title: Calculation of transmembrane current from extracellular potential recordings: a model study.
abstract: BACKGROUND
  A mathematical/computer model of cardiac tissue was used to study the estimation of transmembrane current (EIm) from extracellular potential recordings.
  
  
  RESULTS
  The simulated EIm of transmembrane current was compared with the simulated transmembrane current (Im), and both simulated values were compared with experimentally derived EIm obtained during sinus rhythm and ventricular fibrillation in dogs. We found that although EIm measurements slightly overestimate the duration of the Im waveform, they provide a reasonable approximation of Im during normal conduction and during decremental conduction and conduction block.
  
  
  CONCLUSIONS
  There is a very clear linear correlation between the time spent at or below 25% of the peak inward transmembrane current (Im25), its corresponding estimate (EIm25), the peak inward Im and EIm, and the peak ionic current, providing some evidence that EIm25 may be a suitable in vivo measure of peak ionic current.
authors.affiliation: Institut de Génie Biomédical, Ecole Polytechnique, Montréal, Québec, Canada.
authors.forename: L J
authors.initials: LJ
authors.lastname: Leon
authors.forename: F X
authors.initials: FX
authors.lastname: Witkowski
mesh_terms: D000465:Algorithms; D000818:Animals; D003198:Computer Simulation; D004285:Dogs; D004558:Electric Stimulation; D004562:Electrocardiography; D004594:Electrophysiology; D005110:Extracellular Space / Q000502:physiology*; D005583:Fourier Analysis; D006321:Heart / Q000502:physiology*; D006327:Heart Block / Q000503:physiopathology; D006329:Heart Conduction System / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D014693:Ventricular Fibrillation / Q000503:physiopathology