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September 1, 1995Circulation Research

Optical Transmembrane Potential Measurements During Defibrillation-Strength Shocks in Perfused Rabbit Hearts

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Key result

Defibrillation-strength shocks in isolated rabbit hearts induced hyperpolarization or depolarization near either electrode, with hyperpolarization magnitude 1.8 times that of depolarization (P<0.01).

Population

15 isolated perfused rabbit hearts treated with the potentiometric dye di-4-ANEPPS and diacetyl monoxime

Design

Preclinical

Authors

XZXiaohong ZhouAstraZeneca (Italy)RIRaymond E. IdekerElectrophysiologyTBTimothy F. BlitchingtonDuke Medical Center

Discussion

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Overview

Hypothesis-generating for defibrillation mechanisms in isolated hearts; leaves open translation to clinical shock optimization or human myocardium.

Key Points

  • To evaluate changes in optical transmembrane potential during defibrillation-strength shocks in isolated perfused rabbit hearts.
  • Optical recordings obtained in 15 isolated perfused rabbit hearts using di-4-ANEPPS dye.
  • Shock electrodes sutured on right and left ventricles; fluorescence measured during shock and S1 action potential.
  • Variations in delta F/Fapa% recorded at multiple locations during different phases of stimulation.
  • In macroscopic study, delta F/Fapa% values ranged from 77% to 24% across nine spots (P < .05).
  • Hyperpolarization magnitude was significantly greater than depolarization (1.8 times, P < .01).
  • During diastole, action potential timing was shorter when depolarized (1.1 ms) compared to hyperpolarized (12.8 ms, P < .01).

Structured PICO

P
Population
15 isolated perfused rabbit hearts treated with potentiometric dye to study optical transmembrane potential changes during defibrillation-strength shocks.
I
Intervention
10-ms truncated exponential S2 shock of defibrillation-threshold strength given during the plateau of the last S1 action potential (and during diastole in microscopic study)
O
Outcome
Optical transmembrane potential change (delta F) induced during shocks, expressed as a percentage of the fluorescence change during the S1 upstroke action potential amplitude (delta F/Fapa%)surrogate

Defibrillation-strength shocks induce complex, spatially variable transmembrane potential changes, including both hyperpolarization and depolarization near either electrode.

Cite This Study

Zhou et al. (1995) studied Defibrillation-strength shocks (n=15). Defibrillation-strength shocks was evaluated on Optical transmembrane potential change (delta F/Fapa%). Defibrillation-strength shocks in isolated rabbit hearts induced hyperpolarization or depolarization near either electrode, with hyperpolarization magnitude 1.8 times that of depolarization (P<0.01).

synapsesocial.com/papers/6a6c210847a1bfb288f36aechttps://doi.org/10.1161/01.res.77.3.593
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Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Optical measurements of transmembrane potential changes during electric field stimulation of ventricular cells.1993 · 137 citations
  2. 2Optical recordings of the effect of electrical stimulation on action potential repolarization and the induction of reentry in two-dimensional perfused rabbit epicardium.1993 · 56 citations
  3. 3Prolongation of Ventricular Refractoriness by Defibrillation Shocks May be Due to Additional Depolarization of the Action Potential1992 · 31 citations
  4. 4Virtual cathode effects during stimulation of cardiac muscle. Two-dimensional in vivo experiments.1991 · 127 citations
  5. 5Potential distribution in three-dimensional periodic myocardium. II. Application to extracellular stimulation1990 · 59 citations