KairoSight: Open-Source Software for the Analysis of Cardiac Optical Data Collected From Multiple Species

Abstract

Cardiac optical mapping, also known as optocardiography, employs parameter-sensitive fluorescence dye(s) to image cardiac tissue and resolve the electrical and calcium oscillations that underly cardiac function. This technique is increasingly being used in conjunction with, or even as a replacement for, traditional electrocardiography. Over the last several decades, optical mapping has matured into a “gold standard” for cardiac research applications, yet the analysis of optical signals can be challenging. Despite the refinement of software tools and algorithms, significant programming expertise is often required to analyze large optical data sets, and data analysis can be laborious and time-consuming. To address this challenge, we developed an accessible, open-source software script that is untethered from any subscription-based programming language. The described software, written in python, is aptly named “KairoSight” in reference to the Greek word for “opportune time” (Kairos) and the ability to “see” voltage and calcium signals acquired from cardiac tissue. To demonstrate analysis features and highlight species differences, we employed experimental datasets collected from mammalian hearts (Langendorff-perfused rat, guinea pig, and swine) dyed with RH237 (transmembrane voltage) and Rhod-2, AM (intracellular calcium), as well as human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) dyed with FluoVolt (membrane potential), and Fluo-4, AM (calcium indicator). We also demonstrate cardiac responsiveness to ryanodine (ryanodine receptor modulator) and isoproterenol (beta-adrenergic agonist) and highlight regional differences after an ablation injury. KairoSight can be employed by both basic and clinical scientists to analyze complex cardiac optical mapping datasets without requiring dedicated computer science expertise or proprietary software.

High resolution optical mapping of cardiac electrophysiology in pre-clinical models

“…Furthermore, several other open software packages are also available which can be used with the provided data 14 – 19 , 39 .…”

Action potential metrics and automated data analysis pipeline for cardiotoxicity testing using optically mapped hiPSC-derived 3D cardiac microtissues

“…In recent years, open software packages for analyzing voltage data of intact hearts or tissues have been published [36][37][38][39]. These packages, however, are optimized for impulse propagation, dispersion of APD, or calcium transient dynamics from the surface of intact hearts to investigate triggered activity, alternans, conduction block, and reentry formation.…”

Guidelines for assessment of cardiac electrophysiology and arrhythmias in small animals

“…Excitation-contraction waves can also be optically mapped using dye-free approaches ( 309 , 310 ) and in combination with fluorescent indicators and ultrasound imaging ( 311 ). Here, we will focus on mapping approaches using exogenously delivered V m and/or Ca 2+ indicators because of their widespread use in a variety of animal models ( 312 , 313 ).…”

“…Optical mapping data can be analyzed using various platforms (e.g., MATLAB, R, or Python). Often, custom-made analysis routines are developed by research groups, some of which have been published and are publicly available [e.g., Rhythm ( 349 ), ORCA ( 119 ), Electromap ( 120 ), Kairosight ( 312 ), Cosmas ( 352 )], as well as numerous packages developed by various camera manufacturers. To improve reproducibility, investigators should report not only the software used for analysis, but also any specific settings and the method used to select activation, repolarization, etc., as many of these software packages have multiple options that can be tailored to a specific data set.…”