levante, Valencia, Spain
| | | | - Enrique Berjano
- BioMIT, Department of Electronic Engineering, Universitat Politècnica de València, Valencia, Spain
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Madrid MA, Irastorza RM, Meyra AG, Carlevaro CM. Self-assembly of self-propelled magnetic grains. EPJ Web Conf 2021. [DOI: 10.1051/epjconf/202124906005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, we study bidisperse mixtures of self-propelled magnetic particles of different shapes via discrete element method simulations. We show how these particles self-assemble into clusters and how these clusters depend on the ratio of the mixture, the magnetic interaction, and the shape of the grains. It is found that the mix ratio of the system controls the cluster size. Besides, the intensity of the magnetic dipoles and the shape of the grains in the mixture rule the average number of neighbors in contact and the shape of the clusters. By varying the intensity of the interactions, globular, linear and branched clusters were obtained.
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Irastorza RM, Gonzalez-Suarez A, Pérez JJ, Berjano E. Differences in applied electrical power between full thorax models and limited-domain models for RF cardiac ablation. Int J Hyperthermia 2020; 37:677-687. [DOI: 10.1080/02656736.2020.1777330] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Affiliation(s)
- Ramiro M. Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina
- Instituto de Ingeniería y Agronomía, Universidad Nacional Arturo Jauretche, Florencio Varela, Argentina
| | - Ana Gonzalez-Suarez
- Electrical and Electronic Engineering Department, National University of Ireland, Galway, Ireland
- Translational Medical Device Lab, National University of Ireland, Galway, Ireland
| | - Juan J. Pérez
- BioMIT, Department of Electronic Engineering, Universitat Politècnica de València, Valencia, Spain
| | - Enrique Berjano
- BioMIT, Department of Electronic Engineering, Universitat Politècnica de València, Valencia, Spain
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Fajardo JE, Lotto FP, Vericat F, Carlevaro CM, Irastorza RM. Microwave tomography with phaseless data on the calcaneus by means of artificial neural networks. Med Biol Eng Comput 2019; 58:433-442. [PMID: 31863248 DOI: 10.1007/s11517-019-02090-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 11/25/2019] [Indexed: 11/26/2022]
Abstract
The aim of this study is to use a multilayer perceptron (MLP) artificial neural network (ANN) for phaseless imaging the human heel (modeled as a bilayer dielectric media: bone and surrounding tissue) and the calcaneus cross-section size and location using a two-dimensional (2D) microwave tomographic array. Computer simulations were performed over 2D dielectric maps inspired by computed tomography (CT) images of human heels for training and testing the MLP. A morphometric analysis was performed to account for the scatterer shape influence on the results. A robustness analysis was also conducted in order to study the MLP performance in noisy conditions. The standard deviations of the relative percentage errors on estimating the dielectric properties of the calcaneus bone were relatively high. Regarding the calcaneus surrounding tissue, the dielectric parameters estimations are better, with relative percentage error standard deviations up to ≈ 15%. The location and size of the calcaneus are always properly estimated with absolute error standard deviations up to ≈ 3 mm. Microwave tomography of the calcaneus using phaseless data. Simulations were inspired in Computed Tomography images from real heels (above). Inverse problem was solved using Multilayer Perceptron Artificial Neural Network (below).
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Affiliation(s)
- J E Fajardo
- Instituto de Física de Líquidos y Sistemas Biológicos CONICET - CCT La Plata, La Plata, Argentina
| | - F P Lotto
- Instituto de Física de Líquidos y Sistemas Biológicos CONICET - CCT La Plata, La Plata, Argentina
| | - F Vericat
- Instituto de Física de Líquidos y Sistemas Biológicos CONICET - CCT La Plata, La Plata, Argentina
| | - C M Carlevaro
- Instituto de Física de Líquidos y Sistemas Biológicos CONICET - CCT La Plata, La Plata, Argentina
- Departamento de Ingeniería Mecánica, UTN - FRLP, Berisso, Argentina
| | - R M Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos CONICET - CCT La Plata, La Plata, Argentina.
- Instituto de Ingeniería y Agronomía, UNAJ. Florencio Varela, Buenos Aires, Argentina.
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Fajardo JE, Vericat F, Irastorza G, Carlevaro CM, Irastorza RM. Sensitivity analysis on imaging the calcaneus using microwaves. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab3330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Sánchez HR, Irastorza RM, Carlevaro CM. Uncertainties and temperature correction in molecular dynamic simulations of dielectric properties of condensed polar systems. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.01.077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Fajardo JE, Carlevaro CM, Vericat F, Berjano E, Irastorza RM. Effect of the trabecular bone microstructure on measuring its thermal conductivity: A computer modeling-based study. J Therm Biol 2018; 77:131-136. [PMID: 30196891 DOI: 10.1016/j.jtherbio.2018.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 08/08/2018] [Accepted: 08/17/2018] [Indexed: 11/25/2022]
Abstract
The objective of this work is to quantify the relation between the value of the effective thermal conductivity of trabecular bone and its microstructure and marrow content. The thermal conductivity of twenty bovine trabecular bone samples was measured prior to and after defatting at 37, 47, and 57 °C. Computer models were built including the microstructure geometry and the gap between the tissue and measurement probe. The thermal conductivity (k) measured was 0.39 ± 0.06 W m-1 K-1 at 37 °C, with a temperature dependence of + 0.2%°C-1. Replacing marrow by phosphate-buffered saline (defatting) increased both the computer simulations and measurement results by 0.04 W m-1 K-1. The computer simulations showed that k increases by 0.02-0.04 W m-1 K-1 when the model includes a gap filled by phosphate-buffered saline between the tissue and measurement probe. In the presence of microstructure and fatty red marrow, k varies by ± 0.01 W m-1 K-1 compared with the case considering matrix only, which suggests that there are no significant differences between cortical and trabecular bone in terms of k. The computer results showed that the presence of a gap filled by phosphate-buffered saline around the energy applicator changes maximum temperature by < 0.7 °C, while including the bone microstructure involved a variation of < 0.2 mm in the isotherm location. Future experimental studies on measuring the value of k involving the insertion of a probe into the bone through a drill hole should consider the bias found in the simulations. Thermal models based on a homogeneous geometry (i.e. ignoring the microstructure) could provide sufficient accuracy.
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Affiliation(s)
- Jesús E Fajardo
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina
| | - C Manuel Carlevaro
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina; Universidad Tecnológica Nacional, Facultad Regional Buenos Aires, Buenos Aires, Argentina
| | - Fernando Vericat
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina
| | - Enrique Berjano
- BioMIT, Department of Electronic Engineering, Universitat Politècnica de València, Valencia, Spain
| | - Ramiro M Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), La Plata, Argentina; Instituto de Ingeniería y Agronomía, Universidad Nacional Arturo Jauretche, Argentina.
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Irastorza RM, d'Avila A, Berjano E. Thermal latency adds to lesion depth after application of high-power short-duration radiofrequency energy: Results of a computer-modeling study. J Cardiovasc Electrophysiol 2017; 29:322-327. [DOI: 10.1111/jce.13363] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/27/2017] [Accepted: 10/02/2017] [Indexed: 12/01/2022]
Affiliation(s)
- Ramiro M. Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET); La Plata Argentina
- Instituto de Ingeniería y Agronomía; Universidad Nacional Arturo Jauretche; Florencio Varela Argentina
| | | | - Enrique Berjano
- BioMIT, Department of Electronic Engineering; Universitat Politècnica de València; Valencia Spain
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Irastorza RM, Trujillo M, Berjano E. How coagulation zone size is underestimated in computer modeling of RF ablation by ignoring the cooling phase just after RF power is switched off. Int J Numer Method Biomed Eng 2017; 33:e2869. [PMID: 28146314 DOI: 10.1002/cnm.2869] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 01/29/2017] [Indexed: 06/06/2023]
Abstract
All the numerical models developed for radiofrequency ablation so far have ignored the possible effect of the cooling phase (just after radiofrequency power is switched off) on the dimensions of the coagulation zone. Our objective was thus to quantify the differences in the minor radius of the coagulation zone computed by including and ignoring the cooling phase. We built models of RF tumor ablation with 2 needle-like electrodes: a dry electrode (5 mm long and 17G in diameter) with a constant temperature protocol (70°C) and a cooled electrode (30 mm long and 17G in diameter) with a protocol of impedance control. We observed that the computed coagulation zone dimensions were always underestimated when the cooling phase was ignored. The mean values of the differences computed along the electrode axis were always lower than 0.15 mm for the dry electrode and 1.5 mm for the cooled electrode, which implied a value lower than 5% of the minor radius of the coagulation zone (which was 3 mm for the dry electrode and 30 mm for the cooled electrode). The underestimation was found to be dependent on the tissue characteristics: being more marked for higher values of specific heat and blood perfusion and less marked for higher values of thermal conductivity.
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Affiliation(s)
- Ramiro M Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos (CONICET), Calle 59 No 789, B1900BTE, La Plata, Argentina
- Instituto de Ingeniería y Agronomía, Universidad Nacional Arturo Jauretche, Avenida Calchaquí No 6200, 1888, Florencio Varela, Argentina
| | - Macarena Trujillo
- Instituto Universitario de Matemática Pura y Aplicada, Universitat Politècnica de València, Camí de Vera, 46022, València, Spain
| | - Enrique Berjano
- Biomedical Synergy, Electronic Engineering Department, Universitat Politècnica de València, Camí de Vera, 46022, València, Spain
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Manuel Carlevaro C, Irastorza RM, Vericat F. Chirality in a quaternionic representation of the genetic code. Biosystems 2016; 150:99-109. [PMID: 27378069 DOI: 10.1016/j.biosystems.2016.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 08/14/2016] [Accepted: 08/23/2016] [Indexed: 10/21/2022]
Abstract
A quaternionic representation of the genetic code, previously reported by the authors (BioSystems 141 (10-19), 2016), is updated in order to incorporate chirality of nucleotide bases and amino acids. The original representation associates with each nucleotide base a prime integer quaternion of norm 7 and involves a function that assigns to each codon, represented by three of these quaternions, another integer quaternion (amino acid type quaternion). The assignation is such that the essentials of the standard genetic code (particularly its degeneration) are preserved. To show the advantages of such a quaternionic representation we have designed an algorithm to go from the primary to the tertiary structure of the protein. The algorithm uses, besides of the type quaternions, a second kind of quaternions with real components that we additionally associate with the amino acids according to their order along the proteins (order quaternions). In this context, we incorporate chirality in our representation by observing that the set of eight integer quaternions of norm 7 can be partitioned into a pair of subsets of cardinality four each with their elements mutually conjugate and by putting them into correspondence one to one with the two sets of enantiomers (D and L) of the four nucleotide bases adenine, cytosine, guanine and uracil, respectively. We then propose two diagrams in order to describe the hypothetical evolution of the genetic codes corresponding to both of the chiral systems of affinities: D-nucleotide bases/L-amino acids and L-nucleotide bases/D-amino acids at reading frames 5'→3' and 3'→5', respectively. Guided by these diagrams we define functions that in each case assign to the triplets of D- (L-) bases a L- (D-) amino acid type integer quaternion. Specifically, the integer quaternion associated with a given D-amino acid is the conjugate of that one corresponding to the enantiomer L. The chiral type quaternions obtained for the amino acids are used, together with a common set of order quaternions, to describe the folding of the two classes, L and D, of homochiral proteins.
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Affiliation(s)
- C Manuel Carlevaro
- Instituto de Física de Líquidos y Sistemas Biológicos, 59 Nro. 789, 1900 La Plata, Argentina; Universidad Tecnológica Nacional, Facultad Regional Buenos Aires, Mozart Nro. 2300, C14071VT Buenos Aires, Argentina.
| | - Ramiro M Irastorza
- Instituto de Física de Líquidos y Sistemas Biológicos, 59 Nro. 789, 1900 La Plata, Argentina; Instituto de Ingeniería y Agronomía, Universidad Nacional Arturo Jauretche, 1888 Florencio Varela, Buenos Aires, Argentina.
| | - Fernando Vericat
- Instituto de Física de Líquidos y Sistemas Biológicos, 59 Nro. 789, 1900 La Plata, Argentina; Grupo de Aplicaciones Matemáticas y Estadísticas de la Facultad de Ingeniería (GAMEFI), Universidad Nacional de La Plata, Calle 115 y 48, 1900 La Plata, Argentina.
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Irastorza RM, Trujillo M, Martel Villagrán J, Berjano E. Computer modelling of RF ablation in cortical osteoid osteoma: Assessment of the insulating effect of the reactive zone. Int J Hyperthermia 2016; 32:221-30. [DOI: 10.3109/02656736.2015.1135998] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Brusca MI, Irastorza RM, Cattoni DI, Ozu M, Chara O. Mechanisms of interaction between Candida albicans and Streptococcus mutans: an experimental and mathematical modelling study. Acta Odontol Scand 2013; 71:416-23. [PMID: 22625873 DOI: 10.3109/00016357.2012.690530] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To evaluate the mechanisms of microbial interaction between the oral pathogens Candida albicans and Streptococcus mutans. MATERIALS AND METHODS Growth kinetics for the two micro-organisms, cultured individually or together, were followed experimentally for 36 h. The different growth curves were analysed by means of mathematical modelling. RESULTS Under the experimental conditions, S. mutans final concentration, when grown individually, was 5-times that of C. albicans. Contrarily, when both micro-organisms grew together, this ratio was inversed and C. albicans final concentration was even higher than that of S. mutans. When both micro-organisms share the niche, a model including linear competition among one another was best suited to reproduce the experimental observations. The results of this model show that the initial growth rates of both species are positively influenced by their mutual interaction. However, at longer incubation times, C. albicans prevents bacterial growth and achieves concentrations 4-times higher than when grown individually. CONCLUSIONS The results suggest that C. albicans biofilm formation could be potentiated by the presence of S. mutans by two mechanisms: synergically at short times and by competition at longer periods.
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