Renal arterial calibre after acute unilateral ureteric occlusion.

The immediate effect on renal blood flow following ureteral occlusion may have some relative pertinence in clinical considerations of excretory urography in cases of acute ureteral obstruction where varying appearance times of obstructive nephrograms and pyelograms are observed. Some variance of physiological observation of the changes in renal blood flow has been observed and because of this possible radiological interest a radiological approach to the problem was attempted. Selkurt (1963), using P.A.H. clearance studies, zuggested there was increase in renal blood flow immediately following ureteral occlusion. Finkel et aZ. (1968), using radioisotopic methods with s5Kr and with considerable ureteral occlusion pressure greater than 90 mm. of Hg, suggested that such increase was regional, localized more to the cortex, and was shortly followed after an interval of one hour occlusion time by some reduction in medullary flow. However, an overall increase remained for a two-hour period. Wax (1968), measuring with 1311 Hippuran, showed that effects on the renal blood flow varied with the amount of ureteral occlusion pressure. At lower pressures, up to 75 mm. of Hg, the R.B.F. was elevated, but at 90 mm. decrease was demonstrated by these radioisotopic studies. Murphy and Scott (1966), using electromagnetic flowmeters, showed an increase in renal blood flow with an average ureteral occlusion pressure of 67mm. of Hg. Vaughan et al. (1968) showed an initial rise with flowmeter methods up to five hours, with subsequent reduction after this period of obstruction. The well-established arterial calibre reduction following unilateral occlusion has been well documented by Widen using dogs and Idbohrn in rabbits. They show the gradual constriction of the artery, the calibre of the renal artery decreasing with increasing duration of ligation. Their studies commenced no earlier than four days (Widen, 1958) or seven days (Idbohrn, 1966). The alteration in calibre at earlier periods, as judged by radiographic measurements, has not been subject to detailed study.