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Sensor spacing affects the tissue impedance spectra of rabbit ventricular epicardium.

Publication ,  Journal Article
Waits, CMK; Barr, RC; Pollard, AE
Published in: American journal of physiology. Heart and circulatory physiology
June 2014

This study was designed to test the hypothesis that a complex composite impedance spectra develops when stimulation and recording of cardiac muscle with sufficiently fine spatial resolution in a four-electrode configuration is used. With traditional (millimeter scale) separations, the ratio between the recorded interstitial central potential difference and total supplied interstitial current is constant at all frequencies. This occurs because the fraction of supplied current that redistributes to the intracellular compartment depends on effective membrane resistance between electrodes, which is low, to a much greater extent than effective membrane capacitance. The spectra should therefore change with finer separations at which effective membrane resistance increases, as supplied current will remain primarily interstitial at lower frequencies and redistribute between compartments at higher frequencies. To test this hypothesis, we built arrays with sensors separated (d) by 804 μm, 452 μm, and 252 μm; positioned those arrays across myocyte axes on rabbit ventricular epicardium; and resolved spectra in terms of resistivity (ρt) and reactivity (χt) over the 10 Hz to 4,000 Hz range. With all separations, we measured comparable spectra with predictions from passive membrane simulations that used a three-dimensional structural framework in which intracellular, interstitial, and membrane properties were prescribed based on the limited data available from the literature. At the finest separation, we found mean ρt at 100 Hz and 4,000 Hz that lowered from 395 Ω-cm to 236 Ω-cm, respectively, with maximal mean χt of 160 Ω-cm. This experimental confirmation of spectra development in whole heart experiments is important because such development is central to achieve measurements of intracellular and interstitial passive electrical properties in cardiac electrophysiological experiments using only interstitial access.

Duke Scholars

Published In

American journal of physiology. Heart and circulatory physiology

DOI

EISSN

1522-1539

ISSN

0363-6135

Publication Date

June 2014

Volume

306

Issue

12

Start / End Page

H1660 / H1668

Related Subject Headings

  • Ventricular Function
  • Rabbits
  • Pericardium
  • Models, Statistical
  • Models, Cardiovascular
  • Models, Animal
  • Heart Conduction System
  • Electrophysiologic Techniques, Cardiac
  • Electrodes
  • Dielectric Spectroscopy
 

Citation

APA
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ICMJE
MLA
NLM
Waits, C. M. K., Barr, R. C., & Pollard, A. E. (2014). Sensor spacing affects the tissue impedance spectra of rabbit ventricular epicardium. American Journal of Physiology. Heart and Circulatory Physiology, 306(12), H1660–H1668. https://doi.org/10.1152/ajpheart.00661.2013
Waits, Charlotte Mae K., Roger C. Barr, and Andrew E. Pollard. “Sensor spacing affects the tissue impedance spectra of rabbit ventricular epicardium.American Journal of Physiology. Heart and Circulatory Physiology 306, no. 12 (June 2014): H1660–68. https://doi.org/10.1152/ajpheart.00661.2013.
Waits CMK, Barr RC, Pollard AE. Sensor spacing affects the tissue impedance spectra of rabbit ventricular epicardium. American journal of physiology Heart and circulatory physiology. 2014 Jun;306(12):H1660–8.
Waits, Charlotte Mae K., et al. “Sensor spacing affects the tissue impedance spectra of rabbit ventricular epicardium.American Journal of Physiology. Heart and Circulatory Physiology, vol. 306, no. 12, June 2014, pp. H1660–68. Epmc, doi:10.1152/ajpheart.00661.2013.
Waits CMK, Barr RC, Pollard AE. Sensor spacing affects the tissue impedance spectra of rabbit ventricular epicardium. American journal of physiology Heart and circulatory physiology. 2014 Jun;306(12):H1660–H1668.

Published In

American journal of physiology. Heart and circulatory physiology

DOI

EISSN

1522-1539

ISSN

0363-6135

Publication Date

June 2014

Volume

306

Issue

12

Start / End Page

H1660 / H1668

Related Subject Headings

  • Ventricular Function
  • Rabbits
  • Pericardium
  • Models, Statistical
  • Models, Cardiovascular
  • Models, Animal
  • Heart Conduction System
  • Electrophysiologic Techniques, Cardiac
  • Electrodes
  • Dielectric Spectroscopy