title: Elevated electrochemical impedance in the endoluminal regions with high shear stress: implication for assessing lipid-rich atherosclerotic lesions.
abstract: BACKGROUND
  Identifying metabolically active atherosclerotic lesions remains an unmet clinical challenge during coronary intervention. Electrochemical impedance (EIS) increased in response to oxidized low density lipoprotein (oxLDL)-laden lesions. We hereby assessed whether integrating EIS with intravascular ultrasound (IVUS) and shear stress (ISS) provided a new strategy to assess oxLDL-laden lesions in the fat-fed New Zealand White (NZW) rabbits.
  
  
  RESULTS
  A micro-heat transfer sensor was deployed to acquire the ISS profiles at baseline and post high-fat diet (HD) in the NZW rabbits (n=8). After 9 weeks of HD, serum oxLDL levels (mg/dL) increased by 140 fold, accompanied by a 1.5-fold increase in kinematic viscosity (cP) in the HD group. Time-averaged ISS (ISSave) in the thoracic aorta also increased in the HD group (baseline: 17.61±0.24 vs. 9 weeks: 25.22±0.95dyne/cm(2), n=4), but remained unchanged in the normal diet group (baseline: 22.85±0.53dyn/cm(2) vs. 9 weeks: 22.37±0.57dyne/cm(2), n=4). High-frequency intravascular ultrasound (IVUS) revealed atherosclerotic lesions in the regions with augmented ISSave, and concentric bipolar microelectrodes demonstrated elevated EIS signals, which were correlated with prominent anti-oxLDL immuno-staining (oxLDL-free regions: 497±55Ω, n=8 vs. oxLDL-rich lesions: 679±125Ω, n=12, P<0.05). The equivalent circuit model for tissue resistance between the lesion-free and ox-LDL-rich lesions further validated the experimental EIS signals.
  
  
  CONCLUSIONS
  By applying electrochemical impedance in conjunction with shear stress and high-frequency ultrasound sensors, we provided a new strategy to identify oxLDL-laden lesions. The study demonstrated the feasibility of integrating EIS, ISS, and IVUS for a catheter-based approach to assess mechanically unstable plaque.
authors: Department of Biomedical Engineering and Cardiovascular Medicine, University of Southern California, Los Angeles, CA 90089, USA.
authors: Fei
authors: F
authors: Yu
authors: Juhyun
authors: J
authors: Lee
authors: Nelson
authors: N
authors: Jen
authors: Xiang
authors: X
authors: Li
authors: Qian
authors: Q
authors: Zhang
authors: Rui
authors: R
authors: Tang
authors: Qifa
authors: Q
authors: Zhou
authors: Eun S
authors: ES
authors: Kim
authors: Tzung K
authors: TK
authors: Hsiai
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000175:diagnosis* / Q000503:physiopathology*; D058266:Dielectric Spectroscopy / Q000295:instrumentation*; D054459:Elasticity Imaging Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D050356:Lipid Metabolism; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D033081:Shear Strength; D018084:Ultrasonography, Interventional / Q000295:instrumentation*