EFFECT OF FLOW ON THE RESISTANCE OF MODELED FEMORAL-ARTERY STENOSES

An accurate model of the pressure-flow relationship of a stenosis is n ecessary 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 fix ed component (R(f)) combined with a variable component (R(v)) that inc reased linearly with flow (Q) such that R(v)=S(v)Q. For stenoses of 68 -94 per cent area, R(f) increased from 3.2 to 77.7 milliperipheral res istance units (mPRU), while S-v increased from 0.009 to 0.578 mPRU ml( -1) min and R(v) was dominant for physiological flow rates. It was con cluded that the approximation of a significant stenosis to a fixed res istance is incorrect.