Renal hemodynamics and blood pressure. Intrarenal Doppler evaluation

UNLABELLED: This new technique has been used to evaluate renal hemodynamic pattern because although it is impossible to measure the arterial diameter, the doppler signal is easier to obtain than in the renal artery. In order to define normal patterns we studied 67 untreated patients, with no evidence of acute or chronic disease, using intrarenal doppler ultrasound technique. The mean (SD) systolic, diastolic and mean renal doppler deviation were 2.144 +/- 0.54, 0.688 +/- 0.23 and 0.604 +/- 0.28 kHz respectively. The mean peak doppler frequency was 1.136 +/- 0.34 kHz, and Stuart, Pourcelot and Gosling indexes were 3.6 +/- 0.8, 0.67 +/- 0.06 and 1.31 +/- 0.39 respectively. The mean ejection time was 0.28 +/- 0.03 s. A multiple regression analysis was performed and a marked negative correlation was found between all the velocities and age. Arterial blood pressure was the second determinant of velocity. To examine the influence of blood pressure in renal hemodynamics, we compared normal (diastolic blood pressure below 90 mm Hg) and hypertensive patients (13 patients in each group) matching them for age, sex, weight and height. RESULTS: In addition to blood pressure differences (caused by design) we found that systolic arterial doppler deviation was higher in normotensive than in hypertensive patients (2.152 +/- 0.48 vs 1.730 +/- 0.44 kHz. p < 0.05). As arterial area probably decreases with age, it is possible that low velocity of flow might be caused by an effective plasmatic renal flow fall. Contrary to expected, hypertensive patients blood flow velocity was lower than in normal which suggests that intrarenal arteriolar resistance was increased.(ABSTRACT TRUNCATED AT 250 WORDS)