Circadian rhythm of natriuresis is disturbed in nondipper type of essential hypertension

Circadian rhythm in hypertension: Bibliometrics and knowledge mapping from 1990 to 2022

Recently, research on the circadian rhythm of hypertension has gained popularity. However, few bibliometric analyses have been conducted in this field. In this study, CiteSpace 6.1. R6, VOSviewer 1.6.18, R language (version 4.2.3), R package Bibliometrix (4.1.2), and Microsoft Excel 365 were used to conduct the data mining and knowledge visualization analysis. A total of 1,560 papers from 1,825 institutions in 77 countries were included. Research on the role of circadian rhythms in hypertension is increasing annually. Overall, Chronobiology International published the most literature and Hypertension received the most citations. Ramon Hermida from the Universidade de Vigo in Spain published the most papers and had the most citations. The United States of America and Japan have been the most productive countries. The University of Ferrara, Universidade de Vigo, and the University of California system produced the most publications. Amongst authors, Hermida had the most and longest literature bursts. Keywords such as "chronic kidney disease," "oxidative stress," and "gene expression" have been breakout keywords since 2014. This study revealed the dynamic evolution of research on circadian rhythms in hypertension and provides a knowledge base for researchers.

Sleep blood pressure measured using a home blood pressure monitor was independently associated with cardiovascular disease incidence: the Nagahama study

BACKGROUND

Nocturnal blood pressure (BP) is associated with cardiovascular disease independently of awake BP. However, nocturnal BP measured using an ambulatory monitoring device has limited reproducibility because it is a single-day measurement. We investigated the association between sleep BP measured on multiple days using a timer-equipped home BP monitor and cardiovascular diseases in a general population.

METHODS

The study population comprised 5814 community residents. Participants were required to sleep with wrapping cuffs on their upper arm and BP was measured automatically at 0 : 00, 2 : 00, and 4 : 00. Actigraph was used to determine BP measured during sleep. Participants were also measured home morning and evening BP manually using the same device.

RESULTS

During the 7.3-year mean follow-up period, we observed 117 cases of cardiovascular diseases. The association between sleep BP (per 10 mmHg hazard ratio = 1.31, P < 0.001) and cardiovascular events remained significant (hazard ratio = 1.22, P = 0.036) even after adjusting for office BP and confounding factors, such as sleep-disordered breathing. Individuals with sleep-only hypertension (n = 1047; hazard ratio = 2.23, P = 0.005) had a significant cardiovascular risk. Daytime-only hypertension (n = 264; hazard ratio = 3.57, P = 0.001) and combined sleep and daytime hypertension (n = 1216; hazard ratio = 3.69, P < 0.001) was associated with cardiovascular events to the same extent. Sleep BP dipping was not identified as a significant determinant of cardiovascular events.

CONCLUSION

Sleep BP measured using a home BP monitor was independently associated with the incidence of cardiovascular disease in a general population.

Sex difference in nocturnal blood pressure dipping in adolescents with varying degrees of adiposity

BACKGROUND

For adolescents, abnormal dipping patterns in blood pressure (BP) are associated with early-onset organ damage and a higher risk of cardiovascular disorders in adulthood. Obesity is one of the most common reasons for abnormal BP dipping in young people. However, it is unknown whether the severity of obesity is associated with BP dipping status and whether this association is sex-dependent.

METHODS

499 participants between 12 and 17 years old with overweight or obesity underwent ambulatory blood pressure monitoring (ABPM) between April 2018 and January 2019 in Beijing and Baoding. Participants were grouped by body mass index (BMI) into overweight (BMI 85th-95th percentile), obese (BMI ≥ 95th percentile) and severely obese (BMI ≥ 120% of 95th percentile or ≥ 35 kg/m2) groups. Non-dipping was defined as a < 10% reduction in BP from day to night. The interaction effect between sex and obesity degree was also analyzed.

RESULTS

326 boys and 173 girls were included, of whom 130 were overweight, 189 were obese, and 180 were severely obese. Girls with severe obesity had a higher prevalence of non-dipping, but boys showed no significant differences in BP dipping status between obesity categories. In addition, as obesity severity went up, a more evident increase in night-time SBP was observed in girls than in boys.

CONCLUSIONS

Severely obese is associated with a higher prevalence of non-BP dipping patterns in girls than in boys, which suggests that the relationship between the severity of obesity and BP dipping status might be sex-specific.

d -Alanine Affects the Circadian Clock to Regulate Glucose Metabolism in the Kidney

Key Points

d -Alanine affects the circadian clock to regulate gluconeogenesis in the kidney. d -Alanine itself has a clear intrinsic circadian rhythm, which is regulated by urinary excretion, and acts on the circadian rhythm. d -Alanine is a signal activator for circadian rhythm and gluconeogenesis through circadian transcriptional network.

Background

The aberrant glucose circadian rhythm is associated with the pathogenesis of diabetes. Similar to glucose metabolism in the kidney and liver, d -alanine, a rare enantiomer of alanine, shows circadian alteration, although the effect of d- alanine on glucose metabolism has not been explored. Here, we show that d- alanine acts on the circadian clock and affects glucose metabolism in the kidney.

Methods

The blood and urinary levels of d -alanine in mice were measured using two-dimensional high-performance liquid chromatography system. Metabolic effects of d -alanine were analyzed in mice and in primary culture of kidney proximal tubular cells from mice. Behavioral and gene expression analyses of circadian rhythm were performed using mice bred under constant darkness.

Results

d- Alanine levels in blood exhibited a clear intrinsic circadian rhythm. Since this rhythm was regulated by the kidney through urinary excretion, we examined the effect of d -alanine on the kidney. In the kidney, d -alanine induced the expressions of genes involved in gluconeogenesis and circadian rhythm. Treatment of d- alanine mediated glucose production in mice. Ex vivo glucose production assay demonstrated that the treatment of d -alanine induced glucose production in primary culture of kidney proximal tubular cells, where d -amino acids are known to be reabsorbed, but not in that of liver cells. Gluconeogenetic effect of d -alanine has an intraday variation, and this effect was in part mediated through circadian transcriptional network. Under constant darkness, treatment of d- alanine normalized the circadian cycle of behavior and kidney gene expressions.

Conclusions

d- Alanine induces gluconeogenesis in the kidney and adjusts the period of the circadian clock. Normalization of circadian cycle by d -alanine may provide the therapeutic options for life style–related diseases and shift workers.

Twenty-four hour ambulatory blood pressure monitoring in patients with stable heart failure. Prevalence and associated factors

INTRODUCTION AND OBJECTIVES

Hypertension is highly common in heart failure (HF). However, there is limited information on its prevalence, circadian variation, and relationship with the various HF phenotypes. The objective of this study was to describe the prevalence of hypertension and its patterns in HF.

METHODS

This was a cross-sectional observational study of patients with optimized stable chronic HF. The patients underwent blood pressure (BP) measurement in the office and 24-hour ambulatory monitoring. We estimated the prevalence of hypertension, and its diurnal (controlled, uncontrolled, white coat, and masked) and nocturnal (dipper, nondipper, and reverse dipper) patterns. We also analyzed the factors associated with the different patterns and HF phenotypes.

RESULTS

From 2017 to 2021, 266 patients were included in the study (mean age, 72±12 years, 67% male, 46% with reduced ejection fraction). Hypertension was present in 83%: controlled in 68%, uncontrolled in 10%, white coat in 10%, and masked in 11%. Among patients with high office BP, 51% had white coat hypertension. Among those with normal office BP, 14% had masked hypertension. The prevalence of dipper, nondipper, and reverse dipper patterns was 31%, 43%, and 26%, respectively. Systolic BP was lower in HF with reduced ejection fraction than in HF with preserved ejection fraction (P <.001).

CONCLUSIONS

Ambulatory BP monitoring in HF identified white coat hypertension in more than half of patients with high office BP and masked hypertension in a relevant percentage of patients. The distribution of daytime patterns was similar to that of the population without HF in the literature, but most of the study patients had a pathological nocturnal pattern.

Dietary sodium restriction reduces blood pressure in patients with treatment resistant hypertension

PURPOSE

Patients with treatment resistant hypertension (TRH) are at particular risk of cardiovascular disease. Life style modification, including sodium restriction, is an important part of the treatment of these patients. We aimed to analyse if self-performed dietary sodium restriction could be implemented in patients with TRH and to evaluate the effect of this intervention on blood pressure (BP). Moreover, we aimed to examine if mechanisms involving nitric oxide, body water content and BNP, renal function and handling of sodium were involved in the effect on nocturnal and 24-h BP. Also, measurement of erythrocyte sodium sensitivity was included as a possible predictor for the effect of sodium restriction on BP levels.

PATIENTS AND METHODS

TRH patients were included for this interventional four week study: two weeks on usual diet and two weeks on self-performed sodium restricted diet with supplementary handed out sodium-free bread. At the end of each period, 24-h BP and 24-h urine collections (sodium, potassium, ENaC) were performed, blood samples (BNP, NOx, salt blood test) were drawn, and bio impedance measurements were made.

RESULTS

Fifteen patients, 11 males, with a mean age of 59 years were included. After sodium restriction, urinary sodium excretion decreased from 186 (70) to 91 [51] mmol/24-h, and all but one reduced sodium excretion. Nocturnal and 24-h systolic BP were significantly reduced (- 8 and - 10 mmHg, respectively, p < 0.05). NOx increased, BNP and extracellular water content decreased, all significantly. Change in NOx correlated to the change in 24-h systolic BP. BP response after sodium restriction was not related to sodium sensitivity examined by salt blood test.

CONCLUSION

Self-performed dietary sodium restriction was feasible in a population of patients with TRH, and BP was significantly reduced. Increased NOx synthesis may be involved in the BP lowering effect of sodium restriction.

TRIAL REGISTRATION

The study was registered in Clinical trials with ID: NCT06022133.

Circadian Urinary Excretion of Water, and Not Salt, Is Affected by the White Coat Effect

Hypertension is an important morbidity factor. The prognostic consequences of the white-coat effect have been studied extensively. The repercussion on the circadian rhythm of urinary water and salt excretion in the same subgroup remain, conversely, among the open topics. Postulating an impaired diurnal sodium and volume excretion we decided to investigate both, in subjects with or without a white-coat effect, in the general population. A sample of 1023 subjects, has been considered. We collected 24-h urine samples, divided in day and night, and we measured the blood pressure with an Ambulatory Blood Pressure Monitoring (ABPM). ABPM values were then compared with physician collected in-office values to assign subjects to the group with or without the white-coat effect. Concerning the circadian pattern of urinary sodium excretion, we found no significant differences between the groups. There was instead in the white-coat effect group a higher night/day ratio of urinary water excretion. The white-coat effect, has been considered a potential hypertension precursor, and its consequent handling could be prospectively relevant in hypertension prevention. The absence of repercussions on the urinary circadian sodium excretion pattern and on the potentially related risk factors in subjects with a white coat effect is reassuring. The clinical significance of the impact on the night/day ratio of water excretion needs to be further investigated.

Pathophysiology of the Nondipping Blood Pressure Pattern

The nondipping blood pressure (BP) pattern corresponds to a disruption in the circadian BP rhythm with an insufficient decrease in BP levels during nighttime sleep as observed using 24-hour ambulatory BP monitoring. Patients with nondipping BP pattern have poorer renal and cardiovascular outcomes, independent of their average 24-hour BP levels. The pathophysiology of nondipping BP is complex and involves numerous mechanisms: perturbations of (1) the circadian rhythm, (2) the autonomic nervous system, and (3) water and sodium regulation. This review provides an outline of the pathways potentially involved in the nondipping BP profile in different conditions. A recent hypothesis is also discussed involving the role of gut microbiota in the dipping/nondipping patterns, via the fecal diet-derived short chain fatty acids.

Controversies in Hypertension III: Dipping, Nocturnal Hypertension, and the Morning Surge

A comprehensive approach to hypertension requires out-of-office determinations by home and/or ambulatory monitoring. The 4 phenotypes comparing office and out-of-office pressures in treated and untreated patients include normotension, hypertension, white-coat phenomena, and masked phenomena. Components of out-of-office pressure may be equally as important as mean values. Nighttime pressures are normally 10 - 20% lower than daytime (normal "dipping"). Abnormalities include dipping more than 20% (extreme dippers), less than 10 % (non-dippers), or rising above daytime (risers) and have been associated with elevated cardiovascular risk. Nighttime pressure may be elevated (nocturnal hypertension) in isolation or together with daytime hypertension. Isolated nocturnal hypertension theoretically changes white-coat hypertension to true hypertension and normotension to masked hypertension. Pressure normally peaks in the morning hours ("morning surge") when cardiovascular events are most common. Morning hypertension may result from residual nocturnal hypertension or an exaggerated surge and has been associated with enhanced cardiovascular risk, especially in Asian populations. Randomized trials are needed to determine whether altering therapy based solely on either abnormal dipping, isolated nocturnal hypertension, and/or an abnormal surge is justified.

Sleep Disorders, Comorbidities, Actions, Lower Urinary Tract Dysfunction, and Medications ("Sleep C.A.L.M.") in the evaluation and management of nocturia: A simple approach to a complex diagnosis

INTRODUCTION

Nocturia arises from a fundamental mismatch between nocturnal urine production, storage capacity, and sleep architecture, which may be driven by abnormalities of the genitourinary tract, but also by sleep disorders, medical diseases, patient actions/lifestyle factors, or medications. This article introduces a novel system for organizing the complex differential diagnosis for nocturia, as proposed by an international collective of practicing urologists, physician specialists, and sleep experts: "Sleep CALM"-Sleep Disorders, Comorbidities, Actions, Lower Urinary Tract Dysfunction, and Medications.

METHODS

Narrative review of current evidence regarding the relevance of each "Sleep CALM" factor to nocturia pathogenesis, evaluation, and management.

RESULTS

Nocturia and sleep disorders are highly intertwined and often bidirectional, such that nocturnal awakenings for reasons other than a sensation of bladder fullness should not be used as grounds for exclusion from nocturia treatment, but rather leveraged to broaden therapeutic options for nocturia. Nocturia is an important potential harbinger of several serious medical conditions beyond the genitourinary tract. Urologists should have a low threshold for primary care and medical specialty referral for medical optimization, which carries the potential to significantly improve nocturnal voiding frequency in addition to overall health status. Adverse patient actions/lifestyle factors, lower urinary tract dysfunction, and medication use commonly coexist with disordered sleep and comorbid medical conditions, and may be the primary mediators of nocturia severity and treatment response, or further exacerbate nocturia severity and complicate treatment.

CONCLUSION

"Sleep CALM" provides a memorable and clinically relevant means by which to structure the initial patient history, physical exam, and clinical testing in accordance with current best-practice guidelines for nocturia. Although not intended as an all-encompassing diagnostic tool, the "Sleep CALM" schema may also be useful in guiding individualized ancillary testing, identifying the need for specialty referral and multidisciplinary care, and uncovering first-line treatment targets.

Dipping Status, Ambulatory Blood Pressure Control, Cardiovascular Disease, and Kidney Disease Progression: A Multicenter Cohort Study of CKD

RATIONALE & OBJECTIVE

Ambulatory blood pressure (BP) monitoring allows concurrent evaluation of BP control and nocturnal BP dipping status, both related to adverse outcomes. However, few studies have assessed the prognostic role of combining information on dipping status and achieved ambulatory BP in patients with chronic kidney disease (CKD).

STUDY DESIGN

Prospective observational cohort study.

SETTING & PARTICIPANTS

906 patients with hypertension and CKD attending 1 of 3 Italian nephrology clinics.

EXPOSURE

Four groups were defined by simultaneously classifying systolic ambulatory BP levels as being at goal (daytime SBP <135 and nighttime SBP <120 mm Hg) or above goal, and the presence or absence of nocturnal dipping (nighttime to daytime SBP ratio of <0.9 versus ≥0.9).

OUTCOME

The composite of time to initiation of maintenance dialysis or estimated glomerular filtration rate (eGFR) decline ≥50%, and the composite of fatal and nonfatal cardiovascular events.

ANALYTICAL APPROACH

Multivariable Cox proportional hazards models were used to estimate risks of kidney disease progression and cardiovascular disease in the 4 exposure groups where nocturnal dipping with systolic ambulatory BP at goal was the reference group.

RESULTS

The mean patient age was 63.8 years, 61% were male, and 26.4% had diabetes; eGFR was 41.1 ± 20.8 mL/min/1.73 m². The dipping prevalence in each of the 4 groups was as follows: nocturnal dipping with ambulatory BP at goal, 18.6%; no nocturnal dipping with ambulatory BP at goal, 20.5%; nocturnal dipping with ambulatory BP above goal, 11.8%; and no nocturnal dipping with ambulatory BP above goal, 49.1%. Among patients with ambulatory BP above goal, the risk of cardiovascular events was greater in the absence (HR, 2.79 [95% CI, 1.64-4.75]) and presence (HR, 2.05 [95% CI, 1.10-3.84]) of nocturnal dipping. The same held true for risk of kidney disease progression (HRs of 2.40 [95% CI, 1.58-3.65] and 2.11 [95% CI, 1.28-3.48] in the absence and presence of nocturnal dipping, respectively). Patients at the ambulatory BP goal but who did not experience nocturnal dipping had an increased risk of the cardiovascular end point (HR, 2.06 [95% CI, 1.15-3.68]) and the kidney disease progression outcome (HR, 1.82 [95% CI, 1.17-2.82]).

LIMITATIONS

Lack of a diverse cohort (all those enrolled were White). Residual uncontrolled confounding.

CONCLUSIONS

Systolic ambulatory BP above goal or the absence of nocturnal dipping, regardless of ambulatory BP, is associated with higher risks of cardiovascular disease and kidney disease progression among patients with CKD.

PLAIN-LANGUAGE SUMMARY

Among patients with chronic kidney disease (CKD), ambulatory blood pressure (BP) monitoring improves the identification of individuals at high risk of clinical disease outcomes. Those with uncontrolled ambulatory BP are known to have a higher risk of developing cardiovascular disease and kidney disease progression, particularly when their ambulatory BP does not decline by at least 10% at night. Whether this is also true for patients with presence of optimal ambulatory BP levels but a BP pattern of no nighttime decline is largely unknown. We measured ambulatory BP in 900 Italian patients with CKD and followed them for several years. We found that, independent of ambulatory BP level, the absence of nighttime reductions in BP was associated with worsening of CKD and more frequent cardiovascular events. The absence of nighttime declines in BP is an independent risk factor for adverse events among patients with CKD. Future studies are needed to examine whether treating the absence of nighttime declines in BP improves clinical outcomes.

The relationship between sarcopenia and central hemodynamics in older adults with falls: a cross-sectional study

PURPOSE

Falls are an important cause of morbidity and mortality in geriatric patients. Sarcopenia and central blood pressure may be associated with falls. This study aimed to investigate the association between sarcopenia and blood pressure parameters in older patients with falls.

METHODS

A comprehensive geriatric evaluation of 72 elderly patients was performed using established assessment tests. Peripheral and central hemodynamic measurements, including office DBP and SBP, daytime-night peripheral and central DBP and SBP, cardiac output, augmentation index, pulse wave velocity (PWV), pulse rate, and peripheral resistance and reflection, were measured with a 24-hour ambulatory blood pressure measuring device.

RESULTS

Of 72 patients with a mean age of 77.51 ± 6.5 years, 12 (16.7%) were non-sarcopenic, 32 (44.4%) were probable, nine (12.5%) were confirmed, and 19 (26.4%) were severe sarcopenic. PWV, which is an indicator of arterial stiffness, was found to be significantly higher in the sarcopenic group. The other cardiac risk markers [daytime peripheral SBP, mean arterial pressure (night), pulse pressure (daytime), and peripheral resistance (daytime and night)] were significantly lower in the sarcopenic patients. PWV correlated with gait speed, Katz score, and hand grip strength (Spearman's rho: -0.337, -0.310, and -0.334; P < 0.001, 0.008, and 0.001, respectively). Age and hypertension were the most important factors increasing the risk of falls.

CONCLUSION

Sarcopenia is associated with central and peripheral blood pressure changes in patients with falls. When sarcopenia is diagnosed in older people with falls, 24-hour ambulatory peripheral and central pressures should be evaluated for cardiac risk screening.

Circadian rhythms and renal pathophysiology

The reality of life in modern times is that our internal circadian rhythms are often out of alignment with the light/dark cycle of the external environment. This is known as circadian disruption, and a wealth of epidemiological evidence shows that it is associated with an increased risk for cardiovascular disease. Cardiovascular disease remains the top cause of death in the United States, and kidney disease in particular is a tremendous public health burden that contributes to cardiovascular deaths. There is an urgent need for new treatments for kidney disease; circadian rhythm-based therapies may be of potential benefit. The goal of this Review is to summarize the existing data that demonstrate a connection between circadian rhythm disruption and renal impairment in humans. Specifically, we will focus on chronic kidney disease, lupus nephritis, hypertension, and aging. Importantly, the relationship between circadian dysfunction and pathophysiology is thought to be bidirectional. Here we discuss the gaps in our knowledge of the mechanisms underlying circadian dysfunction in diseases of the kidney. Finally, we provide a brief overview of potential circadian rhythm-based interventions that could provide benefit in renal disease.

Lowering of blood pressure and pulse rate by switching from DPP-4 inhibitor to luseogliflozin in patients with type 2 diabetes complicated with hypertension: A multicenter, prospective, randomized, open-label, parallel-group comparison trial (LUNA study)

AIMS

Sodium-glucose cotransporter-2 inhibitor (SGLT2i) reduces clinic blood pressure (BP), but the effects on BP circadian rhythm remain unclear. The present study aimed to determine the nighttime antihypertensive effect of SGLT2i compared with dipeptidyl peptidase-4 inhibitor (DPP-4i) in patients with type 2 diabetes and hypertension.

MATERIALS AND METHODS

In this randomized, open-label, parallel-group trial, patients treated with DPP-4i were either switched to luseogliflozin 2.5 mg/day (Luseo group;n = 30) or continued DPP-4i (DPP-4i group;n = 26). The patients undertook 24-h ambulatory BP monitoring before and 8 weeks after the group allocation. The primary endpoint was mean change in nighttime systolic BP (SBP).

RESULTS

Nighttime SBP, as well as daytime SBP, was significantly reduced in the Luseo group compared with the DPP-4i group (nighttime, -4.0 ± 11.4 vs. 3.6 ± 10.7 mmHg,P = 0.01; daytime, -4.4 ± 10.9 vs. 3.7 ± 11.9 mmHg,P = 0.01). Similarly, nighttimepulse rate(PR) was significantly reduced in the Luseo group (-2.0 ± 4.8 vs. 0.9 ± 4.8 bpm,P = 0.03). The proportion of patients with abnormal BP circadian rhythms (non-dipper pattern plus riser pattern) was significantly lower in the Luseo group (36.6% vs. 56.7%,P < 0.05).

CONCLUSIONS

Switching from DPP-4i to luseogliflozin decreased nighttime SBP and PR; moreover, BP circadian rhythm was improved.

Effect of nondipper hypertension on coronary artery disease progression in patients with chronic coronary syndrome

Background/aim

It has been suggested that there is a significant progress in coronary artery disease (CAD) by many pathophysiological mechanisms. Nondipper hypertension (NDH) has been shown to have higher target organ damage and have a higher rate of cardiovascular mortality and morbidity. In this study, we investigated the effect of nondipper hypertension on the progression of coronary atherosclerosis.

Materials and methods

A total of 186 patients who underwent coronary angiography twice between 6 months and 3 years were included in the study. Coronary angiography was repeated on the admission day due to angina or positive exercise test and the patients were divided into groups.

Results

Progression of coronary artery disease was detected in 58 of 186 patients. Seventy-one of the total patients were found to be nondipper hypertensive. Nondipper hypertension, hypertension, diabetes mellitus, low-density lipoprotein, and total cholesterol were found to be effective in the progression of CAD. Among these parameters, it was seen that nondipper hypertension and hyperlipidemia were the most important independent risk factors.

Conclusion

Coronary artery disease is a progressive disease, and this progression depends on many reasons. In our study, we showed that nondipper hypertension is a new parameter that is effective in CAD progression.

Association between dietary sodium intake and blood pressure variability in Chinese patients with hypertension

Background

The association between dietary sodium intake and blood pressure variability (BPV) in hypertensive patients remains unclear. The objective of this study was to demonstrate whether dietary sodium intake is a predictor of elevated BPV in Chinese patients with hypertension.

Methods

A total of 235 patients with essential hypertension were enrolled in the Department of Cardiology, Chinese People's Liberation Army (PLA) General Hospital in 2018 to 2019, all of whom underwent 24-h ambulatory blood pressure monitoring. BPV was calculated as the standard deviation (SD), coefficient of variation (CV), variation independent of mean (VIM) of blood pressure measurements, respectively, and divided into diurnal systolic BPV (SBPV), diurnal diastolic BPV (DBPV), nocturnal SBPV, and nocturnal DBPV. 24-h urine samples were collected to measure 24-h urine sodium excretion, which represents dietary sodium intake. The relationship between dietary sodium intake and BPV was analyzed by using Spearman correlations and multiple linear regression analysis.

Results

Nocturnal SBPV-SD, CV, VIM, and nocturnal DBPV-SD in the high urine sodium excretion group were significantly higher than those in the medium and low urine sodium excretion groups, whereas diurnal SBPV-SD, CV, VIM, diurnal DBPV-SD, CV, VIM, and nocturnal DBPV-CV, VIM were not. Using the Spearman correlation analysis, we found a linear correlation between 24-h urine sodium excretion and nocturnal SBPV-SD, CV, VIM (SD, r = 0.22, P = 0.001; CV, r = 0.17, P = 0.009; VIM, r = 0.16, P = 0.020), nocturnal DBPV-SD (r = 0.21, P = 0.001), respectively. After further adjusting for confounding factors by multiple linear regression, the positive correlations remained between 24-h urine sodium excretion and nocturnal SBPV-SD, CV, VIM (SD, β = 0.224, P < 0.001; CV, β = 0.211, P = 0.001; VIM, β = 0.213, P = 0.001), nocturnal DBPV (SD, β = 0.215, P = 0.001), respectively.

Conclusions

Dietary sodium intake is associated with nocturnal SBPV in Chinese patients with hypertension.

Pharmacologic management of nocturnal polyuria: a contemporary assessment of efficacy, safety, and progress toward individualized treatment

This narrative review synthesizes current evidence on the medical management of nocturnal polyuria, including antidiuretic replacement therapy as well as other emerging modalities, with particular emphasis on areas of active investigation and future research directions. Relative to earlier formulations, the pharmacological profiles of novel desmopressin acetate nasal spray and orally disintegrating tablet formulations appear favorable in optimizing the balance between efficacy and safety. Additionally, several highly selective small-molecule arginine vasopressin 2 receptor agonists are under active development, while appropriately timed short-acting diuretics, pharmacotherapy for hypertension, nonsteroidal anti-inflammatory drugs, and sex hormone replacement therapy are also a focal point of extensive ongoing nocturnal polyuria research. Emerging laboratory technologies now make feasible a sub-stratification of nocturnal polyuria patients into substrate-based phenotypes for individualized treatment. An increasingly refined understanding of the pathogenesis of nocturnal polyuria, and arginine vasopressin dysregulation in particular, has also introduced new opportunities for point-of-care testing in patients with nocturnal polyuria.

The hypothalamus and its role in hypertension

For the majority of hypertensive patients, the etiology of their disease is unknown. The hypothalamus is a central structure of the brain which provides an adaptive, integrative, autonomic, and neuroendocrine response to any fluctuations in physiological conditions of the external or internal environment. Hypothalamic insufficiency leads to severe metabolic and functional disorders, including persistent increase in blood pressure. Here, we discuss alterations in the neurochemical organization of the paraventricular and suprachiasmatic nucleus in the hypothalamus of patients who suffered from essential hypertension and died suddenly due to acute coronary failure. The changes observed are hypothesized to contribute to the pathogenesis of disease.

Nocturia and electrocardiographic abnormalities among patients at an inner-city cardiology clinic

AIMS

Nocturia has been increasingly recognized as a potential manifestation of cardiovascular disease. However, the relationship between nocturia and electrocardiographic (ECG) abnormalities has not been studied. This study aims to characterize the diagnostic utility of nocturia in identifying left ventricular hypertrophy (LVH), left atrial enlargement (LAE), and prolonged QTc on ECG.

METHODS

Retrospective analysis of nocturnal voiding frequency and contemporaneous ECG data from consecutive patients evaluated at a university-based outpatient cardiology clinic. Three sets of three incremental binary multiple logistic regression models controlling for (1) age, (2) sex and race, and (3) body mass index, hypertension, diabetes mellitus, and diuretic utilization were performed to determine whether nocturia was predictive of LVH, LAE, and prolonged QTc.

RESULTS

Included patients (n = 143, 77.6% nocturia) were predominantly African-American (89.5%), female (74.1%), and obese (61.5%), of whom 44.1%, 41.3%, and 27.3% had LVH, LAE, and prolonged QTc, respectively. Older age, African-American race, obesity, hypertension, diuretic use, LVH, and LAE were significantly associated with nocturia on univariate analysis. No significant differences were observed in the strength of associations between nocturia and LVH, LAE, or QTc prolongation based on age. Nocturia independently predicted LVH in Models I-III (odds ratios [ORs], 2.99-3.20; relative risks [RRs], 1.18 for all, p ≤ .046) and LAE in Models I-III (ORs, 4.24-4.72; RRs, 1.21 for all, p ≤ .015). No significant associations were observed between nocturia and prolonged QTc.

CONCLUSIONS

Nocturia may be a risk marker for underlying structural cardiac abnormalities.

The relationship between body fat ratio and blood pressure in school-age children

Hypertension (HTN) and obesity prevalences are rising in childhood and it is important to evaluate associations of these situations. The objective of this study is to investigate the relationship between HTN and body fat ratios (BFR) in children. This cross-sectional study was conducted among 134 participants who were directed to pediatric nephrology outpatient clinic with the prediagnosis of primary HTN. Weight, height, body fat ratio, blood pressure, and ambulatory blood pressure monitor (ABPM) was carried out for all the participants. Of the participants, 70 of them were diagnosed as hypertension with ABPM and included in the patient group, 64 of them had elevated office blood pressure (BP) but normotensive according to ABPM were included in the control group. Body fat ratio (BFR) levels of the patient group were higher than the control group (p < 0.05). There were significant linear correlation between night systolic blood pressure (SBP), night diastolic blood pressure (DBP), night mean arterial pressure (MAP), and BFR in the patient group (p < 0.05). There was a negative correlation between BFR and dipper (p = 0.022; p < 0.05) in the patient group. There was no correlation between BFR and blood pressures or dipper in the control group. According to our results BFR levels have significant association with HTN. According to our findings high BFR especially effects night BP, pulses, nondipping, and nighttime values can be evaluated only with ABPM. For prevention of HTN in children, caution should be given to monitor and lower BFR values.

Postpartum Hypertension

PURPOSE OF REVIEW

Hypertension affects approximately 10% of pregnancies and may persist in the postpartum period. Furthermore, de novo hypertension may present after delivery, but its exact prevalence is not verified. Both types of hypertension expose the mother to eventually severe complications like eclampsia, stroke, pulmonary edema, and HELLP (hemolysis, elevated liver enzymes, low platelet) syndrome.

RECENT FINDINGS

Until today, there are limited data regarding the risk factors, pathogenesis, and pathophysiology of postpartum hypertensive disorders. However, there is certain evidence that preeclampsia may in large part be responsible. Women who experienced preeclampsia during pregnancy, although considered cured after delivery and elimination of the placenta, continue to present endothelial and renal dysfunction in the postpartum period. The brain and kidneys are particularly sensitive to this pathological vascular condition, and severe complications may result from their involvement. Large randomized trials are needed to give us the evidence that will allow a timely diagnosis and treatment. Until then, medical providers should increase their knowledge regarding hypertension after delivery because many times there is an underestimation of the complications that can ensue after a misdiagnosed or undertreated postpartum hypertension.

Prevalence of the nocturnal polyuria syndrome in men

AIMS

Nocturnal polyuria (NP) is caused by a wide array of factors, including genitourinary and systemic comorbidities, modifiable behavior, and pharmaceuticals. When an identifying factor is absent, NP may be purely a symptom of the nocturnal polyuria syndrome (NPS) and secondary to blunting of normal arginine vasopressin action within the circadian rhythm. The purpose of this study is to determine the prevalence of NPS in male patients attending a Veterans Affairs outpatient urology clinic.

METHODS

Retrospective database analysis was performed of voiding diaries from men who had established care for lower urinary tract symptoms from 2007 to 2018. Patients were excluded if they reported fewer than two nocturnal voids on voiding diary analysis or had comorbidity associated with NP. Distinct cutoffs were separately employed to identify NP: nocturnal polyuria index (NPi; calculated as nocturnal urine volume divided by 24-hour urine volume) greater than 0.33; and nocturnal urine production (NUP) greater than 90 mL/h.

RESULTS

A total of 283 completed voiding diaries were evaluated and 202 patients had ≥2 nocturnal voids. After exclusions, at NPi greater than 33, the floor and ceiling NPS prevalence values were 21% and 41%, respectively. At NUP greater than 90 mL/h, the floor and ceiling NPS prevalence values were 17% and 32%, respectively.

CONCLUSIONS

The prevalence of NPS in patients with nocturia in the present study lies between 17% and 41%. NPS constitutes a clinically relevant subgroup of nocturia among male patients in the Veterans Affairs outpatient urology setting.

Blood Pressure Increases Before Pulse Rate During the Nocturnal Period in Hypertensive Patients

Ambulatory blood pressure monitoring (ABPM) is used for the evaluation of out-of-office blood pressure (BP), however, knowledge concerning the detailed behavior of nocturnal blood pressure (BP) and pulse rate (PR) is limited.A total of 190 participants (64 ± 15 years, 46.3% males) underwent ABPM for diagnosis of hypertension or evaluation of hypertensive therapy. BP and PR were measured automatically by the oscillometric method. From the hourly average ABPM values, the nocturnal time courses (0 AM to 6 AM) of SBP and PR were determined and compared to each other.In general, SBP fell to the lowest level at around midnight and started to increase progressively towards dawn while PR stayed unchanged until 7 AM. Age and gender affected the time course of SBP, most distinctly in the female patients aged ≥ 60 years. The time course of the increase of SBP was very similar in the patients, with BP dipping and non-dipping. The cardiothoracic ratio (CTR) slightly and renal dysfunction modestly facilitated the increase of nocturnal SBP. The nocturnal increase in SBP was not accompanied by an increase of PR in any group or subgroup. The pathophysiology and clinical significance of the early and exclusive increase in nocturnal BP need to be investigated.Average ABPM values in these hypertensive patients showed that BP starts to increase toward dawn without an increase in PR and that this discrepant behavior between BP and RP was most distinct in females 60 or older. The mechanism and clinical significance of such a discordant variation in BP and PR need to be elucidated.

Circadian Regulation of Blood Pressure: of Mice and Men

PURPOSE OF REVIEW

Blood pressure (BP) exhibits strong diurnal variations that have been shown to be important for normal physiology and health. In this review, we highlight recent advances in both basic and clinic research on how the circadian clock affects these BP rhythms.

RECENT FINDINGS

Tissue-specific and inducible knockout rodent models have provided novel ways to dissect how circadian clocks regulate BP rhythms and demonstrated that loss of these rhythms is associated with the development of disease. The use of circadian-specific research protocols has translated findings from rodent models to humans, providing insight into circadian control of BP, as well as how sleep, activity, and other factors influence diurnal BP rhythms. Circadian mechanisms play an important role in the regulation of diurnal BP rhythms. Future research needs to extend these findings to clinical populations and determine the extent to which circadian factors may play a role in the development of novel treatment approaches to the management of hypertension.

Diurnal Regulation of Renal Electrolyte Excretion: The Role of Paracrine Factors

Many physiological processes, including most kidney-related functions, follow specific rhythms tied to a 24-h cycle. This is largely because circadian genes operate in virtually every cell type in the body. In addition, many noncanonical genes have intrinsic circadian rhythms, especially within the liver and kidney. This new level of complexity applies to the control of renal electrolyte excretion. Furthermore, there is growing evidence that paracrine and autocrine factors, especially the endothelin system, are regulated by clock genes. We have known for decades that excretion of electrolytes is dependent on time of day, which could play an important role in fluid volume balance and blood pressure control. Here, we review what is known about the interplay between paracrine and circadian control of electrolyte excretion. The hope is that recognition of paracrine and circadian factors can be considered more deeply in the future when integrating with well-established neuroendocrine control of excretion.

Comparison of monocyte with high density lipoprotein cholesterol ratio in dipper and nondipper hypertensive patients

Aim: We aimed to compare the monocyte to HDL-cholesterol ratio (MHR) of nondipper hypertension (NDHT) and dipper hypertension patients. Patients & methods: A total of 162 patients were included in the study. Patients were grouped as dipper and nondipper according to 24-h ambulatory blood pressure recordings. Results: The MHR was significantly higher in nondipper hypertension group compared with control (p < 0.001) and dipper hypertension groups (p = 0.03). MHR, hs-CRP and red-cell distribution width (RDW) were independent predictors of nondipper hypertension. Area under the curve was 0.62 (p = 0.034) for MHR and 0.61 (p = 0.012) for hs-CRP in the ROC analysis. Conclusion: MHR has elevated levels in NDHT patients. Increased levels of MHR may evaluate as increased risk of cardiovascular events in NDHT patients.

Nocturia and increase in nocturnal blood pressure: the Nagahama study

OBJECTIVE

Abnormalities in circadian blood pressure (BP) variation, particularly increase in nocturnal BP, have been reported to be risk factors for cardiovascular disease, although the factors associated with BP abnormalities are not fully understood. This study aimed to clarify possible associations of sleep characteristics, including sleep fragmentation, sleep disordered breathing, and nocturia, with sleep BP by simultaneous multiday measurements.

METHODS

A cross-sectional study evaluated 5959 community participants having home-measured data on nocturnal BP change (sleep BP - awaking BP), sleep characteristics, and sleep disordered breathing. Sleep characteristics including the fragmentation index were assessed using wrist-wearable actigraphy, whereas sleep disordered breathing was assessed by 3% oxygen desaturation index obtained using a finger-type monitor. The number of nocturnal urinations was recorded in a sleep diary.

RESULTS

Mean nocturnal SBP change was -8.5 ± 7.9%. A 3% oxygen desaturation index was associated with the BP change independently of the basic covariates (β = 0.051, P = 0.001), although the association became insignificant (P = 0.196) after adjusting the fragmentation index (β = 0.105, P < 0.001). The association of the fragmentation index was also insignificant (P = 0.153) after adjusting measurement season (middle season: β = 0.163, P < 0.001; summer season: β = 0.249, P < 0.001). In contrast, the frequency of urination showed strong and independent association (β = 0.140, P < 0.001), with smaller nocturnal BP drop in participants with frequent urination.

CONCLUSION

Subjective sleep estimates and frequent nocturnal urination may represent a potential risk for circadian BP abnormalities.

Circadian rhythms and the kidney

Numerous physiological functions exhibit substantial circadian oscillations. In the kidneys, renal plasma flow, the glomerular filtration rate and tubular reabsorption and/or secretion processes have been shown to peak during the active phase and decline during the inactive phase. These functional rhythms are driven, at least in part, by a self-sustaining cellular mechanism termed the circadian clock. The circadian clock controls different cellular functions, including transcription, translation and protein post-translational modifications (such as phosphorylation, acetylation and ubiquitylation) and degradation. Disruption of the circadian clock in animal models results in the loss of blood pressure control and substantial changes in the circadian pattern of water and electrolyte excretion in the urine. Kidney-specific suppression of the circadian clock in animals implicates both the intrinsic renal and the extrarenal circadian clocks in these pathologies. Alterations in the circadian rhythm of renal functions are associated with the development of hypertension, chronic kidney disease, renal fibrosis and kidney stones. Furthermore, renal circadian clocks might interfere with the pharmacokinetics and/or pharmacodynamics of various drugs and are therefore an important consideration in the treatment of some renal diseases or disorders.

Osmotic indices and kidney concentrating activity: population-based data on correlates and prognostic power

Background

Research data are limited on indices of osmotic equilibrium and of kidney concentrating activity (KCA). This study investigated correlates and prognostic power of these indices in a sample of the general population.

Methods

Urine osmolality (U-osm), plasma osmolality (P-osm), plasma creatinine and other variables were measured by the Gubbio Study for the 1988-92 exam (baseline). Plasma creatinine and other variables were re-measured in the 2001-07 exam (follow-up). KCA was assessed as the U-osm/P-osm ratio and kidney function as estimated glomerular filtration rate (eGFR).

Results

Baseline data were complete in 4220 adults, of whom 852 died before follow-up and 2795 participated in the follow-up. At baseline, the following independent cross-sectional associations were identified: female sex and higher urine flow with lower values of U-osm, P-osm and U-osm/P-osm ratio (P < 0.01); obesity with higher values of U-osm, P-osm and U-osm/P-osm ratio (P < 0.01); older age and lower eGFR with lower U-osm, lower U-osm/P-osm ratio and higher P-osm (P < 0.05); hypertension and smoking with lower U-osm and lower U-osm/P-osm ratio (P < 0.05) but not with P-osm. From baseline to follow-up, the annualized rate was 1.26% for mortality and -0.74 ± 0.76 mL/min × 1.73 m2 for eGFR change. Mortality was independently predicted by baseline U-osm and baseline U-osm/P-osm ratio (hazard ratio for one higher standard deviation was ≤0.91, 95% confidence interval was ≤0.97, P < 0.01), but not by baseline P-osm. The eGFR change was not independently predicted by baseline values of U-osm, P-osm and U-osm/P-osm ratio (P ≥ 0.4).

Conclusions

Sex, age, obesity, eGFR, urine flow, hypertension and smoking independently associated with U-osm and KCA. U-osm and KCA independently predicted mortality, but not kidney function change over time.

Differences in blood pressure riser pattern in patients with acute heart failure with reduced mid-range and preserved ejection fraction

Aims

Heart failure (HF) is classified into three types according to left ventricular ejection fraction (EF). The effect of blood pressure (BP) on the pathogenesis of each type is assumed to be different. However, the association between the prognosis of each type of HF and abnormal BP variations assessed by ambulatory BP monitoring (ABPM), such as nocturnal hypertension and the riser pattern, remains unclear.

Methods and results

We studied 325 consecutive patients with decompensated HF who were acutely admitted to our hospital and underwent ABPM at discharge. During a mean follow‐up of 30.0 months, 52 cardiovascular and 112 all‐cause deaths occurred. The Cox proportional hazards model showed that the mean values of 24 h, awake, and sleep‐time systolic BP (SBP), and abnormal 24 h ABPM patterns, such as nocturnal hypertension and non‐dipper pattern, were not associated with either all‐cause or cardiovascular mortality in patients with HF with reduced EF (HFrEF), HF with mid‐range EF (HFmrEF), or HF with preserved EF (HFpEF), except for sleep‐time SBP in HFrEF. However, the riser pattern was a significant and independent predictor of all‐cause and cardiovascular deaths in patients with HFpEF (hazard ratio, 2.01; 95% confidence interval, 1.12–3.62; 0.0200; and hazard ratio, 2.48; 95% confidence interval, 1.08–5.90; 0.0332, respectively). Sleep‐time pulse rate was similarly decreased in both the riser and non‐riser groups.

Conclusions

The riser pattern of SBP was associated with an increased risk of adverse outcomes among patients with HFpEF but not HFrEF or HFmrEF.

Biomarkers of nondipper hypertension in prehypertensive and hypertensive patients

Aim: The aim of this study was to evaluate the relation of gamma glutamyl transferase (GGT), neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) with nondipper hypertension. Methods: This study included a total of 409 patients. Patients were grouped into hypertension, prehypertension and normotensive groups, according to their clinical blood pressure. All patients were also followed by ambulatory blood pressure. Results: Mean PLR and NLR were higher in the nondippers compared with dippers among both prehypertensive and hypertensive patients. In addition, PLR (OR: 1.011; 95% CI: 1004-1017; p = 0.001), NLR (OR: 2.296, 95% CI: 1634-3225; p < 0.001), and GGT (OR: 1.067; 95% CI: 1042-1092; p < 0.001) were found to be associated with nondipper pattern among whole study population. Conclusion: The PLR, NLR and GGT values are easily accessible and fairly useful, independently associated with nondipper hypertension for both hypertensive and prehypertensive patients.

Association between sleep disturbance and nocturnal blood pressure profiles by a linear mixed model analysis: the Nagahama study

OBJECTIVES

We aimed to analyze associations of sleep disturbance, including sleep disordered breathing, sleep fragmentation, and sleep efficiency, with abnormal nocturnal blood pressure (BP) profiles that may be risk factors for adverse cardiovascular outcomes.

METHODS

The study included 5854 community residents with 20,725 multi-day measurements. Sleep fragmentation and efficiency were evaluated using a wrist-worn activity monitor. Sleep disordered breathing was assessed using the 3% oxygen desaturation index corrected for actigraphy-determined sleep duration. A timer-equipped standard cuff-oscillometric device was used for home and sleep BP monitoring.

RESULTS

Mean nocturnal systolic BP (SBP) change was -8.6 ± 9.7% (-11.1 ± 12.6 mmHg), and inter-day correlation coefficient of the nocturnal SBP change was 0.443. Results of a linear mixed model analysis using daily measured values identified lower sleep efficiency (coefficient = -0.130, p < 0.001) as a determinant for decreased nocturnal SBP dipping beyond the interday variations of these parameters. Number of nocturnal urinations was another strong determinant (coefficient = 1.191, p < 0.001), although the association of sleep efficiency was independent of nocturnal urination, awake SBP, and sleep disordered breathing (coefficient = -0.102, p < 0.001). Sleep efficiency was also independently associated with sleep SBP level (coefficient = -0.138, p < 0.001). Estimated differences in nocturnal SBP dipping and sleep SBP level as a function of the degree of sleep efficiency (less than 80%) reached 1.63% (1.09-2.17%) and 2.16 mmHg (1.49-2.82%), respectively.

CONCLUSION

More attention should be paid to sleep efficiency as a factor in maintaining circadian BP rhythm.

Estimating the urinary sodium excretion in patients with chronic kidney disease is not useful in monitoring the effects of a low-salt diet

Background

Several epidemiologic studies have suggested that the urine sodium excretion (USE) can be estimated in lieu of performing 24-hour urine collection. However, this method has not been verified in patients with chronic kidney disease (CKD) or in an interventional study. The purpose of this study was to evaluate the usefulness of estimating USE in a prospective low-salt diet education cohort (ESPECIAL).

Methods

A new formula was developed on the basis of morning fasting urine samples from 228 CKD patients in the ESPECIAL cohort. This formula was compared to the previous four formulas in the prediction of 24-hour USE after treatment with olmesartan and low-salt diet education.

Results

Most previously reported formulas had low predictability of the measured USE based on the ESPECIAL cohort. Only the Tanaka formula showed a small but significant bias (9.8 mEq/day, P < 0.05) with a low correlation (r = 0.34). In contrast, a new formula showed improved bias (-0.1 mEq/day) and correlation (r = 0.569) at baseline. This formula demonstrated no significant bias (-1.2 mEq/day) with the same correlation (r = 0.571) after 8 weeks of treatment with olmesartan. Intensive low-salt diet education elicited a significant decrease in the measured USE. However, none of the formulas predicted this change in the measured urine sodium after diet adjustment.

Conclusion

We developed a more reliable formula for estimating the USE in CKD patients. Although estimating USE is applicable in an interventional study, it may be unsuitable for estimating the change of individual sodium intake in a low-salt intervention study.

Relationship between nocturnal polyuria and non-dipping blood pressure in male patients with lower urinary tract symptoms

OBJECTIVE

The aim of the present study was to examine factors of nocturnal polyuria and blood pressure variability in male patients with lower urinary tract symptoms (LUTS) who were treated.

METHODS

Two hundred and forty-two male patients with LUTS who were treated recorded frequency volume charts. We investigated their urinary condition and characteristics, medical history, and medications. Thirty-four of these patients underwent ambulatory blood pressure monitoring (ABPM) for 24 hours to evaluate blood pressure variability.

RESULTS

In the present study, 194 patients (80.2%) had nocturia and 136 (56.2%) had nocturnal polyuria (NP). Among patients with nocturia (≥2 voids/night), 130 (67.0%) had nocturnal polyuria, and 26 of those with nocturia (13.4%) had reduced functional bladder capacity. The use of 2 or more antihypertensive medications was significantly higher in the NP than non-NP group (22.8% vs. 12.3%; P = .035). Significantly more patients in the NP group had non-dipping blood pressure (P = .037). Non-dipping blood pressure was considered a potential factor for NP.

CONCLUSION

We suggest that treatment of non-dipping blood pressure may improve NP.

Comparison of ambulatory blood pressure monitoring and office blood pressure measurements in obese children and adolescents

BACKGROUND

Obesity in adults has been related to hypertension and abnormal nocturnal dipping of blood pressure, which are associated with poor cardiovascular and renal outcomes. Here, we aimed to resolve the relationship between the degree of obesity, the severity of hypertension and dipping status on ambulatory blood pressure in obese children.

METHODS

A total 72 patients with primary obesity aged 7 to 18 years (mean: 13.48 ± 3.25) were selected. Patients were divided into three groups based on body mass index (BMİ) Z-score. Diagnosis and staging of ambulatory hypertension based on 24-h blood pressure measurements, obtained from ambulatory blood pressure monitoring.

RESULTS

Based on our ambulatory blood pressure data, 35 patients (48.6%) had hypertension, 7 (20%) had ambulatory prehypertension, 21 (60%) had hypertension, and 7 patients (20%) had severe ambulatory hypertension. There was a significant relationship between severity of hypertension and the degree of obesity (p < 0.05). Thirty-one patients (88.6%) had isolated nighttime hypertension, and 53 patients (73.6%) were non-dippers. All systolic blood pressure results and loads were similar between groups. Diastolic and mean arterial blood pressure levels during the night, diastolic blood pressure loads, and heart rate during the day were significantly higher in Group 3 (p < 0.05). Nocturnal non-dipping was not associated with severity of obesity.

CONCLUSION

Obesity was associated with severity of hypertension, higher diastolic blood pressure at night, mean arterial pressure at night, diastolic blood pressure loads and heart rate at day. Increase in BMI Z-score does not a significant impact on daytime blood pressure and nocturnal dipping status.

Understanding the Two Faces of Low-Salt Intake

Fierce debate has developed whether low-sodium intake, like high-sodium intake, could be associated with adverse outcome. The debate originates in earlier epidemiological studies associating high-sodium intake with high blood pressure and more recent studies demonstrating a higher cardiovascular event rate with both low- and high-sodium intake. This brings into question whether we entirely understand the consequences of high- and (very) low-sodium intake for the systemic hemodynamics, the kidney function, the vascular wall, the immune system, and the brain. Evolutionarily, sodium retention mechanisms in the context of low dietary sodium provided a survival advantage and are highly conserved, exemplified by the renin-angiotensin system. What is the potential for this sodium-retaining mechanism to cause harm? In this paper, we will consider current views on how a sodium load is handled, visiting aspects including the effect of sodium on the vessel wall, the sympathetic nervous system, the brain renin-angiotensin system, the skin as "third compartment" coupling to vascular endothelial growth factor C, and the kidneys. From these perspectives, several mechanisms can be envisioned whereby a low-sodium diet could potentially cause harm, including the renin-angiotensin system and the sympathetic nervous system. Altogether, the uncertainties preclude a unifying model or practical clinical guidance regarding the effects of a low-sodium diet for an individual. There is a very strong need for fundamental and translational studies to enhance the understanding of the potential adverse consequences of low-salt intake as an initial step to facilitate better clinical guidance.

Prevalence of Hypertensive Phenotypes After Preeclampsia: A Prospective Cohort Study

Preeclampsia is associated with increased cardiovascular and renal risk. The aim of this prospective cohort study was to characterize the early postpartum blood pressure (BP) profile after preeclampsia. We enrolled 115 women with preeclampsia and 41 women with a normal pregnancy in a prospective cohort study. At 6 to 12 week postpartum, we assessed the prevalence of different hypertensive phenotypes using 24-hour ambulatory BP monitoring (ABPM), as well as the risk of salt sensitivity and the variability of BP derived from ABPM parameters. Among patients with preeclampsia, 57.4% were still hypertensive at the office. Daytime ABP was significantly higher in the preeclampsia group (118.9±15.0/83.2±10.4 mm Hg) than in controls (104.8±7.9/71.6±5.3 mm Hg; P<0.01). Differences between groups were similar for nocturnal BP values. Fifty percent of preeclampsia women remained hypertensive on ABPM in the postpartum, of whom 24.3% were still under antihypertensive treatment; 17.9% displayed a white-coat hypertension and 11.6% had masked hypertension. In controls, 2.8% had white-coat hypertension; none had masked hypertension or needed hypertensive treatment. The prevalence of nondippers was similar 59.8% in the preeclampsia group versus 51.4% in controls. High-risk class of salt sensitivity of BP was increased in preeclampsia women (48.6%) compared with controls (17.1%); P<0.01. In conclusion, ABPM 6 to 12 weeks after delivery reveals a high rate of sustained ambulatory, nocturnal, and masked hypertension after preeclampsia. This finding may help identify women who should be included in a postpartum cardiovascular risk management program.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01095939.

Maintenance of negative fluid balance can improve endothelial and cardiac functions in primary hypertensive patients

PURPOSE

The issue of unidentified volume expansion is well recognized as a cause for resistance to antihypertensive therapy. The aim of study is to identify contribution of negative fluid balance to hypertension control and impact on endothelial and cardiac functions among primary hypertensive patients who do not have kidney failure.

MATERIALS AND METHODS

This is a prospective interventional study with one-year follow-up. Preceded by volume status measurements were performed by a body composition monitor (BCM), the patients were put on ambulatory blood pressure monitoring for 24 hours. Then, echocardiographic assessments and flow-mediated dilation (FMD) and carotid intima-media thickness (CIMT) measurements were completed. Patients in one of the two groups were kept negative hydrated during trial with diuretic treatment.

RESULTS

At the end of one-year follow-up, patients in negative hydrated group were found to have significantly lower CIMT, left ventricle mass index, left ventricular end-diastolic diameter, mean systolic and diastolic BP, non-dipper patient ratio, and higher FMD. In negatively hydrated group, target organ damage significantly reduced during trial.

CONCLUSIONS

The significance of negative hydration status with respect to blood pressure control, endothelial and cardiac functions within primary hypertensive patients who do not suffer from kidney failure has been demonstrated.

Comparison of Prognostic Values of Daytime and Night-Time Systolic Blood Pressures on Renal Outcomes in Patients With Chronic Kidney Disease

BACKGROUND

Differences in the predictive value of daytime systolic blood pressure (SBP) and night-time SBP by ambulatory blood pressure monitoring on renal outcomes have not been fully investigated in chronic kidney disease (CKD) patients. This study compared the prognostic value between daytime and night-time SBP on renal outcomes in CKD.Methods and Results:This prospective observational study included 421 patients. The composite renal endpoint was endstage renal disease (ESRD) or death. Cox models were used to determine associations of daytime and night-time SBP with renal outcomes. There were 150 renal events (ESRD, 130; death, 20). Multivariable Cox analyses demonstrated that hazard ratios (HRs) [95% confidence interval (CI)] for composite renal outcomes of every 10-mmHg increase in daytime and night-time SBP levels were 1.13 (1.02-1.26) (P=0.02) and 1.15 (1.05-1.27) (P<0.01), respectively. In addition, compared with the 1st daytime or night-time SBP quartile, HRs (95% CI) for outcomes in the 2nd, 3rd, and 4th quartiles were: daytime SBP, 1.25 (0.70-2.25), 1.09 (0.61-1.94), and 1.58 (0.88-2.85; P=0.13) (P for trend=0.16); night-time SBP, 1.09 (0.61-1.96), 1.31 (0.76-2.28), and 1.82 (1.00-3.30; P=0.049) (P for trend=0.03), respectively.

CONCLUSIONS

Night-time SBP appeared superior to daytime SBP for predicting renal outcomes in this population of patients.

Circadian Rhythm in Kidney Tissue Oxygenation in the Rat

Blood pressure, renal hemodynamics, electrolyte, and water excretion all display diurnal oscillation. Disturbance of these patterns is associated with hypertension and chronic kidney disease. Kidney oxygenation is dependent on oxygen delivery and consumption that in turn are determined by renal hemodynamics and metabolism. We hypothesized that kidney oxygenation also demonstrates 24-h periodicity. Telemetric oxygen-sensitive carbon paste electrodes were implanted in Sprague-Dawley rats (250–300 g), either in renal medulla (n = 9) or cortex (n = 7). Arterial pressure (MAP) and heart rate (HR) were monitored by telemetry in a separate group (n = 8). Data from 5 consecutive days were analyzed for rhythmicity by cosinor analysis. Diurnal electrolyte excretion was assessed by metabolic cages. During lights-off, oxygen levels increased to 105.3 ± 2.1% in cortex and 105.2 ± 3.8% in medulla. MAP was 97.3 ± 1.5 mmHg and HR was 394.0 ± 7.9 bpm during lights-off phase and 93.5 ± 1.3 mmHg and 327.8 ± 8.9 bpm during lights-on. During lights-on, oxygen levels decreased to 94.6 ± 1.4% in cortex and 94.2 ± 8.5% in medulla. There was significant 24-h periodicity in cortex and medulla oxygenation. Potassium excretion (1,737 ± 779 vs. 895 ± 132 μmol/12 h, P = 0.005) and the distal Na⁺/K⁺ exchange (0.72 ± 0.02 vs. 0.59 ± 0.02 P < 0.001) were highest in the lights-off phase, this phase difference was not found for sodium excretion (P = 0.4). It seems that oxygen levels in the kidneys follow the pattern of oxygen delivery, which is known to be determined by renal blood flow and peaks in the active phase (lights-off).

Sleep, insomnia, and hypertension: current findings and future directions

Blood pressure (BP) varies over 24 hours. During normal sleep, BP typically decreases by 10% or more. Research suggests that disordered sleep, particularly sleep deprivation and obstructive sleep apnea, is associated with increased BP and risk of hypertension. Less is known about the relationship between insomnia and hypertension. Population-based studies have reported an association between insomnia symptoms and both prevalent and incident hypertension, particularly in the context of short sleep duration. Furthermore, a number of mechanisms have been proposed to explain the relationship between insomnia and hypertension. However, few studies have examined these proposed mechanisms, and even fewer clinical trials have been conducted to determine if improved sleep improves BP and/or reverses a nondipping BP pattern. Methodological concerns, particularly with respect to the diagnosis of insomnia, no doubt impact the strength of any observed association. Additionally, a large majority of studies have only examined the association between insomnia symptoms and clinic BP. Therefore, future research needs to focus on careful consideration of the diagnostic criteria for insomnia, as well as inclusion of either home BP or ambulatory BP monitoring. Finally, clinical trials aimed at improving the quality of sleep should be conducted to determine if improved sleep impacts 24-hour BP.