Non-dipper phenomenon in essential hypertension is related to blunted nocturnal rise and fall of sympatho-vagal nervous activity and progress in retinopathy

Association between non-dipping blood pressure pattern and different glucometabolic profile during oral glucose tolerance test

It is known that, a not physiological blood pressure (BP) circadian pattern has been associated with increased risk of organ damage and cardiovascular (CV) event. The aim of this study was to assess the association between circadian BP pattern and glucometabolic phenotypes occurring after oral glucose tolerance test (OGTT). We recruited 810 hypertensive Caucasian patients. All participants underwent to OGTT, laboratory test and 24-h ambulatory BP monitoring (ABPM). The analysis of collected data allowed classifying patients based on nocturnal BP profiles into four categories: dippers, non-dippers, extreme dippers, and reverse dippers. Considering the dipping pattern, the proportion of non-dippers in normal glucose tolerance patients with 1-h glucose ≥ 155 mg/dL (NGT ≥ 155) (36.4%) was higher than NGT < 155 (29.6%) and impaired glucose tolerance (IGT) (34.8%), but lower than type 2 diabetes group (T2DM) (52.6%) (p = 0.001). The proportion of dippers was lower in NGT ≥ 155 (47%) and T2DM (34.6%), when compared with NGT < 155 (53.8%) and IGT (51.2%) (p = 0.017). From logistic regression analysis, 1-h glucose ≥ 155 increased the risk of a pathological nocturnal drop in BP by 74%, (OR = 1.740, 95% CI 1.254-2.415, p < 0.0001). In addition, the improvement in 1 unit of Matsuda was responsible for a 3.5% risk decrease (OR = 0.965, 95% CI 0.958-0.971, p < 0.0001), while e-GFR determined a 0.9% risk reduction of nocturnal BP drop (OR = 0.991, 95% CI 0.984-0.999, p = 0.020). Our data demonstrated the existence, in newly diagnosed hypertensive patients, of an association between circadian BP profile and altered glycemic response during OGTT, in particular NGT ≥ 155 subjects are associated with a non-dipper BP pattern, this is clinically relevant because may explain, at least in part, the increased CV risk in this setting of patients.

Evening home blood pressure and pulse rate: age-specific associations with nocturia severity

Previous studies have reported a significant relationship between hypertension and nocturia. However, the underlying pathophysiology associated with pulse rate (PR) remains unclear. In the Japan Morning Surge-Home Blood Pressure Study, a self-administered nocturia questionnaire and evening home blood pressure (BP) and PR measurements (taken on a mean of 11.2 days) were performed on 4310 patients with one or more cardiovascular risk factors (mean: 64.9 years old; 47% male). According to the number of nighttime voids, the study population was divided into three groups (no voids: n = 2382; 1 void: n = 847; ≥2 voids per night: n = 1082). In the multinomial logistic regression analysis adjusted for confounders, diuretic use (OR, 1.23; 95%CI, 1.01-1.50; p < 0.05) was significantly associated with one nocturnal void, whereas evening home systolic BP (SBP) (OR per 1 SD, 1.14; 95%CI, 1.05-1.24; p < 0.01) and evening home PR (OR per 1 SD, 1.12; 95%CI: 1.02-1.24; p < 0.05) were significantly associated with multiple nocturnal voids. In the younger group (<65 years), only evening home PR was significantly related to multiple nighttime voids (p < 0.01), whereas in the older group (≥65 years), only evening home SBP was significantly related to multiple nighttime voids (p = 0.02). In this study, both higher evening home PR and higher evening home SBP were associated with multiple nighttime voids, with the former playing a greater role in the younger participants, and the latter more often associating the older group. An age-stratified approach to reduce the burden of BP or PR might be important to improve sleep quality.

Difficulty initiating sleep in patients with heart failure: Impact of left atrial pressure

BACKGROUND

Patients with heart failure (HF) often complain of sleep discomfort. Previous reports described that difficulty initiating sleep increased the cardiovascular risk in the general population. However, the association between difficulty initiating sleep and cardiac function in patients with HF remains unclear. This study aimed to investigate the associations between difficulty initiating sleep and clinical characteristics and cardiac function in patients with HF.

METHODS

Eighty-seven patients with HF who underwent overnight polysomnography for suspected sleep-disordered breathing were included. Patients were divided into two groups of the longer sleep latency (SL) group (SL ≥14 min, n = 44) and the shorter SL group (SL <14 min, n = 43). The median value of SL was defined as the time from lights-off to falling asleep. We compared the patients' characteristics, laboratory data, and polysomnographic and echocardiographic indices between the two groups.

RESULTS

The patients' median age was 67 years, and 85.1 % were men. There was lower beta blocker use [25 (56.8 %) vs. 34 (79.1 %), p = 0.046] and a higher peak mitral early filling velocity to mitral annular velocity ratio (E/e') [16.5 (14.2-21.7) vs. 13.7 (10.9-16.2), p = 0.005] in the longer SL group than in the shorter SL group. In multivariate logistic analysis, E/e' (odds ratio: 1.10, 95 % confidence interval: 1.01 to 1.19; p = 0.032) and systolic blood pressure before sleeping (odds ratio: 1.05, 95 % confidence interval: 1.00 to 1.10; p = 0.033) were significantly associated with a longer SL in patients with HF.

CONCLUSIONS

Increased left atrial pressure suggested by increased E/e' and increased systolic blood pressure before sleeping is independently associated with difficulty initiating sleep in patients with HF. Management of these hemodynamic imbalances is required to improve difficulty initiating sleep in patients with HF.

Association of nocturnal subconjunctival hemorrhage and non-dipper blood pressure pattern: A benign clue for serious diseases

PURPOSE

To evaluate the association between non-dipper blood pressure pattern and subconjunctival hemorrhage (SCH).

METHODS

Twenty-seven consecutive patients with nocturnal SCH and 27 age, sex-matched controls were enrolled. Demographic, blood parameters, office blood pressure measurements, 24-h ambulatory blood pressure monitoring (ABPM) were evaluated.

RESULTS

Mean diastolic blood pressure (DBP) for nighttime (65.03 ± 7.1 vs. 70.78 ± 10.5, p: 0.22), mean heart rate for nighttime (64.54 ± 8.26 vs. 69.93 ± 9.85, p: 0.034), Minimum Systolic Blood pressure(SBP) and DBP values for nighttime (92.44 ± 9.72 vs. 99.44 ± 10.66, p:0.015 and 51.15 ± 8.31 vs. 57.7 ± 11.2, p: 0.018) were higher, nocturnal fall ratio of SBP and DBP were significantly lower in the SCH ( + ) group compared to SCH (-) group (5.38 ± 8.39 vs. 10.34 ± 6.08, p: 0.016 and 4.26 ± 8.92 vs. 13.78 ± 6.97, p < 0001 respectively). Ten patients (37%) in the SCH (-) group and 18 patients (66.7%) in the SCH ( + ) group were non-dippers (p: 0.029). Mean daytime SBP and DBP were higher compared to office measurements of 4 patients (14.8%) in the SCH (-) group and 11 patients (40.7%) in the SCH ( + ) group (p: 0.033).

CONCLUSION

SCH had a strong association with non-dipper blood pressure pattern, higher nocturnal heart rate and masked hypertension which are precursors of myocardial infarction, stroke and renal failure. So, SCH should be considered as a clue for serious diseases such as coronary artery disease, myocardial infarction, stroke and patients should be evaluated for ABPM.

Renal function outcomes and kidney biopsy features of living kidney donors with hypertension

BACKGROUND

The medium- to long-term outcomes of living kidney donors with hypertension compared to normotensive donors are not well understood, especially with the recent changes in hypertension guidelines.

METHODS

We studied a cohort of 950 living kidney donors using different definitions of hypertension based on either ≥140/90 or ≥130/80 mmHg thresholds and based on either office or ambulatory blood pressure readings. Microstructural features on kidney biopsy at the time of donation were compared using different definitions of hypertension.

RESULTS

After adjusting for years of follow-up, age, sex, and baseline eGFR, hypertension (by any definition) did not significantly predict an eGFR < 45 ml/min/1.73 m² at a median follow-up of 10 years postdonation, though there was a borderline association with ambulatory blood pressure ≥ 130/80 mmHg predicting a 40% decline in eGFR (OR = 1.53, 1.00-2.36; p = .051). Proteinuria was predicted by office blood pressure ≥ 140/90 mmHg and by nondipper profile on nocturnal ambulatory blood pressure measurements. At the time of donation, larger glomeruli and arterial hyalinosis on biopsy were associated with hypertension defined by either ≥140/90 or ≥130/80 mmHg (by office or ambulatory measurements). Nocturnal nondipper status was associated with larger glomeruli size but not arteriolar hyalinosis when compared to dippers.

CONCLUSIONS

In programs that accept donors with controlled hypertension, various definitions of hypertension are associated with histological findings in the donated kidney, but none predict a clinically significant decline in kidney function 10 years after donation. These data support allowing healthy individuals with controlled hypertension to donate a kidney. However, donors with office hypertension (≥140/90 mmHg) and nondippers (regardless of hypertension status) are at greater long-term risk for proteinuria, and particularly for these donors, longer follow-up is warranted.

Circadian Rhythm of Blood Pressure of Dipper and Non-dipper Patients With Essential Hypertension: A Mathematical Modeling Approach

Blood pressure in humans presents a circadian variation profile with a morning increase, a small postprandial valley, and a deeper descent during night-time rest. Under certain conditions, the nocturnal decline in blood pressure can be reduced or even reversed (non-dipper), which is related to a significantly worse prognosis than a normal fall pattern (dipper). Despite several advances in recent years, our understanding of blood pressure's temporal structure, its sources and mechanisms is far from complete. In this work, we developed an ordinary differential equation-based mathematical model capable of capturing the circadian rhythm of blood pressure in dipper and non-dipper patients with arterial hypertension. The model was calibrated by means of global optimization, using 24-h data of systolic and diastolic blood pressure, physical activity, heart rate, blood glucose and norepinephrine, obtained from the literature. After fitting the model, the mean of the normalized error for each data point was <0.2%, and confidence intervals indicate that all parameters were identifiable. Sensitivity analysis allowed identifying the most relevant parameters and therefore inferring the most important blood pressure regulatory mechanisms involved in the non-dipper status, namely, increase in sympathetic over parasympathetic nervous tone, lower influence of physical activity on heart rate and greater influence of physical activity and glucose on the systemic vascular resistance. In summary, this model allows explaining the circadian rhythm of blood pressure and deepening the understanding of the underlying mechanisms and interactions integrating the results of previous works.

Effects of dapagliflozin on blood pressure variability in patients with prediabetes and prehypertension without pharmacological treatment: a randomized trial

AIM

The aim of the study was to evaluate the effect of dapagliflozin on blood pressure variability (BPV) in patients with prediabetes and prehypertension without pharmacological treatment.

METHODS

A double-blind, randomized, placebo-controlled clinical study was performed in 30 patients (30-60 years) diagnosed with prediabetes and prehypertension. Study subjects were divided into two groups: a 10-mg dose of dapagliflozin was administered daily before breakfast for 12 weeks in 15 patients or placebo in the remaining 15 patients. At the beginning and end of the study, clinical and metabolic evaluations were performed, and the 24-h BPV was calculated.

RESULTS

Dapagliflozin significantly decreased body weight (P = 0.010), BMI (P = 0.011), fasting plasma glucose (P = 0.002), glycated hemoglobin A1c (P = 0.004), office systolic blood pressure (SBP) (P = 0.001), office diastolic blood pressure (DBP) (P = 0.011), 24-h SBP (121 ± 8 vs. 117 ± 11 mmHg, P = 0.046), nighttime SBP (114 ± 11 vs. 108 ± 10 mmHg, P = 0.017), nocturnal mean arterial pressure (P = 0.043), and nocturnal hypertensive load (P = 0.015); and it significantly increased the percentage of the dipper circadian BP pattern (16.7 vs. 30.8%, P = 0.047). After the administration of dapagliflozin, some of the patients did not meet the diagnostic criteria for prediabetes (26.9%) or prehypertension (26.9%).

CONCLUSIONS

The administration of 10 mg dapagliflozin once daily for 90 days in patients with prediabetes and prehypertension decreased BPV by reducing 24-h and nighttime SBP, and increasing the dipper circadian BP pattern.

Blood Pressure Management Following Large Vessel Occlusion Strokes: A Narrative Review

Stroke is one of the leading causes of morbidity and mortality worldwide. Intravenous tissue plasminogen activator and mechanical thrombectomy comprise the two major treatments for acute ischemic stroke. Tissue plasminogen activator has been used for more than two decades and guidelines for hemodynamic management following tissue plasminogen activator administration are well established. However, mechanical thrombectomy is a relatively newer therapy and there is a paucity of evidence regarding hemodynamic management following large vessel occlusion strokes. The important tenets guiding the pathophysiology of large vessel occlusion strokes include understanding of cerebral autoregulation, collateral circulation, and blood pressure variability. In this narrative review, we discuss the current American Heart Association-American Stroke Association guidelines for the early management of acute ischemic stroke during different phases of the illness, encountered at different sections of a hospital including the emergency room, the neuro-interventional suite, and the intensive care unit. There is emerging evidence with regard to post-recanalization blood pressure management following large vessel occlusion strokes. Future research directions will include rea-ltime blood pressure variability assessments, identifying the extent of impaired autoregulation, and providing guidelines related to range and personalized blood pressure trajectories for patients following large vessel occlusion strokes.

The Night Effect of Anger: Relationship with Nocturnal Blood Pressure Dipping

Introduction: The circadian pattern of blood pressure is characterized by a physiological drop occurring after sleep onset. The alteration of this phenomenon (non-dipping, extreme dipping, or reverse dipping) is associated with an increased cardiovascular risk. Besides altered autonomic and endocrine circadian rhythms, psychological aspects seem to play a role in this modification. However, the few studies that have analyzed the influence of psychological dimensions on the dipping phenomenon have reported inconsistent results. This study aimed to examine the relationship between anger expression and blood pressure (BP) dipping. Methods: We obtained 24 h ambulatory BP measurements from 151 participants and used them to define three groups according to their dipping status: Dippers (N = 65), Non-Dippers (N = 42), and Extreme Dippers (N = 44). Sociodemographic and anamnestic information was collected, and the State–Trait Anger Expression Inventory was used to assess anger. Results: Analysis of variance evidenced significant higher scores for Trait Anger Temperament and Anger Expression in Extreme Dippers than in both Dippers and Non-Dippers. However, after controlling for confounding variables, there was no significant relationship with trait anger, and only the result concerning the suppression of anger was confirmed. Conclusions: These findings suggest that the analysis of some psychological factors, such as anger, could be necessary to better understand differences in nocturnal BP alterations. Trait anger and suppression of anger may contribute to the description and classification of patients who exhibit a maladaptive dipping phenomenon. However, modifiable (i.e., cigarette consumption) and unmodifiable (i.e., age) risk factors appear to mediate this relationship. Although further studies are necessary to explore this association, these results highlight that some aspects of anger can represent risk factors or markers of maladaptive modulation of the dipping phenomenon.

Nocturnal systolic blood pressure pattern of type 2 diabetic hypertensive men with erectile dysfunction: a cross sectional study from Northern Sri Lanka

Objective

This small scale cross-sectional study was done to identify the common systolic blood pressure pattern (dipping or non-dipping) among type 2 diabetic men with coexisting hypertension and erectile dysfunction(ED). A recent study in the same setting showed that prevalence of ED was high among diabetic men and co-existing hypertension was identified as an independent risk factor. There was a postulation about an association between ED and non-dipping nocturnal blood pressure pattern. So ambulatory blood pressure measurements (ABPM) was obtained for participants to test this prediction. Data was analysed using SPSS 25 Version.

Results

Among 29 participants who underwent ABPM, 21 showed non-dipping pattern of nocturnal systolic blood pressure (72.4%; CI 54.3–86.3). Mean SBP of participants was 125.55 +_14.1 and Mean DBP was 81.5 + _12.82. There was no statistical difference observed in mean SBP and DBP between patients with dipping nocturnal SBP and non-dipping pattern (P > 0.05). Variability of SBP was high among the participants (Mean SD-11.96 +/_2.74) and DBP also showed relatively high variability (SD-9.28 +/_2.9). Mean dipping percentage of the SBP during sleep was 5.54 +/_6.66. A significant difference in heart rate (HR) between patients with non-dipping and dipping pattern was noted (P-0.034).

Assessment of pupillary autonomic functions by dynamic pupillometry in different circadian arterial blood pressure patterns

OBJECTIVE

The aim of the present cross-sectional study was to evaluate the autonomic nervous system by dynamic pupillometry (DP) in normotensive and hypertensive individuals with either a non-dipper-type or a dipper-type circadian rhythm of blood pressure (BP).

PATIENTS AND METHODS

A total of 80 patients were allocated into four groups: normotensive/dipper (n=23), normotensive/nondipper (n=19), hypertensive/dipper (n=18), and hypertensive/nondipper (n=20). Pupil diameters (R0, R1, R2, and R%): latency (Lc), amplitude (Ac), velocity (Vc), and duration (Tc) of pupil contraction: latency (Ld), velocity (Vd), and duration (Td) of pupil dilatation were measured by DP. Among the DP parameters, Vc and Ac were known parasympathetic indices and R% was the major sympathetic index.

RESULTS

Vc and Ac were higher in the dipper normotensives with respect to nondipper normotensives (Vc=5.19±0.85 vs. 4.58±0.71, P=0.017; Ac=1.66±0.27 vs. 1.49±0.28, P=0.048). Vc and Ac were higher in dipper hypertensives with respect to the nondipper subgroup of hypertensive cases (Vc=4.44±0.81 vs. 3.94±0.45, P=0.024; Ac=1.47±0.26 vs. 1.27±0.11, P=0.004). R% was higher in the nondipper subgroup of hypertensives than the dipper subgroup of hypertensive cases (36.7±4.8 vs. 33.5±3.8, P=0.033). Correlation analyses showed moderate positive correlations of night-time decline in BP with Vc (r=0.460, P=0.001) and Ac (r=0.420, P=0.001). There was also a negative correlation between night-time decline in BP and R% (r=-0.259, P=0.001).

CONCLUSION

Nondipping in BP is associated with lower parasympathetic activity both in normotensive and in hypertensives cases. Furthermore, in the nondipper subgroup of hypertensive cases, there is higher sympathetic activity than the dipper subgroup.

A comparative evaluation of the efficacy of dimethylaminoethanol derivative 7–16, C7070 and picamilon in correction of experimental hypertensive neuroretinopathy

Introduction. The efficacy of dimethylaminoethanol (DMAE) derivative 7–16, substance C7070 in comparison with picamylon in hypertensive neuroretinopathy model in white laboratory rats was evaluated.

Materials and methods. For measuring the blood pressure, a system of noninvasive blood pressure measurement in small animals NIBP200 was used. Ophthalmoscopy was performed by using Bx a Neitz ophthalmoscope (Japan) and Osher MaxField 78D lens, OI-78M model. Electroretinography (ERG) was recorded in response to a single stimulation. Biopotentials were presented graphically on the screen with the help of BIOPAC SYSTEMS MP-150 with ACQKNOWLEDGE 4.2 software (USA). To assess a degree of a functional retinal disorder, the b/a coefficient was used.

Results and discussion. The most pronounced protective effect on the model of hypertensive neuroretinopathy is demonstrated by C7070, which is expressed in the notable approximation to the normal eye fundus image and reaching the target values of the b/a coefficient. In the group with correction by DMAE derivative 7–16, a protective effect is observed, which exceeds picamilon, which is expressed in the elimination of soft and solid exudates, vein and venule plethora, vascular tortuosity, arterial spasm, Salus-Gunn I symptom, hemorrhages; the b/a increases significantly by 26% compared to the group without correction (p &lt; 0.05).

Conclusion. The eye fundus image and functional state of the retina are completely restored when correcting experimental hypertensive neuroretinopathy with C7070 in a dose of 50 mg/kg to laboratory rats and partially restored when correcting with DMAE derivative 7–16 in a dose of 25 mg/kg, which in both cases exceeds the protective effect of the reference drug picamilon on the model of hypertensive neuroretinopathy.

Autonomic Regulation of Glucose Homeostasis: a Specific Role for Sympathetic Nervous System Activation

PURPOSE OF REVIEW

Cardiometabolic disorders such as obesity, metabolic syndrome and diabetes are increasingly common and associated with adverse cardiovascular outcomes. The mechanisms driving these developments are incompletely understood but likely to include autonomic dysregulation. The latest evidence for such a role is briefly reviewed here.

RECENT FINDINGS

Recent findings highlight the relevance of autonomic regulation in glucose metabolism and identify sympathetic activation, in concert with parasympathetic withdrawal, as a major contributor to the development of metabolic disorders and an important mediator of the associated adverse cardiovascular consequences. Methods targeting sympathetic overactivity using pharmacological and device-based approaches are available and appear as logical additional approaches to curb the burden of metabolic disorders and alleviate the associated morbidity from cardiovascular causes. While the available data are encouraging, the role of therapeutic inhibition of sympathetic overdrive in the prevention of the metabolic disorders and the associated adverse outcomes requires adequate testing in properly sized randomised controlled trials.

Ambulatory blood pressure monitoring and diabetes complications: Targeting morning blood pressure surge and nocturnal dipping

Ambulatory blood pressure monitoring (ABPM) correlates more closely to organ damages than clinic blood pressure (BP). In the current study we aimed to investigate the association between micro- and macrovascular complications of diabetes and both diurnal and nocturnal variability in BP.A total of 192 patients with type 2 diabetes (T2DM) who had complete data on ABPM were selected. BP categories were defined based on 2017 ACC/American Heart Association BP guideline. The cross-sectional association between different BP phenotypes and diabetes complications including cardiovascular disease (CVD), nephropathy, retinopathy, and neuropathy was assessed using multiple logistic regression models adjusted for age, sex, body mass index, hypertension (HTN), hemoglobin A1c, fasting blood glucose (FBG), triglyceride (TG), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total cholesterol.Approximately 48.9% of participants with T2DM had 24-hour HTN. The prevalence of daytime, nighttime, and clinic HTN were 35.9%, 96.3%, and 53.1%, respectively. Approximately 54.2% of participants had nondipping nocturnal pattern and 28.6% were risers. Nondipping nocturnal BP was associated with CVD, neuropathy, and retinopathy (P = .05, .05, and .014, respectively). Sleep trough morning blood pressure surge (MBPS) was associated with neuropathy (P = .023). Neuropathy was also associated with other components of MBPS (P < .05).We demonstrated that diabetic neuropathy was associated with all the components of MBPS and abnormal dipping status. Our results indicated loss of nocturnal BP dipping but not MBPS as a risk factor for CVD and retinopathy in patients with T2DM. Our findings once again highlighted the importance of ambulatory BP monitoring and targeted antihypertensive therapy directed toward to restore normal circadian BP in patients with T2DM.

Subjective sleep quality, blood pressure, and hypertension: a meta-analysis

Sleep quality is an important aspect of sleep, but no meta-analysis has elucidated its relationship with blood pressure (BP) and hypertension. A meta-analysis was conducted in October 2016 using multiple databases, including Embase and Medline. Studies that assessed subjective sleep quality and BP or hypertension were included. Upon full-text evaluation, 29 articles from 45 041 patients were selected, of which 22 articles were included in the meta-analysis and seven were presented narratively. Poor sleep quality was significantly associated with a greater likelihood of hypertension (odds ratio, 1.48; P value = .01). Poor sleepers had higher average systolic BP (mean difference = 4.37, P value = .09) and diastolic BP (mean difference = 1.25, P value = .32) than normal sleepers without statistical significance. Patients with hypertension had significantly worse sleep quality scores (mean difference = 1.51, P value < .01), while BP dippers had significantly better scores (mean difference = -1.67, P value < .01). The findings highlight the relationship between sleep quality and hypertension.

Ambulatory blood pressure profiles in familial dysautonomia

OBJECTIVE

Familial dysautonomia (FD) is a rare genetic disease that involves extreme blood pressure fluctuations secondary to afferent baroreflex failure. The diurnal blood pressure profile, including the average, variability, and day-night difference, may have implications for long-term end organ damage. The purpose of this study was to describe the circadian pattern of blood pressure in the FD population and relationships with renal and pulmonary function, use of medications, and overall disability.

METHODS

We analyzed 24-h ambulatory blood pressure monitoring recordings in 22 patients with FD. Information about medications, disease severity, renal function (estimated glomerular filtration, eGFR), pulmonary function (forced expiratory volume in 1 s, FEV1) and an index of blood pressure variability (standard deviation of systolic pressure) were analyzed.

RESULTS

The mean (± SEM) 24-h blood pressure was 115 ± 5.6/72 ± 2.0 mmHg. The diurnal blood pressure variability was high (daytime systolic pressure standard deviation 22.4 ± 1.5 mmHg, nighttime 17.2 ± 1.6), with a high frequency of a non-dipping pattern (16 patients, 73%). eGFR, use of medications, FEV1, and disability scores were unrelated to the degree of blood pressure variability or to dipping status.

INTERPRETATION

This FD cohort had normal average 24-h blood pressure, fluctuating blood pressure, and a high frequency of non-dippers. Although there was evidence of renal dysfunction based on eGFR and proteinuria, the ABPM profile was unrelated to the measures of end organ dysfunction or to reported disability.

Blood pressure profile is associated with microalbuminuria and retinopathy in hypertensive nondiabetic patients

BACKGROUND

Target organ damage is important for global cardiovascular risk assessment. The aim of this study was to explore the association between the blood pressure profile and end-organ damage in a hypertensive non-diabetic cohort.

METHODS

A total of 560 consecutive hypertensive nondiabetic patients (mean age: 58.2 ± 13.3 years, 221 men) were included in the study. All patients underwent thorough physical examination including fundoscopic examination. First morning urine samples were obtained from each patient and measurement of the albumin-to-creatinine ratio in first morning urine collection samples was used for diagnosis of microalbuminuria. All patients underwent a 24-h ambulatory blood pressure monitoring and were grouped as dippers and non-dippers according to the presence or absence of >10% decrease in blood pressure during the night, respectively.

RESULTS

The non-dipper group consisted of 247 patients with a non-dipper blood pressure profile, 31 patients with reverse dipping and 4 patients with extreme dipping. Non-dipper patients were significantly older. Coronary artery disease, cerebrovascular disease, hypertensive retinopathy and microalbuminuria were significantly more prevalent in the non-dipper patients. Non-dipping hypertension increased the risk of hypertensive retinopathy by 1.89 times (95% confidence interval, CI:1.35-2.65, p < 0.001) and the risk of microalbuminuria by 2.23 times (95% CI:1.49-3.33, p < 0.001). Non-dipping hypertension was still significantly associated with hypertensive retinopathy and microalbuminuria when adjusted by age and sex.

CONCLUSION

Non-dipping hypertension was associated with increased risk of hypertensive retinopathy and microalbuminuria. Blood pressure profiles should also be considered in assessing the risk for hypertensive patients.

Muscle microcirculation alterations and relation to dipping status in newly diagnosed untreated patients with arterial hypertension-A pilot study

OBJECTIVE

The importance of abnormalities observed in the microcirculation of patients with arterial hypertension (AH) is being increasingly recognized. The authors aimed to evaluate skeletal muscle microcirculation in untreated, newly diagnosed hypertensive patients with NIRS, a noninvasive method that evaluates microcirculation.

METHODS

We evaluated 34 subjects, 17 patients with AH (13 males, 49±13 years, BMI: 26±2 kg/m² ) and 17 healthy controls (12 males, 49±15 years, BMI: 25±3 kg/m² ). The thenar muscle StO₂ (%) was measured by NIRS before, during and after 3-minutes vascular occlusion to calculate OCR (%/min), EF (%/min), and RHT (minute). The dipping status of hypertensive patients was assessed.

RESULTS

The RHT differed between AH patients and healthy subjects (2.6±0.3 vs 2.1±0.3 minutes, P<.001). Dippers had higher EF than nondippers (939±280 vs 710±164%/min, P=.05).

CONCLUSIONS

The study suggests an impaired muscle microcirculation in newly diagnosed, untreated AH patients.

Increased plasma lactate level is associated with subclinical cardiovascular damage in patient with non-dipping hypertension

OBJECTIVE

To evaluate the difference of plasma lactate level between dipping and non-dipping hypertension, and to investigate the effects of lactate on subclinical cardiovascular damages in dipping and non-dipping hypertension.

METHODS

According to 24 h ambulatory blood pressure monitoring, 236 patients with dipping and 152 with non-dipping hypertension were included. Clinical characteristics were collected and compared between dipping and non-dipping groups. Left ventricle hypertrophy (LVH) and N-terminal pro-B type natriuretic peptide (NT-proBNP) level were used to evaluate subclinical cardiovascular damage. Multivariate regression analysis was performed to evaluate the relationship between lactate and LVH and NT-proBNP elevation.

RESULTS

Compared to dipping hypertension, plasma levels of lactate and NT-proBNP in non-dipping hypertension group were significantly higher. Moreover, the value of left ventricle mass index to height (LVMI/height) was also significantly higher in non-dipping group, and the percentage of patient with LVH was also higher in non-dipping group (36.8% vs. 28.9%, P < 0.05). Multivariate regression analysis revealed that in non-dipping group, after fully adjustment, the associations between lactate with LVH and NT-proBNP remained significant, with odds ratio (OR) of 1.18 (95% confidence interval [CI] of 1.13-1.24) in LVH and OR of 1.16 in NT-proBNP (95% CI of 1.10-1.23), respectively. Nonetheless, the associations between lactate with LVH and NT-proBNP elevation in dipping group were diminished to statistical nonsignificance.

CONCLUSION

Plasma lactate level in non-dipping hypertension is significantly higher than dipping hypertension, and this difference may be the potential mechanism non-dipping hypertension contributes to greater targeted organ damage.

Does sympathetic overactivation feature all hypertensives? Differences of sympathovagal balance according to night/day blood pressure ratio in patients with essential hypertension

When evaluating the 'night/day BP ratio', both hypertensives and normotensives can be arbitrarily classified into four groups: extreme dippers (ratio ⩽0.8), dippers (0.8<ratio ⩽0.9), mild dippers (0.9<ratio⩽1.0) and reverse dippers (ratio ⩾1.0). Reverse and mild dipper hypertensives have poorer prognoses compared with the physiological dipper profile, but the prognostic relevance of the extreme dipper profile remains uncertain. The evaluation of heart rate variability (HRV), obtained by 24-h Holter ECG monitoring, is the most frequently used noninvasive form of assessment of the activity of the autonomic nervous system. Reverse and mild dipper hypertensives have reduced HRV, indicating an overactivation of the sympathetic nervous system (SNS); however, the HRV behavior in extreme dippers is still controversial. The goal of this study was to compare HRV indexes of extreme vs. reverse dipper essential hypertensives measured on the basis of time domains. We enrolled 125 hypertensive subjects, divided in 4 quartiles according to day/night blood pressure (BP) ratios. The upper and lower quartiles (31 subjects per quartile) were compared; 30 normotensive subjects were enrolled as a control group. Time domain HRV parameters of the three groups revealed a higher degree of sympathetic activation in the lower quartile (reverse dipper) vs. the upper quartile (extreme) and normotensive controls. HRV parameters related to parasympathetic tone did not show any significant variations among the three groups. Contrary to common belief, not all hypertensives have SNS overactivation.

Covariates of non-dipping and elevated night-time blood pressure in ischemic stroke patients: the Norwegian Stroke in the Young Study

Abnormal night-time blood pressure (BP) reduction is associated with increased cardiovascular risk in hypertension. Little is known about the prevalence and covariates of night-time BP reduction in ischemic stroke patients. Clinic and ambulatory BP measurements were recorded in 268 stroke survivors aged 15-60 years. The degree of night-time dipping was calculated from the difference between day-time and night-time mean BP, and defined as non-dipping if < 10%. Aortic stiffness was derived from carotid-femoral pulse-wave velocity (PWV) by applanation tonometry and carotid intima-media thickness (cIMT) by ultrasound. A non-dipping pattern was found in 38%. Non-dippers had higher PWV, mean cIMT and night-time BP, and included more patients with history of hypertension, diabetes and high for age PWV compared to dippers (all p < 0.05). In multivariate logistic regression analyses, non-dipping was associated with high for age PWV [odds ratio (OR) = 2.28; 95% confidence interval (CI) 1.06-4.92, p < 0.05] independent of history of hypertension and other confounders, while elevated night-time BP was associated with increased cIMT (OR = 3.83; 95% CI 1.01-14.50, p < 0.05) independent of non-dipping status, male gender, obesity, antihypertensive treatment and high for age PWV. In conclusion, in the Norwegian Stroke in the Young Study, non-dipping BP pattern was common and associated with increased aortic stiffness.

Prognostic Significance of Neuroadrenergic Dysfunction for Cardiovascular Events in Patients With Acute Myocardial Infarction

BACKGROUND

The dysregulation of systemic blood pressure (BP) variation or cardiac neuroadrenergic dysfunction is associated with adverse cardiovascular events. We aimed to clarify the prognostic significance of neuroadrenergic dysfunction for cardiovascular events in patients with acute myocardial infarction (AMI).

METHODS AND RESULTS

We enrolled 63 AMI patients (mean age, 67±12 years) underwent ambulatory BP monitoring (ABPM) and cardiac iodine-(123)metaiodobenzylguanidine (MIBG) imaging within 4 weeks after AMI onset. We analyzed the circadian BP pattern and heart-to-mediastinum (H/M) MIBG uptake ratio. All the patients were followed for 2 years. The study endpoint was a composite of major adverse cardiovascular events, including all-cause death, MI, coronary revascularization except for the MI culprit lesion, and stroke. Patients with a non-dipper pattern (n=29) or an H/M ratio <1.96 (n=28) had a worse prognosis than those with either a dipper pattern (n=34) or an H/M ratio ≥1.96 (n=35; log-rank, P=0.013 and 0.010, respectively). Patients with both a non-dipper pattern and an H/M ratio <1.96 (n=12) had a significantly worse prognosis than did the other patients (P=0.0020).

CONCLUSIONS

Dysregulation of BP variation and cardiac MIBG uptake were associated with cardiovascular events following AMI. Examining ABPM with MIBG imaging may potentially improve risk stratification in these patients.

Effects of Carotid Stenting on Nocturnal Nondipping Phenomenon

BACKGROUND

It is well known that nondipper blood pressure (BP) pattern is associated with an increased cardiovascular risk in hypertensive patients. The aim of this study is to observe whether carotid artery stent (CAS) procedure returns nondipper BP pattern to dipper pattern in hypertensive patients.

METHODS

Ambulatory BP monitorization (ABPM) was performed in 152 hypertensive patients who underwent CAS procedure 1 day before, and 1 day and 1 year after the procedure. BP monitorization of patients was classified as dipper and nondipper. BP parameters 1 year after CAS procedure were compared with preprocedure parameters.

RESULTS

According to baseline ambulatory BP follow-ups, a total of 152 hypertensive patients with 122 (80%) nondippers and 30 (20%) dippers were enrolled in this study. According to ABPM results 1 year after CAS procedure, 78 patients (64%) who had nondipper pattern at first transformed into dipper pattern and 44 patients (36%) remained to be nondippers. Moreover, 1 year after CAS procedure, 18 patients (60%) who had dipper pattern at first transformed into nondipper pattern and 12 patients (40%) remained as dippers. When BP follow-up values at 1 year after CAS procedure were compared with BP readings before the procedure, 78 patients (51%) who were nondipper before the procedure transformed into dipper pattern (P ≤ .01), whereas 44 patients (29%) with nondipper pattern remained to be nondippers (P = .01). Twelve patients (7.9%) who had dipper pattern remained to have dipper pattern (P = .768). Eighteen patients who had dipper pattern (12%) transformed into nondipper pattern after the procedure (P < .01). The total number of nondipper pattern patients before CAS procedure was 80.3% (122 patients), whereas this percentage dropped to 40.8% (62 patients) after the CAS procedure (P < .01).

CONCLUSIONS

During 1-year follow-up after CAS procedure, nondipper BP pattern transforms into dipper pattern. This result might be attributed to the contributory effect of CAS procedure to long-term cardiovascular protection.

Even mild depression is associated with among-day blood pressure variability, including masked non-dipping assessed by 7-d/24-h ambulatory blood pressure monitoring

The effect of mild depression on blood pressure (BP) was assessed in 116 Japanese (32-79 years). As compared to non-depressive (Geriatric Depression Scale, GDS-15 score <5) subjects, mild depressives (GDS-15 score: 1-15) had shorter sleep duration (p = 0.021), lower subjective quality of life (health: p = 0.016; life satisfaction: p < 0.001; and happiness: p < 0.001), and higher 7-d systolic BP (p < 0.05). "Masked non-dipping" (dipping on day 1, but non-dipping on at least 1 of the following 6 d) was more frequent among depressive than non-depressive normotensives (p = 0.008). Among-day BP variability may underlie cardiovascular disease accompanying a key component of psychological depression.

Prognostic significance of dipping in older hypertensive patients

BACKGROUND AND AIMS

Arterial hypertension doubles the risk of coronary heart disease, heart and kidney failure, and peripheral arterial disease. Less variation in diurnal ambulatory blood pressure monitoring (ABPM) patterns may affect mortality outcome. Therefore, as hypertension occurs in over 95% of older subjects, the prognostic value of dipping status in older hypertensive patients will be assessed.

METHOD

The retrospective study group consisted of 170 hypertensive patients, aged 75-84 years, enrolled in the years 2005 to 2007. Baseline measures included 24-h ABPM. Diurnal index and dipping status was calculated and stratified the group into dippers (40 patients, 23.5%), non-dippers (65 patients, 38.2%) and reverse-dippers (65 patients, 38.2%).

RESULTS

During a 5-year observation, after baseline we have observed 69 deaths (40.9%) from the whole group of 170 patients with 23 (35.4%) being non-dippers and 36 (55.4%) reverse-dippers. There were significant differences between the groups divided according to diurnal dipping status in survival time, number of recorded deaths and night mean blood pressure. We have identified and confirmed risk factors for the all-cause mortality: age, mean systolic and diastolic blood pressure, diurnal index and dipping status (dipping, non-dipping or reverse-dipping).

CONCLUSION

Reverse-dippers and non-dippers revealed worse prognosis compared with dippers.

Autonomic dysfunction in acute ischemic stroke: an underexplored therapeutic area?

Impaired autonomic function, characterized by a predominance of sympathetic activity, is common in patients with acute ischemic stroke. This review describes methods to measure autonomic dysfunction in stroke patients. It summarizes a potential relationship between ischemic stroke-associated autonomic dysfunction and factors that have been associated with worse outcome, including cardiac complications, blood pressure variability changes, hyperglycemia, immune depression, sleep disordered breathing, thrombotic effects, and malignant edema. Involvement of the insular cortex has been suspected to play an important role in causing sympathovagal imbalance, but its exact role and that of other brain regions remain unclear. Although sympathetic overactivity in patients with ischemic stroke appears to be a negative prognostic factor, it remains to be seen whether therapeutic strategies that reduce sympathetic activity or increase parasympathetic activity might improve outcome.

Peripheral and central effects of melatonin on blood pressure regulation

The pineal hormone, melatonin (N-acetyl-5-methoxytryptamine), shows potent receptor-dependent and -independent actions, which participate in blood pressure regulation. The antihypertensive effect of melatonin was demonstrated in experimental and clinical hypertension. Receptor-dependent effects are mediated predominantly through MT1 and MT2 G-protein coupled receptors. The pleiotropic receptor-independent effects of melatonin with a possible impact on blood pressure involve the reactive oxygen species (ROS) scavenging nature, activation and over-expression of several antioxidant enzymes or their protection from oxidative damage and the ability to increase the efficiency of the mitochondrial electron transport chain. Besides the interaction with the vascular system, this indolamine may exert part of its antihypertensive action through its interaction with the central nervous system (CNS). The imbalance between the sympathetic and parasympathetic vegetative system is an important pathophysiological disorder and therapeutic target in hypertension. Melatonin is protective in CNS on several different levels: It reduces free radical burden, improves endothelial dysfunction, reduces inflammation and shifts the balance between the sympathetic and parasympathetic system in favor of the parasympathetic system. The increased level of serum melatonin observed in some types of hypertension may be a counter-regulatory adaptive mechanism against the sympathetic overstimulation. Since melatonin acts favorably on different levels of hypertension, including organ protection and with minimal side effects, it could become regularly involved in the struggle against this widespread cardiovascular pathology.

A reduced heart rate variability is independently associated with a blunted nocturnal blood pressure fall in patients with resistant hypertension

BACKGROUND

A blunted nocturnal blood pressure (BP) fall is a marker of worse cardiovascular outcomes, and autonomic imbalance may be involved. The objective was to evaluate the associations between the nocturnal BP fall and heart rate variability (HRV) parameters in resistant hypertension.

DESIGN AND METHODS

In a cross-sectional analysis, 424 resistant hypertensive patients performed 24-h ambulatory BP and Holter monitoring, and 221 patients also performed polysomnography. Time-domain HRV parameters evaluated were the standard deviation of all normal RR intervals (SDNN), the standard deviation of the averaged normal RR intervals for all 5-min segments (SDANN), the root mean square of differences between adjacent R-R intervals (rMSSD) and the percentage of adjacent R-R intervals that varied by more than 50 ms (pNN50). Multivariate linear and logistic regressions assessed associations between the nocturnal BP fall and HRV parameters.

RESULTS

Two hundred and sixty-six patients (63%) presented a nondipping pattern. These patients had lower SDNN and SDANN than normal dipping patients, but equal rMSSD and pNN50. On multivariate analysis, after adjustments for several confounders, a reduced SDNN (<70 ms) implied a 2.9 to 3.4-fold [95% confidence interval (CI) 1.2-8.5] and a reduced SDANN (<50 ms) a 3.7 to 4.2-fold (95% CI 1.5-11.4) higher odds of having a nondipping pattern. Further adjustment for the presence and severity of obstructive sleep apnoea did not change the results.

CONCLUSION

Reduced SDNN and SDANN, two HRV parameters that mainly reflect sympathetic overactivity, were independently associated with a blunted nocturnal BP fall in resistant hypertension. These relationships offer insight into physiopathological mechanisms linking the circadian BP variability to cardiovascular outcomes.

The interplay between sympathetic overactivity, hypertension and heart rate variability (review, invited)

The control of arterial pressure is a complex interaction of the long- and short-term influences of hormones, local vascular factors, and neural mechanisms. The autonomic nervous system and its sympathetic arm play important roles in the regulation of blood pressure, and overactivity of sympathetic nerves may have an important role in the development of hypertension and related cardiovascular disorders. The baroreceptor system opposes either increases or decreases in arterial pressure, and the primary purpose of the arterial baroreflex is to keep blood pressure close to a particular set point over a relatively short period of time. The ability of the baroreflex to powerfully buffer acute changes in arterial pressure is well established, but the role of the arterial baroreceptor reflex in long-term control of arterial pressure has been a topic of many debate and controversy for decades. The sympathetic nervous system and arterial baroreceptor reflex control of renal sympathetic nerve activity has been proposed to play a role in long-term control of arterial pressure. The aim of this paper has been to review the postulated role of sympathetic activation.

The hypothalamic neuropeptide FF network is impaired in hypertensive patients

BACKGROUND

The human hypothalamus contains the neuropeptide FF (NPFF) neurochemical network. Animal experiments demonstrated that NPFF is implicated in the central cardiovascular regulation. We therefore studied expression of this peptide in the hypothalamus of individuals who suffered from essential hypertension (n = 8) and died suddenly due to acute myocardial infarction (AMI), and compared to that of healthy individuals (controls) (n = 6) who died abruptly due to mechanical trauma of the chest.

METHODS

The frozen right part of the hypothalamus was cut coronally into serial sections of 20 μm thickness, and each tenth section was stained immunohistochemically using antibody against NPFF. The central section through each hypothalamic nucleus was characterized by the highest intensity of NPFF immunostaining and thus was chosen for quantitative densitometry.

RESULTS

In hypertensive patients, the area occupied by NPFF immunostained neuronal elements in the central sections through the suprachiasmatic nucleus (SCh), paraventricular hypothalamic nucleus (Pa), bed nucleus of the stria terminalis (BST), perinuclear zone (PNZ) of the supraoptic nucleus (SON), dorso- (DMH), ventromedial (VMH) nuclei, and perifornical nucleus (PeF) was dramatically decreased compared to controls, ranging about six times less in the VMH to 15 times less in the central part of the BST (BSTC). The NPFF innervation of both nonstained neuronal profiles and microvasculature was extremely poor in hypertensive patients compared to control.

CONCLUSIONS

The decreased NPFF expression in the hypothalamus of hypertensive patients might be a cause of impairment of its interaction with other neurochemical systems, and thereby might be involved in the pathogenesis of the disease.

Is there diurnal variation of the vestibulosympathetic reflex: implications for orthostatic hypotension

Incidences of adverse cardiac events and orthostatic hypotension are associated with diurnal variations. The primary purpose of the present study was to determine if the vestibulosympathetic reflex (VSR) follows a diurnal variation in humans. We hypothesized that the VSR would be attenuated at night based on the relation between melatonin and the VSR. Arterial blood pressure, heart rate, calf blood flow, and muscle sympathetic nerve activity (MSNA) were measured in nine healthy subjects (28 ± 1 yr, 5 men and 4 women) at rest and during head-down rotation. Each subject was tested during the day at 11:34 ± 13 and again at night 22:10 ± 5. MSNA was significantly decreased at night compared with day (8 ± 1 vs. 11 ± 2 bursts/min, respectively, P < 0.02). Heart rate and arterial blood pressure at rest were significantly increased at night compared with day (heart rate: 70 ± 4 vs. 66 ± 4 beats/min and mean arterial blood pressure: 91 ± 2 vs. 87 ± 1 mmHg, respectively). MSNA and hemodynamic responses to head-down rotation were not significantly altered at night compared with day (changes of 3 ± 1 bursts/min and 25 ± 6% for MSNA and calf blood flow, respectively). The data indicate that MSNA at rest decreases during the late evening hours and exhibits a diurnal variation, whereas the VSR does not. In summary, diurnal variation of orthostatic hypotension in humans does not appear to be associated with changes in the VSR and MSNA at rest.

Divergent retinal vascular abnormalities in normotensive persons and patients with never-treated, masked, white coat hypertension

BACKGROUND

Hypertensive patients with retinal arteriolar abnormalities are at increased risk for cardiovascular events. However, the extent of retinal microvascular changes in naïve, never-treated patients with hypertension of short duration has not been established. In addition to this, the lack of relevant data about other phenotypes of hypertension (masked and white-coat hypertension) determined by ambulatory blood-pressure measurement (ABPM) is notable, despite their relationship to increased cardiovascular risk mediated by underlying target-organ and vascular damage.

METHODS

We conducted a study in which nonmydriatic retinal photography was used to assess central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) diameters and the retinal arteriovenus ratio (AVR) in a group of 103 individuals with never-treated hypertension of recent (< 1 year) appearance, 28 individuals with masked and 20 with white-coat hypertension, and 50 normotensive individuals, as appropriately classified by ABPM.

RESULTS

Patients with sustained and masked hypertension had narrower values of CRAE than did normotensive individuals (86.7±10.1 and 87.6±9.2 vs. 94.8±10.6, P < 0.001 and P = 0.02, respectively). The AVR was lower in patients with sustained hypertension (0.736±0.102), masked hypertension (0.716±0.123), and white-coat hypertension (0.739±0.127) than in normotensive subjects (0.820±0.095), P < 0.001, P < 0.001, and P = 0.03, respectively. Both AVR and CRAE were negatively associated with mean systolic and diastolic daytime, nighttime, and 24-hour blood pressures, even after adjustment for other factors.

CONCLUSIONS

Subtle retinal microvascular signs of pathology are observed in hypertensive patients at early stages of hypertension and in patients with both masked and white coat hypertension. These changes may be indicative or may mediate the differences in cardiovascular mortality in persons with masked and white-coat hypertension, and relevant information about this can be easily accessed with retinal photography.

Short-term increase in particulate matter blunts nocturnal blood pressure dipping and daytime urinary sodium excretion

Short-term exposure to ambient particulate matter with aerodynamic diameters<10 µm were found to be positively associated with blood pressure. Yet, little information exists regarding the association between particles and circadian rhythm of blood pressure. Hence, we analyzed the association of exposure to particulate matter with aerodynamic diameters<10 µm on the day of examination and ≤7 days before with ambulatory blood pressure and with sodium excretion in 359 adults from the general population using multiple linear regression. After controlling for potential confounders, a 10-µg/m3 increase in particulate matter with aerodynamic diameters<10 µm levels was associated with nighttime systolic blood pressure (β=1.32 mm Hg 95% CI, 0.06-2.58 mm Hg at lag 0; P=0.04), nighttime diastolic blood pressure (0.72 mm Hg 95% CI, 0.03-1.42 mm Hg at lag 2; P=0.04), nocturnal systolic blood pressure dipping (-0.96 mm Hg 95% CI, -1.89 to -0.03 mm Hg at lag 0; P=0.044), and daytime urinary sodium excretion (-0.05 log-mmol/min 95% CI, -0.10 to -0.01 log-mmol/min at lag 0; P=0.027) but not with nighttime sodium excretion. The associations with blood pressure rapidly diminished with increasing lag days, and the associations with daytime sodium excretion were maximal with particulate matter with aerodynamic diameters<10 µm in exposures 2 to 5 days before. The associations of short-term increases in particulate matter with aerodynamic diameters<10 µm with higher nighttime blood pressure and blunted systolic blood pressure dipping were preceded by associations with reduced ability of the kidney to excrete sodium during daytime. The underlying mechanism linking air pollution to increased cardiovascular risk may include disturbed circadian rhythms of renal sodium handling and blood pressure.

Effects of restricted fructose access on body weight and blood pressure circadian rhythms

High-fructose diet is known to produce cardiovascular and metabolic pathologies. The objective was to determine whether the timing of high fructose (10% liquid solution) intake affect the metabolic and cardiovascular outcomes. Male C57BL mice with radiotelemetric probes were divided into four groups: (1) 24 h water (control); (2) 24 h fructose (F24); (3) 12 h fructose during the light phase (F12L); (4) 12 h fructose during the dark phase (F12D). All fructose groups had higher fluid intake. Body weight was increased in mice on restricted access with no difference in total caloric intake. Fasting glycemia was higher in groups with restricted access. F24 mice showed a fructose-induced blood pressure increase during the dark period. Blood pressure circadian rhythms were absent in F12L mice. Results suggest that the timing of fructose intake is an important variable in the etiology of cardiovascular and metabolic pathologies produced by high fructose consumption.

Heart rate recovery: a practical clinical indicator of abnormal cardiac autonomic function

The autonomic nervous system (ANS) and cardiovascular function are intricately and closely related. One of the most frequently used diagnostic and prognostic tools for evaluating cardiovascular function is the exercise stress test. Exercise is associated with increased sympathetic and decreased parasympathetic activity and the period of recovery after maximum exercise is characterized by a combination of sympathetic withdrawal and parasympathetic reactivation, which are the two main arms of the ANS. Heart rate recovery after graded exercise is one of the commonly used techniques that reflects autonomic activity and predicts cardiovascular events and mortality, not only in cardiovascular system disorders, but also in various systemic disorders. In this article, the definition, applications and protocols of heart rate recovery and its value in various diseases, in addition to exercise physiology, the ANS and their relationship, will be discussed.

Blood pressure dipping: ethnicity, sleep quality, and sympathetic nervous system activity

BACKGROUND

Blunted blood pressure (BP) dipping is an established predictor of adverse cardiovascular outcomes. Although blunted BP dipping is more common in African Americans than whites, the factors contributing to this ethnic difference are not well understood. This study examined the relationships of BP dipping to ethnicity, body mass index (BMI), sleep quality, and fall in sympathetic nervous system (SNS) activity during the sleep-period.

METHODS

On three occasions, 128 participants with untreated high clinic BP (130-159/85-99 mm Hg) underwent assessments of 24-h ambulatory BP (ABP), sleep quality, (evaluated by sleep interview, self-report, actigraphy) and sleep-period fall in sympathetic activity (measured by waking/sleep urinary catecholamine excretion).

RESULTS

Compared to whites (n = 72), African Americans (n = 56) exhibited higher sleep-period systolic (SBP) (P = 0.01) and diastolic BP (DBP) (P < 0.001), blunted SBP dipping (P = 0.01), greater BMI (P = 0.049), and poorer sleep quality (P = 0.02). SBP dipping was correlated with BMI (r = -0.32, P < 0.001), sleep quality (r = 0.30, P < 0.001), and sleep-period fall in sympathetic activity (r = 0.30, P < 0.001). Multiple regression analyses indicated that these three factors were independent determinants of sleep-period SBP dipping; ethnic differences in dipping were attenuated when controlling for these factors.

CONCLUSIONS

Blunted BP dipping was related to higher BMI, poorer sleep quality, and a lesser decline in sleep-period SNS activity. Although African-American ethnicity also was associated with blunted dipping compared to whites in unadjusted analyses, this ethnic difference was diminished when BMI, sleep quality, and sympathetic activity were taken into account.