Calculation of transmembrane current from extracellular potential recordings: a model study

Area of Science:

• Cardiac electrophysiology
• Computational modeling
• Biomedical engineering

Background:

• Cardiac transmembrane current (Im) is crucial for understanding heart function.
• Estimating Im from extracellular recordings (EIm) is a valuable, non-invasive technique.
• Mathematical models aid in validating and refining EIm estimation methods.

Purpose of the Study:

• To evaluate the accuracy of estimating transmembrane current (EIm) from extracellular potential recordings.
• To compare simulated EIm with simulated and experimentally derived transmembrane current (Im).
• To assess the potential of EIm25 as an in vivo measure of peak ionic current.

Main Methods:

• Utilized a mathematical/computer model of cardiac tissue.
• Simulated transmembrane current (Im) and its estimation (EIm).
• Compared simulated EIm with simulated Im and experimental EIm data from dogs during various cardiac rhythms.

Main Results:

• EIm measurements provided a reasonable approximation of Im during normal conduction, decremental conduction, and conduction block.
• EIm slightly overestimated the duration of the Im waveform.
• A linear correlation was observed between EIm25, Im25, peak Im, and peak EIm.

Conclusions:

• EIm is a viable approximation of cardiac transmembrane current (Im).
• EIm25 demonstrates potential as a suitable in vivo metric for peak ionic current.
• The findings support the use of EIm in clinical and research settings for assessing cardiac electrical activity.