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Optocardiography and Electrophysiology Studies of Ex Vivo Langendorff-perfused Hearts
Published on: November 7, 2019
Extracting surface activation time from the optically recorded action potential in three-dimensional myocardium
Richard D Walton1, Rebecca M Smith, Bogdan G Mitrea
1Institute of Membrane and Systems Biology, Faculty of Biological Sciences, Multidisciplinary Cardiovascular Research Center, University of Leeds, Leeds, United Kingdom.
Biophysical Journal
|January 10, 2012
Summary
Determining cardiac electrical activation time using optical mapping is challenging. This study found that the maximal slope of the optical upstroke (t(F)*) accurately estimates surface electrical activation time (t(E)), outperforming the 50% amplitude method (t(F50)).
Area of Science:
- Cardiovascular Physiology
- Biophysics
- Computational Biology
Background:
- Optical mapping is crucial for studying cardiac electrical activity.
- The 3D nature of optical signals leads to longer optical upstrokes than electrical upstrokes, complicating activation time determination.
- Accurate surface activation time is essential for understanding cardiac electrophysiology.
Purpose of the Study:
- To establish a reliable link between optical upstroke characteristics and precise epicardial surface activation time.
- To compare the accuracy of different optical mapping parameters for determining activation time.
- To validate simulation findings with experimental data.
Main Methods:
- Utilized a hybrid electro-optical model to simulate cardiac wave propagation and optical signals.
- Performed computer simulations to analyze the relationship between optical upstroke features and electrical activation time.
- Conducted validation experiments using microelectrode recordings and optical mapping in isolated rat and pig hearts.
Main Results:
- The time of maximal optical upstroke slope (t(F)*) closely matched the electrical activation time (t(E)) across various optical attenuation lengths in simulations.
- Activation time determined at 50% optical upstroke amplitude (t(F50)) was less accurate than t(F)*.
- Experimental validation confirmed t(F)* as a more accurate measure of t(E) than t(F50) (P = 0.0002).
- Using t(F)* improved measurements of conduction anisotropy and transmural conduction time in pig ventricles.
Conclusions:
- The maximal slope of the optical upstroke (t(F)*) is a superior indicator of epicardial surface electrical activation time (t(E)) compared to the 50% amplitude method (t(F50)).
- This finding enhances the accuracy of optical mapping for assessing cardiac electrical conduction, particularly in complex 3D structures.
- The study provides a validated method for improving the precision of optical mapping in cardiovascular research.
