Post on 03-Jan-2016
Electrical Alignment of a Cardiac Impedance Probe
E Plourde, P Savard, P Le Guyader
Institut de génie biomédical
École Polytechnique de Montréal
Montréal, Canada
September 27th, 2000
Electrical Alignment Of A Cardiac Impedance Probe
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Presentation
• Introduction
• Traditional aligning method
• Electrical alignment of the cardiac impedance probe
• Results
• Conclusion
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Introduction
• Measurements of the myocardial passive electrical properties
• Usually made with the four-electrode technique
• The probe must be aligned
September 27th, 2000
Electrical Alignment Of A Cardiac Impedance Probe
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Traditional aligning method
• Usually aligned by visual inspection
• Problems encountered with the traditional aligning method:– in in vivo studies– if the fibers are not within the visual range of
the experimenter
September 27th, 2000
Electrical Alignment Of A Cardiac Impedance Probe
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Electrical alignment of the cardiac impedance probe (1)
• Modified 4-electrodes technique
• Additional pair of perpendicular potential recording electrodes
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Electrical alignment of the cardiac impedance probe (2)
• Why add two perpendicular potential electrodes?– Symmetrical ellipsoids potential distribution
separated by a line of null potentials
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Electrical Alignment Of A Cardiac Impedance Probe
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Potential distribution for current injected parallel to the fibers
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Potential distribution for current injected perpendicular to the fibers
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Potential distribution for oblique current injection
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Electrical Alignment Of A Cardiac Impedance Probe
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Results - Simulation (bidomain anisotropic model)
• Rotation of the probe• Null potentials at 0o
and 90o
• Discrimination between the longitudinal and transverse orientations
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Results -Experimentation• In preliminary results
– observed potentials near zero on the perpendicular electrodes followed by maximums (0,09mV) at each 90 degrees of rotation
– observed greater potentials in the longitudinal (0,7mV) than transverse orientation (0,65mV)
• Noise problems due to the small potentials measured
September 27th, 2000
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Conclusion
• The method takes advantage of the anisotropy of the myocardium to align the probe
• It is feasible to align the probe without relying on visual inspection
• The method will be used in in vivo studies and on probes placed at the tip of a catheter