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Fischer G, Kofler M, Baumgarten D. Implementation of N-Interval fourier transform analysis - Application to compound action potentials. MethodsX 2023; 11:102441. [PMID: 38023302 PMCID: PMC10630633 DOI: 10.1016/j.mex.2023.102441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 10/14/2023] [Indexed: 12/01/2023] Open
Abstract
N -Interval Fourier Transform Analysis (N -FTA) allows for spectral separation of a periodic target signal from uncorrelated background interference. A N -FTA pseudo-code is presented. The spectral resolution is defined by the repetition rate of the near periodic signal. Acceptance criteria for spectral targets were defined such that the probability of accepting false positives is less than 1 500 . Simulated and recorded neural compound action potentials (CAPs) were investigated. Simulated data allowed for comparison with reference solutions demonstrating the stability of N -FTA at conditions being comparable to real world data. Background activity was assessed with small errors. Evoked target components were assessed down to power spectral density being approximately N times below the background level. Validation was completed investigating a measured CAP. In neurophysiological recordings, this approach allows for accurate separation of near periodic evoked activity from uncorrelated background activities for frequencies below 1kHz.•N-FTA allows for spectral separation of a periodic target signal from uncorrelated interference by analyzing a segment containing N target signal repetitions.•A MATLAB implementation of the algorithm is provided along with simulated and recorded data.•N-FTA was successfully validated using simulated and measured data for CAPs.
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Affiliation(s)
- G. Fischer
- Institute of Electrical and Biomedical Engineering, UMIT – Private University for Health Sciences and Health Technology, Eduard Wallnoefer Zentrum 1, 6060 Hall in Tirol, Austria
| | - M. Kofler
- Department of Neurology, Hochzirl Hospital, 6170 Zirl, Austria
| | - D. Baumgarten
- Institute of Electrical and Biomedical Engineering, UMIT – Private University for Health Sciences and Health Technology, Eduard Wallnoefer Zentrum 1, 6060 Hall in Tirol, Austria
- Institute of Biomedical Engineering and Informatics, Technische Universitt Ilmenau, G.-Kirchhoff-Str. 2, 98693 Ilmenau, Germany
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Segarra I, Cebrian A, Ruiperez-Campillo S, Tormos A, Chorro FJ, Castells F, Alberola A, Millet J. Mini Peltier Cell Array System for the Generation of Controlled Local Epicardial Heterogeneities. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38082704 DOI: 10.1109/embc40787.2023.10340369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
The present study aims to design and fabricate a system capable of generating heterogeneities on the epicardial surface of an isolated rabbit heart perfused in a Langendorff system. The system consists of thermoelectric modules that can be independently controlled by the developed hardware, thereby allowing for the generation of temperature gradients on the epicardial surface, resulting in conduction slowing akin to heterogeneities of pathological origin. A comprehensive analysis of the system's viability was performed through modeling and thermal simulation, and its practicality was validated through preliminary tests conducted at the experimental cardiac electrophysiology laboratory of the University of Valencia. The design process involved the use of Fusion 360 for 3D designs, MATLAB/Simulink for algorithms and block diagrams, LTSpice and Altium Designer for schematic captures and PCB design, and the integration of specialized equipment for animal experimentation. The objective of the study was to efficiently capture epicardial recordings under varying conditions.Clinical relevance- The proposed system aims to induce local epicardial heterogeneities to generate labeled correct signals that can serve as a golden standard for improving algorithms that identify and characterize fibrotic substrates. This improvement will enhance the efficacy of ablation processes and potentially reduce the ablated surface area.
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Wang W, Li W, Liu B, Wang L, Li K, Wang Y, Ji Z, Xu C, Shi X. Temperature dependence of dielectric properties of blood at 10 Hz-100 MHz. Front Physiol 2022; 13:1053233. [PMID: 36388092 PMCID: PMC9644111 DOI: 10.3389/fphys.2022.1053233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 10/14/2022] [Indexed: 11/07/2023] Open
Abstract
The temperature dependence of the dielectric properties of blood is important for studying the biological effects of electromagnetic fields, electromagnetic protection, disease diagnosis, and treatment. However, owing to the limitations of measurement methods, there are still some uncertainties regarding the temperature characteristics of the dielectric properties of blood at low and medium frequencies. In this study, we designed a composite impedance measurement box with high heat transfer efficiency that allowed for a four/two-electrode measurement method. Four-electrode measurements were carried out at 10 Hz-1 MHz to overcome the influence of electrode polarization, and two-electrode measurements were carried out at 100 Hz-100 MHz to avoid the influence of distribution parameters, and the data was integrated to achieve dielectric measurements at 10 Hz-100 MHz. At the same time, the temperature of fresh blood from rabbits was controlled at 17-39°C in combination with a temperature-controlled water sink. The results showed that the temperature coefficient for the real part of the resistivity of blood remained constant from 10 Hz to 100 kHz (-2.42%/°C) and then gradually decreased to -0.26%/°C. The temperature coefficient of the imaginary part was positive and bimodal from 6.31 kHz to 100 MHz, with peaks of 5.22%/°C and 4.14%/°C at 126 kHz and 39.8 MHz, respectively. Finally, a third-order function model was developed to describe the dielectric spectra at these temperatures, in which the resistivity parameter in each dispersion zone decreased linearly with temperature and each characteristic frequency increased linearly with temperature. The model could estimate the dielectric properties at any frequency and temperature in this range, and the maximum error was less than 1.39%, thus laying the foundation for subsequent studies.
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Affiliation(s)
- Weice Wang
- Shaanxi Provincial Key Laboratory of Bioelectromagnetic Detection and Intelligent Perception, Department of Biomedical Engineering, Air Force Medical University, Xi’an, China
| | - Weichen Li
- School of Life Sciences, Northwest University, Xi’an, China
| | - Benyuan Liu
- Shaanxi Provincial Key Laboratory of Bioelectromagnetic Detection and Intelligent Perception, Department of Biomedical Engineering, Air Force Medical University, Xi’an, China
| | - Lei Wang
- Institute of Medical Research, Northwestern Polytechnical University, Xi’an, China
| | - Kun Li
- Faculty of Electrical and Control Engineering, Liaoning Technical University, Huludao, China
| | - Yu Wang
- Faculty of Electrical and Control Engineering, Liaoning Technical University, Huludao, China
| | - Zhenyu Ji
- Shaanxi Provincial Key Laboratory of Bioelectromagnetic Detection and Intelligent Perception, Department of Biomedical Engineering, Air Force Medical University, Xi’an, China
| | - Canhua Xu
- Shaanxi Provincial Key Laboratory of Bioelectromagnetic Detection and Intelligent Perception, Department of Biomedical Engineering, Air Force Medical University, Xi’an, China
| | - Xuetao Shi
- Shaanxi Provincial Key Laboratory of Bioelectromagnetic Detection and Intelligent Perception, Department of Biomedical Engineering, Air Force Medical University, Xi’an, China
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Pleshkov MO, D'Alessandro S, Svetlik M, Starkov D, Zaytsev V, Handler M, Baumgarten D, Saba R, van de Berg R, Demkin V, Kingma H. Fitting the determined impedance in the guinea pig inner ear to randles circuit using square error minimization in the range of 100 Hz to 50 kHz. Biomed Phys Eng Express 2022; 8. [PMID: 35042198 DOI: 10.1088/2057-1976/ac4c4a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 01/18/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE A number of lumped and distributed parameter models of the inner ear have been proposed in order to improve the vestibular implant stimulation. The models should account for all significant physical phenomena influencing the current propagation: electrical double layer (EDL) and medium polarization. The electrical properties of the medium are reflected in the electrical impedance, therefore the aim of this study was to measure the impedance in the guinea pig inner ear and construct its equivalent circuit. APPROACH The electrical impedance was measured from 100 Hz to 50 kHz between a pair of platinum electrodes immersed in saline solution using sinusoidal voltage signals. The Randles circuit was fitted to the measured impedance in the saline solution in order to estimate the EDL parameters (C, W, and Rct) of the electrode interface in saline. Then, the electrical impedance was measured between all combinations of the electrodes located in semicircular canal ampullae and the vestibular nerve in the guinea pig in vitro. The extended Randles circuit considering the medium polarization (Ri, Re, Cm) together with EDL parameters (C, Rct) obtained from the saline solution was fitted to the measured impedance of the guinea pig inner ear. The Warburg element was assumed negligible and was not considered in the guinea pig model. MAIN RESULTS For the set-up used, the obtained EDL parameters were: C=27.09*10-8F, Rct=18.75 kΩ. The average values of intra-, extracellular resistances, and membrane capacitance were Ri=4.74 kΩ, Re=45.05 kΩ, Cm=9.69*10-8F, respectively. SIGNIFICANCE The obtained values of the model parameters can serve as a good estimation of the EDL for modelling work. The EDL, together with medium polarization, plays a significant role in the electrical impedance of the guinea pig inner ear, therefore, they should be considered in electrical conductivity models to increase the credibility of the simulations.
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Affiliation(s)
- Maksim Olegovich Pleshkov
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, Limburg, 6202 AZ, NETHERLANDS
| | | | - Mikhail Svetlik
- Biological Institute, National Research Tomsk State University, Lenin ave., 36, Tomsk, Tomskaâ, 634050, RUSSIAN FEDERATION
| | - Dmitrii Starkov
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, Limburg, 6229 HX, NETHERLANDS
| | - Vasilii Zaytsev
- Physics Faculty, Laboratory for modelling of physical processes in biology and medicine Tomsk, National Research Tomsk State University, Lenin ave., 36, Tomsk, Tomskaâ, 634050, RUSSIAN FEDERATION
| | - Michael Handler
- Institute of Electrical and Biomedical Engineering, UMIT, Eduard-Wallnöfer-Zentrum 1, Hall in Tirol, Tirol, 6060, AUSTRIA
| | - Daniel Baumgarten
- Institute of Electrical and Biomedical Engineering, UMIT, Eduard-Wallnöfer-Zentrum 1, Hall in Tirol, Tirol, 6060, AUSTRIA
| | - Rami Saba
- MED-EL Electromedical Equipment, Fürstenweg 77a, Innsbruck, Tyrol, 6020, AUSTRIA
| | - Raymond van de Berg
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, Limburg, 6229 HX, NETHERLANDS
| | - Vladimir Demkin
- Physics Faculty, National Research Tomsk State University, Lenin ave., 36, Tomsk, Tomskaâ, 634050, RUSSIAN FEDERATION
| | - Herman Kingma
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, Limburg, 6229 HX, NETHERLANDS
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Iacopino S, Filannino P, Artale P, Placentino F, Pesce F, Petretta A. Antral lesion characterization of a new cryoballoon ablation system in terms of local impedance drop: The first reported case. HeartRhythm Case Rep 2021; 7:182-185. [PMID: 33786317 PMCID: PMC7987902 DOI: 10.1016/j.hrcr.2020.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Affiliation(s)
- Saverio Iacopino
- Electrophysiology Unit, Maria Cecilia Hospital, Cotignola, Italy
| | | | - Paolo Artale
- Electrophysiology Unit, Maria Cecilia Hospital, Cotignola, Italy
| | | | - Francesca Pesce
- Electrophysiology Unit, Maria Cecilia Hospital, Cotignola, Italy
| | - Andrea Petretta
- Electrophysiology Unit, Maria Cecilia Hospital, Cotignola, Italy
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A Lead Field Two-Domain Model for Longitudinal Neural Tracts-Analytical Framework and Implications for Signal Bandwidth. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2020; 2020:5436807. [PMID: 32565881 PMCID: PMC7275970 DOI: 10.1155/2020/5436807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 04/07/2020] [Accepted: 04/21/2020] [Indexed: 11/18/2022]
Abstract
Somatosensory evoked potentials are a well-established tool for assessing volley conduction in afferent neural pathways. However, from a clinical perspective, recording of spinal signals is still a demanding task due to the low amplitudes compared to relevant noise sources. Computer modeling is a powerful tool for gaining insight into signal genesis and, thus, for promoting future innovations in signal extraction. However, due to the complex structure of neural pathways, modeling is computationally demanding. We present a theoretical framework which allows computing the electric potential generated by a single axon in a body surface lead by the convolution of the neural lead field function with a propagating action potential term. The signal generated by a large cohort of axons was obtained by convoluting a single axonal signal with the statistical distribution of temporal dispersion of individual axonal signals. For establishing the framework, analysis was based on an analytical model. Our approach was further adopted for a numerical computation of body surface neuropotentials employing the lead field theory. Double convolution allowed straightforward analysis in the frequency domain. The highest frequency components occurred at the cellular membrane. A bandpass type spectral shape and a peak frequency of 1800 Hz was observed. The volume conductor transmitting the signal to the recording lead acted as an additional bandpass reducing the axonal peak frequency from 200 Hz to 500 Hz. The superposition of temporally dispersed axonal signals acted as an additional low-pass filter further reducing the compound action potential peak frequency from 90 Hz to 170 Hz. Our results suggest that the bandwidth of spinal evoked potentials might be narrower than the bandwidth requested by current clinical guidelines. The present findings will allow the optimization of noise suppression. Furthermore, our theoretical framework allows the adaptation in numerical methods and application in anatomically realistic geometries in future studies.
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