Ejection Fraction in the Fast Lane

Ventricular performance is typically evaluated on the basis of primary measurements such as pressure, volume and flow. Representative recordings obtained from a healthy, chronically instrumented conscious dog can be employed to define various metrics, for example, the traditional holosystolic ejection fraction (EF). The metric EF is defined as 1 minus end-systolic volume (ESV) divided by end-diastolic volume (EDV). An alternative proposed 45 years ago refers to the first-third of EF (^⅓EF), which is not (always) identical to first-phase EF1, launched several decades later. All these candidates refer to dimensionless ratios, and are therefore incomplete. Based on the early events during ejection time (ET), Kerkhof-Diaz-Handly (KDH) propose a more powerful metric which has the advantage of carrying physical units. The diastolic phase (TD) is the most variable portion of the cardiac cycle. ECG = electrocardiogram; LVD = left ventricular (equatorial) diameter; Paorta = ascending aorta pressure; Qaorta = ascending aorta flow.