Intravascular Doppler for the evaluation of renal blood flow: validation and demonstration of vessel reactivity.

Aim : To assess the feasibility and to demonstrate the potential clinical a pplication of intravascular doppler in the evaluation of renal blood flow i n patients with hypertension and normal renal arteries. Materials and methods : Intravascular doppler was used to measure renal blo od flow in 19 patients (34 kidneys) during arteriography to rule out renova scular hypertension. Arteriography showed no evidence of renal artery steno sis in any patient. Hemodynamic parameters, renal artery diameter, and dopp ler measurements were undertaken at baseline, after injection of a bolus (1 0 ml) of normal (0.9%) saline, and after injection of isosorbide dinitrate (1 mg diluted in 10 ml normal saline). Results : Repeated measurements of renal blood flow confirmed the reproduci bility of the technique. Basal blood flow was similar in both right and lef t kidneys; injection of vehicle solution (10 ml normal saline) had no effec t on doppler parameters. Injection of isosorbide dinitrate resulted in a si gnificant increase in renal blood flow velocity reflecting an increase in r enal blood flow; this demonstrates the existence of a renal flow reserve. T he degree of increase in renal blood flow varied significantly between kidn eys. Conclusions : Intravascular doppler is a safe, effective, and reproducible technique for measurement of renal blood flow. It allows evaluation of vari ations in renal blood flow in response to diverse vasoactive drugs or other vasomotor stimuli. The present study demonstrated the heterogenous respons e of renal blood flow in response to vasodilator stimuli.