Renal Resistive Index and Cardiovascular and Renal Outcomes in Essential Hypertension

Association between renal function and outcomes after percutaneous transluminal renal angioplasty in hypertensive patients with renal artery stenosis

OBJECTIVE

We investigated the impact of renal function on outcomes after percutaneous transluminal angioplasty.

METHODS

A total of 139 hypertensive patients with atherosclerotic renal artery stenosis (mean age, 70 years, 80.6% men) who underwent renal percutaneous transluminal angioplasty were included. Renal function was evaluated on the basis of estimated glomerular filtration rate (eGFR) and albuminuria/proteinuria, and classified into three categories according to eGFR (≥45, 30-44, and <30 ml/min/1.73 m) and albuminuria/proteinuria [normal-to-mild: albumin/creatinine ratio (ACR) less than 3.0, protein/creatinine ratio (PCR) less than 15; moderate: ACR 3.0-30.0, PCR 15-50; severe: ACR > 30.0, PCR > 50 mg/mmol].

RESULTS

During a median follow-up of 5.4 years, 36.0% of patients developed the primary composite end point, including cardiovascular and renal outcomes. In multivariate Cox regression analysis, eGFR less than 30 (hazard ratio 3.47, P < 0.01) as well as severe albuminuria/proteinuria (hazard ratio 2.63, P < 0.05) was an independent predictor of worse outcome. In the subgroup without events within 1 year after angioplasty (n = 117), the outcome differed among the three renal functional categories at 1 year based on eGFR (log-rank χ = 16.28, P < 0.001) as well as on albuminuria/proteinuria (log-rank χ = 8.30, P < 0.05). At 1 year, 24 patients (20.1%) showed at least 20% decrease in eGFR, and their outcome was worse than that in those with at least 20% increase (n = 23) (hazard ratio 3.50, P < 0.05). Multiple logistic regression analysis indicated that pretreatment moderate-to-severe albuminuria/proteinuria was an independent predictor of at least 20% eGFR decrease (odds ratio 2.82, P < 0.05).

CONCLUSION

Impaired renal function, and in particular, a poor response of eGFR to angioplasty, is associated with worse outcome. Therapeutic effectiveness of renal angioplasty seems to be limited in patients with albuminuria/proteinuria.

Renal systolic time intervals derived from intra-renal artery Doppler as a novel predictor of adverse cardiac outcomes

The aim of this study was to evaluate the use of renal systolic time intervals measured by electrocardiographic gated Doppler ultrasonography for predicting adverse cardiac events. This longitudinal observation study enrolled 205 patients. Renal systolic time intervals, including pre-ejection period (PEP) and ejection time (ET), and ratio of renal PEP to ET, were measured by electrocardiographic gated Doppler ultrasound. The 14 adverse cardiac events identified in this population included 9 cardiac deaths and 5 hospitalizations for heart failure during an average follow up of 30.9 months (25^th-75^th percentile: 30-33 months). Renal PEP (hazard ratio = 1.023, P = 0.001), renal ET (hazard ratio = 0.975, P = 0.001) and renal PEP/ET (per 0.01 unit increase, hazard ratio = 1.060, P < 0.001) were associated with poor cardiac outcomes. The addition of renal PEP/ET to a Cox model containing important clinical variables and renal resistive index further improved the value in predicting adverse cardiac events (Chi-square increase, 9.996; P = 0.002). This study showed that parameters of intra-renal hemodynamics were potential predictors of adverse cardiac outcomes. However, the generalizability of these indicators need to be investigated in future large-scale studies.

Effects of Percutaneous Transluminal Renal Angioplasty on Office and Home Blood Pressure and Home Blood Pressure Variability in Hypertensive Patients With Renal Artery Stenosis

This study included 126 hypertensive patients with renal artery stenosis (mean age, 63 years; 22.2% fibromuscular dysplasia [FMD]) and investigated the effects of percutaneous transluminal renal angioplasty on office and home blood pressure (BP), and BP variability estimates derived from home BP, both at baseline and up to 12 months after angioplasty. Home BP was measured for 7 consecutive days, and the threshold defining uncontrolled home BP was ≥135/85 mm Hg. In both the FMD and atherosclerotic stenosis (ARAS) groups, office and home BP decreased significantly after angioplasty (all P <0.01), but the decrease in morning home (−22±19 versus −10±20 mm Hg; P <0.01) but not in office (−32±24 versus −23±28 mm Hg; P =0.11) systolic BP at 12 months was significantly greater in FMD. In both groups, all morning BP variability indices except the coefficient of variation in ARAS decreased significantly after revascularization (all P <0.05 by repeated-measures ANOVA). The decrease in all morning systolic BP variability estimates was greater for FMD than for ARAS (all P <0.05 by 2-way repeated-measures ANOVA), with the exception of variability independent of the mean ( P =0.11). The prevalence of uncontrolled home BP was 77.0% at baseline and 38.9% after revascularization. Duration of hypertension (odds ratio, 1.48), ARAS (odds ratio, 3.18), and the presence of proteinuria (odds ratio, 2.10) were independent predictors of uncontrolled home BP after revascularization (all P <0.05). In conclusion, renal angioplasty produced a greater decrease of morning home systolic BP in FMD; however, in both groups, it decreased BP variability irrespective of BP response. Measurement of home BP seems to be important for treatment success, especially in ARAS.

Kidney resistive index relates to variations of home blood pressure in chronic kidney diseases

BACKGROUND

Kidney resistive index (RI) correlates with tubulointerstitial changes and predicts renal prognosis. Most patients with chronic kidney diseases (CKDs) manifest high blood pressure and atherosclerotic cardiovascular diseases. In addition, various atherosclerotic indexes relate to variations in blood pressure.

METHODS

Subjects were 70 CKD patients, who visited our office and agreed to measure home blood pressure and receive renal ultrasonography. Cross-sectional analyses were performed.

RESULTS

Patient age was averaged 61 ± 15 (SD) y/o and 60% were male. Mean serum creatinine and proteinuria were 1.2 ± 0.5 mg/dl and 0.2 ± 0.5 g/gCr, respectively. Office blood pressure and kidney RI were 128 ± 17/75 ± 11 mmHg and 0.66 ± 0.08, respectively. Multivariate regression analysis revealed that age and office blood pressure independently correlated to kidney RI (p < 0.05 for each). Home blood pressure was averaged 122 ± 7/70 ± 6 mmHg. Both standard deviation and the maximal-minimal difference in home systolic blood pressure related to kidney RI (p < 0.05).

CONCLUSIONS

The present results indicate that office blood pressure correlates to kidney RI, which predicts renal prognosis. In addition, our data implicate that kidney RI relates to variations in home systolic blood pressure, and suggest that kidney RI may be a good index for atherosclerosis in CKD patients.

Organogenesis and foetal haemodynamics during the normal gestation of healthy black-rumped agoutis (Dasyprocta prymnolopha, Wagler, 1831) bred in captivity

The objective of this study was to define the patterns of organogenesis and foetal haemodynamics during the normal gestation of healthy agoutis (Dasyprocta prymnolopha) kept in captivity. Thirty pregnant agoutis that ranged in size from small to medium and weighed between 2.5 and 3 kg underwent B-mode and Doppler ultrasonography for the biometric evaluation of the foetal organs. The foetal aortic blood flow proved to be predominantly systolic, and the measured flow velocity was 78.89 ± 2.95 cm/s, with a maximum pressure gradient of 2.12 ± 0.27 mmHg. The liver was characterized by its large volume, occupying the entire cranial aspect of the abdominal cavity, and it was associated cranially with the diaphragm and caudally with the stomach. The flow velocity in the portal vein was estimated to equal 12.17 ± 2.37 cm/s, with a resistivity index of 0.82 ± 0.05. The gallbladder was centrally located and protruded cranially towards the diaphragm. The spleen was visualized as an elongated structure with tapered cranial and caudal extremities, and the foetal kidneys were visualized bilaterally in the retroperitoneal region, with the right kidney positioned slightly more cranially than the left. The morphological characterization and hemodynamic analysis of the foetal organs of black-rumped agoutis via B-mode and Doppler ultrasonography allow determination of the vascular network and of reference values for the blood flow required for perfusing the anatomical elements essential for maintaining the viability of foetuses at different gestational ages.

The Renal Arterial Resistance Index Predicts Worsening Renal Function in Chronic Heart Failure Patients

BACKGROUND/AIM

The renal arterial resistance index (RRI) is a Doppler measure, which reflects abnormalities in the renal blood flow. The aim of this study was to verify the value of RRI as a predictor of worsening renal function (WRF) in a group of chronic heart failure (CHF) outpatients.

METHODS

We enrolled 266 patients in stable clinical conditions and on conventional therapy. Peak systolic velocity and end diastolic velocity of a segmental renal artery were obtained by pulsed Doppler flow, and RRI was calculated. Creatinine serum levels were evaluated at baseline and at 1 year, and the changes were used to assess WRF occurrence.

RESULTS

During follow-up, 34 (13%) patients showed WRF. RRI was associated with WRF at univariate (OR: 1.13; 95% CI: 1.07-1.20) as well as at a forward stepwise multivariate logistic regression analysis (OR: 1.09; 95% CI: 1.03-1.16; p = 0.005) including the other univariate predictors.

CONCLUSIONS

Quantification of arterial renal perfusion provides a new parameter that independently predicts the WRF in CHF outpatients. Its possible role in current clinical practice to better define the risk of cardiorenal syndrome progression is strengthened.

Association of Renal Resistive Index with Markers of Extrarenal Vascular Changes in Patients with Systemic Lupus Erythematosus

Recent data suggest that renal hemodynamic parameters obtained by duplex Doppler sonography, especially the intrarenal resistive index (RRI), may be associated with systemic vascular changes. We evaluated the relationships between RRI and arterial stiffness, assessed by aortic pulse wave velocity, and between RRI and subclinical atherosclerosis, assessed by measuring carotid intima-media thickness in patients with systemic lupus erythematosus. We enrolled 39 patients with systemic lupus erythematosus (mean age 39 y) compared with 19 healthy controls, matched for age and sex. Each participant underwent 24 h of ambulatory blood pressure, aortic pulse wave velocity, carotid intima-media thickness and RRI measurements. RRI correlated significantly with aortic pulse wave velocity (r = 0.44, p = 0.006), and with carotid intima-media thickness (r = 0.46, p = 0.003). Both correlations held (p = 0.01), even after correction for age, mean arterial pressure and glomerular filtration rate. Our results suggest that the RRI may be considered a marker of systemic vascular changes and probably a predictor of cardiovascular risk in patients with systemic lupus erythematosus.

Significant Correlation between Brachial Pulse Pressure Index and Renal Resistive Index

BACKGROUND

The renal resistive index (RI) is calculated as (peak systolic velocity - minimum diastolic velocity)/peak systolic velocity, and has been significantly associated with renal function. Pulse pressure index (PPI) is derived from a formula similar to renal RI, i.e. (systolic blood pressure - diastolic blood pressure)/systolic blood pressure. The purpose of this study was to investigate whether brachial PPI had a significant correlation with renal RI and could be used in identifying patients with impaired renal function.

METHODS

We consecutively enrolled 255 patients referred for echocardiographic examination. The renal RI was measured from Doppler ultrasonography and blood pressure was measured from an ABI-form device.

RESULTS

Patients with brachial PPI ≥ 0.428 (mean value of brachial PPI) had a lower estimated glomerular filtration rate (eGFR) than those with brachial PPI < 0.428 (p < 0.001). After the multivariate analysis was completed, brachial PPI had a significant correlation with renal RI (unstandardized coefficient β = 0.53, p < 0.001). The areas under the curve for brachial PPI and renal RI in prediction of eGFR < 45 mL/min/1.73 m(2) were 0.682 and 0.893 (both p < 0.001), respectively.

CONCLUSIONS

Brachial PPI was significantly correlated with renal RI. Patients with higher brachial PPI had a more reduced renal function. Hence, brachial PPI may be able to quickly reflect the intrarenal vascular hemodynamics, and may serve as an important tool for screening and follow-up for patients with abnormal renovascular resistance.

KEY WORDS

Chronic kidney disease; Pulse pressure index; Resistive index.

Left ventricular dilatation and subclinical renal damage in primary hypertension

OBJECTIVE

A new classification of left ventricular geometry based on left ventricular dilatation and concentricity has recently been developed. This classification identifies subgroups differing with regard to systemic haemodynamics, left ventricular function and cardiovascular prognosis. We investigated the relationship between the new classification of left ventricular geometry and subclinical renal damage, namely urine albumin excretion and early intrarenal vascular changes in primary hypertensive patients.

METHODS

A total of 449 untreated hypertensive patients were studied. Four different patterns of left ventricular hypertrophy (eccentric nondilated, eccentric dilated, concentric nondilated and concentric dilated hypertrophy) were identified by echocardiography. Albuminuria was measured as the albumin-to-creatinine ratio. Early intrarenal vascular changes, expressed as the renal volume to resistive index ratio, were evaluated by ultrasound and Doppler scan.

RESULTS

Patients with concentric dilated left ventricular hypertrophy had higher albumin excretion rates (P = 0.0258) and prevalence of microalbuminuria (P < 0.0001) and lower renal volume to resistive index ratio than patients with concentric nondilated hypertrophy (P = 0.0093). Patients with eccentric dilated hypertrophy showed a higher prevalence of microalbuminuria than patients with eccentric nondilated hypertrophy (P < 0.0001). Moreover, patients with chamber dilatation showed a higher prevalence of microalbuminuria (P = 0.0002) and lower renal volume to resistive index ratio (P = 0.0107) than patients without chamber dilatation. After adjusting for potentially confounding variables, left ventricular chamber dilatation was an independent predictor of subclinical renal damage.

CONCLUSION

Left ventricular dilatation is associated with subclinical renal damage in hypertension. These findings extend previous reports and provide a pathophysiological rationale for the observed unfavourable prognosis in patients with left ventricular dilatation.

Renal Resistive Index and mortality in critical patients with acute kidney injury

BACKGROUND

The predictive role of Doppler Renal Resistive Index (RRI) for mortality was shown in chronic kidney disease. In selected populations of intensive care unit (ICU), RRI predicts acute kidney injury (AKI) occurrence and anticipates persistent AKI. No data are available about mortality. We investigated whether RRI assay at AKI diagnosis could predict AKI mortality in a 10-bed-mixed medical-surgical and trauma ICU of a tertiary referral teaching hospital. The association between RRI and persistent AKI at discharge was investigated.

METHODS

One hundred and twenty-five of 1512 patients admitted from January 2010 to March 2013 who developed AKI during ICU stay were enrolled. Kidney function was evaluated daily according to risk, injury, failure, loss and end-stage criteria. At AKI diagnosis, we measured RRI. The association between RRI at AKI diagnosis and ICU death or persistent AKI at ICU discharge was analysed by multivariable logistic regression analysis.

RESULTS

At AKI diagnosis, RRI was 0·77 (0·70-0·88) in survivors and 0·85 in nonsurvivors (0·79-0·94) (P = 0·002). RRI values were significantly associated with ICU death (OR = 1·63-95% CI 1·06-2·49, P = 0·025). A RRI cut-off value of 0·77 was identified by receiver operating characteristic curve. Multivariate analysis selected RRI and abdominal hypertension as strongest predictors of AKI mortality. At AKI diagnosis, RRI was 0·78 (0·70-0·85) or 0·85 (0·73-0·92) (P = 0·026) in patients with or without persistent AKI at discharge. Multivariate analysis selected RRI at AKI diagnosis as the strongest predictor of persistent AKI.

CONCLUSIONS

High RRI values at AKI diagnosis are strictly and independently associated with in-ICU mortality and persistent AKI at ICU discharge.

Renal Resistive Index Predicts Postoperative Blood Pressure Outcome in Primary Aldosteronism

The renal resistive index (RI) calculated by Doppler ultrasonography has been reported to be correlated with renal structural changes and outcomes in patients with essential hypertension or renal disease. However, little is known about this index in primary aldosteronism. In this prospective study, we examined the utility of this index to predict blood pressure (BP) outcome after adrenalectomy in patients with primary aldosteronism. We studied 94 patients with histopathologically proven aldosteronoma who underwent surgery. Parameters on renal function, including renal flow indices, were examined and followed up for 12 months postoperatively. The renal RI of the main, hilum, and interlobar arteries was significantly higher in patients with aldosteronoma compared with 100 control patients. BP, estimated glomerular filtration rate, and urinary albumin excretion significantly decreased after adrenalectomy. The resistive indices of all compartment arteries were significantly reduced 1 month after adrenalectomy and remained stable for 12 months. Patients whose interlobar RI was in the highest tertile at baseline had higher systolic BP after adrenalectomy than those whose RI was in the lowest tertile. Logistic regression analysis demonstrated that the RI of the interlobar and hilum arteries could be an independent predictive marker for intractable hypertension (systolic BP ≥140 mm Hg, increased BP, taking ≥3 antihypertensive agents, or increased number of agents) even after adrenalectomy. Therefore, in patients with aldosteronoma, the renal RI indicates partially reversible renal hemodynamics and renal structural damages that would influence postoperative BP outcome.

Determinants and Prognostic Significance of the Renal Resistive Index

BACKGROUND

The noninvasive assessment of renal hemodynamics is currently possible by assessing the renal resistive index (RRI) derived from intrarenal Doppler arterial waveforms as (peak systolic velocity - end-diastolic velocity)/peak systolic velocity. In this review, we outline the important determinants of the RRI to clarify the true identity of the RRI and highlight its potential diagnostic and prognostic value in renal and cardiovascular pathology.

SUMMARY

Although the RRI was initially considered to reflect intrarenal vascular pathological processes, this index is actually a product of a complex interaction between renal and systemic vascular wall properties and hemodynamic factors. Indeed, studies in patients and general populations consistently demonstrated a significant and direct association between the RRI and central or peripheral pulse pressure independent of other covariables. Moreover, studies in renal transplant patients also showed that the RRI mainly reflects characteristics of the recipient but not those of the graft. Thus, the major influence of the systemic hemodynamics on the intrarenal arterial waveforms excludes RRI as a specific marker of renal vascular pathology. On the other hand, because the RRI reflects pulsatility in renal arteries, it might be useful for the early detection of renal microvascular damage. Future longitudinal studies are still needed to clarify whether the detection of Doppler changes in intrarenal arteries might yield an improvement in the adverse cardiovascular and renal outcome.

CONCLUSION

Published studies on RRI imply that the interaction between the systemic hemodynamics and peripheral circulation in the kidney is a complex physiological phenomenon. In addition to renal vascular properties, the central hemodynamic factors significantly influence the intrarenal arterial Doppler waveform patterns. Previous research also suggested an important role of the RRI for the evaluation of renal target organ damage, particularly in patients with increased pulsatility of the intrarenal blood flow.

Associations between increased renal resistive index and cardiovascular events

BACKGROUND AND PURPOSE

Chronic kidney disease is a risk factor for cardiovascular disease (CVD). Renal resistive index (RI) measured by Doppler ultrasonography is associated with renal impairment. We investigated the relationship between RI and cardiac function, and evaluated the utility of RI for predicting cardiac events in patients with CVD.

METHODS AND RESULTS

Renal Doppler ultrasonography and echocardiography were performed in a total of 452 patients with CVD. Correlations of RI with serum creatinine and estimated glomerular filtration rate (eGFR) were significant but not strong (r = 0.37, p < 0.001; r = -0.42, p < 0.001, respectively). RI correlated positively with age, left atrial volume index, left ventricular mass index, and early transmitral velocity to mitral annular early diastolic velocity (e') ratio (E/e'), and showed significant negative correlations with e' and diastolic blood pressure. Between two subgroups-112 patients hospitalized with cardiovascular events (Group A) and 200 age- and eGFR-matched controls (Group B)-RI was significantly higher in Group A than in Group B, although age and eGFR were similar.

CONCLUSIONS

RI reflects the impairment of intrarenal hemodynamics that cannot be adequately elucidated by eGFR alone. Assessment of renal RI may be useful in conjunction with prognostic estimates for patients with CVD.

Diagnostic value of urinary protein and creatinine in combination with renal ultrasound examination in early renal damage of patients with hypertension

Objective:

To evaluate the diagnostic value of urinary protein and creatinine in combination with renal Doppler ultrasound examination in early renal damage of patients with hypertension.

Methods:

One hundred twenty two hypertensive patients who were treated in our hospital from December 2013 to June 2014 were selected for this study, including 33, 41 and 48 cases of Stage I, Stage II and Stage III hypertension respectively. Meanwhile, 30 healthy subjects were selected as the control group. They received urinary protein, creatinine and renal Doppler ultrasound examination.

Results:

The urinary protein levels of Stage I, II and Stage III hypertensive patients were significantly different from that of the control group (p<0.05). Urinary creatinine levels were similar (p>0.05) in stage I and II but different from control (p<0.05) in stage III. Doppler ultrasound examination showed that Stage I hypertensive patients had similar renal longest diameter (RLD), renal parenchymal thickness (RPT) and ratio of RPT/renal sinus thickness to those of the control group (p>0.05), and RLDs of Stage II hypertensive patients and the control group were not significantly different (p>0.05).

Conclusion:

Urinary protein and creatinine levels in combination with renal Doppler ultrasound examination could diagnose early renal damage in patients with hypertension.

Renal resistive index and mortality in chronic kidney disease

Renal resistive index (RRI) measured by Doppler ultrasonography is associated with cardiovascular events and mortality in hypertensive, diabetic, and elderly patients. We studied the factors associated with high RRI (≥0.70) and its associations with mortality in chronic kidney disease patients without renal artery stenosis. We included 1962 patients with an estimated glomerular filtration rate of 15 to 59 mL/min per 1.73 m(2) who also had RRI measured (January 1, 2005, to October 2011) from an existing chronic kidney disease registry. Participants with renal artery stenosis (60%-99% or renal artery occlusion) were excluded. Multivariable logistic regression model was used to study factors associated with high RRI (≥0.70), and its association with mortality was studied using Kaplan-Meier plots and Cox proportional hazards model. Hypertension was prevalent in >90% of the patients. In the multivariable logistic regression, older age, female sex, diabetes mellitus, coronary artery disease, peripheral vascular disease, higher systolic blood pressure, and the use of β blockers were associated with higher odds of having RRI≥0.70. During a median follow-up of 2.2 years, 428 patients died. After adjusting for covariates, RRI≥0.70 was associated with increased mortality (adjusted hazard ratio, 1.29; 95% confidence interval, 1.02-1.65; P<0.05). This association was more pronounced among younger patients and those with stage 3 chronic kidney disease. Noncardiovascular/non-malignancy-related deaths were higher in those with RRI≥0.70. RRI≥0.70 is associated with higher mortality in hypertensive chronic kidney disease patients without clinically significant renal artery stenosis after accounting for other significant risk factors. Its evaluation may allow early identification of those who are at risk thereby potentially preventing or delaying adverse outcomes.

Living kidney donation does not adversely affect serum calcification propensity and markers of vascular stiffness

Living kidney donors (LKDs) experience a decline in glomerular filtration rate (GFR) after donation. Calcification propensity (T50 ) can be determined by a blood test predicting all-cause mortality in patients with chronic kidney disease. We studied the impact of kidney donation on T50 and markers of arterial stiffness. We analyzed T50 prospectively before and 1 year after kidney donation in 21 LKDs along with fetuin-A, mineral metabolism markers, kidney length, pulse wave velocity (PWV), augmentation index (AI), and renal resistive index (RRI) as markers of arterial stiffness. We studied the impact of kidney donation on these parameters. LKDs were 54 ± 10 years old and had a GFR of 101 ± 18 ml/min/1.73 m(2) before donation, decreasing to 67 ± 8 ml/min/1.73 m(2) after donation (P < 0.001). Despite this, T50 improved after donation (290 ± 53 to 312 ± 38 min, P = 0.049). This change was inversely related to plasma phosphate (P = 0.03), which declined after donation (P = 0.002). Fetuin-A levels increased after donation (P = 0.01). Upon donation, the length of the remaining kidney increased (P < 0.001) while PWV, AI, and RRI remained unchanged. Calcification propensity was not adversely affected by kidney donation. This indicates that T50 is independent from GFR in LKDs and that kidney donation does neither worsen calcification propensity nor markers of vascular stiffness at 1 year.

Doppler indexes of left ventricular systolic and diastolic flow and central pulse pressure in relation to renal resistive index

BACKGROUND

The cardio-renal interaction occurs via hemodynamic and humoral factors. Noninvasive assessment of renal hemodynamics is currently possible by assessment of renal resistive index (RRI) derived from intrarenal Doppler arterial waveforms as ((peak systolic velocity - end-diastolic velocity)/peak systolic velocity). Limited information is available regarding the relationship between RRI and cardiac hemodynamics. We investigated these associations in randomly recruited subjects from a general population.

METHODS

In 171 participants (48.5% women; mean age, 52.2 years), using pulsed wave Doppler, we measured RRI (mean, 0.60) and left ventricular outflow tract (LVOT) and transmitral (E and A) blood flow peak velocities and its velocity time integrals (VTI). Using carotid applanation tonometry, we measured central pulse pressure and arterial stiffness indexes such as augmentation pressure and carotid-femoral pulse wave velocity.

RESULTS

In stepwise regression analysis, RRI independently and significantly increased with female sex, age, body weight, brachial pulse pressure, and use of β-blockers, whereas it decreased with body height and mean arterial pressure. In multivariable-adjusted models with central pulse pressure and arterial stiffness indexes as the explanatory variables, we observed a significant and positive correlation of RRI only with central pulse pressure (P < 0.0001). Among the Doppler indexes of left ventricular blood flow, RRI was significantly and positively associated with LVOT and E peak velocities (P ≤ 0.012) and VTIs (P ≤ 0.010).

CONCLUSIONS

We demonstrated that in unselected subjects RRI was significantly associated with central pulse pressure and left ventricular systolic and diastolic Doppler blood flow indexes. Our findings imply that in addition to the anthropometric characteristics, cardiac hemodynamic factors influence the intrarenal arterial Doppler waveform patterns.

Renal haemodynamics and severity of carotid atherosclerosis in hypertensive patients with and without impaired renal function

BACKGROUND AND AIM

Renal resistance index (RRI), assessed by Duplex-Doppler sonography, has been classically considered as a mere expression of intrarenal vascular resistance. Recent studies, however, have showed that RRI is also influenced by upstream factors, especially arterial compliance, confirming its possible role as a marker of systemic vascular alterations. Several studies have shown that carotid intima-media thickness (cIMT) and carotid plaques (cP), assessed by ultrasonography, are documented markers of subclinical organ damage as well as expression of progressive atherosclerotic disease, and that they get worse with the progressive deterioration of renal function. The study was aimed to evaluate the relationship between RRI and severity of carotid atherosclerosis in hypertensive subjects with and without impaired renal function.

METHODS AND RESULTS

The study population, including 263 hypertensive patients (30-70 years), was split into 3 groups based on cIMT and presence of cP (cIMT ≤ 0.9 mm and no cP; cIMT > 0.9 mm and no cP; cP). All patients were also divided into 2 subgroups (normal renal function; CKD stage I-IV). A stepwise increase in RRI corresponding to the groups of progressive severity of carotid atherosclerosis was observed (respectively 0.61 ± 0.07, 0.65 ± 0.06, 0.68 ± 0.06; p < 0.001). A strong positive correlation was observed between RRI and cIMT in the whole population (r = 0.43; p < 0.001) and in the subgroups with (r = 0.42; p < 0.001) and without (r = 0.39; p < 0.001) CKD. These associations remained statistically significant even after adjustment for various confounding factors.

CONCLUSION

Showing a close association between RRI and severity of carotid atherosclerosis, our results strengthen the concept that RRI is a marker of systemic vascular changes.

Renal resistive index as a marker of vascular damage in cardiovascular diseases

The article presents changeability of renal resistive index (RRI) in various cardiovascular diseases and considers the usefulness of the marker and interpretational difficulties of the index. The values of RRI are not specific to an individual disease, but in a selected group of patients, it seems to be a perfect marker of cardiovasculorenal changes and a predictor of rapid loss of a renal function. The RRI usually does not reflect the vascular resistance, but is dependent on total and local vascular bed compliance changing with age, in the course of consecutive diseases and the influence of drugs. Under specific conditions, RRI appears to be a good marker of vascular damage. This review summarizes current concepts in RRI interpretation against the cardiovascular pathologies, focusing on the vascular damage association with regard to the complex nature of RRI value variability.

Ultrasound Doppler renal resistive index: a useful tool for the management of the hypertensive patient

The Doppler-derived renal resistive index has been used for years in a variety of clinical settings such as the assessment of chronic renal allograft rejection, detection and management of renal artery stenosis, evaluation of progression risk in chronic kidney disease, differential diagnosis in acute and chronic obstructive renal disease, and more recently as a predictor of renal and global outcome in the critically ill patient. More recently, evidence has been accumulating showing that an increased renal resistive index not only reflects changes in intrarenal perfusion but is also related to systemic hemodynamics and the presence of subclinical atherosclerosis, and may thus provide useful prognostic information in patients with primary hypertension. On the basis of these results, the evaluation of renal resistive index has been proposed in the assessment and management of patients with primary hypertension to complement other signs of renal abnormalities.

Additive interaction of oral health disorders on risk of hypertension in a Japanese urban population: the Suita Study

BACKGROUND

This study assessed the relationship between different oral health markers-periodontitis, gingival bleeding, tooth number, and occlusal status-and hypertension in a Japanese urban population.

METHODS

A total of 1,643 participants with no prior cardiovascular disease (mean age = 66.6 years; 43.4% women) underwent comprehensive health checkups, including a lifestyle questionnaire and dental examination in the Suita Study.

RESULTS

In the multivariable-adjusted logistic model, none of the individual oral health markers, namely severe periodontitis, gingival bleeding, lowest quartile of tooth number, and malocclusion, were significantly associated with increased odds of hypertension. The additive effects of oral health markers on hypertension were examined and showed that, compared with subjects with no component of the oral health markers, the multivariale-adjusted odds ratio of hypertension in those with ≥3 components was 1.82 (95% confidence interval (CI) = 1.23-2.72; P = 0.003). In the subpopulation without antihypertensive medication (n = 1,148; 59.8% women), a significant graded relationship between multivariable-adjusted systolic blood pressure and the number of components was found (P trend = 0.03), and, compared with subjects with no component of the oral health markers, having ≥3 components was related to a higher systolic blood pressure (β = 5.41; 95% CI = 1.16-9.66; P = 0.01).

CONCLUSIONS

There is an additive relationship between oral health disorders and risk of hypertension. Our results suggest that the existence of moderate or severe oral health disorders-that is, several concomitant oral health disorders-is associated with risk of hypertension.

Reference Values and Factors Associated With Renal Resistive Index in a Family-Based Population Study

Increased renal resistive index (RRI) has been recently associated with target organ damage and cardiovascular or renal outcomes in patients with hypertension and diabetes mellitus. However, reference values in the general population and information on familial aggregation are largely lacking. We determined the distribution of RRI, associated factors, and heritability in a population-based study. Families of European ancestry were randomly selected in 3 Swiss cities. Anthropometric parameters and cardiovascular risk factors were assessed. A renal Doppler ultrasound was performed, and RRI was measured in 3 segmental arteries of both kidneys. We used multilevel linear regression analysis to explore the factors associated with RRI, adjusting for center and family relationships. Sex-specific reference values for RRI were generated according to age. Heritability was estimated by variance components using the ASSOC program (SAGE software). Four hundred women (mean age±SD, 44.9±16.7 years) and 326 men (42.1±16.8 years) with normal renal ultrasound had mean RRI of 0.64±0.05 and 0.62±0.05, respectively ( P <0.001). In multivariable analyses, RRI was positively associated with female sex, age, systolic blood pressure, and body mass index. We observed an inverse correlation with diastolic blood pressure and heart rate. Age had a nonlinear association with RRI. We found no independent association of RRI with diabetes mellitus, hypertension treatment, smoking, cholesterol levels, or estimated glomerular filtration rate. The adjusted heritability estimate was 42±8% ( P <0.001). In a population-based sample with normal renal ultrasound, RRI normal values depend on sex, age, blood pressure, heart rate, and body mass index. The significant heritability of RRI suggests that genes influence this phenotype.

The renal arterial resistance index: a marker of renal function with an independent and incremental role in predicting heart failure progression

AIMS

The renal arterial resistance index (RRI) is a measure of renal blood flow obtained by Doppler ultrasonography, which has been demonstrated to reflect both vascular and parenchymal renal abnormalities. The aim of the study was to evaluate clinical correlates and the prognostic relevance of RRI in a group of patients affected by chronic heart failure (CHF).

METHODS AND RESULTS

We enrolled 250 CHF outpatients in a stable clinical condition and receiving conventional therapy. Peak systolic velocity and end-diastolic velocity of a segmental renal artery were obtained by pulsed Doppler flow. Then the RRI was calculated. Standard renal function assessment was obtained by the measurement of creatinine serum levels and the estimation of the glomerular filtration rate (GFR). During follow-up (21.4 ± 11.3 months), 41 patients experienced heart failure progression (hospitalization and/or heart transplantation and/or death due to worsening heart failure). Considered as a continuous variable, RRI was associated with events at univariate [hazard ratio (HR) 1.14; 95% confidence interval (CI) 1.09-1.19; P < 0.001] as well as at multivariate Cox regression analysis (HR 1.08; 95% CI 1.02-1.13; P = 0.004) after correction for independent predictors of the reference model. When the RRI was added to the reference model including GFR, a significant improvement of reclassification according to both category-free net reclassification improvement (NRI, 47%; 95% CI 13-80%; P = 0.006) and integrated discrimination improvement (IDI, 0.034; 95% CI 0.006-0.061; P = 0.016) was observed.

CONCLUSIONS

Quantification of arterial renal perfusion provides a new parameter that independently predicts CHF patient outcome, thus strengthening its possible role in current clinical practice in order to better characterize renal function and stratify patients' prognosis.

Preclinical cardiorenal interrelationships in essential hypertension

A diseased heart causes numerous adverse effects on kidney function, and vice versa renal disease can significantly impair cardiac function. Beyond these heart-kidney interrelationships at the clinical level, a reciprocal association has been suggested to exist even in the early stages of those organs' dysfunction. The aim of the present review is to provide evidence of the presence of a preclinical cardiorenal syndrome in the particular setting of essential hypertension, focusing on the subsequent hypertensive sequelae on heart and kidneys. In particular, a plethora of studies have demonstrated not only the predictive role of kidney damage, as expressed by either decreased glomerular filtration or increased urine albumin excretion, for adverse left ventricular functional and structural adaptations but also preclinical heart disease, i.e. left ventricular hypertrophy that is associated with deterioration of renal function. Notably, these reciprocal interactions seem to exist even at the level of microcirculation, since both coronary flow reserve and renal hemodynamics are strongly related with clinical and preclinical renal and cardiac damage, respectively. In this preclinical setting, common pathophysiological denominators, including the increased hemodynamic load, sympathetic and renin-angiotensin system overactivity, increased subclinical inflammatory reaction, and endothelial dysfunction, account not only for the reported associations between overt cardiac and renal damage but also for the parallel changes that occur in coronary and renal microcirculation.

The renal arterial resistive index and stage of chronic kidney disease in patients with renal allograft

Objective

The study investigated the optimal threshold value of renal arterial resistive index as assessed by Doppler ultrasonography determining chronic kidney disease stage 4 or higher in patients with renal allograft.

Methods

In a cross-sectional study the renal arterial resistive index were obtained in interlobar arteries by Doppler ultrasonography in 78 patients with renal allograft. The stage of chronic kidney disease was determined by the estimated glomerular filtration rate equation.

Results

The median renal arterial resistive index was 0.61 (interquartile range, 0.56 to 0.66). We observed a significant association between renal arterial resistive index above the upper quartile and chronic kidney disease stage 4 or higher (relative risk, 4.64; 95% confidence interval, 1.71 to 12.55; p = 0.003 by Fisher’s exact test). Multivariate logistic regression analysis showed that renal arterial resistive indices (p = 0.02) and time since transplantation (p = 0.04), but not age, gender, or blood pressure were significantly associated with chronic kidney disease stage 4 or higher.

Conclusion

A renal arterial resistive index higher than 0.66 may determine the threshold value of chronic kidney disease stage 4 or higher in patients with renal allograft.