Left ventricular performance is closely related to the physical properties of the arterial system: Landmark clinical investigations in the 1970s and 1980s.

Left ejection fraction (LVEF)--resulting from the difference between end-diastolic volume (EDV) and end-systolic volume (ESV), divided by EDV--is a poor index of left ventricular (LV) systolic performance due to its dependency on load conditions, inotropic state and LV remodelling. The characteristic impedance of the ascending aorta (Zc) integrates factors opposing LV ejection during the early ejection period when arterial wave reflection can be neglected. Zc is related to the pressure wave velocity (C) and the cross-sectional area of the aorta.