Characteristics of the flow velocity-pressure gradient relation in the assessment of stenoses: an in vitro study

Abstract

Objectives. The flow velocity-pressure gradient (v-dp) relation is clinically used to assess coronary stenoses. This in vitro study aimed to investigate the ability to determine the impact of each individual stenosis in the setting of two consecutive stenoses, the effect of variable stenosis reference diameters and the impact of one or two wires in a stenosis, on the v-dp relation. Methods. The model consisted of a reservoir and different sized tubes and stenoses. Pressure gradient and flow velocity were assessed with a pressure and a Doppler wire. By plotting flow velocity and pressure gradient on an X-Y plot, the v-dp relation was determined. Results. The v-dp relation of a proximal stenosis was not influenced by a distal stenosis. The diameter of the segment where flow velocity was measured influenced the v-dp relation. This could be corrected by substituting flow velocity with volume flow. The presence of one or two wires in a stenosis made the v-dp relation substantially steeper. Conclusions. The v-dp relation can be used to determine the significance of each individual stenosis in arteries with consecutive stenoses, provided that the distance between the stenoses is large enough. The diameter of the segment where flow velocity is measured and the presence of one or two wires substantially affect the v-dp relation. (Neth Heart J 2008;16:156-62.)

Clinical important hemodynamic characteristics for serial stenosed coronary artery

“…An alternative means for invasive flow measurements is presented by the calculation of models in which blood flow can be virtually simulated, a method that is called computational fluid dynamics (CFD). In fact, several in vitro studies [6,10,16,17,18] have shown that CFD allows reliable physiologic blood flow simulation and measurements of WSS, wall pressure, and mass flow. A detailed hemodynamic evaluation of disturbed flow in the post stenotic region may give additional insight of the progression of atherosclerosis and may have useful clinical value, such as early detection of a highly stenosed artery segment, prediction of future disease progression, and treatment planning 2.1 Artery reconstruction A Somatom Sensation 64 Scanner (Siemens Medical Systems, Erlangen, Germany) was used in non-enhanced spiral scan technique with a slice thickness of 0.75 mm, a table feed of 1 mm/s, and an increment of 2 mm (Fig.…”

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CT perfusion angiography; beware of artifacts!

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