What is preload also known as?

Preload refers to the degree of stretch of the cardiac muscle fibers at the end of diastole, just before the heart contracts. It is often equivalent to the volume of blood returning to the heart, particularly reflected in the measurement of end diastolic pressure. This pressure is critical for understanding cardiac output since an increase in preload typically leads to an increase in stroke volume according to the Frank-Starling law of the heart. Therefore, recognizing that preload is synonymous with end diastolic pressure highlights its role in assessing the heart's filling status and overall function.

In contrast, systolic pressure refers to the pressure in the arteries during heartbeats, mean arterial pressure is an average blood pressure in a person's arteries during one cardiac cycle, and total peripheral resistance involves the total resistance to blood flow in the peripheral vasculature. These concepts are related to different aspects of cardiovascular physiology but do not accurately describe preload.