Sympathetic Neural Mechanisms Underlying Attended and Unattended Blood Pressure Measurement

Relationship between sleep-breathing events induced nocturnal blood pressure surge and sympathetic nervous activity in patients with obstructive sleep apnea

OBJECTIVE

Nocturnal blood pressure (BP) surge is a characteristic phenomenon in patients with obstructive sleep apnea (OSA) associated with sympathetic nerve overactivity. This study aimed to explore the relationship between the sleep-breathing events induced nocturnal BP surge and sympathetic nerve activity.

METHODS

A total of 85 patients with moderate-to-serve OSA and 44 controls were included in the study between April 2022 and October 2023 based on the inclusion and exclusion criteria. Full-night BP and heart rate variability (HRV) were monitored continuously and synchronized with polysomnography (PSG). The average of nocturnal BPs was taken as the asleep BP and the average of the highest BPs induced by all sleep-breathing events as the asleep peak BP. Nocturnal short-term BP variability (BPV) was calculated as follows: event-related systolic BP elevation (ΔSBP) as the gap between the peak and the lowest value of post-apneic SBP, BP index as the number of ΔSBP ≥ 12 mm Hg within 30 s/h, and the percentage of BP fluctuation induced by sleep-breathing events (PBPF) as the ratio of BP index and apnea-hypopnea index. Patients with OSA were divided into two subgroups (high- and low-BP surge groups) according to the median PBPF. The sympathetic nerve activity was reflected by plasma norepinephrine (NE) level and HRV. The PSG and BP parameters were compared among three groups, and the correlation between nocturnal short-term BPV and sympathetic nerve activity was analyzed.

RESULTS

Patients with OSA were fatter and suffered from dyslipidemia and sympathetic nerve overactivity compared to controls. The high-BP surge group displayed higher sympathetic nerve activity and more severe hypoxia compared with the low-BP surge group. The Pearson correlation analysis showed a positive correlation of the higher nocturnal short-term BPV with increased sympathetic nerve activity (all P < 0.05). After excluding confounding factors, such as age, body mass index, and smoking history, the multiple linear regression revealed a positive correlation of the LF/HF (ratio of low-frequency to high-frequency power, indicating the activity of sympathetic nerve activity) with the BP index (β = 7.337, P < 0.001), ΔSBP (β = 2.797, P < 0.001), and PBPF (β = 9.036, P < 0.001). The plasma NE level also had a positive correlation with the BP index (β = 3.939, P = 0.022) and PBPF (β = 8.752, P < 0.001).

CONCLUSION

The sleep-breathing events induced nocturnal BP surge was positively correlated with sympathetic nerve activity in patients with moderate-to-serve OSA.

Agreement between resting heart rate measured by unattended automated office and office blood pressure measurement, ambulatory blood pressure monitoring, or electrocardiography

The application of unattended blood pressure measurement (uAOBPM) for resting heart rate (RHR) assessment is unknown. To assess the agreement between RHR measured during uAOBPM and other methods, the authors conducted a comparability study with office blood pressure measurement (OBPM), ambulatory blood pressure monitoring (ABPM), and electrocardiogram (ECG) in a group of 110 participants referred for ABPM. RHR measured with uAOBPM (70.8 ± 12.5 bpm) was significantly lower than OBPM (72.8 ± 12.6 bpm) but higher than measured by 24 h ABPM (67.5 ± 10.2 bpm). There was no significant difference was found between RHR measured by uAOBPM and daytime ABPM (70.3 ± 11.2 bpm) or ECG (69.1 ± 11.6 bpm). Using Bland-Altman statistics, the authors discovered a small difference in agreement between RHR measured by uAOBPM and daytime ABPM (bias: 0.4 with 95% confidence interval: -0.8 to 1.6 bpm), with a poorer agreement with OBPM (bias -2 with 95% confidence interval: -2.8 to -1.3 bpm) and ECG (bias 1.6 with 95% confidence interval: 0.5 to 2.7 bpm). The authors found significant agreement between uAOBPM and ECG in identifying subjects with RHR > 80 bpm OBPM, with Cohen's kappa coefficients of 0.783 and 0.671, respectively. Their findings indicate that RHR measured with uAOBPM remains in acceptable agreement with OBPM, ABPM, and ECG, the best agreement obtained with RHR from daytime ABPM.

White Coat Hypertension & Cardiovascular Outcomes

PURPOSE OF REVIEW

This review aims to inform the reader of the complexity of blood pressure responses when comparing blood pressure measured in the medical environment to that outside the medical environment. In addition, we summarize what is known about current predictors of white coat hypertension, reevaluate the relationship of white coat hypertension to cardiovascular outcomes, and provide some clinical guidance on management.

RECENT FINDINGS

Differences in outcomes exist when white coat effect occurs in unmedicated people versus the white coat effects in those on antihypertensive therapy. White coat hypertension is relatively common, carries a small but definite increase in cardiovascular risk, and is prone to conversion to sustained hypertension. Future research will hopefully tease out the roles of ancillary findings that characterize a white coat hypertensive (like modest elevations in creatinine, glucose and triglycerides) in the elevated cardiovascular risk, and test the effectiveness of mitigation strategies in these patients.

Comparative Effects of Neurodynamic Slider and Tensioner Mobilization Techniques on Sympathetic Nervous System Function: A Randomized Controlled Trial

Objective: To investigate the effect of slider and tensioner neurodynamic techniques (NDTs) on the sympathetic nervous system (SNS) activity, aiming to identify which technique more effectively modulates autonomic responses in asymptomatic individuals. Materials and Methods: In this double-blind controlled trial, a total of 90 healthy participants were randomly allocated into three groups: slider, tensioner, and control. Skin conductance (SC) was continuously monitored throughout the entire 20 min experiment, while body temperature and blood pressure were measured pre- and post-intervention. Results: The SC levels significantly increased in both the slider and tensioner groups compared to the control group during the intervention and end rest period on the left leg (slider vs. control: p < 0.001, d = 1.20; tensioner vs. control: p < 0.001, d = 1.64) and on the right leg (slider vs. control: p < 0.001, d = 1.47; tensioner vs. control: p < 0.001, d = 0.73). There were no significant differences between the two NDTs on the left (p < 0.13, d = 0.89) and right legs (p < 1.00, d = 0.36). The body temperature of the slider group showed a significant increase compared to both the control group (p < 0.001, d = 0.95) and the tensioner group (p < 0.001, d = 1.48). There were no significant differences between the groups in systolic (p = 0.95) or diastolic blood pressure (p = 0.06). There were no side-specific effects on SNS activity between the left and right legs (p < 0.019) during all intervention phases. Conclusions: Significant sympathoexcitatory responses were elicited by both slider and tensioner NDTs in asymptomatic participants, demonstrating their efficacy in modulating the SNS. The differences between the two techniques were not statistically significant; however, the tensioner NDT showed a slightly more pronounced effect, suggesting that the tensioner NDT can be considered superior in terms of overall SNS effect. These findings indicate that both techniques may have the potential to enhance autonomic regulation in clinical practice; however, the tensioner NDT may be more effective. The consistent responses across participants highlight the systemic benefits of NDTs, providing a foundation for further research into their application in symptomatic populations. This study contributes to evidence-based practice by providing baseline data that support the development of theoretical frameworks and aid in clinical decision-making.

The role of gut microbiota in the development of salt-sensitive hypertension and the possible preventive effect of exercise

INTRODUCTION

The aim of the present study is to analyze the data indicating an association between high salt intake and the gastrointestinal microbiota in the development of salt-sensitive hypertension in animals and men. It is also, to discuss the preventive effects of exercise on gut-induced hypertension by favorably modifying the composition of gut microbiota.

AREAS COVERED

Salt sensitivity is quite common, accounting for 30%-60% in hypertensive subjects. Recently, a novel cause for salt-sensitive hypertension has been discovered through the action of gut microbiota by the secretion of several hormones and the action of short chain fatty acids (SCFAs). In addition, recent studies indicate that exercise might favorably modify the adverse effects of gut microbiota regarding their effects on BP. To identify the role of gut microbiota on the incidence of hypertension and CVD and the beneficial effect of exercise, a Medline search of the English literature was conducted between 2018 and 2023 and 42 pertinent papers were selected.

EXPERT OPINION

The analysis of data from the selected papers disclosed that the gut microbiota contribute significantly to the development of salt-sensitive hypertension and that exercise modifies their gut composition and ameliorates their adverse effects on BP.

Impact of nocturnal blood pressure dipping on recurrence of atrial fibrillation after pulmonary vein isolation

Lack of the typical nocturnal blood pressure (BP) fall, i.e non-dipper, has been known as a cardiovascular risk. However, the influence of non-dipper on atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) has been unclear. We investigated the clinical impact of non-dipping as evaluated by 24-hour ambulatory BP monitoring on the long-term outcome of AF recurrence post-PVI in 76 AF patients with a history of increased BP. The PVI procedure was successful in all 76 patients (mean age, 66±9years; antihypertensive medication, 89%; non-paroxysmal AF, 24%). Twenty patients had AF recurrence during a median follow-up of 1138 days. There was no difference in BP levels between the AF recurrence and non-recurrence groups (average 24 h systolic BP:126 ± 17 vs.125 ± 14 mmHg; P = 0.84). On the other hand, the patients with non-dipper had a higher AF recurrence than those with dipper (38.9% vs.15.0%; P = 0.018). In Cox hazard analysis adjusted by age, non-paroxysmal AF and average 24-hr systolic BP level, the non-dipper was an independent predictor of AF recurrence (HR 2.78 [95%CI:1.05-7.34], P = 0.039). Non-dipper patients had a larger left atrial (LA) volume index than the dipper patients (45.9 ± 17.3 vs.38.3 ± 10.2 ml/m2, P = 0.037). Among the 58 patients who underwent high-density voltage mapping in LA, 11 patients had a low-voltage area (LVA) defined as an area with a bipolar voltage < 0.5 mV. However, there was no association of LVA with non-dipper or dipper (22.2% vs.16.1%, P = 0.555). Non-dipper is an independent predictor of AF recurrence post-PVI. Management of abnormal diurnal BP variation post-PVI may be important.

Highlights from the New European Society of Hypertension Guidelines Document

The present editorial will review the main recommendations included in the recent guidelines for the diagnosis and treatment of hypertension issued by the European Society of Hypertension. Emphasis will be given to some crucial issues of major relevance for current clinical practice, such as office and out-of-office blood pressure measurements, blood pressure threshold and targets, combination drugs, the position of beta-blocking drugs in the therapeutic intervention, and renal denervation.

Sympathetic Neural Mechanisms in Hypertension: Recent Insights

PURPOSE OF REVIEW

To examine published and unpublished data documenting the role of sympathetic neural factors in the pathogenesis of different hypertensive phenotypes. These phenotypes relate to attended or unattended blood pressure measurements, to nighttime blood pressure profile alterations, and to resistant, pseudoresistant, and refractory hypertension. Results of original clinical studies as well as of recent meta-analyses based on the behavior of different sympathetic biomarkers in various hypertensive forms will be also discussed.

RECENT FINDINGS

Studies performed in the past decade have shown that office blood pressure measurements, including in recent years those characterizing unattended or attended blood pressure assessment, are associated with profound changes in the behavior of different sympathetic biomarkers. This is the case for the clinical hypertensive phenotypes characterized by alterations in the nocturnal blood pressure profile and by sleep duration abnormalities. This is also the case for the clinical conditions defined as resistant, refractory, and pseudoresistant hypertension. Data reviewed in the present paper highlight the relevance of sympathetic neural factors in the development and progression of different clinical hypertensive phenotypes. This suggests that a common hallmark of the majority of the essential hypertensive states detectable in current clinical practice is represented by the alteration in the sympathetic blood pressure control.

Blood pressure control measures and cardiovascular outcomes: a prospective hypertensive cohort

PURPOSE

We investigated whether blood pressure (BP) control measures, visit-to-visit BP variability, and time in therapeutic range (TTR) are associated with future cardiovascular outcomes in hypertensive patients.

MATERIALS AND METHODS

Among 1,408 hypertensive patients without cardiovascular disease, we prospectively evaluated the incident major cardiovascular events over 6 years. In newly diagnosed patients, antihypertensive drug treatment was initiated. We estimated two markers of on-treatment BP control, (1) visit-to-visit BPV as the coefficient of variation of office systolic BP (BP-CV), and (2) TTR calculated as the percentage of office systolic BP measurements within 120-140mmHg across visits.

RESULTS

The hypertensive cohort (672 males, mean age 60 years, 31% newly diagnosed) had a mean systolic/diastolic BP of 142/87 mmHg. The mean number of visits was 4.9 ± 2.6, while the mean attained systolic/diastolic BP during follow-up was 137/79 mmHg using 2.7 ± 1.1 antihypertensive drugs. The BP-CV and TTR were 9.1 ± 4.1% and 45 ± 29%, respectively, and the incidence of the composite outcome was 8.3% (n = 117). After adjustment for relevant confounders and standardization to z-scores, BP-CV and TTR were associated with a 43% (95% CI, 27-62%) increase and a 33% (95% CI, 15-47%) reduction in the outcome. However, the joint evaluation of TTR and BP-CV in a common multivariable model indicated that a standardized change of TTR was associated with the outcome to a greater extent than BP-CV (mean hazard ratios of 30% vs. 24%, respectively). When combined with the higher BP standardized-CV quartile, the lower TTR quartile predicted the outcome by 2.3 times (95% CI, 1.1-5.4) compared to the inverse TTR and BP-CV quartile pattern.

CONCLUSION

High BP-CV or low TTR was associated with future cardiovascular events in a cohort of treated hypertensive patients. As a determinant, the extent of TTR value appears greater than BP-CV when these measures are considered in the same multivariable model.

Blood pressure response to close or loose contact between physician and patient during attended office blood pressure measurement

PURPOSE

Compared to unattended office blood pressure (uOBP), attended office blood pressure (aOBP) is higher. It is not known, however, to what extent distance between physician and patient influences blood pressure (BP) values.

MATERIALS AND METHODS

Participants were stable hypertensive patients, followed in the university hospital-based out-patient center. During a session, automated office BP was measured three times after a pre-set five-minute pause, using the Omron 907 device; both aOBP and uOBP were done, in a random order. Simultaneously, beat-to-beat BP measurement was performed using the Finapress device. During aOBP, some participants were in close contact with the physician while others were in loose contact where the doctor was sitting in the room about 2.5 m apart. One year later, the second session with the same protocol was organized, but the close and loose contact were interchanged. The data were analyzed using a paired t-test.

RESULTS

Complete data were collected in 32 patients, baseline uOBP was 122.8 ± 14.8/69.5 ± 11.7 mmHg. Systolic and diastolic aOBP with close contact was higher by 4.6 ± 6.9 and 1.9 ± 3.4 mmHg (p < 0.0007 and 0.0039, respectively), while aOBP with loose contact was not different from uOBP. Beat-to-beat BP increased during aOBP by 6.5 ± 8.5/3.3 ± 4.8 mmHg. The increase persisted during all the three aOBP measurements (p < 0.0001 for all systolic and diastolic BP values); the results were similar for close and loose contact. The peak increase during uOBP was of similar magnitude as during aOBP but it lasted shorter: it reached the significance level of p < 0.0001 only during the first uOBP measurement.

CONCLUSIONS

Compared to uOBP, aOBP values were higher with close, but not with loose contact between physician and patient. These differences were, however, not detected by beat-to-beat BP measurement.

Unattended versus Attended Blood Pressure Measurement: Relationship with Retinal Microcirculation

Though the relationship between both “attended” and “unattended” BP and several forms of target organ damage have been evaluated, data on retinal arteriolar alterations are lacking. The aim of our study was to evaluate the relationship between “attended” or “unattended” BP values and retinal arteriolar changes in consecutive individuals undergoing a clinical evaluation and assessment of retinal fundus at an ESH Excellence Centre. An oscillometric device programmed to perform 3 BP measurements, at 1 min intervals and after 5 min of rest was used on all individuals to measure BP with the patient alone in the room (“unattended”) or in the presence of the physician (“attended”) in the same day in a random order. The retinal arteriole’s wall thickness (WT) was measured automatically by a localization algorithm as the difference between external (ED) and internal diameter (ID) by adaptive optics (RTX-1, Imagine Eyes, Orsay, Francia). Media-to-lumen ratio (WLR) of the retinal arterioles and cross-sectional area (WCSA) of the vascular wall were calculated. Results: One-hundred-forty-two patients were examined (mean age 57 ± 12 yrs, 48% female, mean BMI 26 ± 4). Among them, 60% had hypertension (84% treated) and 11% had type 2 diabetes mellitus. Unattended systolic BP (SBP) was lower as compared to attended SBP (129 ± 14.8. vs. 122.1 ± 13.6 mmHg, p < 0.0001). WLR was similarly correlated with unattended and attended SBP (r = 0.281, p < 0.0001 and r = 0.382, p < 0.0001) and with unattended and attended diastolic BP (r = 0.34, p < 0.001 and r = 0.29, p < 0.0001). The differences between correlations were not statistically significant (Steiger’s Z test). Conclusion: The measurement of “unattended” or “attended” BP provides different values, and unattended BP is lower as compared to attended BP. In this study a similar correlation was observed between attended and unattended BP values and structural changes of retinal arterioles.

High waist circumference is a risk factor for hypertension in normal-weight or overweight individuals with normal metabolic profiles

This study aims to investigate the relationship between waist circumference and hypertension risk in normal‐weight/overweight individuals with normal cardiometabolic profiles. The authors included 7217 normal‐weight and overweight individuals with normal cardiometabolic profiles from the 2001 to 2014 US National Health and Nutrition Examination Survey. The authors summarized demographic characteristics, cardiometabolic profiles, and behavioral factors across waist circumference quartiles. Then, in the logistic regression analysis, the authors observed a positive and significant association between waist circumference (as a continuous variable) and the prevalence of hypertension in all three models (nonadjusted, minimally adjusted, and fully adjusted), with odds ratios (95% confidence intervals) of 1.76 (1.65–1.86), 1.29 (1.20–1.39), and 1.24 (1.09–1.40), respectively. When analyzed as a categorical variable, individuals in the highest waist circumference group had a 1.48‐fold increased risk of hypertension than the lowest group in the fully adjusted model. Moreover, the Cox regression analysis revealed a positive and significant association between waist circumference and all‐cause mortality in individuals with hypertension in the nonadjusted model (HR, 1.27; 95% CI, 1.10–1.47) and the fully adjusted model (HR, 1.59; 95% CI, 1.22–2.06). In conclusions, our results showed that, even in those with normal metabolic profiles, high waist circumference was significantly associated with the increased prevalence of hypertension. And once hypertension has been established, patients with high waist circumference showed elevated all‐cause mortality. Therefore, waist circumference should be routinely measured and controlled regardless of metabolic profiles.

Identifying and treating resistant hypertension in PRECISION: A randomized long-term clinical trial with aprocitentan

The design and baseline data of the PRECISION study, which evaluates the effect of the dual endothelin receptor antagonist aprocitentan on blood pressure (BP) in patients with resistant hypertension (RHT) are presented. The study is a blinded, randomized, parallel-group Phase 3 study and its three-part design assesses the short-term and sustained long-term effects of aprocitentan on BP. Results are expected in 2022. Patients with uncontrolled BP (measured as unattended automated office BP) despite the use of three or more antihypertensive medications for at least 1 year were screened. They were switched to a single-tablet triple fixed combination antihypertensive therapy for at least 4 weeks before entering a single-blind placebo run-in period. The 4-week placebo run-in period further excluded placebo responders. The randomization period consisted of three sequential parts: (1) a 4-week double-blind part with aprocitentan 12.5 mg, 25 mg, or placebo (1:1:1 ratio); (2) a 32-week single-blind part with aprocitentan 25 mg; and (3) a 12-week randomized withdrawal part with aprocitentan 25 mg or placebo (1:1 ratio). The purpose was to demonstrate the BP lowering effect of aprocitentan in RHT (Part 1) and the persistence of this effect (Parts 2 and 3). Out of 1965 screened patients, 730 were randomized resulting in an overall inclusion failure rate of 62.8%. The most common reason for exclusion (44.4% of all screened patients) was failure to meet the BP inclusion criteria. These results underline the high proportion of pseudoresistant hypertension among patients referred for RHT.

Sympathetic nervous system and hypertension: New evidences

Evidences collected in the past few years have strengthened the concept that the sympathetic nervous system plays a primary role in the development and progression of the hypertensive state, starting from the early stage, and in the hypertension-related cardiovascular diseases. Several pathophysiological mechanisms are involved. Among them the genetic background, the immune system in conjunction with sympathetic activation. The present review will briefly discuss the importance of the above mentioned mechanisms in the development of hypertension. The paper will also examine the sympathetic mechanisms underlying attended vs unattended blood pressure measurements as well as their role in resistant vs pseudo-resistant hypertension. Finally evidence from recent meta-analysis on the relevance of sympathetic nerve traffic activation in the pathogenesis of hypertension will be briefly discussed.

Do recent meta-analyses truly prove that treatment with blood pressure-lowering drugs is beneficial at any blood pressure value, no matter how low? A critical review

Current European guidelines for the management of hypertension and on cardiovascular disease prevention place the threshold for pharmacological treatment at a SBP level of 140 mmHg or above, with the exception of patients at very high risk (mainly because of coronary heart disease). This is in agreement with the current definition of hypertension, that is, the level of blood pressure at which the benefits of treatment outweigh the risks of treatment, as documented by clinical trials. This rationale and definition was recently challenged by meta-analyses using individual participant-level data from 48 randomized trials by the Blood Pressure Lowering Treatment Trialists' Collaboration (BPLTTC). The authors calculated for a fixed 5 mmHg pharmacological reduction of SBP an overall 10% risk reduction for major cardiovascular events. It was concluded that there was no reliable evidence of heterogeneity of treatment effects by baseline SBP categories; that the effect was independent from the presence of cardiovascular disease; applied also to old and very old individuals up to 84 years or beyond; and that BP-lowering was also beneficial in individuals with normal or high-normal SBP down to a baseline SBP less than 120 mmHg. In this report, we identify and discuss a number of shortcomings of the BPLTTC meta-analyses. In our view, the conclusions by the BPLTTC must be - together with accompanying suggestions to abandon the definition of hypertension - strongly rejected as they are not justified and may be harmful for cardiovascular health in individuals without hypertension.

White-Coat Hypertension: Pathophysiological and Clinical Aspects: Excellence Award for Hypertension Research 2020

Few issues of modern cardiovascular medicine have been as controversial as the relationship between white-coat hypertension (WCH), that is, a common condition in which office blood pressure is elevated while out-of-office blood pressure (ambulatory blood pressure or home blood pressure) is normal. While earlier studies showed no increased risk of cardiovascular events in WCH compared with the normotensive state, more recent studies have changed this conclusion by showing that an increased cardiovascular risk represents a trait of this hypertensive phenotype. The present article will review a number of issues related to WCH, that is, its definition, pathophysiological background, clinical alterations, and prognostic significance. This will be done by considering the available evidence published during the last decades, with special focus on the data collected in PAMELA (Pressioni Arteriose Monitorate e Loro Associazioni)-a research project performed with a cross-sectional and longitudinal design, which has provided a series of novel clinical information on WCH throughout the years. The final part of the article will discuss the therapeutic implications of the abovementioned evidence, as well as some controversial or still undefined issues related to WCH, whose investigation will be an important goal to pursue by future research.