Effects of frictional losses and pulsatile flow on the collapse of stenotic arteries.

High-grade stenosis can produce conditions in which the artery may collapse. A one-dimensional numerical model of a compliant stenosis was developed from the collapsible tube theory of Shapiro. The model extends an earlier model by including the effects of frictional losses and unsteadiness. The model was used to investigate the relative importance of several physical parameters present in the in vivo environment. The results indicated that collapse can occur within the stenosis. Frictional loss was influential in reducing the magnitude of collapse. Large separation losses could prevent collapse outright even with low downstream resistances. However, the degree of stenosis was still the primary parameter governing the onset of collapse. Pulsatile solutions demonstrated conditions that produce cyclic collapse within the stenosis. This study predicts certain physiologic conditions in which collapse of arteries may occur for high-grade stenoses.