A Simple ImageJ-Based Method to Measure Cardiac Rhythm in Zebrafish Embryos

Zebrafish has an advantage of optical clarity within the body during its early developmental stage. Therefore, organs, including the heart, can be observed and analyzed in a non-invasive manner. Previously, heart rate measurement was analyzed by a complicated system, programming language, fluorescence transgenic zebrafish, or expensive setup that was not feasible and practical. In this study, we established a simple dissecting microscope with Charge-coupled Device (CCD) to capture the signal of heartbeat, and used ImageJ software as an open source platform to analyze cardiac rhythm for the atrium and the ventricle. We subjected astemizole to zebrafish embryos, and applied our apparatus to precisely detect heart arrhythmia (Atrium-Ventricle block) induction. In other words, we provided a simple, economical, and reliable method to measure cardiac rhythm in zebrafish embryos, which is able to evaluate whether cardiac rhythm is affected by chemical compounds.