Effect of flow on the resistance of modelled femoral artery stenoses

Abstract

An accurate model of the pressure-flow relationship of a stenosis is necessary for the correct interpretation of haemodynamic measurements. Modelled femoral artery stenoses were tested in vitro and the pressure drop: flow ratio (resistance) was most accurately represented by a fixed component (Rf) combined with a variable component (Rv) that increased linearly with flow (Q) such that Rv = SvQ. For stenoses of 68-94 per cent area, Rf increased from 3.2 to 77.7 milliperipheral resistance units (mPRU), while Sv increased from 0.009 to 0.578 mPRU ml-1 min and Rv was dominant for physiological flow rates. It was concluded that the approximation of a significant stenosis to a fixed resistance is incorrect.

Patient-specific non-invasive estimation of pressure gradient across aortic coarctation using magnetic resonance imaging

“…In the past, researchers have been using a series of simplified equations, either empirical or derived from fluid mechanics theory, for the non-invasive clinical estimation of the pressure gradient in cardiovascular stenosis (including in heart valves, [ 4 1 _ T D $ D I F F ] atherosclerosis, and AoCo). In these simplified models, flow velocity and the geometry of the flow channel in the stenosis were estimated from either Doppler echocardiography [10][11][12][13][14][15][16][17][18][19][20] or magnetic resonance imaging (MRI) [21][22][23] measurements. This non-invasive procedure seemed to achieve fair agreement in the diagnosis of stenosis in heart valves and [ 4 1 _ T D $ D I F F ] atherosclerosis, and has been extended to analyze other vascular diseases [24,25].…”

An improved reduced-order model for pressure drop across arterial stenoses

“…In this case, Eq (16) becomes of the form: Δp = AQ+BQ 3 . Similarly, in several previous studies [6,14,15,53] expressions with two coefficients are used for the steady problem. The results shown in Figs 5a-5c and 5g and 5h reveal that these two terms are adequate here for obtaining results close to the 3D CFD results, providing an FFR that remained reasonably close to CFD within the diagnostically sensitive range.…”