engleski

Collapse in high-grade stenosis during pulsatile flow experiments

It has been hypothesized that blood flow through high grade stenotic arteries may produce conditions in which elastic flow choking may occur. The development of atherosclerotic plaque fracture may be exacerbated by the compressive stresses during collapse. This study explored the effects of pulsatile flow on stenotic flow collapse. Pulsatile flow was produced using a gear pump controlled by a digitized physiologic waveform. Upstream and downstream mean pressures and pulsatile flow rates were measured and digitized. An improved model of arterial stenosis was created using an elastomer with an incremental modulus of elasticity matched to a bovine carotid artery in the relevant range of collapse. Additionally, the model retained a very thick wall in the stenotic region similar to arterial disease. Pulsatile flow experiments in this model revealed a range of conditions in which intermittant choking caused a paradoxical collapse of the stenosis during systole with expansion during diastole. The stenosis severity was dynamic through the pulse cycle and was significantly greather under flow than the nominal severity. Flow choking was observed for pulsatile pressure drops close to those previously reported for steady flow. For 80 % nominal stenosis by diameter, collapse occurred for pulsatile pressure drops of 80 mm Hg. High frequency wall motion was visible optically, but not by ultrasound. The results indicate that flow choking and stenotic compression may be significant in thick – walled arterial stenoses subjected to pulsatile flow.

Pulsatile flow; choking compression; stenotic compression

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