Central pulse pressure and aortic stiffness determine renal hemodynamics: pathophysiological implication for microalbuminuria in hypertension

Early Detection of Postoperative Acute Kidney Injury in Acute Stanford Type A Aortic Dissection With Doppler Renal Resistive Index

OBJECTIVES

This study aimed to evaluate the early efficiency of Doppler renal resistive index (DRRI) in prediction of acute kidney injury (AKI) after surgery in acute Stanford Type A aortic dissection (AAAD) patients.

METHODS

Sixty-one AAAD patients who planned to receive Sun's surgical management were prospectively enrolled. The DRRI was measured by ultrasonography Doppler on the day before surgery (DRRI_pre ), on admission to the intensive care unit (DRRI_T0 ), 6 hours after surgery (DRRI_T6 ), 24 hours after surgery (DRRI_T24 ), and 48 hours after surgery (DRRI_T48 ). The maximum DRRI value (DRRI_max ) was recorded. The AKI was evaluated according to the classifications of the Acute Kidney Injury Network. The DRRI and serum creatinine (sCr) were compared between the pre- and postoperative time stations, as well as between the AKI and no-AKI groups.

RESULTS

Thirty-nine (63.9%) patients suffered from AKI, and 12 (19.6%) patients received dialysis. No significant difference was found in DRRI_pre (0.63 ± 0.04 versus 0.65 ± 0.06, P = .059) and sCr_pre (84.13 ± 23.77 versus 94.29 ± 51.11, P = .383) between the two groups with and without AKI. Both the DRRI and sCr increased significantly after surgery in the AKI groups (P < .001). However, the DRRI reached its maximum 6 hours after surgery, whereas the sCr reached its maximum after 24 hours. Both the DRRI and sCr improved 48 hours after surgery. The area under the receiver operating characteristic curve for DRRI_max (0.864, 95% confidence interval: 0.770-0.957) and DRRI_T6 (0.861, 95% confidence interval: 0.766-0.957) was larger than the other three DRRIs measured at different time points. The cutoff value of DRRI_max was 0.71, a sensitivity of 76.9% and specificity of 95.5%.

CONCLUSIONS

Postoperative DRRI predicts the AKI earlier than sCr after AAAD surgery. The best time to detect DRRI was 6 hours after surgery.

Increased renal resistive index in type 2 diabetes: Clinical relevance, mechanisms and future directions

Type 2 diabetes is a global health challenge. In type 2 diabetes both microvascular (nephropathy, retinopathy, neuropathy) and macrovascular complications arise. In kidney, renal pathological changes leading to diabetic nephropathy are mainly secondary to atherosclerosis of the intra and extra renal arteries together with microangiopathy of the glomerular capillaries, afferent arterioles and efferent arterioles. Renal resistive index (RRI) is defined as a ratio of the difference between maximum and minimum (end-diastolic) flow velocity to maximum flow velocity derived from the Doppler measurements of main renal and intrarenal (segmental/interlobar) arteries. Renal resistive index is tightly related to renal arteriolosclerosis, and represents an integrated index of arterial compliance, pulsatility and downstream microvascular impedance. In meantime, growing suggest that RRI has also been closely related with atherosclerosis. Most studies performed in type 2 diabetes showed RRI is increased in type 2 diabetes. In this review, we summarize the data regarding RRI with regard to performed studies, pathogenesis and prognosis, especially focusing on type 2 diabetes (T2D). We also review the data regarding the development of metabolic syndrome (MetS) and RRI.

Sex differences in associations of cardio-ankle vascular index with left ventricular function and geometry

The cardio-ankle vascular index (CAVI) is a measure of global arterial stiffness. We hypothesized that CAVI is associated with left ventricular (LV) function and geometry in individuals without structural heart disease. We measured CAVI in 600 participants (mean age 60.3±14.6 years, 54% men) without history of atherosclerotic cardiovascular disease who were referred for transthoracic echocardiography. Linear regression analysis was used to assess the association of CAVI with LV function (peak mitral annular systolic s' and early diastolic velocity e') and structure (LV mass index (LVMI) and relative wall thickness (RWT)). Older age, male sex, lower body mass index, history of hypertension, diabetes and chronic kidney disease were each associated with a higher CAVI (adjusted R² = 0.56, all p < 0.01). A higher CAVI was associated with lower s' and e', and greater RWT, independent of age, sex, systolic BP and other conventional cardiovascular risk factors (all p < 0.05); a borderline association of higher CAVI with greater LVMI ( p = 0.05) was present. Associations with e', s' and RWT were similar in women and men but the association with LVMI was stronger in women than in men ( p for interaction = 0.02, multivariable-adjusted β = 6.92, p < 0.001 in women; p > 0.1 in men). In conclusion, a higher CAVI, a measure of global arterial stiffness, is associated with worse LV systolic function, worse diastolic relaxation, and greater LV RWT in both men and women, and with LVMI in women.

Split renal function in patients with unilateral atherosclerotic renal artery stenosis-effect of renal angioplasty

OBJECTIVE

To evaluate the effect of percutaneous transluminal renal angioplasty (PTRA) on split renal function (SRF) in patients with unilateral atherosclerotic renal artery stenosis (ARAS).

METHODS

We performed a retrospective analysis of all consecutively examined patients at our centre with significant ARAS undergoing PTRA during 2002-07. A significant ARAS was defined as a lesion with a trans-stenotic mean arterial pressure gradient of at least 10 mmHg or a diameter stenosis >50% on angiography. Ambulatory (24 h) systolic and diastolic blood pressure (ASBP and ADBP, respectively) and calculated SRF using ^99mTc-DTPA renal scintigraphy were evaluated before (baseline) and 4 weeks after PTRA.

RESULTS

ASBP and ADBP were significantly lower 4 weeks after PTRA compared with baseline levels. Although total estimated glomerular filtration rate (eGFR; four-variable Modification of Diet in Renal Disease equation) had not changed by PTRA, analysis of SRF showed significantly increased eGFR in stenotic kidneys and a comparable reduction in eGFR in non-stenotic kidneys 4 weeks after PTRA.

CONCLUSIONS

In patients with unilateral ARAS, PTRA significantly improved eGFR in stenotic kidneys and decreased filtration in contralateral, non-stenotic kidneys. These potentially beneficial effects may not be apparent when total renal function remains stable. The clinical significance of these findings needs to be evaluated further.

Noninvasive assessment of haemodynamics in resistant hypertension: the role of the renal resistive index

OBJECTIVE

The association of resistant hypertension (RHTN) with renal haemodynamics is unclear. Our aim was to evaluate differences in haemodynamic characteristics of patients with RHTN compared with patients with controlled hypertension (HTN) at the level of the heart, kidney and aorta.

METHODS

We studied 50 patients with RHTN confirmed by ambulatory blood pressure monitoring and 50 controlled hypertensive patients matched for age and sex. All participants underwent renal Doppler ultrasound to determine the renal resistive index (RRI), a complete echocardiographic study including measurements of diastolic function and evaluation of augmentation index.

RESULTS

Hypertensive patients with RHTN compared with those without RHTN had a significantly decreased E/A ratio (by 0.12, P = 0.043), an increased E/e' ratio (by 3.1, P < 0.001), increased albumin-to-creatinine ratio levels (by 49 mg/g, P = 0.023) and a significantly higher RRI (by 0.078, P < 0.001) but similar augmentation index values (P = 0.79). Logistic regression revealed that presence of RHTN was the strongest predictor of an RRI more than 0.7 after controlling for other haemodynamic variables including blood pressure levels. Receiver-operator characteristic analysis revealed an area under the curve for prediction of RHTN by the RRI alone of 80.3% (95% confidence interval: 0.72-0.89, P < 0.001). An RRI cut-point of 0.648 has a sensitivity of 78% and a specificity of 72% for prediction of RHTN.

CONCLUSION

In a well treated hypertensive population, patients with RHTN show more pronounced renal and cardiac haemodynamic dysfunction compared with patients with controlled HTN. A greater RRI seems to be associated with RHTN and may help identify such patients.

Aortic-to-brachial stiffness gradient and kidney function in type 2 diabetes

OBJECTIVES

A reversed aortic-to-brachial stiffness gradient (ab-SG), defined as aortic pulse wave velocity (aPWV) greater than brachial PWV (bPWV), was recently shown to predict mortality independent of aPWV in dialysis patients. Patients with type 2 diabetes mellitus (T2DM) have increased risk of renal damage and exhibit haemodynamic abnormalities at rest and during exercise that may alter the ab-SG. This study aimed to examine ab-SG in patients with T2DM by comparison with nondiabetic controls during rest and exercise, and to determine associations between ab-SG, aPWV, and kidney function.

METHODS

Study participants were 60 patients with T2DM and 60 age and sex-matched nondiabetic controls (58 ± 8 years, 55% male both). ab-SG was defined as the quotient of bPWV (carotid-to-radial) and aPWV (carotid-to-femoral) recorded via applanation tonometry. Kidney function was assessed using estimated glomerular filtration rate (eGFR). The exercise substudy was undertaken in 21 patients with T2DM and 21 matched nondiabetic controls during semirecumbent exercise.

RESULTS

ab-SG was significantly lower in patients with T2DM (0.99 ± 0.2 vs. 1.2 ± 0.3, P < 0.001) and aPWV, but not bPWV, was significantly higher (P < 0.001 and P = 0.25). A total of 58% of patients with T2DM vs. 27% of nondiabetic controls (χ = 11.0, P < 0.001) had a reversed ab-SG (aPWV ≥ bPWV). ab-SG predicted eGFR independent of age, sex, T2DM status, and cardiovascular risk factors (β = 13.2, P = 0.024), whereas aPWV did not (β = -0.88, P = 0.30). Exercise ab-SG was significantly lower in patients with T2DM (0.97 ± 0.2 vs. 1.2 ± 0.2, P < 0.001), but did not predict eGFR.

CONCLUSIONS

Patients with T2DM have a reversed ab-SG during rest and exercise. Resting ab-SG predicts kidney function independent of aPWV, implying a reversed ab-SG may have a pathophysiological function.

Central Hemodynamics for Management of Arteriosclerotic Diseases

Arteriosclerosis, particularly aortosclerosis, is the most critical risk factor associated with cardiovascular, cerebrovascular, and renal diseases. The pulsatile hemodynamics in the central aorta consists of blood pressure, flow, and stiffness and substantially differs from the peripheral hemodynamics in muscular arteries. Arteriosclerotic changes with age appear earlier in the elastic aorta, and age-dependent increases in central pulse pressure are more marked than those apparent from brachial pressure measurement. Central pressure can be affected by lifestyle habits, metabolic disorders, and endocrine and inflammatory diseases in a manner different from brachial pressure. Central pulse pressure widening due to aortic stiffening increases left ventricular afterload in systole and reduces coronary artery flow in diastole, predisposing aortosclerotic patients to myocardial hypertrophy and ischemia. The widened pulse pressure is also transmitted deep into low-impedance organs such as the brain and kidney, causing microvascular damage responsible for lacunar stroke and albuminuria. In addition, aortic stiffening increases aortic blood flow reversal, which can lead to retrograde embolic stroke and renal function deterioration. Central pressure has been shown to predict cardiovascular events in most previous studies and potentially serves as a surrogate marker for intervention. Quantitative and comprehensive evaluation of central hemodynamics is now available through various noninvasive pressure/flow measurement modalities. This review will focus on the clinical usefulness and mechanistic rationale of central hemodynamic measurements for cardiovascular risk management.

Renal resistive index reflects Fontan pathophysiology and predicts mortality

OBJECTIVES

The renal resistive index (RRI) reflects non-renal pathophysiology, such as great artery stiffness, haemodynamics and even end-organ damage in patients with hypertension. This study was conducted to clarify the clinical significance of the RRI in Fontan pathophysiology.

METHODS

We measured the RRI in 280 consecutive Fontan patients and 36 healthy controls.

RESULTS

The patients exhibited a higher RRI than the controls (0.71±0.07 vs 0.60±0.04, p<0.0001). A high central venous pressure, low arterial pressure, greater pulse pressure and low arterial oxygen saturation (SaO₂) independently predicted a high RRI (p<0.05-0.0001). The RRI was inversely correlated with the peak oxygen uptake (PVO₂) and 24-hour creatine clearance, and was positively correlated with the plasma levels of brain natriuretic peptide (BNP) (p<0.0001 for all). The high RRI was also associated with liver dysfunction and postprandial hyperglycaemia during the oral glucose tolerance test (p<0.001). During the follow-up period, 18 patients died. Age, RRI, SaO₂, BNP, use of diuretics and antiarrhythmic drugs, and PVO₂ predicted mortality. When PVO₂ was excluded, RRI (HR: 1.13; 95% CI: 1.04 to 1.23; p<0.01) or RRI ≥0.81 (HR: 12.0; 95% CI: 3.4 to 50; p<0.0001) independently predicted mortality.

CONCLUSIONS

The RRI reflected heart failure severity, hepatorenal function and glucose intolerance, and predicted all-cause mortality in Fontan patients. Therefore, the RRI may be a useful marker of Fontan-associated multiorgan pathophysiology.

Aortic-Brachial Arterial Stiffness Gradient and Cardiovascular Risk in the Community: The Framingham Heart Study

A recent study reported that the aortic-brachial arterial stiffness gradient, defined as carotid-radial/carotid-femoral pulse wave velocity (PWV ratio), predicts all-cause mortality better than carotid-femoral pulse wave velocity (CFPWV) alone in dialysis patients. However, the prognostic significance of PWV ratio for cardiovascular disease (CVD) in the community remains unclear. Accordingly, we assessed the correlates and prognostic value of the PWV ratio in 2114 Framingham Heart Study participants (60±10 years; 56% women) free of overt CVD. Mean PWV ratio decreased from 1.36±0.19 in participants aged <40 years to 0.73±0.21 in those aged ≥80 years. In multivariable linear regression, older age, male sex, higher body mass index, diabetes mellitus, lower high-density lipoprotein cholesterol, higher mean arterial pressure, and higher heart rate were associated with lower PWV ratio (P<0.001 for all). During a median follow-up of 12.6 years, 248 first CVD events occurred. In Cox regression models adjusted for standard CVD risk factors, 1-SD changes in CFPWV (hazard ratio, 1.33; 95% confidence interval, 1.10-1.61) and PWV ratio (hazard ratio, 1.32; 95% confidence interval, 1.09-1.59) were associated with similar CVD risks. Models that included conventional CVD risk factors plus CFPWV or PWV ratio gave the same C statistics (C=0.783). Although PWV ratio has been reported to provide incremental predictive value over CFPWV in dialysis patients, we could not replicate these findings in our community-based sample. Our findings suggest that the prognostic significance of PWV ratio may vary based on baseline CVD risk, and CFPWV should remain the criterion standard for assessing vascular stiffness in the community.

Contributions of aortic pulse wave velocity and backward wave pressure to variations in left ventricular mass are independent of each other

Aortic pulse wave velocity (PWV) and backward waves, as determined from wave separation analysis, predict cardiovascular events beyond brachial blood pressure. However, the extent to which these aortic hemodynamic variables contribute independent of each other is uncertain. In 749 randomly selected participants of African ancestry, we therefore assessed the extent to which relationships between aortic PWV or backward wave pressures (Pb) (and hence central aortic pulse pressure [PPc]) and left ventricular mass index (LVMI) occur independent of each other. Aortic PWV, PPc, forward wave pressure (Pf), and Pb were determined using radial applanation tonometry and SphygmoCor software and LVMI using echocardiography; 44.5% of participants had an increased left ventricular mass indexed to height^1.7. With adjustments for age, brachial systolic blood pressure or PP, and additional confounders, PPc and Pb, but not Pf, were independently related to LVMI and left ventricular hypertrophy (LVH) in both men and women. However, PWV was independently associated with LVMI in women (partial r = 0.16, P < .001), but not in men (partial r = 0.03), and PWV was independently associated with LVH in women (P < .05), but not in men (P = .07). With PWV and Pb included in the same multivariate regression models, PWV (partial r = 0.14, P < .005) and Pb (partial r = 0.10, P < .05) contributed to a similar extent to variations in LVMI in women. In addition, with PWV and Pb included in the same multivariate regression models, PWV (P < .05) and Pb (P < .02) contributed to LVH in women. In conclusion, aortic PWV and Pb (and hence pulse pressure) although both associated with LVMI and LVH produce effects which are independent of each other.

Focus on the Novel Cardiovascular Drug LZC696: from Evidence to Clinical Consideration

LCZ696, a first-in-class angiotensin receptor neprilysin inhibitor (ARNI), is comprised of the angiotensin receptor blocker valsartan and the neprilysin inhibitor pro-drug sacubitril (AHU377). After oral administration, AHU377 is rapidly metabolized to the active neprilysin inhibitor LBQ657. LCZ696 exerts its effects of diuresis, natriuresis, vasodilation and aldosterone secretion inhibition through simultaneous renin-angiotensin-aldosterone system (RAAS) blockade and natriuretic peptides system (NPS) enhancement. Powerful evidence including PARAMETER and PRARDIGM-HF trials have shown that LCZ696 outperforms RAAS inhibition in treating patients with hypertension and heart failure with reduced ejection fraction (HFrEF), and is well tolerated. In addition, accumulating evidence also suggests its potential use in heart failure with preserved ejection fraction (HFpEF), chronic kidney disease (CKD), post-myocardium infarction (post-MI) and stroke. Both the FDA and CHMP have approved LCZ696 for treatment of HFrEF. Despite all this, some special issues (e.g. use in specific subgroups, adverse events, contraindications and cost-effectiveness analysis) should be considered before its implementation in clinical practice.

Relationship between exercise capacity and urinary liver-type fatty acid-binding protein in middle-aged and older individuals

BACKGROUND

The underlying mechanism linking the decline in exercise capacity with renal dysfunction remains unclear. Urinary liver-type fatty acid-binding protein (L-FABP) levels reflect the degree of peritubular capillary blood flow, an important factor for renal dysfunction with aging. The aim of this study was to examine the relationship between exercise capacity and urinary L-FABP levels.

METHODS

This was a cross-sectional study of 187 middle-aged and older individuals (aged 50-83 years) without chronic kidney disease (CKD). We assessed urinary L-FABP levels, peak oxygen consumption ([Formula: see text]), and grip strength.

RESULTS

Urinary L-FABP levels inversely correlated with both [Formula: see text] (r _s  = -0.349) and grip strength (r _s  = -0.485). When the participants were divided into four groups according to the median values of aerobic fitness and muscular strength ([Formula: see text] and grip strength), urinary L-FABP levels were the highest in participants with lower levels of aerobic fitness and muscular strength (2.95 ± 1.43 μg/g creatinine) and the lowest in the participants with higher levels of aerobic fitness and muscular strength (1.33 ± 0.76 μg/g creatinine). The difference between the two groups was significant (P < 0.001).

CONCLUSION

Our results demonstrate that both [Formula: see text] and grip strength were inversely associated with urinary L-FABP levels in middle-aged and older individuals without CKD. This suggests that a decline in exercise capacity is associated with a reduction in peritubular capillary blood flow, providing a novel insight into the underlying mechanism linking the decline in exercise capacity to the development of renal dysfunction.

Functional vascular contributions to cognitive impairment and dementia: mechanisms and consequences of cerebral autoregulatory dysfunction, endothelial impairment, and neurovascular uncoupling in aging

Increasing evidence from epidemiological, clinical and experimental studies indicate that age-related cerebromicrovascular dysfunction and microcirculatory damage play critical roles in the pathogenesis of many types of dementia in the elderly, including Alzheimer's disease. Understanding and targeting the age-related pathophysiological mechanisms that underlie vascular contributions to cognitive impairment and dementia (VCID) are expected to have a major role in preserving brain health in older individuals. Maintenance of cerebral perfusion, protecting the microcirculation from high pressure-induced damage and moment-to-moment adjustment of regional oxygen and nutrient supply to changes in demand are prerequisites for the prevention of cerebral ischemia and neuronal dysfunction. This overview discusses age-related alterations in three main regulatory paradigms involved in the regulation of cerebral blood flow (CBF): cerebral autoregulation/myogenic constriction, endothelium-dependent vasomotor function, and neurovascular coupling responses responsible for functional hyperemia. The pathophysiological consequences of cerebral microvascular dysregulation in aging are explored, including blood-brain barrier disruption, neuroinflammation, exacerbation of neurodegeneration, development of cerebral microhemorrhages, microvascular rarefaction, and ischemic neuronal dysfunction and damage. Due to the widespread attention that VCID has captured in recent years, the evidence for the causal role of cerebral microvascular dysregulation in cognitive decline is critically examined.

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.

Is cancer a severe delayed hypersensitivity reaction and histamine a blueprint?

Longevity and accumulation of multiple context-dependent signaling pathways of long-standing inflammation (antigen-load or oxidative stress) are the results of decreased/altered regulation of immunity and loss of control switch mechanisms that we defined as Yin and Yang of acute inflammation or immune surveillance. Chronic inflammation is initiated by immune disruptors-induced progressive changes in physiology and function of susceptible host tissues that lead to increased immune suppression and multistep disease processes including carcinogenesis. The interrelated multiple hypotheses that are presented for the first time in this article are extension of author's earlier series of 'accidental' discoveries on the role of inflammation in developmental stages of immune dysfunction toward tumorigenesis and angiogenesis. Detailed analyses of data on chronic diseases suggest that nearly all age-associated illnesses, generally categorized as 'mild' (e.g., increased allergies), 'moderate' (e.g., hypertension, colitis, gastritis, pancreatitis, emphysema) or 'severe' (e.g., accelerated neurodegenerative and autoimmune diseases or site-specific cancers and metastasis) are variations of hypersensitivity responses of tissues that are manifested as different diseases in immune-responsive or immune-privileged tissues. Continuous release/presence of low level histamine (subclinical) in circulation could contribute to sustained oxidative stress and induction of 'mild' or 'moderate' or 'severe' (immune tsunami) immune disorders in susceptible tissues. Site-specific cancers are proposed to be 'severe' (irreversible) forms of cumulative delayed hypersensitivity responses that would induce immunological chaos in favor of tissue growth in target tissues. Shared or special features of growth from fetus development into adulthood and aging processes and carcinogenesis are briefly compared with regard to energy requirements of highly complex function of Yin and Yang. Features of Yang (growth-promoting) arm of acute inflammation during fetus and cancer growth will be compared for consuming low energy from glycolysis (Warburg effect). Growth of fetus and cancer cells under hypoxic conditions and impaired mitochondrial energy requirements of tissues including metabolism of essential branched amino acids (e.g., val, leu, isoleu) will be compared for proposing a working model for future systematic research on cancer biology, prevention and therapy. Presentation of a working model provides insightful clues into bioenergetics that are required for fetus growth (absence of external threat and lack of high energy-demands of Yin events and parasite-like survival in host), normal growth in adulthood (balance in Yin and Yang processes) or disease processes and carcinogenesis (loss of balance in Yin-Yang). Future studies require focusing on dynamics and promotion of natural/inherent balance between Yin (tumoricidal) and Yang (tumorigenic) of effective immunity that develop after birth. Lawless growth of cancerous cells and loss of cell contact inhibition could partially be due to impaired mitochondria (mitophagy) that influence metabolism of branched chain amino acids for biosynthesis of structural proteins. The author invites interested scientists with diverse expertise to provide comments, confirm, dispute and question and/or expand and collaborate on many components of the proposed working model with the goal to better understand cancer biology for future designs of cost-effective research and clinical trials and prevention of cancer. Initial events during oxidative stress-induced damages to DNA/RNA repair mechanisms and inappropriate expression of inflammatory mediators are potentially correctable, preventable or druggable, if future studies were to focus on systematic understanding of early altered immune response dynamics toward multistep chronic diseases and carcinogenesis.

The Critical Role of Pulmonary Arterial Compliance in Pulmonary Hypertension

The normal pulmonary circulation is a low-pressure, high-compliance system. Pulmonary arterial compliance decreases in the presence of pulmonary hypertension because of increased extracellular matrix/collagen deposition in the pulmonary arteries. Loss of pulmonary arterial compliance has been consistently shown to be a predictor of increased mortality in patients with pulmonary hypertension, even more so than pulmonary vascular resistance in some studies. Decreased pulmonary arterial compliance causes premature reflection of waves from the distal pulmonary vasculature, leading to increased pulsatile right ventricular afterload and eventually right ventricular failure. Evidence suggests that decreased pulmonary arterial compliance is a cause rather than a consequence of distal small vessel proliferative vasculopathy. Pulmonary arterial compliance decreases early in the disease process even when pulmonary artery pressure and pulmonary vascular resistance are normal, potentially enabling early diagnosis of pulmonary vascular disease, especially in high-risk populations. With the recognition of the prognostic importance of pulmonary arterial compliance, its impact on right ventricular function, and its contributory role in the development and progression of distal small-vessel proliferative vasculopathy, pulmonary arterial compliance is an attractive target for the treatment of pulmonary hypertension.

Arterial stiffness and decline of renal function in a primary care population

Arterial stiffness is an important pathophysiological factor linking cardiovascular disease and kidney disease. Controversy exists as to whether arterial stiffness causes renal function decline, or kidney dysfunction leads to stiffening or whether the association is mutual. We aimed to investigate the longitudinal association between arterial stiffness and annual rate of renal function decline. We prospectively investigated in a primary care population whether carotid-femoral pulse wave velocity (PWV) was associated with estimated glomerular filtration rate (eGFR) and annual decline in eGFR in participants aged ⩾40 years without overt kidney disease. Baseline data on PWV and eGFR were available for 587 participants; follow-up measurements with a mean duration of 5.6 years were available for 222 patients. PWV, female gender and mean arterial pressure were independently associated with eGFR at baseline, although age confounded this association. More importantly, baseline PWV, age and eGFR were independent predictors of renal function decline. Stratification for age showed that the effect of PWV on rate of eGFR decline was amplified with advancing age. On the other hand, baseline eGFR did not determine annual change in PWV, suggesting a unidirectional association between arterial stiffness and eGFR. Arterial stiffness amplifies age-related renal function decline, suggesting that arterial stiffness plays a causal role in the development of renal damage, at least at later stages of age-related renal function decline, possibly through impaired renal autoregulation and increased arterial blood pressure pulsatility.

Association between central aortic pulsatility and glomerular filtration rate in patients with coronary artery disease

Objective:

Aortic stiffness and chronic kidney disease share common risk factors. Increased aortic stiffness is a predictor of lower estimated glomerular filtration rate (eGFR) at lower levels of renal functions. We aimed to investigate the association between invasively measured central aortic pulsatility (AP) as an indicator of aortic stiffness and eGFR in a population with coronary artery disease and without overt renal disease.

Methods:

This study had a cross-sectional design. Data were retrospectively collected. We evaluated 72 patients (44 males and 28 females; mean age 59.0±10.3 years) with coronary artery disease. eGFR was calculated with dividing the Cockcroft–Gault formula by body surface area. Direct measurements of aortic blood pressures were utilized to calculate pulse pressure and AP. Multiple linear regression analysis was performed to test the relationship between eGFR and AP, independent from potential confounders.

Results:

eGFR was significantly correlated with age (r=0.489, p<0.001), body surface area (r=0.324, p=0.006), weight (r=0.323, p=0.006), aortic pulse pressure (r=-0.371, p=0.001), and AP (r=-0.469, p<0.001). In multiple linear regression analysis, AP was independently associated with eGFR (p=0.035), beside the age and body surface area. An AP cut-off level of >0.71 had 84% sensitivity and 72% specificity in predicting eGFR of <90 mL/min per 1.72 m² (receiver–operating characteristic area under curve: 0.851, 95% CI: 0.760–0.942, p<0.001).

Conclusion:

We found an independent relationship between invasively measured AP and eGFR in patients with coronary artery disease. Moreover, a higher AP may predict lower eGFR. These results may be utilized to predict eGFR from AP during invasive procedures.

Relationship Between Carotid Atherosclerosis and Pulse Pressure with Renal Hemodynamics in Hypertensive Patients

BACKGROUND

Structural atherosclerotic damage, arterial stiffness, pulse pressure (PP), and renal hemodynamics may interact and influence each other. Renal resistance index (RRI) appears as a good indicator of systemic vascular changes. The aim of our study was to assess the independent relationships of carotid intima-media thickness (cIMT), aortic pulse wave velocity (aPWV), and peripheral PP with RRI in hypertensives with various degrees of renal function.

METHODS

We enrolled 463 hypertensive patients (30-70 years) with normal renal function (group 0; n = 280) and with chronic kidney disease (groups I-V; n = 183). All subjects underwent ultrasonographic examination of intrarenal and carotid vasculature, as well as a 24-h ambulatory blood pressure monitoring.

RESULTS

A statistically significant difference in RRI, cIMT, aPWV, and clinic PP was observed in the different 6 groups (all P < 0.001), even after adjustment for age. RRI correlated with cIMT (r = 0.460, P < 0.001), aPWV (r = 0.386, P < 0.001), clinic PP (r = 0.279, P < 0.001), and 24-h PP (r = 0.229, P < 0.001) in the entire study population. These correlations were similar in subjects with and without renal dysfunction. In the overall study population, the association between RRI, cIMT, and clinic PP remained statistically significant even after adjustment for various confounding factors, whereas the relationship between RRI and aPWV was lost in multivariate analysis.

CONCLUSIONS

cIMT and clinic PP rather than directly aPWV are associated with intrarenal hemodynamics. Our results confirm that in hypertensives RRI not only detects derangement of intrarenal circulation but may also be considered as a sensor of systemic vascular changes, independently of level of renal function.

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.

Renal Ultrasound (and Doppler Sonography) in Hypertension: An Update

Ultrasound (US) allows the non-invasive evaluation of morphological changes of kidney structure (by means of B-Mode) and patterns of renal and extrarenal vascularization (by means of color-Doppler and contrast-enhanced US). In hypertensive subjects it offers a relevant contribution to the diagnosis of early renal damage, acute or chronic nephropathies and nephrovascular disease. However, morphological changes are often detected late and non-specific and in recent years evidence has increased regarding the clinical relevance of renal resistive index (RRI) for the study of vascular and renal parenchymal renal abnormalities. RRI is measured by Doppler sonography in an intrarenal artery, as the difference between the peak systolic and end-diastolic blood velocities divided by the peak systolic velocity. At first RRI was proved to be a marker of renal disease onset and progression; later the influence of systemic vascular properties on RRI was shown and authors claimed its use as an independent predictor of cardiovascular risk rather than of renal damage. Indeed, renal vascular resistance is only one of several renal (vascular compliance, interstitial and venous pressure), and extrarenal (heart rate, pulse pressure) determinants that concur to determine RRI individual values but not the most important one. The clinical relevance of RRI measurement as a surrogate endpoint of specific renal damage or/and as surrogate endpoint of atherosclerotic diffuse vascular damage is still debated.To summarize, from the literature: (a) In hypertensives with normal renal function and no albuminuria, especially in younger people, RRI is an early marker of renal damage that is especially useful when hypertension and diabetes concur in the same subjects. In these subjects RRI could improve current clinical scores used to stratify early renal damage. In older subjects RRI increases in accordance with the increase in systemic vascular stiffness and, because of this close relationship, RRI is also a marker of systemic atherosclerotic burden and the role of renal determinants can weaken. The clinical relevance was not specifically investigated. (b) In transplant kidney and in chronic renal disease high (>0.80) RRI values can independently predict renal failure. The recent claim that systemic (pulse pressure) rather than renal hemodynamic determinants sustain this predictive role of RRI, does not significantly reduce this predictive role of RRI. (c) Doppler ultrasound allows diagnosis and grading of renal stenosis in both fibromuscolar dysplastic and atherosclerotic diseases. Moreover, by RRI assay Doppler ultrasound can indirectly measure the hemodynamic impact of renal artery stenosis on the homolateral kidney, by virtue of the stenosis-related decrease in pulse pressure. However, in elderly subjects with atherosclerotic renal artery stenosis coexisting renal diseases can independently increase RRI by the augmentation in renal vascular stiffness and tubulo-interstitial pressure and hidden changes due to renal artery stenosis.

The internist and the renal resistive index: truths and doubts

The renal resistive index (RRI) is measured by Doppler sonography in an intrarenal artery, and is the difference between the peak systolic and end-diastolic blood velocities divided by the peak systolic velocity. The RRI is used for the study of vascular and renal parenchymal renal abnormalities, but growing evidence indicates that it is also a dynamic marker of systemic vascular properties. Renal vascular resistance is only one of several renal (vascular compliance, interstitial and venous pressure), and extrarenal (heart rate, aortic stiffness, pulse pressure) determinants that combine to determine the RRI values, and not the most important one. RRI cannot always be considered a specific marker of renal disease. To summarize from the literature: (1) hydronephrosis, abdominal hypertension, renal vein thrombosis and acute kidney injury are all associated with an acute increase in interstitial and venous pressure that determine RRI values. In all these conditions, RRI is a reliable marker of the severity of renal damage. (2) The hemodynamic impact of renal artery stenosis can be assayed by the RRI decrease in the homolateral kidney by virtue of decreasing pulse pressure. However, renal diseases that often coexist, increase renal vascular stiffness and hide the hemodynamic effect of renal stenosis. (3) In transplant kidney and in chronic renal disease, high RRI values (>0.80) can independently predict renal and clinical outcomes, but systemic (pulse pressure) rather than renal hemodynamic determinants sustain the predictive role of RRI. (4) Higher RRI detects target renal organ damage in hypertension and diabetes when renal function is still preserved, as a marker of systemic atherosclerotic burden. Is this the fact? We attempt to answer.

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.

Arterial Stiffness Gradient

BACKGROUND

Aortic stiffness is a strong predictor of cardiovascular mortality in various clinical conditions. The aim of this review is to focus on the arterial stiffness gradient, to discuss the integrated role of medium-sized muscular conduit arteries in the regulation of pulsatile pressure and organ perfusion and to provide a rationale for integrating their mechanical properties into risk prediction.

SUMMARY

The physiological arterial stiffness gradient results from a higher degree of vascular stiffness as the distance from the heart increases, creating multiple reflective sites and attenuating the pulsatile nature of the forward pressure wave along the arterial tree down to the microcirculation. The stiffness gradient hypothesis simultaneously explains its physiological beneficial effects from both cardiac and peripheral microcirculatory points of view. The loss or reversal of stiffness gradient leads to the transmission of a highly pulsatile pressure wave into the microcirculation. This suggests that a higher degree of stiffness of medium-sized conduit arteries may play a role in protecting the microcirculation from a highly pulsatile forward pressure wave. Using the ratio of carotid-femoral pulse wave velocity (PWV) to carotid-radial PWV, referred to as PWV ratio, a recent study in a dialysis cohort has shown that the PWV ratio is a better predictor of mortality than the classical carotid-femoral PWV.

KEY MESSAGES

Theoretically, the use of the PWV ratio seems more logical for risk determination than aortic stiffness as it provides a better estimation of the loss of stiffness gradient, which is the unifying hypothesis that explains the impact of aortic stiffness both on the myocardium and on peripheral organs.

Correlation of Central Blood Pressure to Hypertensive Target Organ Damages During Antihypertensive Treatment: The J-TOP Study

BACKGROUND

Some previous studies have shown that central blood pressure (BP) is more closely related to cardiovascular risks than brachial BP. This study compared the correlations between asymptomatic organ damages and each of central BP, brachial clinic BP, and home BP during antihypertensive treatment.

METHODS

In the Japan Morning Surge-Target Organ Protection (J-TOP) study, which compared bedtime or awakening dosing of candesartan (+diuretics as needed) among subjects with home systolic BP (SBP) higher than 135 mm Hg, we evaluated 180 hypertensive patients who successfully underwent pulse wave analysis by HEM-9000AI and measured their urinary albumin/creatinine ratio (UACR) and left ventricular mass index (LVMI) (n = 144) at baseline and after 6 months of treatment.

RESULTS

During antihypertensive treatment, significant reductions were found in central SBP, UACR, and LVMI (all P < 0.001). Multiple regression analyses showed that the decrease in central SBP was associated with those of log-transformed UACR (β = 0.24, P < 0.01) and LVMI (β = 0.23, P = 0.04), independently of the decrease in both clinic and home SBP. The goodness-of-fit of the association between the reduction in SBP and the UACR (P < 0.01) or LVMI (P = 0.04) was improved by adding central SBP to the SBP measurement.

CONCLUSION

These findings suggest that the change in central BP could be an important therapeutic target during antihypertensive treatment, in addition to peripheral clinic and home BP.

Genetic predisposition to albuminuria is associated with increased arterial stiffness: role of elastin

BACKGROUND AND PURPOSE

The Munich Wistar Frömter (MWF) rat strain represents an experimental model to study cardiovascular alterations under conditions of progressive albuminuria. The aim of this study was to evaluate the association between genetic predisposition to albuminuria and the development of arterial stiffness and/or vascular remodelling.

EXPERIMENTAL APPROACH

Experiments were performed in mesenteric arteries from 12-week-old MWF, Wistar Kyoto (WKY) and consomic MWF-6(SHR) and MWF-8(SHR) rats in which chromosomes 6 or 8 associated with albuminuria from MWF were replaced by the respective chromosome from spontaneously hypertensive rats (SHR).

KEY RESULTS

Incremental distensibility, wall stress and strain were reduced, and arterial stiffness was significantly increased in albuminuric MWF compared with WKY. Albuminuria suppression in both consomic strains was associated with lower β-values in MWF-8(SHR) and MWF-6(SHR) compared with MWF. Moreover, elastin content was significantly lower in MWF external elastic lamina compared with WKY and both consomic strains. In addition, a reduction in arterial external and internal diameter and cross-sectional area was detected in MWF compared with WKY, thus exhibiting an inward hypotrophic remodelling. However, these alterations remained unchanged in both consomic strains.

CONCLUSION AND IMPLICATIONS

These data demonstrate that albuminuria in MWF is associated with increased arterial stiffness due to a reduction of elastin content in the external elastic lamina. Moreover, inward hypotrophic remodelling in MWF is not directly associated with albuminuria. In contrast, we demonstrated that two major genetic loci affect both the development of albuminuria and arterial stiffness, thus linking albuminuria and impairment of mechanical properties of resistance arteries.

Albuminuria as a marker of arterial stiffness in chronic kidney disease patients

AIM: To access the association between albuminuria levels and arterial stiffness in non-diabetic patients with hypertension and chronic kidney disease (CKD) stages 1-2, treated with renin angiotensin blockade agents plus other hypertensive drugs when needed.

METHODS: One hundred fifteen patients [median age 52 years (68% males)] were consequently enrolled in the study. For each patient, we recorded gender, age, body mass index (BMI), peripheral systolic blood pressure (pSBP), peripheral diastolic blood pressure, peripheral pulse pressure, central systolic blood pressure (cSBP), central diastolic blood pressure (cDBP), central pulse pressure (cPP), hematocrit, hemoglobin, hsCRP, total cholesterol triglycerides, high-density lipoprotein-C, low-density lipoprotein-C, calcium, phosphorus, parathormone, and albumin, as well as 24 h urine albumin excretion. According to 24-h urine albumin collection, patients were then classified as those with moderately increased albuminuria (formerly called macroalbuminuria) (≤ 300 mg/d) and those with severely increased albuminuria (formerly called macroaluminuria (> 300 mg/d). We considered aortic stiffness (AS) indices [carotid femoral pulse wave velocity (PWVc-f) and augmentation index (AIx)] as primary outcomes of the study. We explored potential correlations between severely increased albuminuria and AS indices using a multiple linear regression model.

RESULTS: Fifty-eight patients were included in the moderately increased albuminuria group and 57 in the severely increased albuminuria. Blood pressure measurements of the study population were 138 ± 14/82 ± 1.3 mmHg (systolic/diastolic). There were no significant differences in age, sex, and BP measurements between the two groups. Patients with severely increased albuminuria had higher PWV and AIx than patients with moderately increased albuminuria (P < 0.02, P < 0.004, respectively). In addition these patients exhibited higher BMI (P < 0.03), hsCRP (P < 0.001), and fibrinogen levels (P < 0.02) compared to patients with moderately increased albuminuria. In multivariate linear regression analysis, severely increased albuminuria (β = 1.038, P < 0.010) pSBP (β = 0.028, P < 0.034) and Ht (β = 0.171, P = 0.001) remained independent determinants of the increased PWVc-f. Similarly, severely increased albuminuria (β = 4.385, P < 0.012), cSBP (β = 0.242, P < 0.001), cPP (β = 0.147, P < 0.01) and Ht levels (β = 0.591, P < 0.013) remained independent determinants of increased AIx.

CONCLUSION: These findings demonstrate an independent association between AS indices and severely increased albuminuria in non-diabetic, hypertensive patients with CKD stages 1-2 treated with renin angiotensin aldosterone system blockers.

Aortic Blood Flow Reversal Determines Renal Function

Aortic stiffness determines the glomerular filtration rate (GFR) and predicts the progressive decline of the GFR. However, the underlying pathophysiological mechanism remains obscure. Recent evidence has shown a close link between aortic stiffness and the bidirectional (systolic forward and early diastolic reverse) flow characteristics. We hypothesized that the aortic stiffening–induced renal dysfunction is attributable to altered central flow dynamics. In 222 patients with hypertension, Doppler velocity waveforms were recorded at the proximal descending aorta to calculate the reverse/forward flow ratio. Tonometric waveforms were recorded to measure the carotid-femoral (aortic) and carotid-radial (peripheral) pulse wave velocities, to estimate the aortic pressure from the radial waveforms, and to compute the aortic characteristic impedance. In addition, renal hemodynamics was evaluated by duplex ultrasound. The estimated GFR was inversely correlated with the aortic pulse wave velocity, reverse/forward flow ratio, pulse pressure, and characteristic impedance, whereas it was not correlated with the peripheral pulse wave velocity or mean arterial pressure. The association between aortic pulse wave velocity and estimated GFR was independent of age, diabetes mellitus, hypercholesterolemia, and antihypertensive medication. However, further adjustment for the aortic reverse/forward flow ratio and pulse pressure substantially weakened this association, and instead, the reverse/forward flow ratio emerged as the strongest determinant of estimated GFR ( P =0.001). A higher aortic reverse/forward flow ratio was also associated with lower intrarenal forward flow velocities. These results suggest that an increase in aortic flow reversal (ie, retrograde flow from the descending thoracic aorta toward the aortic arch), caused by aortic stiffening and impedance mismatch, reduces antegrade flow into the kidney and thereby deteriorates renal function.

M2 macrophage accumulation in the aortic wall during angiotensin II infusion in mice is associated with fibrosis, elastin loss, and elevated blood pressure

Macrophages accumulate in blood vessels during hypertension. However, their contribution to vessel remodeling is unknown. In the present study, we examined the polarization state of macrophages (M1/M2) in aortas of mice during hypertension and investigated whether antagonism of chemokine receptors involved in macrophage accumulation reduces vessel remodeling and blood pressure (BP). Mice treated with ANG II (0.7 mg·kg(-1)·day(-1), 14 days) had elevated systolic BP (158 ± 3 mmHg) compared with saline-treated animals (122 ± 3 mmHg). Flow cytometry revealed that ANG II infusion increased numbers of CD45(+)CD11b(+)Ly6C(hi) monocytes and CD45(+)CD11b(+)F4/80(+) macrophages by 10- and 2-fold, respectively. The majority of macrophages were positive for the M2 marker CD206 but negative for the M1 marker inducible nitric oxide synthase. Expression of other M2 genes (arginase-1, Fc receptor-like S scavenger receptor, and receptor-1) was elevated in aortas from ANG II-treated mice, whereas M1 genes [TNF and chemokine (C-X-C motif) ligand 2] were unaltered. A PCR array to identify chemokine receptor targets for intervention revealed chemokine (C-C motif) receptor 2 (CCR2) to be upregulated in aortas from ANG II-treated mice, while flow cytometry identified Ly6C(hi) monocytes as the main CCR2-expressing cell type. Intervention with a CCR2 antagonist (INCB3344; 30 mg·kg(-1)·day(-1)), 7 days after the commencement of ANG II infusion, reduced aortic macrophage numbers. INCB334 also reduced aortic collagen deposition, elastin loss, and BP in ANG II-treated mice. Thus, ANG II-dependent hypertension in mice is associated with Ly6C(hi) monocyte and M2 macrophage accumulation in the aorta. Inhibition of macrophage accumulation with a CCR2 antagonist prevents ANG II-induced vessel fibrosis and elevated BP, highlighting this as a promising approach for the future treatment of vessel remodeling/stiffening in hypertension.

Predictive value of dynamic renal resistive index (DRIN) for renal outcome in type 2 diabetes and essential hypertension: a prospective study

BACKGROUND

Hypertension (EH) and type 2 diabetes (T2DM) are major causes of chronic kidney disease (CKD) and identification of predictors of CKD onset is advisable. We aimed to assess whether dynamic renal resistive index (DRIN), as well as other markers of systemic vascular damage, are able to predict albuminuria onset and estimated glomerular filtration rate (eGFR) decline in patients with T2DM or EH.

METHODS

In this prospective observational cohort study, 27 T2DM and 43 EH patients, free of CKD at baseline, were followed-up for 4.1 ± 0.6 years. Resistive Index (RI), endothelium-dependent (FMD) and independent vasodilation in the brachial artery (after glyceryl trinitrate - GTN - 25 μg s.l.), carotid-femoral Pulse Wave Velocity (PWV), Augmentation Index (AIx), DRIN (%RI change after GTN 25 μg s.l.) were evaluated.

RESULTS

Patients developing microalbuminuria were older, more frequently T2DM, with higher UACR at baseline, and showed higher DRIN (-2.8 ± 6.7 vs -10.6 ± 6.4 %, p = 0.01) and PWV (9.9 ± 1.3 vs 7.9 ± 1.5 m/s, p = 0.004) at baseline. The best predictors of microalbuminuria onset were DRIN > -5.16 % in T2DM (sensitivity 0.83, specificity 0.80) and PWV > 8.6 m/s in EH (sensitivity 0.96, specificity 1.00). Individuals whose eGFR declined (n = 27) had higher eGFR at baseline, but similar vascular characteristics; however in EH showing eGFR decline, baseline DRIN and PWV were higher. PWV showed a steeper progression during follow-up in patients developing albuminuria (Visit-outcome interaction: p = 0.01), while DRIN was early compromised but no further impaired (Visit-outcome interaction: p = 0.04).

CONCLUSIONS

PWV and DRIN are able to predict microalbuminuria onset in newly diagnosed EH and T2DM. DRIN is early compromised in T2DM patients developing microalbuminuria.

Exercise excess pressure and exercise-induced albuminuria in patients with type 2 diabetes mellitus

Exercise-induced albuminuria is common in patients with type 2 diabetes mellitus (T2DM) in response to maximal exercise, but the response to light-moderate exercise is unclear. Patients with T2DM have abnormal central hemodynamics and greater propensity for exercise hypertension. This study sought to determine the relationship between light-moderate exercise central hemodynamics (including aortic reservoir and excess pressure) and exercise-induced albuminuria. Thirty-nine T2DM (62 ± 9 yr; 49% male) and 39 nondiabetic controls (53 ± 9 yr; 51% male) were examined at rest and during 20 min of light-moderate cycle exercise (30 W; 50 revolutions/min). Albuminuria was assessed by the albumin-creatinine ratio (ACR) at rest and 30 min postexercise. Hemodynamics recorded included brachial and central blood pressure (BP), aortic stiffness, augmented pressure (AP), aortic reservoir pressure, and excess pressure integral (Pexcess). There was no difference in ACR between groups before exercise ( P > 0.05). Exercise induced a significant rise in ACR in T2DM but not controls (1.73 ± 1.43 vs. 0.53 ± 1.0 mg/mol, P = 0.002). All central hemodynamic variables were significantly higher during exercise in T2DM (i.e., Pexcess, systolic BP and AP; P < 0.01 all). In T2DM (but not controls), exercise Pexcess was associated with postexercise ACR ( r = 0.51, P = 0.002), and this relationship was independent of age, sex, body mass index, heart rate, aortic stiffness, antihypertensive medication, and ambulatory daytime systolic BP (β = 0.003, P = 0.003). Light-moderate exercise induced a significant rise in ACR in T2DM, and this was independently associated with Pexcess, a potential marker of vascular dysfunction. These novel findings suggest that Pexcess could be important for appropriate renal function in T2DM.

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.

Pulse pressure does not predict the response of diabetic nephropathy to glucose-lowering therapy

We aimed to study whether pulse pressure (PP) predicts the response of diabetic nephropathy to glucose-lowering treatment. Patients with uncontrolled type 2 diabetes were followed for decrease in albuminuria after insulin/oral-hypoglycemic treatment. A total of 143 patients were followed for a median time of 10.5 months in a cohort study. Fasting blood sugar and HbA1C significantly decreased, while systolic, diastolic and pulse pressures remained constant during intervention. Median albuminuria decreased from 18.4 mg/day [10-40] to 16.4 mg/day [9-28] at the end of study (p-value < 0.005). The number of patients with normo/micro/macro-albuminuria changed from 98/36/9 to 108/31/4 (p-value < 0.001). No significant difference in baseline PP (47.5 ± 1.61 vs. 45.9 ± 1.81 mmHg; p-value = 0.51) or final PP (47.0 ± 2.41 vs. 49.4 ± 2.38 mmHg; p-value = 0.47) existed between those with decreased and increased albuminuria. PP was not a significant predictor of albuminuria changes in receiver operating characteristic curve (p-value = 0.77) and regression (p-value = 0.98) analyses. Benefits of glycemic control in diabetic nephropathy are independent of PP.

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.

Prevalence of renal artery disease and its prognostic significance in patients undergoing coronary bypass grafting

Several studies demonstrated the prognostic importance of renal failure and peripheral artery disease in patients undergoing coronary artery bypass grafting (CABG), but data regarding the prognostic value of renal artery disease in this context are scarce. We aimed to study the prevalence and prognostic value of renal artery disease in patients undergoing CABG. We assessed by duplex ultrasound the renal arteries of 429 consecutive patients who underwent CABG, of whom 401 had satisfactory imaging quality to detect >60% renal artery stenosis (RAS) and/or an elevated resistive index (ERI>0.80). Of the 401 subjects included (age 68±10 years, 83% men), 40 (10%) had RAS and 35 (9%) had ERI. Nine patients (2.2%) had both conditions. Patients were followed up for 12.4±7.0 months. The primary outcome was composite, including 30-day death, stroke, and/or myocardial infarction. In a multivariate model adjusted for age, gender, cardiovascular (CV) risk factors, renal function, chronic obstructive pulmonary disease, the use of off-pump CABG, CV co-morbidities, and drugs, the presence of ERI was strongly associated with the occurrence of the composite outcome (odds ratio 4.3, 95% confidence interval 1.7 to 9.9, p=0.0006). Similarly, ERI, not RAS, was significantly associated with the 30-day acute kidney disease and the midterm mortality, as well as fatal and nonfatal CV events. In conclusion, regardless of renal function and other factors, the renal resistive index is a strong predictor of CV and renal events after CABG. Renal duplex ultrasound can identify a subgroup of patients at high risk of CABG.