Computer-simulated physiology experiments: where are we coming from and where might we go?

in the calf (i.e., intermittent claudication), which disappears within several minutes of ceasing activity. The hemodynamic basis for the intermittent claudication is shown in Figure 6. When walking begins, the resistance in the deep femoral vascular bed decreases and Qdf increases (active hyperemia). As this occurs, Qt falls precipitously. Although the calf muscle is also contracting, it is unable to significantly decrease its resistance because it is already nearly maximally dilated at rest because of the very low resting perfusion pressure. The reason for the fall in calf blood flow is that the pressure distal to the external iliac lesion decreases as Rdf decreases and Qdf increases. The resulting loss of perfusion pressure to the tibia1 vascular bed causes a passive reduction in flow to the calf. This is another example of the “vascular steal” phenomenon. The reduction in calf blood flow at a time of high oxygen demand results in ischemic pain.