A 1D pulse wave propagation model of the hemodynamics of calf muscle pump function

Abstract

The calf muscle pump is a mechanism which increases venous return and thereby compensates for the fluid shift towards the lower body during standing. During a muscle contraction, the embedded deep veins collapse and venous return increases. In the subsequent relaxation phase, muscle perfusion increases due to increased perfusion pressure, as the proximal venous valves temporarily reduce the distal venous pressure (shielding). The superficial and deep veins are connected via perforators, which contain valves allowing flow in the superficial-to-deep direction. The aim of this study is to investigate and quantify the physiological mechanisms of the calf muscle pump, including the effect of venous valves, hydrostatic pressure, and the superficial venous system. Using a one-dimensional pulse wave propagation model, a muscle contraction is simulated by increasing the extravascular pressure in the deep venous segments. The hemodynamics are studied in three different configurations: a single artery–vein configuration with and without valves and a more detailed configuration including a superficial vein. Proximal venous valves increase effective venous return by 53% by preventing reflux. Furthermore, the proximal valves shielding function increases perfusion following contraction. Finally, the superficial system aids in maintaining the perfusion during the contraction phase and reduces the refilling time by 37%. © 2015 The Authors. International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons Ltd.

Anatomy of Extramuscular Soleus Veins: Clinical Impact

“…Keijsers et al [31] admitted that the collapsibility of the veins and the dynamics of the venous valves that direct the blood toward the heart and shield hydrostatic pressure are believed to be the main physiological factors in the muscle pump effect. Thus they studied the dynamics of calf muscle pump function during a muscle contraction using the different model configurations that were reported in four sections which examine the course of the deep venous collapse, the effect of venous valves, the effect of hydrostatic pressure, and the importance of the superficial system, respectively.…”

Modeling regulation of vascular tone following muscle contraction: Model development, validation and global sensitivity analysis

“…In order to solve the full system of equations for pressure a fit of the tube law is used as derived in Keijsers et al [4].…”

“…Therefore, the 1D arterio-venous model as described in Keijsers et al. [4] was extended with a regulation model for the vascular tone, which includes both the myogenic and metabolic effects described by Spronck et al [11], combined with the baroreflex model of Ursino [12] to include all three mechanisms. In an initial explorative analysis, the intuitively most important model parameters representing the gain of the myogenic and metabolic mechanism were fitted to match the measured in vivo flow response to a muscle contraction in the supine position.…”

“…Arterial inflow rises during subsequent muscle relaxation as the perfusion pressure is increased due to the pressure shielding of the closed proximal valve ( Figure 1B) [2]. Furthermore, the opening of the distal and perforating valves [3] allows venous refilling [4] from both the arterial and superficial venous system. In summary, the muscle pump effect increases blood flow through an increase in arterio-venous pressure drop.…”

“…In a previous study [4], we examined the role of venous valves, hydrostatic pressure and the superficial veins during the muscle pump using a mathematical model. Although the model was able to simulate the increased venous return during muscle contraction and the elevated arterial flow during muscle relaxation, the predicted flow augmentation was low compared to the increase in arterial flow increase measured during in vivo calf muscle A c c e p t e d M a n u s c r i p t contractions [5].…”