title: Two-Point Stretchable Electrode Array for Endoluminal Electrochemical Impedance Spectroscopy Measurements of Lipid-Laden Atherosclerotic Plaques.
abstract: Four-point electrode systems are commonly used for electric impedance measurements of biomaterials and tissues. We introduce a 2-point system to reduce electrode polarization for heterogeneous measurements of vascular wall. Presence of endoluminal oxidized low density lipoprotein (oxLDL) and lipids alters the electrochemical impedance that can be measured by electrochemical impedance spectroscopy (EIS). We developed a catheter-based 2-point micro-electrode configuration for intravascular deployment in New Zealand White rabbits. An array of 2 flexible round electrodes, 240 µm in diameter and separated by 400 µm was microfabricated and mounted on an inflatable balloon catheter for EIS measurement of the oxLDL-rich lesions developed as a result of high-fat diet-induced hyperlipidemia. Upon balloon inflation, the 2-point electrode array conformed to the arterial wall to allow deep intraplaque penetration via alternating current (AC). The frequency sweep from 10 to 300 kHz generated an increase in capacitance, providing distinct changes in both impedance (Ω) and phase (ϕ) in relation to varying degrees of intraplaque lipid burden in the aorta. Aortic endoluminal EIS measurements were compared with epicardial fat tissue and validated by intravascular ultrasound and immunohistochemistry for plaque lipids and foam cells. Thus, we demonstrate a new approach to quantify endoluminal EIS via a 2-point stretchable electrode strategy.
authors: Division of Cardiology, Department of Medicine, Ronald Reagan UCLA Medical Center, Los Angeles, CA, 90073, USA.|Department of Bioengineering, Henry Samueli School of Engineering and Applied Sciences, University of California, Los Angeles, CA, 90073, USA.|Department of Molecular, Cellular and Integrative Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90073, USA.
authors: René R Sevag
authors: RR
authors: Packard
authors: Electrical and Mechanical Engineering, California Institute of Technology, Pasadena, CA, USA.
authors: XiaoXiao
authors: X
authors: Zhang
authors: Electrical and Mechanical Engineering, California Institute of Technology, Pasadena, CA, USA.
authors: Yuan
authors: Y
authors: Luo
authors: Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
authors: Teng
authors: T
authors: Ma
authors: Department of Bioengineering, Henry Samueli School of Engineering and Applied Sciences, University of California, Los Angeles, CA, 90073, USA.
authors: Nelson
authors: N
authors: Jen
authors: Division of Cardiology, Department of Medicine, Ronald Reagan UCLA Medical Center, Los Angeles, CA, 90073, USA.|Department of Bioengineering, Henry Samueli School of Engineering and Applied Sciences, University of California, Los Angeles, CA, 90073, USA.
authors: Jianguo
authors: J
authors: Ma
authors: Division of Cardiology, Department of Medicine, Ronald Reagan UCLA Medical Center, Los Angeles, CA, 90073, USA.|Department of Bioengineering, Henry Samueli School of Engineering and Applied Sciences, University of California, Los Angeles, CA, 90073, USA.|Department of Molecular, Cellular and Integrative Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90073, USA.
authors: Linda L
authors: LL
authors: Demer
authors: Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.
authors: Qifa
authors: Q
authors: Zhou
authors: Department of Biostatistics, Fielding School of Public Health, University of California, Los Angeles, CA, USA.
authors: James W
authors: JW
authors: Sayre
authors: Division of Cardiology, Department of Medicine, Ronald Reagan UCLA Medical Center, Los Angeles, CA, 90073, USA.
authors: Rongsong
authors: R
authors: Li
authors: Electrical and Mechanical Engineering, California Institute of Technology, Pasadena, CA, USA.
authors: Yu-Chong
authors: YC
authors: Tai
authors: Division of Cardiology, Department of Medicine, Ronald Reagan UCLA Medical Center, Los Angeles, CA, 90073, USA. thsiai@mednet.ucla.edu.|Department of Bioengineering, Henry Samueli School of Engineering and Applied Sciences, University of California, Los Angeles, CA, 90073, USA. thsiai@mednet.ucla.edu.|Department of Molecular, Cellular and Integrative Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90073, USA. thsiai@mednet.ucla.edu.
authors: Tzung K
authors: TK
authors: Hsiai
mesh_terms: D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D058266:Dielectric Spectroscopy / Q000295:instrumentation* / Q000379:methods*; D004041:Dietary Fats / Q000009:adverse effects* / Q000494:pharmacology; D004195:Disease Models, Animal; D004566:Electrodes; D006949:Hyperlipidemias / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008077:Lipoproteins, LDL / Q000378:metabolism*; D010496:Pericardium / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D058226:Plaque, Atherosclerotic / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D011817:Rabbits
chemical_list: D004041:Dietary Fats; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein
keywords: Atherosclerosis; Electrochemical impedance spectroscopy; Flexible electronics; Lipid-rich plaque