Study type: Medical/biological study (experimental study, theoretical study)

Effect of electrode surface area on thresholds for AC stimulation and ventricular fibrillation. med./bio.

Published in: IEEE Trans Biomed Eng 2007; 54 (10): 1829-1836

Aim of study (acc. to author)

This study was conducted to establish the relationship between electric stimulation and ventricular fibrillation thresholds for electrode size and stimulation frequency in guinea pigs in vivo.

Background/further details

Thirty-four healthy adult male guinea pigs, weighing approximately 800-1200 grams were anesthetized, and their chests opened to expose the heart. Eleven electrodes with following contact surface areas were applied: 0.1, 0.2, 0.8, 1.26, 2.01, 2.34, 3.08, 4.1, 7.91, 16.4, and 26.79 mm2.
In the first group, the relationship between electrode size and current was explored in ten guinea pigs and the current thresholds recorded when blood pressure collapse and ventricular fibrillation occured. In the second group, frequency depency (20, 40, 80, and 160 Hz) was examined on the relationship between electrode size and current in thirteen guinea pigs.
Based on the experimental data, a theoretical framework to explain the electrode size-stimulation threshold variation for both low strength alternating current stimulation and ventricular fibrillation initiation was presented.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: 5 seconds
Exposure 2: 20–160 Hz
Exposure duration: 5 seconds

General information

for further information see: O. Z. Roy, G. C. Park and J. R. Scott "Intracardiac catheter fibrillation thresholds as a function of the duration of 60 Hz current and electrode area", IEEE Trans. Biomed. Eng., vol BME-24, no. 5, pp 430-435, Mays 1977

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Waveform
Exposure duration 5 seconds
Exposure setup
Exposure source
Setup electrodes placed on the surface of the right ventricle just above the apex, return electrode placed on the rear paw
Parameters
Measurand Value Type Method Mass Remarks
cf. remarks - - - - electrode surface area: 0.1 - 26.79 mm²
cf. remarks - - - - current: 25 µA - 3000 µA

Exposure 2

Main characteristics
Frequency 20–160 Hz
Type
Waveform
Exposure duration 5 seconds
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
cf. remarks - - - - electrode surface area: 0.2, 2.01, 16.4 mm²
cf. remarks - - - - current: 25 µA - 3000 µA

Reference articles

  • Roy OZ et al. (1977): Intracardiac Catheter Fibrillation Thresholds as a Function of the Duration of 60 Hz Current and Electrode Area.
  • Han J et al. (1966): Fibrillation Threshold of Premature Ventricular Responses.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

On a log-log graph (horizontal and vertical axes are logarithimic scales), electrode size had a piecewise-linear relationship with the current thresholds to induce blood pressure collapse and ventricular fibrillation. Above the liminal area, the threshold increased proportional.
The frequency had no further effect on the relationship between electrode size and current.

Study character:

Study funded by

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