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Browsing by Subject "Talkachova Lab"

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    Cardiac Voltage Analysis Software for Interpretation of Transmembrane Voltage Movies Obtained via the Langendorff Perfusion Setup
    (2021) Callaway, Trenton; Talkachova, Alena; Ravikumar, Vasanth
    Using the Langendorff perfusion setup to study and compare healthy and arrhythmic heart conditions is an increasingly common practice. This technique requires the ex-vivo perfusion of the heart, wherein cardiac tissue is injected with a voltage sensitive fluorescent dye, allowing for video analysis of electrical activity in the heart under normal and arrhythmic conditions. When conducted in this study, this technique resulted in recorded movies of cardiac tissue interpretable as 3D matrices whereby the spatial dimensions are defined by the movie resolution of 80 by 80 pixels, and the temporal dimension is based on the length of the movie in frames. The goal of this project was to further develop and investigate the efficiency of a data analysis application, CVAS (Cardiac Voltage Analysis Software), which is capable of analyzing these matrices in a user-friendly, intuitive way. This MATLAB based software is designed to be capable of creating highly modular plots, calculations, and optical maps for analysis on both paced and arrhythmic data. This task is one that would heavily benefit contemporary electrophysiological cardiology, and provide easy assessment of electrophysiological properties of the heart during normal and abnormal cardiac rhythms. By collecting new data for this software to analyze, CVAS was critiqued and improved to optimize its ease of use and interaction with researchers. Additionally, its ability to generate high quality and immediately presentable optical maps, plots, and calculations for both paced and arrhythmic data was strengthened. CVAS’s current capabilities include loading in and masking optical movie data sets, visualizing the electrical activity of the heart with fluorescence movies and action potential traces, and allowing for visualization and analysis of both paced and arrhythmic data sets through the use of action potential duration, activation time, conduction velocity, dominant frequency, and multiscale frequency maps.
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    Software Design to Aid in Analysis of Cardiac Voltage Matrices Obtained Via the Langendorff Perfusion Technique
    (2020) Callaway, Trenton; Talkachova, Alena; Ravikumar, Vasanth
    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.