Effect of current flow on the membrane potential of cardiac muscle

Weidmann, Silvio

doi:10.1113/jphysiol.1951.sp004667

Cited by 463 publications

(251 citation statements)

References 6 publications

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“…Halting of myocardial excitation by a hyperpolarizing impulse after the excitation threshold has been reached was described by Weidmann. 29 It was proposed 26 that with increasing phase-2 durations first, the mechanism of depolarization after hyperpolarization might be predominating, thus resulting in lower voltages at the DFT. Then, with longer phase-2 durations the effect of hyperpolarization after depolarization may outweigh the beneficial effect of depolarization after hyperpolarization on the other side of the myocardial cells, thus leading to an increase of the voltage at the DFT.…”

Section: Discussionmentioning

confidence: 99%

Influence of Phase Duration of Biphasic Waveforms on Defibrillation Energy Requirements With a 70-μF Capacitance

et al. 1998

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Background-Phase duration of biphasic shocks may be an important determinant of defibrillation success. The purpose of this study was to investigate the effect of changing phase duration of biphasic pulses delivered by 70-F capacitors on defibrillation energy requirements. This may be clinically relevant for the optimization of implantable cardioverterdefibrillator design and programming. Methods and Results-Defibrillation thresholds (DFTs) were determined for 13 waveforms in 13 pigs by application of a 70-F capacitance and a transvenous/submuscular lead system. In part I, phase-1 duration varied, preserving a phase-1/phase-2 duration ratio of 60%/40%. The phase-1 durations were 1, 2, 3, 4, 5, and 6 ms. The DFT was lowest (22.9Ϯ7 J) for phase 1ϭ3 ms compared with phase 1ϭ1 ms (36.4Ϯ7.5 J), 2 ms (25Ϯ6.5 J), 4 ms (25Ϯ7.6 J), 5 ms (30.7Ϯ7.3 J), or 6 ms (32.9Ϯ8.1 J) (PϽ.001). In part II, phase-1 duration was 3 ms but phase-2 duration varied: 0.7, 1.3, 2, 2.7, 3.3, 4, and 6 ms. Significant DFT minima were found at phase 2ϭ2 ms (22.5Ϯ4.2 J) and phase 2ϭ4 ms (22.5Ϯ4.2 J) compared with phase 2ϭ0.7 ms (31.7Ϯ9.3 J), phase 2ϭ3.3 ms (26.7Ϯ6.1 J), or phase 2ϭ6 ms (28.3Ϯ6.8 J) (PϽ.05). Conclusions-The strength-duration curve of biphasic defibrillation shocks demonstrates a single optimum for phase-1 duration. In contrast, two optima with minimal energy requirements were found for phase-2 duration. Optimization of both phases of low-capacitance biphasic shocks may reduce energy requirements for defibrillation. (Circulation. 1998;97:2073-2078.)

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Section: Discussionmentioning

confidence: 99%

Influence of Phase Duration of Biphasic Waveforms on Defibrillation Energy Requirements With a 70-μF Capacitance

et al. 1998

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“…That this was not the case was already evident since Weidmann's (6,7) pioneering work showed that the conductance during the action potential is very low. The experimental reason for this became clear with the discovery of the inwardrectifier current, I K1 (8-10) (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Modelling the heart: insights, failures and progress

Noble

2002

BioEssays

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SummaryMathematical models of the heart have developed over a period of about 40 years. Cell types in all regions of the heart have been modelled and they are now being incorporated into anatomically detailed models of the whole organ. This combination is leading to the creation of the first 'virtual organ,' which is being used in drug discovery and testing, and in simulating the action of devices, such as cardiac defibrillators. Simulation is a necessary tool of analysis in attempting to understand biological complexity. We often learn as much from the failures as from the successes of mathematical models. It is the iterative interaction between experiment and simulation that is important. Examples are given where this process has been instrumental in some of the major advances in the field.

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“…During an action potential, the opening and closing of one set of channels leads to a change in membrane potential, thereby allowing a different set of channels to open. These changes lead to entrance or exit of different ions, and subsequent changes in transmembrane potential (3)(4)(5)(6)(7).…”

Section: Action Potentials Drive Heart Beatmentioning

confidence: 99%

RNAs that make a heart beat

Mitra

Coller²

2016

Ann. Transl. Med.

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An increase in stress-associated microRNAs has been observed in the heart after an induced myocardial infarction. Liu and colleagues now demonstrate that one of these stress-associated microRNAs, miR-223-3p, can regulate a component of the voltage-gated channel that mediates rapid outward efflux of potassium during an action potential. Aberrations in the potassium current have been associated with ventricular arrhythmia and heart disease. Strikingly, introducing a small RNA antagonist directed against miR-223-3p into rat hearts, while also inducing a myocardial infarction, resulted in a reduction in arrhythmias. We place these studies in the larger context of the field and discuss the potential of anti-miR-223-3p molecules as new therapeutics for myocardial infarction.

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Effect of current flow on the membrane potential of cardiac muscle

Cited by 463 publications

References 6 publications

Influence of Phase Duration of Biphasic Waveforms on Defibrillation Energy Requirements With a 70-μF Capacitance

Influence of Phase Duration of Biphasic Waveforms on Defibrillation Energy Requirements With a 70-μF Capacitance

Modelling the heart: insights, failures and progress

RNAs that make a heart beat

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