Accelerated decline in renal perfusion with aging in essential hypertension

A clinical score to predict recovery in end-stage kidney disease due to acute kidney injury

Background

Acute kidney injury (AKI) is a major contributor to end-stage kidney disease (ESKD). About one-third of patients with ESKD due to AKI recover kidney function. However, the inability to accurately predict recovery leads to improper triage of clinical monitoring and impacts the quality of care in ESKD.

Methods

Using data from the United States Renal Data System from 2005 to 2014 (n = 22 922), we developed a clinical score to predict kidney recovery within 90 days and within 12 months after dialysis initiation in patients with ESKD due to AKI. Multivariable logistic regressions were used to examine the effect of various covariates on the primary outcome of kidney recovery to develop the scoring system. The resulting logistic parameter estimates were transformed into integer point totals by doubling and rounding the estimates. Internal validation was performed.

Results

Twenty-four percent and 34% of patients with ESKD due to AKI recovered kidney function within 90 days and 12 months, respectively. Factors contributing to points in the two scoring systems were similar but not identical, and included age, race/ethnicity, body mass index, congestive heart failure, cancer, amputation, functional status, hemoglobin and prior nephrology care. Three score categories of increasing recovery were formed: low score (0-6), medium score (7-9) and high score (10-12), which exhibited 90-day recovery rates of 12%, 26% and 57%. For the 12-month scores, the low, medium and high groups consisted of scores 0-5, 6-8 and 9-11, with 12-month recovery rates of 16%, 33% and 62%, respectively. The internal validation assessment showed no overfitting of the models.

Conclusion

A clinical score derived from information available at incident dialysis predicts renal recovery at 90 days and 12 months in patients with presumed ESKD due to AKI. The score can help triage appropriate monitoring to facilitate recovery and begin planning long-term dialysis care for others.

Association of Noise Annoyance with Measured Renal Hemodynamic Changes

BACKGROUND

Chronic mental stress is recognized as a modifiable risk factor for cardiovascular disease. The aim of this study was to demonstrate that noise annoyance-induced stress is associated with changes in renal hemodynamics.

METHODS

Renal hemodynamic parameters were measured using steady-state input clearance with infusion of para-aminohippuric acid and inulin in individuals with normal, high normal, and elevated blood pressure. All individuals ranked subjective annoyance due to noise in everyday life on a 7-grade Likert scale. The median of all rankings was used as a cutoff point to divide the group into noise-annoyed and non-noise-annoyed individuals. Different renal hemodynamic parameters were calculated based on the Gomez equation.

RESULTS

Noise-annoyed individuals (n = 58) showed lower renal plasma flow (599 ± 106 vs. 663 ± 124 mL/min, p = 0.009), lower renal blood flow (1,068 ± 203 vs. 1,172 ± 225 mL/min, p = 0.047), higher filtration fraction (22.7 ± 3.3 vs. 21.3 ± 3.0, p = 0.012), higher renal vascular resistance (88.9 ± 25.6 vs. 75.8 ± 22.9 mm Hg/[mL/min], p = 0.002), and higher resistance of afferent arteriole (2,439.5 ± 1,253.4 vs. 1,849.9 ± 1,242.0 dyn s-1 cm-5, p = 0.001) compared to non-noise-annoyed individuals (n = 55). There was no difference in measured glomerular filtration rate (133 ± 11.8 vs. 138 ± 15 mL/min, p = 0.181), resistance of efferent arteriole (2,419.4 ± 472.2 vs. 2,245.8 ± 370.3 dyn s-1 cm-5, p = 0.060), and intraglomerular pressure (64.0 ± 3.1 vs. 64.6 ± 3.5 mm Hg, p = 0.298) between the groups. After adjusting for age, renal plasma flow, renal blood flow, and renal vascular resistance remained significantly different between the groups, with a trend in increased afferent arteriolar resistance and filtration fraction.

CONCLUSION

In this study, noise annoyance was associated with reduced renal perfusion attributed to increased renal vascular resistance predominantly at the afferent site. Long-term consequences of this renal hemodynamic pattern due to noise annoyance need to be investigated.

Reversal of an unfavorable effect of hydrochlorothiazide compared to angiotensin converting enzyme inhibitor on serum uric acid and oxypurine levels by estrogen-progestin therapy in hypertensive postmenopausal women

Background: The aim was to assess the effect of estrogen-progestin therapy (EPT) on serum levels of uric acid (SUA) and its precursors xanthine (X) and hypoxanthine (HX), and on uric acid (UA) renal excretion in hypertensive postmenopausal women treated with an angiotensin-converting enzyme inhibitor (ACEI) or thiazide diuretic (HCTZ) (ClinicalTrials.gov identifier: NCT03921736, registered 19 April 2019). Methods: Postmenopausal women with untreated essential hypertension were recruited to the study. The control group consisted of 40 postmenopausal women with normal blood pressure. Hypertensive women were randomized to two groups: hydrochlorothiazide (n = 50) or perindopril (n = 50) and to a group receiving or not receiving EPT (EPT+/EPT-) due to vasomotor symptoms. The follow-up period was one year. Blood pressure measurements as well as blood tests for SUA and its precursors X and HX were performed at baseline and after 12 months. Results: In hypertensive women, baseline serum X and HX were significantly higher when compared to the group of normotensive women. Treatment with HCTZ led to a statistically significant increase in SUA in the subgroup of EPT- women. In this group concentrations of X and HX increased significantly after 12 months. UA/X significantly decreased after treatment with HCTZ. Lack of EPT resulted in a decrease of renal plasma flow in the HCTZ group. However, in the HCTZ and EPT + group, SUA decreased significantly when compared to baseline. None of these unfavorable effects was observed in the ACEI group regardless of EPT. Conclusions: 1) EPT prevents the development of hyperuricemia during antihypertensive treatment with thiazide diuretics. 2) Arterial hypertension and menopause cause impairment of UA excretion and increase the levels of SUA and its precursors X and HX. 3) EPT reduces the risk of hyperuricemia in postmenopausal women.

Aging Vs. Hypertension: An Autopsy Study of Sclerotic Renal Histopathological Lesions in Adults With Normal Renal Function

BACKGROUND AND AIMS

Arterial hypertension and glomerular ischemia coexist in elderly patients with hypertension. Thus, 2 conflicting therapeutic purposes, i.e., reduction of pressure overload and maintenance of renal arterial perfusion, must be considered in elderly patients with hypertension. This study examined this issue from the perspective of renal histopathology.

METHODS

Adult autopsied kidneys without apparent renal disease were analyzed for histopathological features that might be related to aging or hypertension. Mean glomerular volume (GV), global glomerulosclerosis (GGS), arteriosclerotic lesions (AL), arteriolar hyalinosis (AH), and interstitial fibrosis/tubular atrophy (IF/TA) were evaluated.

RESULTS

This study included 59 Japanese autopsy patients, of whom 28 (47%) were hypertensive. Overall, GGS, IF/TA, and AL, but not GV or AH, tended to increase with aging. Multivariate analysis revealed that age, but not hypertension, was an independent factor associated with GGS, IF/TA, and AL. In contrast, hypertension was independently associated with GV. AH was not associated with age or hypertension in this autopsy series. Of note, in the late elderly group (≥75 years), GGS was significantly lower in hypertensives than in normotensives. No such trend was found in the non-elderly (<65 years) or early elderly groups (65-74 years).

CONCLUSIONS

Normal aging has a major impact on the development of renal sclerotic lesions compared to hypertension in adults with no apparent renal disease. Hypertension may play a role in maintaining downstream glomerular perfusion in the aging kidney.

Loss of a kidney during fetal life: long-term consequences and lessons learned

Epidemiological studies reveal that children born with a solitary functioning kidney (SFK) have a greater predisposition to develop renal insufficiency and hypertension in early adulthood. A congenital SFK is present in patients with unilateral renal agenesis or unilateral multicystic kidney dysplasia, leading to both structural and functional adaptations in the remaining kidney, which act to mitigate the reductions in glomerular filtration rate and sodium excretion that would otherwise ensue. To understand the mechanisms underlying the early development of renal insufficiency in children born with a SFK, we established a model of fetal uninephrectomy (uni-x) in sheep, a species that similar to humans complete nephrogenesis before birth. This model results in a 30% reduction in nephron number rather than 50%, due to compensatory nephrogenesis in the remaining kidney. Similar to children with a congenital SFK, uni-x sheep demonstrate a progressive increase in arterial pressure and a loss of renal function with aging. This review summarizes the compensatory changes in renal hemodynamics and tubular sodium handling that drive impairments in renal function and highlights the existence of sex differences in the functional adaptations following the loss of a kidney during fetal life.

Sexual dimorphism: the aging kidney, involvement of nitric oxide deficiency, and angiotensin II overactivity

Females develop less age-dependent loss of renal function, which may be in part due to cardiorenal protective effects of estrogens. The impact of androgen level on cardiovascular-renal health is controversial. Estrogen acts through multiple mechanisms, sometimes beneficial, sometimes damaging, which makes it difficult to predict the effect of hormone replacement therapy (HRT) in an aging population. Nitric oxide (NO) deficiency occurs in aging and contributes to age-dependent cardiovascular risk and kidney damage. The increased oxidative stress of aging has effects at multiple sites in the NO biosynthetic pathway to lower NO production/action. Loss of NO together with activated angiotensin promotes some of the decrements in cardiovascular-renal function seen with age, which may be related to actions of the sex steroids.

Hypercholesterolemia promotes early renal dysfunction in apolipoprotein E-deficient mice

Background

Aging and dyslipidemia are processes which can lead to deleterious consequences to renal function. Therefore, the aim of this study was to determine the effects of both hypercholesterolemia and aging on renal function in mice.

Methods

Male hypercholesterolemic apolipoprotein E-deficient mice (ApoE, n = 13) and age-matched C57BL/6 control mice (C57, n = 15) were studied at 2 (young) and 8 (adult) month-old. At each time point, animals were placed in metabolic cages for 24 hours to urine volume and urinary creatinine quantification. Blood samples were collected for serum cholesterol, urea and creatinine measurements. Glomerular filtration rate (GFR) was estimated through creatinine clearance determination. Mesangial expansion was evaluated by Periodic Acid Schiff staining, renal fibrosis was determined through Masson's trichrome staining and neuronal nitric oxide synthase (nNOS) expression in the kidney was performed by Western Blotting. To statistical analysis two-way ANOVA followed by Fisher's post hoc test was used.

Results

Total plasma cholesterol was increased about 5-fold in ApoE mice at both time points compared to C57 animals. At 2-month-old, GFR was already markedly reduced in ApoE compared to C57 mice (187 ± 28 vs 358 ± 92 μL/min, p < 0.05). Adult C57 (-77%) and ApoE (-50%) mice also presented a significant reduction of GFR. In addition, serum urea was significantly increased in young ApoE animals compared to C57 mice (11 ± 1.3 vs 7 ± 0.9 mmol/L, p < 0.01). A significant mesangial expansion was observed at 2-month old ApoE mice compared to C57 mice (35 ± 0.6 vs 30 ± 0.9%, respectively, p < 0.05), which was aggravated at 8-month old animals (40 ± 3 and 35 ± 3%, respectively). Tubulointersticial fibrosis was augmented at both young (17 ± 2%, p < 0.05) and adult (20 ± 1%, p < 0.05) ApoE mice compared to respective C57 age controls (8 ± 1 and 12 ± 2%, respectively). The expression of nNOS was markedly reduced in a time-dependent manner in both strains.

Conclusions

These data show that both hypercholesterolemia and aging contribute to the loss of renal function in mice.

Sexual dimorphism, the aging kidney, and involvement of nitric oxide deficiency

Females develop less age-dependent loss of renal function, in part because of cardiorenal protective effects of estrogens. The low androgen level in women also may be protective, although the animal and clinical data are controversial. Both estrogen and androgens act through multiple mechanisms, sometimes beneficial, sometimes damaging, which makes it difficult to predict the impact of hormone replacement therapy in an aging population. Nitric oxide (NO) deficiency contributes to age-dependent cardiovascular risk and kidney damage in animal models. The increased oxidative stress of aging impacts at multiple sites in the NO biosynthetic pathway to decrease NO production/action. Endothelial dysfunction develops with aging and is delayed in women, in association with a delayed increase in asymmetric dimethylarginine. Animal data suggest that the aging kidney develops NO deficiency because of changes in the neuronal NO synthase. Relative preservation of NO production in females contributes to the better cardiovascular and renal responses to aging.

Angiotensinogen genotype predicts abnormal renal hemodynamics in young hypertensive patients

OBJECTIVE

In essential hypertensive patients, blunted renal plasma flow responsiveness to angiotensin II suggests a pathologic increase in angiotensin II in the kidneys. This blunting has been associated with the angiotensinogen 235TT genotype. As several measures of renal function decline with age, we sought to determine the interaction of age and genotype on this intermediate phenotype.

DESIGN AND METHODS

Three hundred fifteen participants had renal plasma flow response to subpressor doses of angiotensin II (3 ng/kg/min) measured by para-aminohippuric acid clearance in high-sodium balance. Individuals were divided by median age into young (<45 years) and older (> or =45 years) sets. A subset of participants was also studied after administration of captopril.

RESULTS

Age, baseline renal plasma flow, BMI and angiotensinogen 235 genotype independently predicted renal plasma flow responsiveness to angiotensin II. Renal plasma flow responses were lower in older individuals than younger (P = 0.03, hypertensive patients; P = 0.004, normotensive individuals). Both hypertensive patients and normotensive individuals carrying either angiotensinogen 235MM or MT genotypes showed this inverse association (P = 0.005, hypertensive patients; P = 0.05, normotensive individuals). However, among angiotensinogen 235TT homozygotes the pattern differed: normotensive individuals had a fall in renal vascular responsiveness with age (P = 0.01) but hypertensive patients did not (P = 0.72). Young hypertensive patients already showed blunted responses. Of all genotype subsets, only angiotensinogen 235TT hypertensive patients showed enhancement (P = 0.03) of the renal vascular responsiveness to angiotensin II after captopril.

CONCLUSION

The angiotensinogen 235TT variant predicts premature blunting of renal vascular responsiveness among young hypertensive patients. This abnormal response is corrected by angiotensin-converting enzyme inhibition. This first report of age and genotype interaction may have important implications in the profiling and management of essential hypertension.

Sexual dimorphism of the aging kidney: role of nitric oxide deficiency

GFR falls with aging in humans and rats due to renal vasoconstriction and structural damage. The rate of deterioration is influenced by race/genetic background, environment, and sex, with females protected. Part of the female advantage relates to protective effects of estrogens. There is little information on impact of aging on the distribution/cardiovascular actions of the estrogen receptor subtypes. In rats, androgens may contribute to injury, but in men, high testosterone levels predict cardiovascular health. In women, the association is controversial. Nitric oxide deficiency contributes to the hypertension and renal dysfunction of aging, which may be delayed in the female.

Determination of reference arterial blood pressure values by indirect methods for Kangal dogs

OBJECTIVES

To obtain reference arterial blood pressure values from Kangal dogs, a local giant breed found in Turkey.

METHODS

Arterial blood pressure measurements were obtained from 48 healthy Kangal dogs using oscillometric and Doppler techniques. The ages of the dogs ranged from two to 96 months, with a mean (sd) age of 36 (16) months.

RESULTS

The effect of age on systolic, diastolic and mean arterial pressures determined by the oscillometric technique and on systolic pressure determined by the Doppler technique was significant (P<0.001). Blood pressure was found to be higher in mature dogs compared with that in immature dogs. The effect of sex and the interaction between age and sex were not significant (P>0.05). There was a direct relationship between age and oscillometric systolic, diastolic and mean arterial pressures and Doppler systolic arterial blood pressure both in the whole group and the immature group (P<0.05). Correlation between age and systolic arterial blood pressure measured either by oscillometric or Doppler techniques was not significant in the mature group.

CLINICAL SIGNIFICANCE

The Kangal dog is bred in various countries including Turkey. It is known that giant breed dogs, such as the Kangal dog, are predisposed to cardiovascular disease. Canine arterial blood pressure values are highly breed and age dependent, so a reference value for any other breed is inappropriate for Kangal dogs. Therefore, it is important to measure arterial blood pressure of Kangal dogs.

[Creatinine clearance and drug prescriptions for the elderly. A study of 419 patients older than 70 years admitted through the emergency department]

INTRODUCTION

The incidence of drug-related adverse events increases with age. In approximately 20% of cases, these events necessitate hospitalization. By taking into account the physiological changes associated with aging when prescribing drugs, physicians can prevent some of these events. The objective of this study was to analyze the prescriptions written by general practitioners for elderly patients admitted to the emergency department in relation to the patient's creatinine clearance.

PATIENTS AND METHODS

Of 968 consecutive patients older than 70 years, 419 underwent a plasma creatinine assay on admission and were included in this study. Creatinine clearance was calculated with Cockcroft's formula. The patients were classified into two groups according to creatinine clearance:<30 mL/min (group I) and >or=30 mL/min (group II).

RESULTS

Creatinine clearance was<30 mL/min in 84 of the 419 patients (group I) and >or=30 mL/min in 335 (group II). Mean age was significantly higher in group I than in group II (87 +/- 6 vs 81 +/- 6 years, p<0.001), as was mean plasma creatinine concentration (113 +/- 23 vs 83 +/- 19 mmol/L, p<0.001), while mean weight was significantly lower (57 +/- 10 vs 69 +/- 13 kg, p<0.001. In group I, 82 drugs with precautions concerning renal function had been prescribed for 69 (82%) patients, and in group II, 331 such drugs for 174 (52%) patients. Of the 82 drugs prescribed in group I that required precaution, 47 (57%) were contraindicated or prescribed at an inappropriate dose in view of the creatinine clearance. Irrespective of pharmacokinetic parameters, the mean number of drugs taken per patient was 5 +/- 2 in group I and 6 +/-2 in group II.

CONCLUSION

In prescribing drugs for elderly patients, especially those whose weight is low, careful attention should be paid to renal function.

Changes in renal hemodynamics and structure in the aging kidney; sexual dimorphism and the nitric oxide system

With advancing age the kidney shows both functional declines (falls in GFR) and development of structural damage. In most individuals this occurs slowly and does not lead to severe renal impairment unless additional insults are superimposed. There is a pronounced sexual dimorphism with females protected, due both to beneficial effects of the estrogens and damaging effects of androgens, some of which act directly on the glomerular mesangial cell to regulate growth and extracellular matrix production. Nitric oxide is a major factor in regulation of vascular tone and growth and becomes deficient with advancing age, as endothelial dysfunction develops. Although the abundance of the substrate, L-arginine, is well maintained during aging, there are increases in the concentration of circulating endogenous nitric oxide synthase (nNOS) inhibitors, which will contribute, to the endothelial dysfunction. There is a clear sexual dimorphism in the NO system, with pre-menopausal females producing more NO than men. Within the kidney, declines in the abundance and activity of the neuronal form of the nitric oxide synthase (nNOS) correlate with development of disease. In the male rat where injury and dysfunction occurs, nNOS abundance declines markedly, whereas in the protected female, renal nNOS abundance is maintained. Taken together, it is likely that age-dependent declines in NO generation contribute to age-dependent kidney damage.

Kidney Aging: From Phenotype to Genetics

Aging is a physiological process that causes structural and functional changes in human body systems, sometimes leading to various organ failure. As far as the kidney is concerned, both genetic factors and environmental agents may influence the tissues damage in elderly people and the related loss of function. On the other hand, functional adaptations to structural changes appear to be compromised by co-morbid conditions that are frequently found in elderly people, such as atherosclerosis and hypertension. It is not yet known whether physiological aging is inevitably accompanied by a decline in renal function or how rapidly it might happen. The discovery of molecular mechanisms responsible for tissue damage in aging could offer new perspectives on interventions. The role of nitric oxide, oxidative stress, the renin-angiotensin system, changes in length of telomeres, and klotho gene expression are important subjects for further in-depth studies about aging. A better understanding of physiological renal aging could improve the clinical approach to this process and widen the therapeutic possibilities offered by transplantation.

beta-Blockers in hypertension: is carvedilol different?

Most studies assessing the effects of beta-blockers were carried out with traditional, beta(1)-selective beta-blockers, such as metoprolol and atenolol. Pathophysiologic and pharmacologic studies have documented that not all beta-blockers are created equal. In particular, the pharmacologic and clinical profiles of the newer, vasodilating beta-blockers, such as carvedilol, have been shown to differ from those of the traditional beta-blockers. These differences, although relevant in the younger patient with hypertension, are particularly important in elderly patients in whom traditional beta-blockers may not be as effective or as well tolerated as the newer vasodilating agents.

Essential hypertension

Hypertension is a frequent, chronic, age-related disorder, which often entails debilitating cardiovascular and renal complications. Blood pressure is usually noted in combination with other cardiovascular risk factors. Diagnosis of hypertension increasingly relies on automated techniques of blood pressure measurement. The pathophysiology of essential hypertension depends on the primary or secondary inability of the kidney to excrete sodium at a normal blood pressure. The central nervous system, endocrine factors, the large arteries, and the microcirculation also have roles in the disorder. Although monogenic forms of blood pressure dysregulation exist, hypertension mostly arises as a complex quantitative trait that is affected by varying combinations of genetic and environmental factors. Non-pharmacological strategies can reduce blood pressure. Antihypertensive drug treatment diminishes the complications of hypertension. The concept that a few major genes will provide the final clue to the pathogenesis of essential hypertension is an oversimplification that contradicts the heterogeneous nature of this disorder. Further integration of genetic, molecular, clinical, and epidemiological research could disclose subsets of patients in whom specific combinations of genetic and environmental factors raise blood pressure, and might lead to more individualised treatment.

Asymmetric dimethylarginine, blood pressure, and renal perfusion in elderly subjects

BACKGROUND

Reduced availability of nitric oxide (NO) is thought to contribute to the age-associated increase of renovascular tone and blood pressure. We assessed blood concentrations of the endogenous NO synthase inhibitor asymmetric dimethylarginine (ADMA) as well as renal hemodynamics, comparing young (n=24, 13 men, 25+/-1 years) and elderly (n=24, 13 men, 69+/-2 years) healthy subjects and elderly subjects with essential hypertension (n=24, 13 men, 70+/-2 years).

METHODS AND RESULTS

Plasma ADMA concentration and renovascular resistance (RVR) were significantly higher (P<0.05) and effective renal plasma flow (ERPF) significantly lower (P<0.05) in elderly (2.77+/-0.20 micromol/L, 125+/-10 mm Hg/mL per minute, 487+/-26 mL/min per 1.73 m2) than in young healthy subjects (1.30+/-0.11, 77+/-3, 654+/-18). Both ADMA levels and RVR were higher and ERPF lower in the hypertensive elderly subjects (3.53+/-0.23, 163+/-11, 427+/-19; P<0.05 versus both groups). In contrast, plasma concentrations of the biologically inactive stereoisomer symmetric dimethylarginine, l-arginine, and homocysteine were similar in the 3 groups studied. In the logistic regression analysis only ADMA was an independent determinant of both ERPF (P<0.001; r2=0.80) and RVR (P<0.002; r2=0.86). In addition, ADMA (P<0.002) and serum glucose (P<0.036) were independently related (r2=0.67) to the level of blood pressure.

CONCLUSIONS

These results are compatible with the notion that accumulation of the endogenous NO synthase inhibitor ADMA in senescent individuals is involved in the decrease of renal perfusion and increase of blood pressure.

Left ventricular remodeling and renal function in never-treated essential hypertension

In the general population, renal function linearly declines with age; hypertension may accelerate this decline. Because concentric left ventricular (LV) hypertrophy is a strong marker of the severity of hypertension, the influence of LV geometry on the age-associated decline in renal function was assessed in 195 normotensive subjects and 645 patients with never-treated essential hypertension with an average duration of 30 mo. According to LV mass and relative wall thickness, hypertensive patients were divided into normal LV (NL, 48%), concentric remodeling (CR, 19%), and concentric (CH, 22%) and eccentric (EH, 11%) hypertrophy. GFR and effective renal plasma flow (ERPF) were estimated by isotopic clearance technique. GFR and ERPF were inversely correlated with age in normotensive and hypertensive subjects, and no marked influence of the BP level or the presence of LV hypertrophy was detected. However, the slope of the regression line of GFR versus age was accentuated (P < 0.01) in patients with CH or CR (slope values of -0.95 +/- 0.11, -0.86 +/- 0.14 ml/min per yr, respectively) when compared with patients with EH or NL (slope values of -0.58 +/- 0.16 and -0.58 +/- 0.08 ml/min per yr, respectively). No such results were obtained when creatinine clearance was considered. Urinary albumin excretion was higher in patients with concentric or eccentric LV hypertrophy than in patients with concentric LV remodeling or normal LV. These results demonstrate that in never-treated essential hypertension, the age-associated decline in GFR is markedly influenced by the concentric pattern of LV response to hypertension rather than the level of BP and/or the presence of LV hypertrophy.

Why beta-blockers are not cardioprotective in elderly patients with hypertension

Despite the fact that beta-blockers have been used for the treatment of hypertension for more than 30 years, no study has shown that their use reduces morbidity and mortality in the elderly. To the contrary, the British Medical Research Council trial in the elderly documented that although blood pressure was lowered effectively and significantly by atenolol, morbidity and mortality in the beta-blocker group did not differ from that of the placebo group. Not only was beta-blocker monotherapy not effective, but patients who received the combination of beta-blockers and diuretics fared consistently worse than those on diuretics alone. beta-blockers are less effective than diuretics in lowering blood pressure, and are poorly tolerated in the elderly. The reason for their inefficacy in the elderly may be related to their inherent unfavorable effect on systemic hemodynamics and pathophysiologic findings in the arterial tree, heart, kidneys, brain, and on the metabolism of lipids and carbohydrates. Decreased beta-adrenergic responsiveness with age and comorbid conditions makes beta-blockers unattractive. Thus, they should not be considered appropriate for first-line therapy of uncomplicated hypertension in the geriatric population.

Pulsating renal blood flow distribution measured using power Doppler ultrasound: correlation with hypertension

Arterial compliance is associated with the first stage of hypertension and atherosclerosis. We propose here a compliance index, which measures pulsating renal blood flow distribution using a power Doppler ultrasound (US). We assessed the relationship between the compliance index and blood pressure and between the compliance index and risk factors of atherosclerosis. The subjects consisted of 136 consecutive patients (96 males, 40 females) who underwent a physical checkup. Ages ranged from 40 to 60 years with a mean of 50.1 years. Patients with past renal disease and/or renal dysfunction were excluded. Using a power Doppler US combined with an ECG-gated and echo-tracking system, we recorded the vascular distribution of the renal parenchyma at 8 to 10 time points during an interval of the R wave of the ECG. Using a color pixel counting technique, we calculated the area (A) corresponding to the colored vascular distribution at power Doppler US. The relationships between A and the time points (t) were fitted to a quadratic equation. The compliance index of renal parenchymal vessels was obtained by twice differentiating the quadratic equation obtained above (d2A/dt2), and taking the result as a new hemodynamic index. In the univariate correlation analysis, the compliance index was correlated with age (r=-0.26, p=0.002), systolic blood pressure (r=-0.33, p=0.0001), diastolic blood pressure (r=-0.45, p<0.0001), serum uric acid (r=-0.28, p=0.001), and body mass index (r=-0.32, p=0.0002). On the multivariate stepwise regression analysis, the compliance index was significantly correlated with diastolic blood pressure (beta=-0.36, p<0.0001) and body mass index (beta=-0.18, p<0.0001). In conclusion, the compliance index is a candidate for a new hemodynamic marker of renal blood flow abnormality caused by hypertension.

Renal function in the oldest-old on an acute geriatric ward

AIM

Evaluation of renal function and relation to risk factors for renal failure in very old patients admitted to an acute geriatric ward.

METHODS

Retrospective chart review of patients aged 80 years and over, admitted to the acute geriatric ward from August 1998 till August 1999. Recorded data were: age, gender, previous medical history, primary diagnosis, medication use, weight, serum creatinine, BUN, sodium, potassium, cholesterol, urine and ultrasound of the kidney. The creatinine clearance was estimated by the Cockcroft-Gault formula, the glomerular filtration rate by the MDRD equation.

RESULTS

220 (60 males/160 females) patients were included. The mean serum creatinine on admisssion and discharge was 1.17 +/- 0.45 mg/dL and 1.11 +/- 0.48 mg/dL respectively. The mean estimated creatinine clearance in the very old was 38.11 +/- 12.04 mL/min on admission and 39.00 +/- 11.01 mL/min on discharge. Renal failure arbitrarily defined as an estimated creatinine clearance on admission of less than 30 mL/min was found in 26.4% of the patients. Only a significant correlation between failure to thrive and renal failure was found (p < 0.0001). The correlation coefficient between the Cockcroft-Gault and the MDRD formula was r = 0.66 (p < 0.0001); between the Cockcroft-Gault and the reciprocal serum creatinine was r = 0.60 (p < 0.0001) and between the MDRD and the reciprocal serum creatinine was r = 0.87 (p < 0.0001).

CONCLUSION

The weak correlation between the Cockcroft-Gault and other estimations of GFR in the acutely ill elderly, confirms the need to have a reliable estimation of glomerular filtration rate in the elderly. Renal failure defined as a Cockgroft-Gault <30 mL/min is found in 26.4% of the oldest-old admitted to an acute geriatric department. The elderly with renal failure is more often admitted for failure to thrive. No great differences were observed between renal function on admission and discharge.

Glucose tolerance and age-associated decline in renal function of hypertensive patients

BACKGROUND

Renal function is thought to decrease with age in the general population, but the determinants of this age-associated evolution are poorly understood. Hypertension and diabetes mellitus, two leading causes of chronic renal failure in the elderly, may accelerate this decline.

PATIENTS AND METHODS

Urinary clearances of [99mTc]diethylene triaminopentaacetic acid (DTPA) (glomerular filtration rate) and [131I]hippuran (effective renal plasma flow) were assessed in 227 never-treated essential hypertensives aged 20-69 years. Based on the oral glucose tolerance test, the study population consisted of 4% patients with previously unknown diabetes mellitus, 24% with impaired glucose tolerance and 72% with normal glucose tolerance.

RESULTS

When the population of 218 non-diabetic subjects was considered, glomerular filtration rate was inversely correlated with age and arterial blood pressure, and positively correlated with effective renal plasma flow, filtration fraction and fasting plasma glucose. In multivariate analysis, age and blood pressure were independent determinants of renal plasma flow, whereas renal plasma flow, age and fasting plasma glucose were independent determinants of glomerular filtration rate. The slope of the regression line relating glomerular filtration rate to age was steeper in patients with impaired glucose tolerance than in those with normal glucose tolerance (-1.52 +/- 0.28 versus -0.65 +/- 0.12, P < 0.01).

CONCLUSIONS

These results suggest that impaired glucose tolerance, which is seldom searched for in patients with essential hypertension, may be an important determinant of the age-associated decline in renal function.

Clinical usefulness of duplex ultrasonography for the assessment of renal arteriosclerosis in essential hypertensive patients

The present study was carried out to investigate whether the renal resistive index (RRI), obtained by ultrasonic duplex scanning, is useful for the evaluation of renal arteriosclerosis in essential hypertensive patients. We also studied the relationships between RRI and other kinds of hypertensive target-organ damage, including carotid atherosclerosis. One hundred and two patients (56.4+/-9.4 years) with untreated mild or moderate essential hypertension were examined. The normal range of RRI was determined for 12 normal age-matched volunteers (55.0+/-6.6 years). Hypertensive organ damage was evaluated by funduscopy, electrocardiograms, and carotid B-mode imaging. Based on the mean and distribution of RRI in normal volunteers (0.60+/-0.05), the normal upper limit of RRI was found to be 0.7. RRI was correlated with creatinine clearance (CCr) (r=-0.61, p<0.05), and blood urea nitrogen (r=0.46, p<0.05), but not with serum creatinine. In addition, the incidence of abnormal RRI (>0.7) was higher in patients with left ventricular hypertrophy and in those with advanced carotid atherosclerosis (p<0.01, respectively). Thus, RRI appears to be more strongly associated with CCr than with serum creatinine, and it increases in patients with hypertensive end-organ damage. The assessment of RRI may be useful for the evaluation of early renal damage in essential hypertension.

Non-invasive blood pressure measurements in cats: clinical significance of hypertension associated with chronic renal failure

The systolic, mean and diastolic pressures as well as the heart rate were measured using the oscillometric method, on a total of 104 cats (60 cats in the normal group, and 44 in the renal disease group) which were brought into Azabu University Animal Hospital. The blood pressure in the normal group was systolic: 115.4 +/- 10.1 mmHg, mean: 96.2 +/- 12.2 mmHg, and diastolic: 73.7 +/- 10.7 mmHg. Although no difference in heart rate, the renal disease group showed significantly (p < 0.05) higher values for systolic, mean, and diastolic pressure when compared with the normal group. Moreover, when plasma renin activity, angiotensin I and II, and aldosterone concentrations were measured in other cats (11 normal and seven with chronic renal failure), all cats with chronic renal failure showed significantly (p < 0.05) higher values than the normal group. It is, therefore, indicated that hypertension due to stimulating renin-angiotensin-aldosterone system may have manifested in cats with renal dysfunction.

A clinical evaluation of blood pressure through non-invasive measurement using the oscillometric procedure in conscious dogs

The oscillometric procedure was used to measure the heart rate as well as the systolic, mean, and diastolic blood pressures of 152 dogs (102 in the control group, 13 in the group with renal disease, 37 in the group with heart disease) who were brought to Azabu University of Veterinary Teaching Hospital. It was demonstrated that the blood pressure and heart rate of the control group lowered and tended to become stable as the number of measurements increased. No appreciable difference was identified in the measurements of either blood pressure or heart rate in the forelimbs and tail head. With regard to gender, males showed a significantly higher value than females (p < 0.05). No interaction was identified between age and blood pressure. No difference was identified in the heart rate in all groups. In an investigation of blood pressure in all groups, the renal disease group showed significantly higher values (p < 0.05) than either the control or the heart disease group in all values of systolic, mean and diastolic pressures. These results indicated that dogs with renal disease can manifest hypertension.

Renal function in the elderly: impact of hypertension and cardiac function

In senescence renal function is thought to decline markedly even in the absence of renal disease. It has also been proposed that the changes in renal function with age are not uniform and that confounding factors such as hypertension or atherosclerosis may play a role. We performed a comprehensive study to compare several aspects of renal function in four groups: (i) young healthy normotensive subjects (N = 24; 13 males; mean age 26 +/- 3 years); (ii) elderly healthy normotensive subjects (elderly NT; N = 29; 13 males; 68 +/- 7 years); (iii) elderly treated and untreated hypertensive patients (elderly HT; N = 25; 13 males; 70 +/- 6 years); and (iv) elderly patients with compensated mild to moderate heart failure (elderly HF; N = 14; 6 males; 69 +/- 6 years). Compared to young subjects mean GFR (C(In)) and ERPF (C(PAH)) were significantly lower in the elderly, despite similar mean plasma creatinine levels (young, 121 +/- 11, 650 +/- 85 ml/min/1.73 m2; elderly NT, 103 +/- 11, 486 +/- 102; elderly HT, 103 +/- 13, 427 +/- 55; elderly HF, 92 +/- 14, 377 +/- 103). Nevertheless, GFR was within the normal range in the majority of elderly NT and HT, but not in elderly HF. ERPF was significantly lower in elderly HT as compared with elderly NT, and still lower in elderly HF. Mean renovascular resistance and filtration fraction were significantly higher in the elderly, particularly in elderly HT and HF as compared with the young. Mean fractional excretion of Na+ was similar in all groups studied, but the lithium clearance was significantly lower in the elderly, suggesting a greater proximal and less distal sodium reabsorption in senescence. In the elderly, mean PTH concentration and urinary excretion of pyridoline cross-links were significantly higher and mean 25-(OH)D3, calcitriol and phosphate concentrations significantly lower; the correlation between PTH and GFR was significant (r = -0.432, P < 0.001). The results document that the decrease in renal hemodynamics with senescence is less marked than suggested by some studies using less stringent methodology and inclusion criteria. Comorbid conditions confound renal function in the elderly. Age-associated changes in renal hemodynamics are accompanied by significant alterations of renal hormones and of renal sodium handling.

Computed tomography-derived intrarenal blood flow in renovascular and essential hypertension

The effect of renal artery stenosis on intrarenal perfusion and volume in renovascular hypertensive patients is unclear. Alterations in these attributes may ultimately be involved in deterioration of renal function. We measured whole kidney, cortical, and medullary perfusion and volume with electron beam computed tomography (EBCT) in 33 hypertensive patients, with well-preserved renal function, scheduled for renal angiography. EBCT-derived whole kidney perfusion was lower in patients with atherosclerotic renal artery stenosis (RAS; N = 20) than in fibromuscular dysplasia (FMD; N = 10) or essential hypertension (N = 28; P < 0.05), as was cortical perfusion (2.44 +/- 0.16 vs. 3.26 +/- 0.17 and 3.07 +/- 0.09 ml/min/cc tissue, respectively, P < 0.005), but medullary perfusion was similar. Whole kidney, cortical, and medullary perfusion correlated inversely with degree of stenosis in FMD, but not in atherosclerotic RAS. Renal volumes were similar. These results demonstrate that, in contrast to patients with FMD, in patients with atherosclerotic RAS the decrease in cortical perfusion is not directly related to the degree of stenosis in the main renal artery. Factors other than the stenosis itself may play a role in the pathophysiology of atherosclerotic RAS and associated renal failure.

Does the renin-angiotensin system determine the renal and systemic hemodynamic response to sodium in patients with essential hypertension?

Many patients with essential hypertension respond to a high dietary sodium intake with a rise in blood pressure. Experimental evidence suggests that the renal hemodynamic response to sodium determines, at least partially, this rise in blood pressure. Our aim was to clarify the role of the renin-angiotensin system in the renal and systemic adaptation to a change in dietary sodium. We studied changes in mean arterial pressure (MAP) (millimeters of mercury), effective renal plasma flow (ERPF), body weight, and immunoreactive renin in 17 patients with essential hypertension and 15 normotensive control subjects, randomly crossing over between a 3-week sodium-restricted (50 mmol/24 h) and a sodium-replete (200 mmol/24 h) diet period. In addition, the effects of renin inhibition by remikiren (600 mg, single oral dose) were studied during the high sodium period. In normotensive control subjects, high sodium intake had no effect on MAP or body weight, whereas ERPF increased (490 +/- 19 to 535 +/- 21 mL/min, P < .05) and immunoreactive renin decreased (32 +/- 6 to 14 +/- 1 pg/mL). In hypertensive subjects, high sodium intake induced a heterogeneous response of MAP (median change, 2.6 mm Hg; range, -4.7 to +21.2; P = NS) and ERPF (median change, 21 mL/min; range, -33 to +98; P = NS). Body weight increased from 81.3 +/- 1.9 to 82.5 +/- 2.0 kg (P < .05), and immunoreactive renin decreased from 18 +/- 3 to 10 +/- 1 pg/mL (P < .05). Interestingly, the patients with a distinct rise in MAP showed a blunted ERPF response to high sodium intake (r = -.70, P < .01) and an increase in body weight (r = .76, P < .001). Moreover, the increase of ERPF was more pronounced in patients with a larger fall in immunoreactive renin (r = .77, P < .001). After administration of remikiren, a heterogeneous response in ERPF was observed: the patients with the blunted ERPF response to high sodium intake showed the largest ERPF rise (r = .70, P < .01). The remikiren-induced rise in ERPF correlated (r = .68, P < .01) with the fall in MAP (114 +/- 2 to 110 +/- 2 mm Hg). In conclusion, in patients with essential hypertension a rise in blood pressure in response to high sodium intake appears to partially be the result of insufficient renal vasodilatation. This seems to be due to an inadequate (intrarenal?) renin-angiotensin system response to increased sodium intake.

ACE inhibitors. Differential use in elderly patients with hypertension

High blood pressure (BP) in the elderly must not be ignored as a normal consequence of aging. The criteria for the diagnosis of hypertension and the necessity to treat it are the same in elderly and younger patients. The aim of treatment of elderly hypertensive patients is to decrease BP safely and to reduce risk factors associated with cerebrovascular, cardiovascular and renal morbidity and mortality. The treatment of elderly hypertensive patients should be adjusted according to the needs of the individual, based upon age, race, severity of hypertension, co-existing medical problems, other cardiovascular risk factors, target-organ damage, risk-benefit considerations and costs. In addition to the elevated BP, other cardiovascular risk factors include smoking, glucose intolerance, hyperinsulinaemia, dyslipidaemia, hypercreatininaemia, peripheral vascular disease, left ventricular hypertrophy, and microalbuminuria (or albuminuria). Thus, the choice of initial antihypertensive therapy in elderly hypertensive patients should be based not only on the expected response, but also on the effects of therapy on lipid, potassium, glucose and uric acid levels, and left ventricular anatomy and function. Co-existing medical conditions (such as asthma, diabetes mellitus, heart failure, renal failure, gout, coronary artery disease, hyperlipidaemia and peripheral vascular disease) are major determinants for the selection of antihypertensive medications. With previous therapies (diuretics, beta-blockers, etc.), good BP control in the elderly was associated with clear and statistically significant reductions in stroke-related morbidity and mortality, but the overall effects on cardiovascular and renal complications of hypertension was either more variable or less obvious. Angiotensin converting enzyme (ACE) inhibitors are not only efficacious antihypertensive agents in the elderly, but also appear promising in counteracting some of the cardiovascular and renal consequences of hypertension. They are well tolerated and have a relatively low incidence of adverse effects. ACE inhibitors possess ancillary characteristics that are potentially beneficial for many elderly patients, including reduction of left ventricular mass, lack of metabolic and lipid disturbances, no adverse CNS effects, no risk of induction of heart failure, and a low risk of orthostatic hypotension. Since ACE inhibitors may improve perfusion to the heart, kidney and brain, they are well worth considering for the treatment of elderly patients with hypertensive target organ damage, especially in patients with heart failure, and diabetic patients with early nephropathy.

Hypertension in the elderly

Elderly people have a very high prevalence of hypertension, which markedly increases their risk for cardiovascular morbidity and mortality. Convincing evidence demonstrates the effectiveness of antihypertensive therapy in reducing these risks significantly. With appropriate caution, most elderly hypertensives can be treated and thereby protected from many of the debilities of old age.