60 Hz ventricular fibrillation thresholds for large-surface-area electrodes

Roy, O. Z.; Scott, John R.; Trollope, B. J.

doi:10.1007/bf02443961

Cited by 8 publications

(3 citation statements)

References 8 publications

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“…The physiological mechanisms involved may be more complicated in this clinical setting. Similarly, VF induction using 60-Hz AC current applied for 1-5 seconds also requires far lower currents than we consider in this article (Roy, et al, 1986). but the mechanisms presumably implicate heterogeneous catecholamine release from cardiac innervation and other complications (Tamargo, etal., 1975;Euler, 1980;Kowey, et al, 1983).…”

Section: The Ventricular Fibriliation Thresholdmentioning

confidence: 73%

The Electrical Thresholds of Ventricular Myocardium

Winfree

1990

Cardiovasc electrophysiol

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The Electrical Thresholds of Ventricular Myocardium. According to the basic principles of electrophysiology, an action potential cannot propagate three‐dimensionally if its front is too sharply curved. The critical radius of curvature is estimated for ventricular myocardium as 1/3 mm and checked against experimental determinations of the pacing threshold. An implication of the agreement found is that pacemaker electrodes can be improved by optimizing their tip curvatures. The same basic principles imply that there should exist a vortex‐like action potential, which has in fact heen found in both two‐ and three‐dimensional settings. It rotates in 120 msec and has a 2/3‐cm diameter. This diameter can he used to derive the electrical threshold for fibrillation in normal ventricular myocardium: ahout 16 mA, depending on electrode geometry. This compares favorably with ohservations. As theory suggests, the ratio of this threshold to the pacing threshold seems independent of pulse duration and depends on electrode geometry: the minimum ratio is about five for large electrodes. Electrical defihrillation in normal myocardium should require local potential gradients of about 6 V/cm or current densities near 20 mA/cm2, roughly as observed, but much more uniform deHhrillating fields are needed to achieve this theoretical minimum throughout the myocardium. It is suggested that in normal myocardium, the transition from monomorphic tachycardia or ventricular flutter to fibrillation in some cases may be a consequence of the three‐dimensional geometry of vortex‐like action potentials; the transition should take a long time in two‐dimensional preparations unless they are pervaded hy discontinuities or other nonuniformities. (J Cardiovasc Electrophysiol, Vol. 1, pp. 393–410, October 1990)

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Section: The Ventricular Fibriliation Thresholdmentioning

confidence: 73%

The Electrical Thresholds of Ventricular Myocardium

Winfree

1990

Cardiovasc electrophysiol

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“…Furthermore, it is necessary to stimulate a critical cardiac volume to induce cardiac arrhythmia [27]. In experimental studies this [29][30][31][32][33][34]. It was shown that fibrillating current densities decreased nonlinearly with increasing electrode area.…”

Section: Taser Pulsesmentioning

confidence: 99%

“…1 cm²) the fibrillation threshold increases by 1.9-fold to 9.4 A rms /m² which is 130.6-fold the excitation threshold. All these levels are reported to be associated with 50% fibrillation probability [30,31,35]. To assess fibrillation probabilities it was decided to use experimental results which had been adopted by safety standards [36][37][38] and, hence, reflect broad consensus.…”

Section: Taser Pulsesmentioning

confidence: 99%

Cardiac fibrillation risk of TASER X-26 dart mode application

Leitgeb

Niedermayr

Loos

et al. 2011

Wien Med Wochenschr

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In view of reported fatalities there are still controversial discussions on whether electronic stun law enforcement weapons can cause cardiac fibrillation. Experimental data are contradictory. Simplified theoretical estimations led to a negligible low risk of 8.10(-7). With a detailed numerical-anatomical model of an adult man (NORMAN) cardiac exposure to Taser X26 high-tension pulses was quantitatively assessed and the fibrillation risk estimated by accounting for its dependence on excited volume based on 3D cardiac exposure patterns. For distance mode and worst case dart hits it could be demonstrated that cardiac exposure can reach the 30% fibrillation risk level. Risk reduces considerably if direct current flow across the heart is prevented. The overall fibrillation risk of Taser application is further reduced by the limited probability of critical hits. However, in agreement with experimental findings it is demonstrated that cardiac fibrillation risk of Taser X26 dart mode application is small, however, not negligible.

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Tests on a shocking device—the stun gun

Roy

Podgorski

1989

Med. Biol. Eng. Comput.

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60 Hz ventricular fibrillation thresholds for large-surface-area electrodes

Cited by 8 publications

References 8 publications

The Electrical Thresholds of Ventricular Myocardium

The Electrical Thresholds of Ventricular Myocardium

Cardiac fibrillation risk of TASER X-26 dart mode application

Tests on a shocking device—the stun gun

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