Frank-Starling mechanism, fluid responsiveness, and length-dependent activation: Unravelling the multiscale behaviors with an in silico analysis
Fig 1
Length-dependent activation, the Frank-Starling mechanism and vascular filling therapy.
Length-dependent activation (LDA) is a cardiac cell property highlighted by the length-tension relationship (left). As the length of the cardiac cell increases, the peak force during an isometric twitch contraction increases. It is commonly admitted that LDA underlies the Frank-Starling (FS) mechanism, a property of the cardiac pump (right). As the length of cardiac fibers prior to contraction (namely, the preload) increases, the ejected blood volume (namely, the stroke volume) increases, up to physiological limits. The FS mechanism is also often assumed to be the basis for fluid therapy. If the patient is operating on the “ascending portion” of the FS curve, the patient is said to be “fluid-responsive”, as a substantial stroke volume increase should be observed upon vascular filling. In this study, we revisit the three concepts of LDA, FS mechanism, and vascular filling and we build a computational model of the human cardiovascular system to investigate thoroughly the true nature of the relationship between the latter.