A theoretical model of a compliant arterial stenosis.

Recent clinical and experimental evidence indicates that coronary artery stenoses may rapidly change their size and shape in response to alterations in vasomotor tone and intraluminal pressure. This theoretical study models a partially compliant arterial stenosis to examine the hemodynamic impact of these alterations. In rigid vessels, a 98% reduction in luminal area would predictably produce subendocardial ischemia in the resting state. In contrast, stenoses, with part of the arterial wall normal by the underlying plaque, responded to vasoconstriction and to changes in intraluminal pressure. With part of the arterial wall normal by the plaque, both vasoconstriction and decreases in intraluminal pressure could increase the hemodynamic severity of the stenosis. Further, the more eccentrically positioned the underlying plaque was, the greater the effects of vasoconstriction and intraluminal pressure on stenotic severity. Thus the morphological configuration of the plaque and the normal wall segment in the stenosis appear to be important determinants of the hemodynamic response of the stenosis to vasoconstriction and blood pressure changes. In turn, these changes in stenotic severity can greatly influence flow through the vessel.