O'Keefe Erin, Singh Paramvir
University of Miami
Augusta University Medical Center
Preload, also known as left ventricular end-diastolic pressure (LVEDP), measures the degree of the ventricular stretch when the heart is at the end of diastole. Preload, in addition to afterload and contractility, is one of the 3 main factors that directly influence stroke volume (SV), the amount of blood pumped out of the heart in 1 cardiac cycle. Affected by changes in venous tone and circulating blood volume, changes in preload directly affect stroke volume, influencing cardiac output and the heart's overall function. Understanding preload, its effects, and how pharmacological treatments can manipulate it is essential to understanding overall cardiac physiology (see Cardiac Preload).
前负荷，也称为左心室舒张末期压力（LVEDP），用于测量心脏舒张末期心室的拉伸程度。除后负荷和心肌收缩力外，前负荷是直接影响每搏输出量（SV，即心脏在一个心动周期中泵出的血液量）的三个主要因素之一。前负荷受静脉张力和循环血容量变化的影响，其变化直接影响每搏输出量，进而影响心输出量和心脏的整体功能。了解前负荷、其作用以及药物治疗如何对其进行调节，对于理解心脏整体生理学至关重要（见心脏前负荷）。
