Doppler flow wire evaluation of renal blood flow reserve in hypertensive patients with normal renal arteries

Purpose: To study the vasomotor responses of the renal microcirculation in patients with essential hypertension. Methods: We studied the reactivity of the renal microcirculation to papaver ine, with intraarterial Doppler and quantitative arteriography, in 34 renal arteries of 19 hypertensive patients without significant renal artery sten osis. Isosorbide dinitrate was given to maximally dilate proximal renal art eries. APV (average peak brood flow velocity) was used as an index of renal blood how. Results: Kidneys could be divided into two distinct sub-groups based on the ir response to papaverine. An increase in APV of up to 55% occurred in 21 k idneys, an increase > 55% in 13 kidneys. Within each group the values were normally distributed. Both baseline APV and the effect of papaverine on mea n velocity differed significantly between groups. Conclusion: There seems to be a subgroup of patients with essential hyperte nsion that has an impaired reactivity to papaverine, consistent with. a fun ctional impairment of the renal microcirculation. Further studies are requi red to determine whether this abnormality contributes to or results from el evated blood pressure.