[Determining the degree of stenosis of peripheral arteries. Hemodynamic and ultrasound principles].

With colour duplex sonography, the identification and quantification of arterial stenoses in peripheral arteries had become feasible in reasonable time. However, the haemodynamic considerations are more complicated in peripheral arteries than in carotid arteries. This is attributable to the much longer vessel length, the influences of peripheral resistance, the frequency of multiple stenoses and combinations of occlusion and stenosis with multiple collateral vessels. Different qualitative and quantitative approaches are used: b-mode sonography, spectral analysis, velocity measurements, continuity equation and estimation of systolic pressure gradients (Bernoulli equation). Although standardized criteria in the grading of stenoses are not commonly used, the peak velocity ratio (PVR as a ratio of intra-and prestenotic velocity) seems to be mathematically founded, usefully versatile and reliable.