Diffusion-weighted MRI sequences (DW-MRI) of the kidney: normal findings, influence of hydration state and repeatability of results.

PURPOSE: This study was performed to determine the apparent diffusion coefficient (ADC) of the normal kidney using diffusion-weighted magnetic resonance imaging (DW-MRI) sequences and to analyse both the changes due to hydration state and results repeatability. MATERIALS AND METHODS: Ten volunteers underwent DW-MRI imaging of the kidneys with a breath-hold single-shot spin-echo planar imaging (SE-EPI) sequence in the axial and coronal planes with b values of 300, 500, 800 s/mm(2), in different states of hydration. Urine osmolarity (OsmU) and sodium excretion (NaU) were measured at the time of each examination. ADC maps were created for all b values, and ADC values were calculated and compared between different states of hydration. In five subjects, the protocol was conducted twice to test data repeatability. RESULTS: ADC values were lower with higher b values (3.00 vs. 2.47 vs. 1.99 x 10(-3) mm(2)/s with b values of 300, 500, 800 s/mm(2), respectively). ADC values in different hydration states were not statistically different. Measurements were reproducible. OsmU and NaU were statistically different in the different states of hydration (p<0.01). CONCLUSIONS: ADC values significantly decrease with higher b values. Average ADC values in the normal kidney are reproducible. Hydration state does not significantly influence mean ADC values.

Metabolic syndrome and ambulatory arterial stiffness index in non-diabetic patients with primary hypertension.

Increased arterial stiffness and the presence of metabolic syndrome (MS) have been shown to predict cardiovascular events in patients with primary hypertension. We investigated the relationship between a recently proposed index of arterial stiffness derived from ambulatory blood pressure (BP) monitoring and MS in 156 untreated, non-diabetic patients with primary hypertension. Ambulatory arterial stiffness index (AASI) was defined as 1 minus the regression slope of diastolic over systolic BP readings obtained from 24-h recordings. A modified National Cholesterol Education Program definition for MS was used, with body mass index replacing waist circumference. The prevalence of MS was 23%. Patients with MS were more frequently male (0.0291) and had increased serum uric acid (P=0.0005), high-sensitivity C-reactive protein (P=0.0259), as well as total and low-density lipoprotein (LDL)-cholesterol (P=0.0374 and P=0.0350, respectively) as compared to those without MS. After adjusting for these confounders, the association between AASI and the presence of MS was statistically significant (P=0.0257). Moreover, the prevalence of increased AASI (upper tertile, that is >or=0.550) was greater in patients with MS (P=0.0156). After adjusting for age and 24-h mean BP, the presence of MS entailed a more than twofold greater risk for increased AASI (0.0280). MS is associated with increased AASI in non-diabetic patients with primary hypertension. These data support the role of this new index of arterial stiffness as a marker of risk and help to explain the high cardiovascular morbidity and mortality that is observed in hypertensive patients with MS.

Metabolic syndrome is associated with early signs of organ damage in nondiabetic, hypertensive patients.

OBJECTIVES: Hypertensive patients with metabolic syndrome (MS) are at greater risk for cardiovascular disease. To get a better understanding of the pathophysiology underlying this association, we evaluated the relationship between MS and subclinical organ damage in essential hypertensive patients. DESIGN AND SETTING: A total of 354 untreated, nondiabetic patients with primary hypertension were included in the study. A modified ATP III definition for MS was used, with body mass index replacing waist circumference. Albuminuria was measured as albumin to creatinine ratio, left ventricular mass index (LVMI) was assessed by echocardiography and carotid abnormalities by ultrasonography. RESULTS: The prevalence of MS was 25%. Patients with MS were more likely to be smokers (P = 0.004) and had higher serum uric acid levels (P = 0.004). Moreover, they showed higher urinary albumin excretion (P = 0.0004) and LVMI (P = 0.0006), increased intima-media thickness (P = 0.045), as well as higher prevalence of microalbuminuria (P = 0.03) and left ventricular hypertrophy (LVH; P = 0.003). After adjusting for age, gender and duration of hypertension, we found that the presence of MS entails a twofold greater risk for microalbuminuria (P = 0.04), LVH (P = 0.003) and carotid abnormalities (P < 0.05). When patients were stratified according to the number of components of MS, albuminuria (P = 0.002) and LVMI (P = 0.005) increased progressively across categories. CONCLUSIONS: Metabolic syndrome is associated with subclinical organ damage in nondiabetic, essential hypertensive patients. These data may, in part, explain the high cardiovascular morbidity and mortality that is observed in hypertensive patients with MS.

Creatinine clearance and signs of end-organ damage in primary hypertension.

A reduction in renal function is associated with high cardiovascular morbidity and mortality in hypertension. The aim of the present study was to investigate the relationship between creatinine clearance and subclinical organ damage in 957 never previously treated, middle-aged patients with primary hypertension. Renal function was estimated by means of the serum creatinine level using the Cockcroft-Gault formula; left ventricular hypertrophy (LVH) was determined according to electrocardiographic criteria; and retinal vascular changes were evaluated by direct ophthalmoscopy. Creatinine clearance was, on the average, 83+/-21.2 ml/min, and the prevalence of LVH and retinopathy was 13 and 49%, respectively. Creatinine clearance was inversely related to the duration of disease (r=-0.132, P<0.0001), systolic blood pressure (r=-0.110, P=0.001), serum glucose (r=-0.090, P=0.007), total cholesterol (r=-0.196, P<0.0001), and LDL-cholesterol (r=-0.196, P<0.0001). Patients in the lower quintile of creatinine clearance showed a higher prevalence of electrocardiogram (ECG) determined LVH (P=0.04), as well as retinal changes (P=0.02). The risk of having LVH or retinal vascular changes increases significantly with each s.d. decrease in creatinine clearance, regardless of traditional cardiovascular risk factors. Moreover, patients with ECG-determined LVH and retinal changes showed lower creatinine clearance as compared to those with lesser degrees of target organ involvement (P<0.01). In conclusion, a mild reduction in creatinine clearance is associated with preclinical end-organ damage in patients with normal creatinine and primary hypertension. These data may help explain the high cardiovascular mortality observed in patients with renal dysfunction. Routine evaluation of creatinine clearance could be useful for identifying patients at higher cardiovascular risk.

Left ventricular geometry and function in patients with essential hypertension and microalbuminuria.

BACKGROUND: Microalbuminuria has recently emerged as a strong, independent predictor of cardiovascular mortality in patients with essential hypertension, yet the pathophysiological mechanisms underlying this association remain to be elucidated. OBJECTIVE: To study the relationship between microalbuminuria and left ventricular geometry and function and extra-cardiac vascular changes in a group of 211 untreated hypertensive patients. METHODS: Albuminuria was evaluated as albumin-to-creatinine ratio in three non-consecutive first morning urine samples. Left ventricular mass index and function were assessed by M-B mode echocardiography and carotid wall thickness by high-resolution ultrasound scan. RESULTS: The prevalences of microalbuminuria and left ventricular hypertrophy were 14 and 47% respectively. Patients in the top quartile of albuminuria showed a higher left ventricular mass index (57 +/- 1.8, 55 +/- 2, 47 +/- 1.4 and 48 +/- 1.6 g/m2.7, respectively; P< 0.0001) as well as a higher prevalence of left ventricular hypertrophy (72, 65, 26 and 25%, respectively; P< 0.001) and especially concentric hypertrophy (56, 47, 17 and 21%, respectively; P< 0.0001) in the four quartiles of albuminuria. Microalbuminuric patients showed depressed left ventricular performance as indicated by a reduced midwall fractional shortening (15.7 +/- 0.3, 15.9 +/- 0.3, 16.7 +/- 0.4 and 16.8 +/- 0.3%, respectively; P< 0.02). Furthermore patients in the top quartile of albuminuria showed increased carotid wall thickness as compared to normoalbuminuric patients (0.78 +/- 0.03, 0.7 +/- 0.04, 0.65 +/- 0.03 and 0.6 +/- 0.03 mm, respectively; P < 0.001). CONCLUSIONS: Hypertensive patients with microalbuminuria show a higher prevalence of unfavourable left ventricular geometric patterns, depressed left ventricular function and early signs of extra-cardiac vascular damage. These findings strengthen the role of microalbuminuria as an indicator of subclinical cardiovascular disease and may account for the worse outcome that is usually associated with increased urinary albumin excretion in essential hypertension.

Prevalence and clinical correlates of microalbuminuria in essential hypertension: the MAGIC Study. Microalbuminuria: A Genoa Investigation on Complications.

The prevalence of microalbuminuria and its relationship with several cardiovascular risk factors and target organ damage were evaluated in a cohort of 787 untreated patients with essential hypertension. Albuminuria was measured as the albumin-to-creatinine ratio in three nonconsecutive, first morning urine samples. The prevalence of microalbuminuria was 6.7%. Albuminuric patients were more likely to be men and to be characterized by higher blood pressure, body mass index, and uric acid levels and lower HDL cholesterol and HDL cholesterol-to-LDL cholesterol ratio. Piecewise linear regression analysis demonstrated that uric acid and diastolic blood pressure significantly influence albuminuria and together account for a large part of its variations. K-means cluster analysis performed on the entire cohort of patients confirmed that microalbuminuria is associated with a worse cardiovascular risk profile. Furthermore, microalbuminuria was associated with the presence of target organ damage (eg, electrocardiographic [ECG] abnormalities and retinal vascular changes). Age and the presence of microalbuminuria act as independent risk factors for the development of ECG abnormalities and retinal vascular changes. Cluster analysis allowed us to identify three subgroups of patients who differed in the presence or absence of microalbuminuria, retinopathy, and ECG abnormalities. We conclude that the prevalence of microalbuminuria in essential hypertension is lower than previously reported. Increased urinary albumin excretion is associated with a worse cardiovascular risk profile and is a concomitant indicator of early target organ damage.

Microalbuminuria: a marker of cardiovascular risk and organ damage in essential hypertension.

Microalbuminuria (Mi) is thought to reflect diffuse vascular damage and to predict cardiovascular morbidity and mortality in essential hypertension, although its pathogenesis remains to be fully elucidated. The relationship between microalbuminuria and several cardiovascular risk factors and target organ damage was evaluated in a large cohort of untreated essential hypertensive patients. Albuminuria was measured as the albumin to creatinine ratio in three non consecutive first morning urine samples. Cardiac damage was evaluated by ECG and retinal vascular changes by direct ophtalmoscopy. In a subgroup of 23 patients with Mi and in a control group of 22 normoalbuminurics, selected from the entire cohort of patients and carefully matched for age, gender, body mass index (BMI) and duration of disease, we also measured left ventricular mass index by M-B mode echocardiography, common carotid wall thickness by high resolution US-scan, and renal vascular resistances by US-doppler of interlobar arteries. K-means cluster analysis performed on the entire cohort of patients showed that microalbuminuria is associated with the presence of an unfavorable risk profile and target organ damage. Furthermore, microalbuminuric hypertensive patients have a larger left ventricular mass index, increased intima media thickness of carotid arteries and higher intrarenal vascular resistances as compared to a well matched group of normoalbuminuric patients. We conclude that in essential hypertension increased urinary albumin excretion can be useful to identify patients for whom more aggressive preventive strategies and/or additional treatment measures are advisable.

Prevalence of micro- and macroalbuminuria and their relationship with other cardiovascular risk factors in essential hypertension.

A cohort of 227 untreated essential hypertensive patients from north-western Italy was studied in order to evaluate the prevalence of micro- and macroalbuminuria and their relationship with other cardiovascular risk factors. Albuminuria was evaluated as the albumin to creatinine ratio (Alb/Cr) in three non-consecutive first morning samples. The prevalence of microalbuminuria and macroalbuminuria was 10% and 2.2%, respectively. Albuminuric patients showed higher blood pressure, serum creatinine, triglycerides and uric acid as well as a greater prevalence of retinopathy. Stepwise multiple regression analysis demonstrated that only a small part of variations in albuminuria was explained by changes in blood pressure. Duration of disease did not seem to influence microalbuminuria. The presence of hypertensive retinopathy was associated with greater albuminuria, longer duration of hypertension, and higher prevalence of major ECG changes, but not with higher blood pressure levels. Microalbuminuria, rather than a consequence of elevated blood pressure levels, seems to be a marker of a syndrome featuring, among other characteristics, essential hypertension. Furthermore, microalbuminuria must be considered as an independent cardiovascular risk factor.