| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
AJP - Heart and Circulatory Physiology, Vol 253, Issue 6 1418-H1424, Copyright © 1987 by American Physiological Society
ARTICLES |
J. L. Jones, R. E. Jones and G. Balasky
Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
According to the most commonly accepted hypothesis, ventricular defibrillation is produced by exciting cells in a critical mass of the ventricle. For monophasic defibrillator waveforms, this hypothesis correctly predicts a direct correlation between defibrillation threshold in the transthoracic calf model and excitation threshold for extracellular field stimulation in the cultured cell model. To further test the hypothesis, we determined whether symmetrical biphasic waveforms, which reduce defibrillation threshold in the calf to approximately 65% of that of the corresponding monophasic waveform (14), decrease excitation threshold in the cultured cell model. Experiments were performed on 100- to 250-microns aggregates from 10- to 12-day-old chick embryos. Excitation threshold strength-duration curves obtained at extracellular potassium (Ko) = 6.5 mM and pacing interval of 1,000 ms showed a significant reduction for symmetrical biphasic rectangular waveforms, when compared with the corresponding monophasic waveforms for durations greater than 3 ms. At the rheobase, the threshold ratio between the biphasic and monophasic waveforms was 0.63 (SE = 0.02). Transmembrane potentials during stimulation showed that excitation takes place during the second portion of the biphasic waveform for intensities that are subthreshold for the monophasic waveform. The relative effectiveness of the biphasic waveform (5-ms duration) increases under "fibrillation conditions" of short pacing interval (300 ms) and high extracellular potassium (10.5 mM). These results show that symmetrical biphasic waveforms decrease excitation threshold in the cultured cell model and that the degree of threshold reduction is dependent on Ko and beat rate.
This article has been cited by other articles:
|
|
 |
|
  J. P. Daubert and S.-S. Sheu Mystery of Biphasic Defibrillation Waveform Efficacy: Is it Calcium? J. Am. Coll. Cardiol., September 2, 2008; 52(10): 836 - 838. [Full Text] [PDF]
|
|
|
|
 |
|
 W. Tang, M. H. Weil, S. Sun, H. P. Povoas, K. Klouche, T. Kamohara, and J. Bisera A Comparison of Biphasic and Monophasic Waveform Defibrillation After Prolonged Ventricular Fibrillation Chest, September 1, 2001; 120(3): 948 - 954. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. H. Tovar and J. L. Jones Electrophysiological Deterioration During Long-Duration Ventricular Fibrillation Circulation, December 5, 2000; 102(23): 2886 - 2891. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Huang, B. H. KenKnight, D. L. Rollins, W. M. Smith, and R. E. Ideker Ventricular Defibrillation With Triphasic Waveforms Circulation, March 21, 2000; 101(11): 1324 - 1328. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X. Zhou, W. M. Smith, R. K. Justice, J. L. Wayland, and R. E. Ideker Transmembrane potential changes caused by monophasic and biphasic shocks Am J Physiol Heart Circ Physiol, November 1, 1998; 275(5): H1798 - H1807. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Schauerte, F. A. Schondube, M. Grossmann, H. Dorge, F. Stein, B. Dohmen, A. Moumen, K. Erena, B. J. Messmer, P. Hanrath, et al. Influence of Phase Duration of Biphasic Waveforms on Defibrillation Energy Requirements With a 70-µF Capacitance Circulation, May 26, 1998; 97(20): 2073 - 2078. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. O. Cummins, M. F. Hazinski, R. E. Kerber, P. Kudenchuk, L. Becker, G. Nichol, B. Malanga, T. P. Aufderheide, E. M. Stapleton, K. Kern, et al. Low-Energy Biphasic Waveform Defibrillation: Evidence-Based Review Applied to Emergency Cardiovascular Care Guidelines : A Statement for Healthcare Professionals From the American Heart Association Committee on Emergency Cardiovascular Care and the Subcommittees on Basic Life Support, Advanced Cardiac Life Support, and Pediatric Resuscitation Circulation, April 28, 1998; 97(16): 1654 - 1667. [Full Text] [PDF]
|
|
|
|
 |
|
 S. B. Knisley Tamara C. Baynham Line Stimulation Parallel to Myofibers Enhances Regional Uniformity of Transmembrane Voltage Changes in Rabbit Hearts Circ. Res., August 19, 1997; 81(2): 229 - 241. [Abstract] [Full Text]
|
|
|
|
|
|
S. Behrens, C. Li, P. Kirchhof, F. L. Fabritz, and M. R. Franz Reduced Arrhythmogenicity of Biphasic Versus Monophasic T-Wave Shocks: Implications for Defibrillation Efficacy Circulation, October 15, 1996; 94(8): 1974 - 1980. [Abstract] [Full Text]
|
|
|
|
|
|
Y. Yamanouchi, K. A. Mowrey, G. R. Nadzam, D. G. Hills, M. W. Kroll, J. E. Brewer, A. M. Donohoo, B. L. Wilkoff, and P. J. Tchou Large Change in Voltage at Phase Reversal Improves Biphasic Defibrillation Thresholds: Parallel-Series Mode Switching Circulation, October 1, 1996; 94(7): 1768 - 1773. [Abstract] [Full Text]
|
|
|
|
|
|
O. H. Tovar and J. L. Jones Biphasic Defibrillation Waveforms Reduce Shock-Induced Response Duration Dispersion Between Low and High Shock Intensities Circ. Res., August 1, 1995; 77(2): 430 - 438. [Abstract] [Full Text]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
