Understanding preload and preload reserve within the conceptual framework of a limited range of possible left ventricular end-diastolic volumes.

Understanding preload and preload reserve within the conceptual framework of a limited range of possible left ventricular end-diastolic volumes. Adv Physiol Educ. 2020 Sep 01;44(3):414-422 Authors: Peverill RE Abstract Preload has been variously defined, but if there is to be a direct relationship with activity of the Frank-Starling mechanism in its action to increase the force and extent of contraction, preload must directly reflect myocardial stretch. The Frank-Starling mechanism is activated during any stretch of a cardiac chamber beyond its resting size, which is present immediately before contraction. Every left ventricle has an intrinsic and limited range of possible volumes at end diastole. There is a curvilinear relationship between left ventricular (LV) end-diastolic pressure (LVEDP) and LV end-diastolic volume (LVEDV), and, at maximal or near maximal LVEDV, there will be a high LVEDP. Within the possible range, the LVEDV will be determined by the extent of filling, any change in LVEDV will result in changed activity of the Frank-Starling mechanism, and change in LVEDV might, therefore, be considered to represent change in preload. On the other hand, it is the difference between the current and the maximal possible LVEDV (or the preload reserve) that may be of the most clinical relevance. There is a reciprocal relationship between preload and preload reserve, with minor or absent LV preload reserve indicating that there will...
Source: Adv Physiol Educ - Category: Universities & Medical Training Authors: Tags: Adv Physiol Educ Source Type: research