Software Design to Aid in Analysis of Cardiac Voltage Matrices Obtained Via the Langendorff Perfusion Technique

Abstract

There does not currently exist any open source software usable by researchers to create and analyze optical mappings of the heart. When analyzing the heart and especially its action potentials, ex-vivo perfusion of the heart is performed using the Langendorff perfusion setup. Next, voltage sensitive fluorescent dye is injected into the ex-vivo heart, illuminating the target area with a 532 nm wavelength green laser tuned to the dye’s activation range. The illuminated area of the heart can then be recorded at high frames per second (fps) to create a movie which collects light intensity data correlating to the transmembrane voltage of the heart at that pixel. This creates a voltage matrix for every frame, where each pixel is a numerical value. The goal of this project is to find out if the process of analyzing this three dimensional voltage matrix can be made intuitive, available, and open source. The creation of the software is being done on MATLAB (Natick, MA) and incorporates a user friendly graphics user interface (GUI) , that allows the user to quickly and easily analyse this three dimensional matrix of fluorescence values in a multitude of ways. The software aims to allow the user to input the file name of their fluorescence data, along with the fps used in the experiment, and from that perform several calculations. The software is intended to automatically locate the start and end frames of every action potential (AP) in the data. With this, the user is able to plot the AP across the frame numbers, calculate and map the dominant frequency (DF) and multiscale frequency (MSF) of the action potentials, determine the mean conduction velocity of the transmembrane voltage, create colour maps for both activation time (AT) and action potential duration (APD), and lastly display an animation of the voltage as is flows across the tissue. The benefits of creating a robust software go beyond the provision of effective and intuitive analysis. This software would also allow for quick and easy modifications that would otherwise require rewriting sections of code to perform. As an example, this software is able to account for various frame rates, desired voltage thresholds for identifying action potential initiation, alterations to color mapping domains, and more. The ease of life provided will allow more institutions to conduct similar studies to those currently being done in the Talkachova Lab at the University of Minnesota Twin Cities, helping to further the understanding of cardiac signals, arrhythmia, and healthy heart activity.