[Color-Doppler ultrasonography and hypertension. Functional assessment of the renal region]. / Eco color Doppler e malattia ipertensiva. Valutazione funzionale del distretto renale.

ABSTRACT

Color-Doppler US can be used for the morphofunctional assessment of most arterial districts. In hypertension, color-Doppler US can be used to study the renal arteries for both the diagnosis of renovascular hypertension and better physiopathologic assessment of renal arterial blood flow in essential hypertension. To this purpose, we studied renal flow characteristics with the resistive index in both basal conditions and after pharmacologic stimulation with angiotensin-converting enzyme inhibitors. The resistive index was seen to rise in parallel with hypertension severity, as measured by mean arterial pressure; the change was statistically significant (p < 0.05). Values rose step by step from 57.4 (+/- 4.96) in the right renal artery and from 56.6 (+/- 4.18) in the left one in controls, up to 62.2 (+/- 6.6) in the right and 62.3 (+/- 7) in the left renal arteries of severe hypertensives. After pharmacologic stimulation in controls and in mild hypertensives, resistive index values rose significantly (+2.32 +/- 2.1 and +3.5 +/- 5.2, respectively), while in more advanced stages of the disease this index remained unvaried from a statistical point of view (+0.5 +/- 1.7 in moderate and -0.2 +/- 2.1 in severe hypertensives). These data can be explained by reduced capability of renal blood flow autoregulation, as a consequence of a defined vascular damage. In the follow-up of more severe stages of the disease, although pharmacologic treatment had been optimized and mean arterial pressure values reduced (109.08 vs. 118.25 mmHg), even after a prolonged therapeutic wash-out, an abnormal RI response persisted in controls (-1.79 +/- 2.62 vs. -0.94 +/- 1.64), due to persistent arteriolar damage. To date, it is still to be defined if our studies can be applied not only to populations but also to single patients.