Biphasic waveforms

FIGURE 6.2 Instant-reversal biphase waveform used by the Food Engineering group at McGill University. (From Amiali, M., Inactivation of Escherichia coli 0157 H7 and Salmonella enteritidis in liquid egg products using pulsed electric field, PhD Dissertation, McGill University, Montreal, Quebec, Canada, 2005.)... 

Biphasic waveforms are observed at most extracellular sites, because most sites are neither the origin or termination of excitation. Further, most real extracellular waveforms are more complicated and last longer than those shown in Figure 19.9, because they show the composite effect from many different fibers rather than a single one in isolation. 

M. O. Sweeney, A. Natale, K. J. Volosin, C. D. Swerdlow, J. H. Baker, and P. Degroot. Prospective randomized comparison of 50%/50% versus 65%/65% tilt biphasic waveform on defibrUlation in humans. Pacing Clin Electrophysiol, 24(l) 60-65, January 2001. 

Figure 6.11 Unipolar potentials from a current dipole moving along the horizontal x-axis. Dipole length is L c) the unit of the x-axis is L c- The recording electrode is at distance SL c and lOLcc (a) horizontal dipole orientation, biphasic waveforms, and high spatial resolution (b) vertical dipole orientation, monophasic waveforms, and largest signal amplitude of...

This is confirmed by Figure 6.12, which shows a large positional discriminative property. The waveform in Figure 6.12(b) is even triphasic. Figure 6.12(a) and (c) show biphasic waveforms with a large high-frequency content, but the recorded voltage difference is small. 

Shepard RK, DeGroot PJ, Pacifico A, Wood MA, Ellenbogen KA. Prospective randomized comparison of 65%/65% versus 42%/42% tilt biphasic waveform on defibrillation thresholds in humans. J Interv Card Electrophysiol 2003 8 221-5. 

Zhang Y, Boddicker KA, Davies LR, Jones JL, Kerber RE. Surgical open-chest ventricular defibrillation triphasic waveforms are superior to biphasic waveforms. Pacing Clin Electrophysiol 2004 27 941-8. 

Jung J, Hahn SJ, Heisel A, Buob A, Schubert BD, Siaplaouras S. Defibrillation efficacy and pain perception of two biphasic waveforms for internal cardioversion of atrial fibrillation. J Cardiovasc Electrophysiol 2003 14 837-40. 

Explore the imbalanced biphasic waveform, less anodic charge than cathodic, as a way to extend the excitation range. 

The waveform pattern obtain by duplex scanning can also be used for diagnosing proximal or distal disease (/6,77). A triphasic waveform in the common femoral artery indicates that the ipsUateral proximal vessels are normal. A biphasic waveform would indicate stenosis that is not significant, and a monophasic waveform would signify the presence of significant stenosis or occlusion (Fig. 3). A low-end diastolic velocity indicates a tight stenosis or occlusion distal to the measurement (Fig. 4). 

Biphasic waveforms, 28-18 Biplanar radiography method, in wrist joint study, 49-27 Bipolar electrodes, 28-6 Birch, L.H., 18-8 Blackstone, E.H., 10-9 Blindsight, 4-8 Blink reflex, 4-2 Blix,M 8-13 Bloebaum, R.D., 50-10 Blood flow regulation,... 

Fig. 6.4 TLN electrode oxidation after 1 week operation with triangular biphasic waveforms with 1.4 V amplitude. The active electrodes are on the bottom left comer. The others were not driven. Decrease in injected charge measured. Figure taken from [17], with permission 2011 IEEE...

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