“…For optically accessible hearts, such as those in early chick (<5 days of incubation) (McQuinn et al, 2007), frog (Deniz et al, 2012), and zebrafish embryos, simple video microscopy can provide a wealth of information on the hemodynamic conditions within the heart. A camera mounted on an inverted microscope records the beating heart, and the resulting images are used to measure heart rate, cardiac rhythm, vessel diameters, blood velocity, heart tube shape, and/or changes in heart wall motion (Suga et al, 1973; Hou and Burggren, 1995; Kopp et al, 2005; Lucitti et al, 2005; Jamison et al, 2013; Liu et al, 2016). From these measurements and possibly in combination with pressure data, parameters such as shear stress on the endocardium, stroke volume, cardiac output, ejection fraction, systolic and diastolic area as well as inflow/outflow rates, total arterial compliance, and total vascular resistance may be calculated (Kopp et al, 2005; Lucitti et al, 2005; Deniz et al, 2012; Jamison et al, 2013; Stovall et al, 2016).…”