[The haemodynamic effects of renal artery stenosis (author's transl)]

Three reasons are suggested for the difficulty of judging the haemodynamic effects of renal artery stenosis: 1. The flow characteristics in the renal arteries of dogs indicate that, at the critical level of reduction to one third of normal diameter, a further change of only 0.5 mm. will cause a 50% alteration in flow volume. Variations of this order of magnitude cannot be reliably measured on the angiogram. 2. The production of turbulence, which can increase the effect of a stenosis considerably, depends, amongst other things, on the nature of the surface of the stenosis and this cannot be judged. 3. The effect of a stenosis depends on peripheral resistance in the kidney.