Relationships of vascular function with measures of ambulatory blood pressure variation

The relationship between glycemic variability and blood pressure variability in normoglycemic normotensive individuals

BACKGROUND AND AIM

Glycemic fluctuations around a mean glucose level, referred as glycemic variability and blood pressure variability (BPV) are considered as independent risk factors for cardiovascular diseases, all-cause mortality, and cardiovascular disease-mortality. With this background in mind, we aimed to investigate the association between glycemic variability and BPV and their association in normoglycemic and normotensive individuals.

MATERIALS AND METHOD

Twenty-seven normotensive normoglycemic individuals were recruited. Twenty-four hour Holter devices were utilized to measure ambulatory blood pressure (BP) while continuous glucose monitoring (CGM) devices were applied to measure glycemic variability simultaneously to the subjects. These devices were kept on for 48 h. For BP recordings, daytime, nighttime, and 24-h BP determinations, their mean and SD were calculated. From CGM measurements, mean blood glucose (MBG), SD of blood glucose, the mean amplitude of glycemic excursions (MAGE), the mean of daily differences (MODD), coefficient of variation (correction of variability for the MBG), and daytime and nighttime blood glucose were determined.

RESULTS

The mean age of the subjects was 23.8 ± 2.7 years and 66% were women (18/27). In the correlation analysis between glycemic variability parameters and BPV parameters, SD of 24-h SBP was correlated with the SD of MBG (r = 0.52, P = 0.006), MAGE (r = 0.49, P = 0.009), and MODD (r = 0.46, P = 0.015). SD of daytime SBP was correlated with, MAGE (r = 0.42, P = 0.03) and MODD (r = 0.43, P = 0.02).

CONCLUSION

We report correlation between glycemic variability and BPV variables in normoglycemic and normotensive healthy individuals.

Blood pressure variability in normotensive perimenopausal women: Non-dipping status, maximum blood pressure and arterial stiffness

BACKGROUND

Postmenopausal women are more likely to have uncontrolled hypertension and are at higher risk of cardiovascular disease compared with age-matched men. Blood pressure variability is emerging as a predictor of adverse cardiovascular outcomes and may be implicated in the relationship between menopause and worsened vascular health in women. We conducted an observational study, BRAVE (Blood pRessure And Vascular hEalth around menopause) to study this relationship.

METHOD

Normotensive perimenopausal women were recruited. Blood pressure variability was measured through 24-h blood pressure monitoring. Vascular health was assessed through arterial stiffness (carotid-femoral pulse wave velocity), carotid intima-media thickness and endothelial function (reactive hyperemic index). Multivariate models were performed to identify factors associated with blood pressure variability and arterial stiffness in perimenopausal women.

RESULTS

Forty-nine healthy women (mean age 52.9 ± 4.0, 63% postmenopausal) were recruited. There was a high prevalence (40%) of night non-dipping, a measure of an abnormal pattern of blood pressure variability. Aside from night dipping, other measures of blood pressure variability were similar between premenopausal and postmenopausal women. In the multivariate analysis, body mass index was the only factor associated independently with different measures of blood pressure variability, including the maximum overnight blood pressure (ß = 1.95, p < 0.01). The latter was also significantly associated with arterial stiffness (ß = 0.035, p = 0.048). Finally, poor sleep was independently associated with an increase in arterial stiffness.

CONCLUSIONS

Abnormal blood pressure variability, particularly night non-dipping, is common in normotensive perimenopausal women. Maximum overnight blood pressure is independently associated with arterial stiffness and may identify women at higher cardiovascular risk.

Impact of cumulative SBP and serious adverse events on efficacy of intensive blood pressure treatment: a randomized clinical trial

BACKGROUND

Intensive blood pressure lowering is increasingly gaining attention. In addition to higher baseline blood pressure, cumulative SBP, visit-to-visit variability, and treatment-induced serious adverse events (SAEs) could impact treatment efficacy over time. Our aim was to assess the impact of cumulative SBP and SAEs on intensive hypertension treatment efficacy in the Systolic Blood Pressure Intervention Trial (SPRINT) population during follow-up.

METHODS

Secondary analysis of the SPRINT study: a randomized, controlled, open-label trial including 102 clinical sites in the United States. We included 9068 SPRINT participants with 128 139 repeated SBP measurements. Participants were randomly assigned to intensive (target SBP < 120 mmHg) versus standard treatment (target SBP between 135 and 139 mmHg). We used cumulative joint models for longitudinal and survival data analysis. Primary outcome was a composite outcome of myocardial infarction, other acute coronary syndromes, acute decompensated heart failure, stroke, and cardiovascular mortality.

RESULTS

Although intensive treatment decreased the risk for the primary SPRINT outcome at the start of follow-up, its effect lost significance after 3.4 years of follow-up in the total SPRINT population and after 1.3, 1.3, 1.1, 1.8, 2.1, 1.8, and 3.4 years among participants with prevalent chronic kidney disease, prevalent cardiovascular disease, women, black individuals, participants less than 75 years, those with baseline SBP more than 132 mmHg, and individuals who suffered SAEs during follow-up, respectively.

CONCLUSION

The initial beneficial impact of intensive hypertension treatment might be offset by cumulative SBP and development of SAEs during follow-up.

Circadian clock-mediated regulation of blood pressure

Most bodily functions vary over the course of a 24h day. Circadian rhythms in body temperature, sleep-wake cycles, metabolism, and blood pressure (BP) are just a few examples. These circadian rhythms are controlled by the central clock in the suprachiasmatic nucleus (SCN) of the hypothalamus and peripheral clocks located throughout the body. Light and food cues entrain these clocks to the time of day and this synchronicity contributes to the regulation of a variety of physiological processes with effects on overall health. The kidney, brain, nervous system, vasculature, and heart have been identified through the use of mouse models and clinical trials as peripheral clock regulators of BP. The dysregulation of this circadian pattern of BP, with or without hypertension, is associated with increased risk for cardiovascular disease. The mechanism of this dysregulation is unknown and is a growing area of research. In this review, we highlight research of human and mouse circadian models that has provided insight into the roles of these molecular clocks and their effects on physiological functions. Additional tissue-specific studies of the molecular clock mechanism are needed, as well as clinical studies including more diverse populations (different races, female patients, etc.), which will be critical to fully understand the mechanism of circadian regulation of BP. Understanding how these molecular clocks regulate the circadian rhythm of BP is critical in the treatment of circadian BP dysregulation and hypertension.

Change in blood pressure variability in patients with acute ischemic stroke and its effect on early neurologic outcome

Background

How short-term blood pressure variability (BPV) is affected in the acute stage of ischemic stroke and whether BPV is associated with early neurologic outcomes remains unclear.

Methods

Patients who admitted for ischemic stroke within 24 h of symptom onset were consecutively identified between January 2010 and January 2015. BP profiles measured in real-time were summarized into short-term, 24-h time intervals, based on standard deviation (SD) and mean of systolic BP (SBP_SD) during the first 3 days. The primary outcome was daily assessment of early neurological deterioration (END). The associations between short-term SBP_SD values and the secular trend for primary outcome were examined.

Results

A total of 2,545 subjects (mean age, 67.1 ± 13.5 years old and median baseline National Institutes of Health Stroke Scale score, 3) arrived at the hospital an average of 6.1 ± 6.6 h after symptom onset. SBP_SD values at day 1 (SD#D1), SD#D2, and SD#D3 were 14.4 ± 5.0, 12.5 ± 4.5, and 12.2 ± 4.6 mmHg, respectively. Multivariable analyses showed that SD#D2 was independently associated with onset of END at day 2 (adjusted odds ratio, 1.08; 95% confidence interval, 1.03–1.13), and SD#D3 was independently associated with END#D3 (1.07, 1.01–1.14), with adjustments for predetermined covariates, SBP_mean, and interactions with daily SBP_SD.

Conclusion

Short-term BPV changed and stabilized from the first day of ischemic stroke. Daily high BPV may be associated with neurological deterioration independent of BPV on the previous day.

Correlation between ambulatory blood pressure variability and vasodilator function in middle-aged normotensive individuals

OBJECTIVE

The aim of this study was to investigate the association between ambulatory blood pressure variability and vasodilator function in a cohort of normotensive middle-aged individuals.

PARTICIPANTS AND METHODS

This was a cross-sectional study of 285 randomly selected 40-59-year-old normotensive participants who underwent 24-h ambulatory blood pressure monitoring and brachial artery ultrasound assessment. Systolic and diastolic blood pressure variability (BPV) of 24-h, daytime, and night-time were calculated using the coefficients of variation (CV) and the average real variability (ARV) index. Brachial arterial endothelium-dependent vasodilation (EDD) was assessed in response to increased flow and endothelium-independent vasodilation (EID) was assessed in response to nitroglycerin. Relationships were explored using univariate and multivariate linear regression.

RESULTS

The EDD were negatively associated with the CV of 24-h systolic blood pressure (SBP), the ARV of 24-h SBP, and diastolic blood pressure (DBP) in univariate analysis. However, the CV and ARV of 24-h SBP remained associated independently with % EDD in multivariate analysis. In addition, the mean levels of 24-h SBP and DBP, the CV of 24-h SBP and DBP, the ARV of 24-h SBP and DBP, the CV of daytime SBP, and the ARV of daytime DBP were all associated with % EID. However, in a multiple linear regression model, adjusting for covariates, only the CV and ARV of 24-h SBP, and the ARV of 24-h DBP were correlated negatively but weakly with % EID.

CONCLUSION

Our results indicated that a higher 24-h BPV was associated independently with decreased endothelial-dependent and endothelial-independent vasodilator functions in a middle-aged normotensive population. Although 24-h BPV was associated with vasodilator function, relationships were attenuated after adjusting for covariates.

Chronic vagal nerve stimulation prevents high-salt diet-induced endothelial dysfunction and aortic stiffening in stroke-prone spontaneously hypertensive rats

Parasympathetic activity is often reduced in hypertension and can elicit anti-inflammatory mechanisms. Thus we hypothesized that chronic vagal nerve stimulation (VNS) may alleviate cardiovascular end-organ damage in stroke-prone spontaneously hypertensive rats. Vagal nerve stimulators were implanted, a high-salt diet initiated, and the stimulators turned on (VNS, n = 10) or left off (sham, n = 14) for 4 wk. Arterial pressure increased equally in both groups. After 4 wk, endothelial function, assessed by in vivo imaging of the long posterior ciliary artery (LPCA) after stimulation (pilocarpine) and inhibition (N(ω)-nitro-l-arginine methyl ester) of endothelial nitric oxide synthase (eNOS), had significantly declined (-2.3 ± 1.2 μm, P < 0.05) in sham, but was maintained (-0.7 ± 0.8 μm, nonsignificant) in VNS. Furthermore, aortic eNOS activation (phosphorylated to total eNOS protein content ratio) was greater in VNS (0.83 ± 0.07) than in sham (0.47 ± 0.08, P < 0.05). After only 3 wk, ultrasound imaging of the aorta demonstrated decreased aortic strain (-9.7 ± 2.2%, P < 0.05) and distensibility (-2.39 ± 0.49 1,000/mmHg, P < 0.05) and increased pulse-wave velocity (+2.4 ± 0.7 m/s, P < 0.05) in sham but not in VNS (-3.8 ± 3.8%, -0.70 ± 1.4 1,000/mmHg, and +0.1 ± 0.7 m/s, all nonsignificant). Interleukin (IL)-6 serum concentrations tended to be higher in VNS than in sham (34.3 ± 8.3 vs. 16.1 ± 4.6 pg/ml, P = 0.06), and positive correlations were found between NO-dependent relaxation of the LPCA and serum levels of IL-6 (r = +0.70, P < 0.05) and IL-10 (r = +0.56, P < 0.05) and between aortic eNOS activation and IL-10 (r = +0.48, P < 0.05). In conclusion, chronic VNS prevents hypertension-induced endothelial dysfunction and aortic stiffening in an animal model of severe hypertension. We speculate that anti-inflammatory mechanisms may contribute to these effects.

Time Rate of Blood Pressure Variation Is Associated With Endothelial Function in Patients With Metabolic Syndrome

The time rate of blood pressure (BP) variation indicates the speed of BP fluctuations. Previous studies have demonstrated that the time rate of BP variation was associated with target organ damage. However, the association between time rate of BP variation and endothelial function has not been evaluated.24-hour ambulatory blood pressure monitoring (ABPM) was performed in 61 patients with metabolic syndrome. Time rate of BP variation was calculated from BP recordings of ABPM. Endothelial function was assessed using reactive hyperemia-peripheral arterial tonometry index (RHI) by EndoPat2000. Multiple linear regression models were used to detect the association between time rate of BP variation and RHI.Among all the subjects (n = 61), the multiple linear regression models revealed that the daytime rate of systolic blood pressure (SBP) variation was independently associated with RHI (β = -0.334, P = 0.008). A 0.1 mmHg/minute increase in the daytime rate of SBP variation correlated with a decline of 0.20 in RHI. The same effect was also found in the subjects with eGFR ≥ 60 mL/ (minute*1.73 m(2)). A greater association was found in those who were not taking a statin, β-blocker, ACEI/ARB, or diuretic and those without diabetes compared with those with any antihypertensive medication or with diabetes. Other ambulatory blood pressure parameters and central hemodynamics were not found to be associated with RHI.Our findings have shown that the daytime rate of SBP variation was associated with endothelial function in patients with metabolic syndrome, independent of other BP parameters and central hemodynamics.

Nonalcoholic fatty liver disease is an independent risk factor for atherosclerosis in young adult men

INTRODUCTION

The possible cause of accelerated atherosclerosis in NAFLD may be the relationship with the MetS and its components. Our primary goal was to evaluate the relationship between NAFLD and subclinical atherosclerosis in adult male patients between 20 and 40 years of age. Moreover, we aimed to investigate the changes in this association according to the presence or absence of MetS.

METHOD

Sixty-one male patients with biopsy-proven NAFLD and 41 healthy male volunteers were enrolled. In order to exclude any interference of confounding factors, we studied a specifically selected group with no additional cardiovascular risk. PWV, CIMT and FMD levels were measured in all patients and controls.

RESULTS

The levels of cf-PWV were significantly higher in SS and NASH patients compared to the control group (P < 0.001); no significant difference was found between SS and NASH patients (P > 0.05). We found significantly decreased FMD levels in patients with SS and NASH compared with control subjects (P < 0.001). Subjects with NASH had significantly greater CIMT measurements than the SS and controls (P = 0.026, P < 0.001, respectively). Although, NAFLD patients with MetS had increased cf-PWV and CIMT and reduced FMD compared to healthy subjects (P < 0.05), no significant difference existed between NAFLD with Mets and NAFLD without MetS in terms of cf-PWV, CIMT and FMD (P > 0.05) CONCLUSION: The present study showed that the presence of NAFLD leads to increased risk of endothelial dysfunction and atherosclerosis in adult male patients, independent of MetS.