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In Vitro Estimation of the Electrical Performance of Bipolar Pacing Electrode Systems
Author(s) -
WALTON CHRISTOPHER,
ECONOMIDES APOLLO P.
Publication year - 1988
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1988.tb06311.x
Subject(s) - electrode , materials science , waveform , electrical impedance , trailing edge , voltage , amplitude , biomedical engineering , optoelectronics , analytical chemistry (journal) , medicine , composite material , electrical engineering , optics , chemistry , chromatography , physics , engineering
With the current interest in bipolar stimulation, there is a need for greater understanding of the electrical contributions of the two electrodes in this type of pacing. This has been investigated using a specially designed cell in which an electrode under test was immersed in a buffered saline solution (pH 7.42) at 37–38°C. Four electrode types were studied: a single stimulating electrode (6 mm 2 dish tip, Pt‐black coated) and three indifferent electrodes. The indifferent electrodes were a 41 mm 2 polished Pt ring, a Pt‐black coated version of the same electrode, and a titanium pacemaker enclosure which was included to allow comparison with the unipolar situation. These electrodes were tested individually against a chlorided silver reference electrode of negligible (1–2Ω) impedance, the results being processed in such a way as to allow estimation of the properties of the stimulating electrode taken in combination with each of the indifferents. Constant current pulses (1–10 mA amplitude, 0.5 and 1.0 ms duration) were applied and measurements made from the resulting voltage waveforms. These were V 1 and V 2 , the potential at the leading and trailing edge of the pulse, and Va, the post‐pulse potential at 20 ms following the trailing edge. The potential V 1 ‐ V 2 is electrode dependent and allows the determination of the energy loss due to polarization to be calculated. Sinusoidal AC signals (0.1 Hz‐10 kHz, 20 μA maximum amplitude) were also employed, allowing determination of sensing impedance. Under all conditions, the calculated performance of the stimulating electrode with the coated ring was nearly equivalent to that with the pacemaker enclosure. The performance with the uncoated ring was in all respects markedly inferior, displaying almost double the energy loss on pulsing, post‐stimulus potentials an order of magnitude larger and sensing impedance increased by a factor of up to 8.