Changes In Renal Resistive Index Research Articles

Favorable effect of renal denervation on elevated renal vascular resistance in patients with resistant hypertension and type 2 diabetes mellitus.

To assess the effect of renal denervation (RDN) on renal vascular resistance and renal function in patients with drug-resistant hypertension (HTN) and type 2 diabetes mellitus (T2DM). Fifty-nine patients (mean age 60.3 ± 7.9 years, 25 men) with resistant HTN [mean 24-h ambulatory blood pressure (BP) 158.0 ± 16.3/82.5 ± 12.7 mmHg, systolic/diastolic] and T2DM (mean HbA1c 7.5 ± 1.5%) were included in the single-arm prospective study and underwent RDN. Renal resistive index (RRI) derived from ultrasound Doppler; estimated glomerular filtration rate (Chronic Kidney Disease Epidemiology Collaboration formula), office and 24-h ambulatory BP were measured at baseline, 6, and 12 months after RDN to evaluate the respective changes in renal vascular resistance, renal function, and BP during treatment. Forty-three patients completed 12 months follow-up. The RRI changed depending on the baseline value. Specifically, the RRI decreased significantly in patients with elevated baseline RRI values ≥ 0.7 {n = 23; -0.024 [95% confidence interval (CI): -0.046, -0.002], p = 0.035} and did not change in those with baseline RRI < 0.7 [n = 36; 0.024 (95% CI: -0.002, 0.050), p = 0.069]. No significant change was observed in eGFR whereas BP was significantly reduced at 12 months after RDN by -10.9 (95% CI: -16.7, -5.0)/-5.5 (95% CI: -8.7, -2.4) mmHg, systolic/diastolic. No relationship was found between the changes in RRI and BP. Our study shows that RDN can decrease elevated renal vascular resistance (RRI > 0.7) and stabilize kidney function in patients with RHTN and T2DM independently of its BP-lowering effect.

Post-mortem distribution of Iodinated Contrast Media (ICM) (iodixanol versus iopromide) in the porcine kidney after multiple bolus injections in vivo into the supra-renal aorta1.

Iodinated contrast media (ICM) are widely used for diagnostic and interventional procedures in radiology and cardiology. Ideally, they should not interact with blood cells or vascular wall cells to avoid deteriorations of the blood circulation. However, it is well known that ICM can affect erythrocytes as well as endothelial cells which consequently might perturb especially the microcirculation. In former studies the influence of two ICM (iodixanol versus iopromide) on the vascular system, the development of blood stasis, on changes in renal resistive index (RRI) and vascular diameters, and on the post-mortem distribution of iodine as marker for ICM in the explanted kidneys was examined. The modus of ICM application into the supra-renal aorta followed the regime in interventional cardiology, so that 10 bolus injections were administered at steady intervals (iopromide 4,32 ml / iodixanol 5 ml) accompanied by infusion of 500 ml isotonic NaCl-solution.In the present study, the post-mortem X-ray analysis revealed that there were no differences in iodine content in the regions of the mid-cortex and the medullo-pelvic transition zone of the kidneys after application of both ICM. Remarkable differences, however, were found in the region of the capsule-near cortex, where the application of iopromide led to a significantly lower iodine content in the microcirculation. This is in good agreement with former studies, in which a maldistribution in this area, presumably due to a decrease in arteriolar inflow as a result of stasis/occlusion was shown.

Aestivation motifs explain hypertension and muscle mass loss in mice with psoriatic skin barrier defect.

Recent evidence suggests that arterial hypertension could be alternatively explained as a physiological adaptation response to water shortage, termed aestivation, which relies on complex multi-organ metabolic adjustments to prevent dehydration. Here, we tested the hypothesis that chronic water loss across diseased skin leads to similar adaptive water conservation responses as observed in experimental renal failure or high salt diet. We studied mice with keratinocyte-specific overexpression of IL-17A which develop severe psoriasis-like skin disease. We measured transepidermal water loss and solute and water excretion in the urine. We quantified glomerular filtration rate (GFR) by intravital microscopy, and energy and nitrogen pathways by metabolomics. We measured skin blood flow and transepidermal water loss (TEWL) in conjunction with renal resistive indices and arterial blood pressure. Psoriatic animals lost large amounts of water across their defective cutaneous epithelial barrier. Metabolic adaptive water conservation included mobilization of nitrogen and energy from muscle to increase organic osmolyte production, solute-driven maximal anti-diuresis at normal GFR, increased metanephrine and angiotensin 2 levels, and cutaneous vasoconstriction to limit TEWL. Heat exposure led to cutaneous vasodilation and blood pressure normalization without parallel changes in renal resistive index, albeit at the expense of further increased TEWL. Severe cutaneous water loss predisposes psoriatic mice to lethal dehydration. In response to this dehydration stress, the mice activate aestivation-like water conservation motifs to maintain their body hydration status. The circulatory water conservation response explains their arterial hypertension. The nitrogen-dependency of the metabolic water conservation response explains their catabolic muscle wasting.

Early changes in renal resistive index and mortality in diabetic and nondiabetic kidney transplant recipients: a cohort study

BackgroundRenal resistive index (RI) predicts mortality in renal transplant recipients (RTR). However, its predictive value may be different according to the time of measurement. We analysed RI changes between 1 month and 3 months after transplantation and its predictive value for death with a functioning graft (DWFG).MethodsWe conducted a retrospective study in 1685 RTR between 1985 and 2017. The long-term predictive value of changes in RI value from 1 month to 3 months was assessed in diabetic and non-diabetic RTR.ResultsBest survival was observed in RTR with RI < 0.70 both at 1 and 3 months, and the worst survival was found in RTR with RI ≥ 0.70 both at 1 and 3 months (HR = 3.77, [2.71–5.24], p < 0.001). The risk of DWFG was intermediate when RI was < 0.70 at 1 month and ≥ 0.70 at 3 months (HR = 2.15 [1.29–3.60], p = 0.003) and when RI was ≥0.70 at 1 month and < 0.70 at 3 months (HR = 1.90 [1.20–3.03], p = 0.006).In diabetic RTR, RI was significantly associated with an increased risk of death only in those with RI < 0.70 at 1 month and ≥ 0.70 at 3 months (HR = 4.69 [1.07–20.52], p = 0.040). RI considered as a continuous variable at 1 and 3 months was significantly associated with the risk of DWFG in nondiabetic but not in diabetic RTR.ConclusionRI changes overtime and this impacts differently diabetic and nondiabetic RTR. RI short-term changes have a strong prognosis value and refines the risk of DWFG associated with RI.

Renal resistive index in IgA nephropathy and renal scleroderma vasculopathy

BackgroundRenal Ultra-Sound (US) and Doppler US provide measurements which reflect changes in renal and systemic haemodynamic. The renal resistive index (RRI), obtained through the Doppler spectrum analysis of renal small arteries, is altered in several pathologic conditions. Glomerulonephritis cause minor RRI changes, while renal scleroderma vasculopathy (RSV) leads to significant RRI modifications. The aim of our study was to assess RRI in IgA nephropathy (IgAN) and RSV in a retrospective observational study and to investigate determinants of the RRI in these groups of patients. MethodsWe enrolled 61 IgAN patients [23 female, median age 41 (33–58) years] and 80 SSc patients [71 female, median age 52 (43–60) years]. RRI was evaluated in all patients at the time of enrolment. Laboratory tests and clinical assessment were evaluated in all patients. ResultsIgAN patients showed lower RRI values than RSV patients [0.70 (0.65–0.73) vs 0.66 (0.62–0.72), p < 0.01], while no significant difference in longitudinal length was observed. Median age was significantly lower in IgAN patients than in RSV patients [41 (33–58) vs 52 (43–60), p < 0.05] while IgAN patients showed a higher prevalence of high blood pressure than RSV patients (39.3% vs 13.8%, p < 0.01). The multiple regression analysis, weighted for age, showed that RRI inversely correlates with estimated glomerular filtration rate (β coefficient = −0.524, p < 0.0001). ConclusionHigher RRI were found in RSV patients than IgAN patients. IgAN is characterized mainly by glomerular injury, not leading to major RRI changes.

Diurnal variation of renal resistive index over 24-hour period in hypertensive patients and healthy controls.

There are no data in the literature to our knowledge related to changes in renal resistive index (RRI) values over 24-h period and the importance of detecting these changes in patients who have hypertension (HT). In this study, we aimed to investigate the variation of RRI values over 24-h period and its usability in hypertensive patients. A total of 118 subjects (80 with HT and 38 healthy controls) were included in the study. Morning, midday, evening, and midnight RRI, renal pulsatility index, and accelerated time were measured by Doppler ultrasonography (US). B-mode US and elastograpic assessment were performed only in the morning. Temporal RRI varied significantly (p < 0.001). The highest and lowest levels were found in the morning and evening, respectively. All temporal RRI levels were significantly higher in patients with HT (both p < 0.001). The absolute and relative increases in RRI (ΔRRI) levels were similar in two groups. All temporal RRI measurements positively correlated with the patient age, pulse pressure, renal cortical thickness, and cortical stiffness. However, absolute-ΔRRI and relative-ΔRRI positively correlated with the age. Absolute-ΔRRI positively correlated with the pulse pressure and cortical stiffness, and no correlation was observed between relative-ΔRRI and these variables. Of the four temporal measurements, morning RRI were found to be independently associated with cortical stiffness (p < 0.001). RRI measurements varied over 24-h period in patients with HT and/or healthy controls. Morning RRI was significantly higher than other day time, and it is also related to renal cortical stiffness.

Renal resistive index significantly increased in hypertensive children and it is independently related to the pulse pressure and left ventricular mass index

ABSTRACTBackground: To the best our knowledge there is no data in the literature related to changes in renal resistive index (RRI) values in children who have hypertension (HT). In this study, we aimed to investigate the changes of RRI values and it is usability in children with HT.Methods: A total of 75 children; 48 with newly diagnosed HT and 27 healthy controls were included in the study. Routine history, physical examination, and laboratory examinations were performed. Left ventricular (LV) dimensions and systolic-diastolic functions, septum and posterior wall thickness (IVSd and PWd) and LV mass index (LVMI) were calculated by echocardiography. In addition to routine renal ultrasonography (US), renal pulsatility indexes (RPI), accelerated time and RRI were measured. Increased RRI was accepted as >0.70.Results: Increased RRI was detected in 25 (52%) of HT patients. Systolic and diastolic blood pressure (SBP and DBP), and pulse pressure (PP), low-density lipoprotein cholesterol and triglyceride levels, RRI, RPI, kidney length, IVSd, PWd, and LVMI were significantly higher in patients with HT (both p < 0.05). SBP and PP, PWd, LV ejection fraction, LV fractional shortening, and LVMI were positively correlated with the RRI. High-density lipoprotein cholesterol was negatively correlated with the RRI. Of these measurements, RRI values were found to be independently associated with PP and LVMI (p < 0.05).Conclusions: In hypertensive children, RRI was significantly higher than healthy controls and it is also related with LVMI and PP.

VASCULAR STIFFNESS IN TRUE RESISTANT HYPERTENSIVE PATIENTS AFTER RENAL DENERVATION

Objective: Patients with resistant hypertension (RHTN) are characterized by higher incidence and severity of vascular damage resulting in excess stiffness assessed by pulse wave velocity (PWV) and renal resistive index (RRI). RHTN is also associated with increased renin-angiotensin-aldosterone system (RAAS) activity promoting vascular and kidney fibrosis. Aim of the study was to investigate the link between vascular damage and plasma aldosterone concentration (PAC) in severe hypertensive patients before and after renal denervation (RD). Design and method: 25 patients (mean age 56 ± 10 years, 9 males) with confirmed true RHTN with standardized multidrug combination treatment underwent renal denervation (Symplicity RDN System, Medtronic, USA) between January 2012 and October 2015. Markers of vascular damage, office blood pressure (BP) and PAC were evaluated before and twelve months after procedure. RRI was noninvasively assessed by ultrasonography (Vivid 7 Dimension, GE, USA), PWV was calculated by applanation tonometry (SphygmoCor XCEL, AtCor Medical, Australia). Aldosterone plasma concentration (normal limits 10–105 pg/ml) were determined by immunofluorescence method. Results: There was a significant decrease of office systolic and diastolic BP (−24.5/−13.2 mmHg, respectively, P < 0.05) levels a year after RDN. Arterial stiffness measured by PWV improved significantly 12 months after procedure (10.1 ± 1.8 to 9.3 ± 2.0 m/s, P < 0.05). Patients with RHTN were characterized by rather high RRI at baseline and values remained mostly unchanged during follow-up (0.7 ± 0.08 and 0.71 ± 0.08 respectively; P = 0.87). PAC slightly but significantly decreased a year after procedure (−13.6 ± 6 pg/ml, P = 0.008). Changes in PWV were associated both with decrease of PAC (r = 0.562, P = 0.04) and office BP levels (r = 0.546, P = 0.03). There was lack of association between RRI changes, office BP and PAC changes. Conclusions: Effective treatment of resistant hypertension improves vascular stiffness partly through decrease of blood pressure and aldosterone levels. However renal RRI remains mostly unchanged without clear link to BP level and RAAS activity.

Effect of fluid challenge on renal resistive index after major orthopaedic surgery: A prospective observational study using Doppler ultrasonography

BackgroundA postoperative renal resistive index (RRI)>0.70 has the best threshold to early predict acute kidney injury (AKI). The response of RRI to a postoperative fluid challenge (FC) is unknown. The aim of our study was to assess the impact of a FC on RRI in suspected hypovolaemia patients after orthopaedic surgery. DesignIn this single-centre observational study, we prospectively screened 156 patients in the recovery room after having undergone a hip or knee replacement. InterventionsForty-six patients with a RRI>0.70 and requiring FC were included. RRI and cardiac output (CO) were measured before and immediately after a fluid challenge with 500mL of isotonic saline. A decrease in RRI>5% was considered significant (renal responders). ResultsOverall, FC resulted in a consistent decrease in RRI (from 0.74 [0.72–0.79] to 0.70 [0.68–0.73], P<0.01). Thirty-four patients (74%) showed a significant decrease in their RRI (from 0.74 [0.73–0.79] to 0.69 [0.67–0.72], P<0.05, versus non-responders: from 0.73 [0.72–0.75] to 0.72 [0.71–0.79], P=NS). CO increased equally among renal responders and non-responders (P=0.56). No correlation was found between changes in RRI and CO (r2=0.04; P=0.064). AKI was more common in renal non-responders (7/12) than in responders (3/34, P=0.001). ConclusionsAfter major orthopaedic surgery, a FC can decrease RRI in suspected hypovolaemia patients at risk of postoperative AKI, but the changes are not correlated to changes in CO. Decreases in RRI were associated with better renal outcome.

Longitudinal prospective observational type study about determinants of renal resistive index variations in chronic renal failure patients treated with conventional medical and dietetic therapy.

This longitudinal prospective observational type study was conceived with the aim to examine the impact on renal resistive index (RRI) of the variables that we can manipulate with therapeutic and or dietetic interventions in a chronic kidney disease population in order to known which of these variables was statistically related to changes in RRI and therefore could become the object of the greatest therapeutic effort. This study was undertaken between May 2016 to May 2017 in the outpatient nephrology and urology clinic of San Donato Hospital in Arezzo. The study population (84 patients: 47 males and 37 females) was randomly selected among the chronic kidney patients (with various degrees of renal impairment) affected by hypertension and or diabetes mellitus. After a comprehensive medical examination these patients were submitted to determination of serum creatinine, glycated hemoglobin, 24-hour urinary albumin excretion and finally renal Doppler ultrasonography. Then the patients were submitted to a full therapeutic and dietetic intervention to ameliorate the renal impairment by a wide range of actions and after on average a one-year interval were submitted again to a new medical examination and a second determination of serum creatinine, glycated hemoglobin, 24-hour urinary albumin excretion and a new renal Doppler ultrasonography too. The comparison between basal and final data revealed a slight reduction in the mean of bilateral renal resistance indices (Delta RRI: -0.0182 ± 0.08), associated to a slight increase in the mean glomerular filtration rate (Delta GFR: 0.8738 ± 10.95 ml/min/1.73 m2), a reduction in mean body weight (Delta weight: -1.9548 ± 5.26 Kg) and mean BMI (Delta BMI: -0.7643 ± 2.10 Kg/m2) as well as a reduction in the mean systolic blood pressure (Delta systolic blood pressure: -8.8333 ± 25.19 mmHg). Statistical analysis showed statistically significant correlations (p < 0.05) between Delta RRI and Delta weight (p < 0.03), Delta BMI (p < 0.02) and Delta systolic blood pressure (p < 0.05). Despite the many limitations the our study clearly identifies the targets (yet widely known) to act on to prevent kidney alterations related to RRI and provides further evidence, if any, of the utility of RRI as a key parameter in monitoring patients with chronic renal failure and as a valuable tool to drive the clinical efforts to contrast the kidney disease.

Renal resistive index--a valid tool to assess renal endothelial function in humans?

In humans, renal endothelial function is assessed by the vasoconstrictive response to L-NG-monomethyl arginine (L-NMMA). We hypothesized that Doppler sonographic measurements of the renal resistive index in response to inhibition of nitric oxide synthase offer a new methodological approach for testing renal endothelial function. Forty-one patients without nephropathy were included. Para-aminohippurate and inulin clearance were performed under basal conditions and during L-NMMA infusion. In parallel, renal resistive index was assessed by Doppler sonography, and central blood pressure was determined. Following nitric oxide synthase inhibition, renal resistive index increased significantly, and 29% of our patients developed Doppler sonographic diastolic zero flow. Renal plasma flow decreased in response to L-NMMA, and conversely, renal vascular resistance increased. There was no correlation of renal vascular resistance and renal resistive index at baseline and during nitric oxide synthase inhibition. Changes in renal resistive index were not related to changes in renal perfusion or renal vascular resistance. Renal resistive index correlated with central pulse pressure at baseline and during L-NMMA infusion, whereas renal vascular resistance did not correlate with central pulse pressure. Our data do not support the hypothesis that renal resistive index is a tool to test renal endothelial function in humans and should not be used interchangeably with renal vascular resistance.

Multimodal evaluation of renal perfusional changes due to extracorporeal shock wave lithotripsy

To examine the effect of extracorporeal shock wave lithotripsy (ESWL) on renal perfusion before and after treatment, by assessing renal resistive index (RI) using colour Doppler ultrasonography (CDUS), magnetic resonance perfusion imaging (MRPI), radionuclide renography and big-endothelin-1 values (Big-ET-1). In 69 normotensive patients the RI was measured before, 1, 3, 6 and 24 h after ESWL using CDUS. The RI values, measured in interlobar/arcuate arteries, were correlated with the findings on MRPI, done before and within 24 h after ESWL. In addition, renal plasma flow (RPF, assessed on radionuclide renography) and Big-ET-1 levels (a potent vasoconstrictor peptide), served as a control for evaluating renal perfusion. The patients were stratified in three age groups, i.e. <or=39, 40-59 and >or=60 years, with 23 patients in each group. The mean (sd) RI increased significantly in the treated kidneys, from 0.64 (0.05) before to 0.72 (0.08) after ESWL (P = 0.001). Only in patients aged >or=60 years did the RI continue to increase over the 24 h. MRPI showed a decrease of renal blood flow (RBF) in all age groups, but most significantly in those aged >or=60 years. The radionuclide renography and big-ET-1 levels changed significantly only in the oldest group. The best correlation was between RI and RBF changes detected by MRPI. ESWL obviously causes disturbances of renal perfusion, particularly in elderly patients (>or=60 years). Measurement of RI with Doppler techniques might provide useful information for the clinical diagnosis of renal damage.

Contribution of the renin-angiotensin system to the intrarenal resistive index in chronic unilateral partial ureteral obstruction in dogs.

We investigated the role of the renin-angiotensin system on intrarenal hemodynamics in chronic unilateral partial ureteral obstruction (UPUO) using Doppler ultrasound (US). In 11 dogs with chronic UPUO, we determined the renal resistive index (RI) before and 1 h after the intravenous infusion of an angiotensin-converting enzyme (ACE) inhibitor (captopril), an angiotensin II receptor type 1 (ART1) antagonist (L-158,809), and the combination of these two drugs. Change in resistive index (ΔRI) was calculated as RI after the administration of each tested material minus baseline RI. At the baseline measurement, significant differences in RI were seen between obstructed and nonobstructed kidneys. ACE inhibitor, ART1 antagonist, or the combination of these drugs did not result in any significant changes in RI in either obstructed or nonobstructed kidneys. However, in obstructed kidneys, ΔRI in the combination of ACE inhibitor and ART1 antagonist were significantly greater than those in ACE inhibitor or ART1 antagonist alone, whereas there were no significant differences in those values in nonobstructed kidneys. These observations suggest that the renin-angiotensin system in dogs with chronic UPUO may not contribute significantly to the differences in intrarenal RI between obstructed and nonobstructed kidneys. However, the angiotensin-producing pathways and angiotensin II receptor subtypes other than ACE and ART1 may have some different effects between obstructed and nonobstructed kidneys.

Changes of Renal Blood Flow in Nephroptosis: Assessment by Color Doppler Imaging, Isotope Renography and Correlation with Clinical Outcome after Laparoscopic Nephropexy

Objective: Previously, we have detected changes in renal blood flow secondary to nephroptosis by assessing the renal resistive index (RI) using color Doppler imaging (CDI). The aim of the current study was to compare two diagnostic methods, CDI and isotope renography (IRG), for detection of renal blood flow impairment in patients with nephroptosis. Methods: 26 patients with nephroptosis and flank pain underwent CDI and isotope renography (IRG) before and after laparoscopic nephropexy. The RI was assessed in segmental arteries with the patient in both the supine and erect position. Pre- and postoperative patient symptoms, results of Doppler measurements and IRG findings were assessed. Results: Preoperatively, 23 of 26 symptomatic patients showed a mean reduction in RI of more than 0.10 on the affected side, while only 7 of 26 patients had abnormal findings on preoperative IRGs. Postoperatively, none of the patients with preoperative changes in Doppler parameters showed any posture-related changes in RI. On postoperative IRG, obtained in 4 of 7 patients, normalization of renal perfusion was documented. Twenty out of 26 patients were asymptomatic postoperatively; in the remaining 6 patients symptoms were markedly improved. Conclusion: Impairment of renal blood flow due to nephroptosis was detected with both CDI and IRG. RI measurement by CDI appears to be significantly more sensitive in detecting renal blood flow impairment. RI should be assessed in patients with nephroptosis and may impact on the decision for laparoscopic nephropexy.

Changes of Renal Blood Flow in Nephroptosis: Assessment by Color Doppler Imaging, Isotope Renography and Correlation with Clinical Outcome after Laparoscopic Nephropexy

Previously, we have detected changes in renal blood flow secondary to nephroptosis by assessing the renal resistive index (RI) using color Doppler imaging (CDI). The aim of the current study was to compare two diagnostic methods, CDI and isotope renography (IRG), for detection of renal blood flow impairment in patients with nephroptosis. 26 patients with nephroptosis and flank pain underwent CDI and isotope renography (IRG) before and after laparoscopic nephropexy. The RI was assessed in segmental arteries with the patient in both the supine and erect position. Pre- and postoperative patient symptoms, results of Doppler measurements and IRG findings were assessed. Preoperatively, 23 of 26 symptomatic patients showed a mean reduction in RI of more than 0.10 on the affected side, while only 7 of 26 patients had abnormal findings on preoperative IRGs. Postoperatively, none of the patients with preoperative changes in Doppler parameters showed any posture-related changes in RI. On postoperative IRG, obtained in 4 of 7 patients, normalization of renal perfusion was documented. Twenty out of 26 patients were asymptomatic postoperatively; in the remaining 6 patients symptoms were markedly improved. Impairment of renal blood flow due to nephroptosis was detected with both CDI and IRG. RI measurement by CDI appears to be significantly more sensitive in detecting renal blood flow impairment. RI should be assessed in patients with nephroptosis and may impact on the decision for laparoscopic nephropexy.

Changes in Renal Resistive Index and Urinary Albumin Excretion in Hypertensive Patients under Long-Term Treatment with Lisinopril or Nifedipine GITS

Introduction: Increased renal vascular resistance and microalbuminuria are associated with hypertensive target organ damage and may be predictors of hypertensive nephrosclerosis. Aim: We investigated changes in renal resistive index (RI) and urinary albumin excretion (UAE) in a group of patients with primary hypertension before and during long-term antihypertensive treatment. Methods: Thirty-two patients were randomized to receive antihypertensive treatment with either a calcium channel blocker (nifedipine GITS, up to 90 mg/day, n = 16) or an ACE inhibitor (lisinopril, up to 20 mg/day, n = 16), alone or in association with a diuretic (chlortalidone, 25 mg/day). Blood pressure, renal resistive index (by US Doppler) and UAE (mean of three nonconsecutive timed urinary collections, µg/min) were evaluated at baseline and over the course of 24 months of treatment. Results: Both regimens effectively lowered blood pressure (mean blood pressure from 123 ± 1.8 at baseline to 103 ± 1.5 mm Hg at 24 months in the lisinopril group and from 122 ± 1.9 at baseline to 104 ± 0.8 at 24 months in the nifedipine group, p < 0.001 for both groups). Overall, blood pressure decrease was associated with a reduction in UAE and no change in RI throughout the study. However, despite similar blood pressure reduction, the two regimens showed different specific effects. Lisinopril was associated with a significant decrease in both UAE (33.8 ± 16.2 at baseline and 9.1 ± 2.1 at 24 months, p < 0.01) and renal RI (0.61 ± 0.02 at baseline and 0.56 ± 0.04 at 24 months, p < 0.05) while nifedipine GITS did not significantly influence UAE (35.7 ± 12.2 at baseline and 31.2 ± 12.1 at 24 months, n.s.) or RI (0.61 ± 0.01 at baseline and 0.59 ± 0.02 at 24 months, n.s.). Conclusion: Effective blood pressure control over a long period of time reduces the severity of organ damage, namely UAE while maintaining renovascular resistance in patients with essential hypertension. Different classes of antihypertensive agents might convey additional specific renal protection beyond blood pressure control. These data could be useful in devising individualized therapeutic strategies in hypertensive patients at increased renal risk.

Doppler ultrasonographic evaluation of the early changes in renal resistive index in cirrhotic patients undergoing liver transplantation.

Renal vasoconstriction commonly occurs in decompensated liver cirrhosis and is entirely reversible after hepatic transplantation. In this study we evaluated by Doppler ultrasonography the changes of renal vascular resistance occurring during the first month after transplantation. In 16 cirrhotic patients the intrarenal resistive index at the level of interlobar arteries and the blood urea nitrogen and serum creatinine levels were measured before (range, 1 to 34 days) and after transplantation (days 1, 3, 7, 14, 30). Before transplantation the median resistive index value was 0.69 (95% CI, 0.65 to 0.71) and eight of 16 patients showed abnormal values (0.70 or more). After transplantation, the median resistive index was significantly decreased on all the evaluation days, and no patient had abnormal values on posttransplantation day 7. No significant correlation was found between resistive index and serum creatinine or blood urea nitrogen levels. Doppler ultrasonography is a simple tool to evaluate the recovery of normal intrarenal arterial resistance levels after liver transplantation. One week appears to be the optimal timing to evaluate the renal resistive index in the posttransplantation period.

Partial ureteral obstruction: role of renal resistive index in stages of obstruction and release

Objectives. To study the changes in renal resistive index (RI) and renal function before and after release of different grades of partial unilateral ureteral obstructions. Methods. Ten dogs were subjected to right partial ureteral obstruction. Grade 1 (mild) obstruction was applied to 5 dogs (group A) and grade 3 (moderate and severe) obstruction was applied to the other 5 dogs (group B). Obstruction was maintained for 8 weeks, followed by release of obstruction. All dogs were subjected to excretory urography, technetium-99m mercaptoacetyltriglycine diuretic renography with calculation of half-time drainage (T 1 2 ), and bilateral renal Doppler ultrasonography before the start of the experiment, after 8 weeks of obstruction, and every 2 weeks during the 8 weeks after release of obstruction. Results. In both groups, after induction of right ureteral obstruction, there was a dramatic decrease of effective renal plasma flow (ERPF), increase of RI, and increase of T 1 2 of the right kidney. Relief of obstruction was associated with normalization of T 1 2 , reversal of RI, and recovery of ERPF to near basal values. No correlation was found between ERPF at the end of the recovery period and the functional parameters (T 1 2 , RI, or ERPF) of the obstructed kidney before release of obstruction. Conclusions. (1) Unilateral partial ureteral obstruction produces an elevation of RI and T 1 2 and a fall in ERPF of the corresponding kidney. (2) After relief of obstruction, renal function is regained with associated reversal of RI. (3) Functional parameters (T 1 2 , RI, or ERPF) of the obstructed kidney do not predict the recovery of ERPF after release of obstruction. (4) Rapid reversal of a previously elevated RI is an early indicator of recoverability of renal function after relief of ureteral obstruction.

Partial ureteric obstruction: a study of Doppler ultrasonography and diuretic renography in different grades and durations of obstruction.

To study the changes in renal resistive index (RI) and renal function with time during different grades of partial unilateral ureteric obstruction, and to determine the correlation between the ultrasonographic and renographic findings. Ten dogs underwent right partial ureteric obstruction: grade 1 (mild) obstruction was applied in five dogs (group A) and grade 3 (moderate and severe) obstruction in the other five (group B). All dogs were assessed using excretory urography, diuretic renography with the calculation of half-time drainage (T 1/2) and bilateral renal Doppler ultrasonography before the experiment began, after one week of obstruction, and every 2 weeks during 8 weeks of obstruction. In both groups, after the induction of right ureteric obstruction, there was a progressive decrease of effective renal plasma flow (ERPF) and a progressive increase of the RI of the right kidney at the end of the first and second weeks of obstruction, with an almost stable value thereafter. The decrease of ERPF and the increase of RI in the right kidney were correlated with the degree of obstruction. There was also a dramatic increase of T 1/2 of the right kidney that correlated with the degree of obstruction. Concomitantly, there was a significant compensatory increase of ERPF and a significant decrease of the RI of the left kidney in both groups. The compensatory increase in CRPF limited the loss in total ERPF in both groups. The contribution of obstructed kidney to the total ERPF was significantly reduced in both groups. At the end of the eighth week, taking all kidneys together, there was a statistically significant negative correlation between the ERPF and RI, and between ERPF and T 1/2 and a positive correlation between T 1/2 and RI. Unilateral partial ureteric obstruction increased the RI and T 1/2 and decreased the ERPF of the corresponding kidney, together with a decrease of RI and an increase in ERPF of the contralateral kidney. The more severe the obstruction, the greater the increase in RI and T 1/2 and the decrease in ERPF. After the obstruction stabilized, RI and T 1/2 were positively correlated.