Circadian hemodynamics in men and women with high blood pressure: dipper vs. nondipper and racial differences

Cognitive behavior therapy for insomnia for untreated hypertension with comorbid insomnia disorder: The SLEEPRIGHT clinical trial

Insomnia and poor sleep are associated with an increased risk of developing cardiovascular disease (CVD) and its precursors, including hypertension. In 2022, the American Heart Association (AHA) added inadequate sleep to its list of health behaviors that increase the risk for CVD. It remains unknown, however, whether the successful treatment of insomnia and inadequate sleep can reduce heightened CVD risk. SLEEPRIGHT is a single-site, prospective clinical trial designed to evaluate whether the successful treatment of insomnia results in improved markers of CVD risk in patients with untreated hypertension and comorbid insomnia disorder. Participants (N = 150) will undergo baseline assessments, followed by a 6-week run-in period after which they will receive cognitive behavior therapy for insomnia (CBT-I), comprised of 6 hourly sessions with an experienced CBT-I therapist over a 6-week period. In addition to measures of insomnia severity, as well as both subjective and objective measures of sleep, the primary outcome measures are nighttime blood pressure (BP) and BP dipping assessed by 24-h ambulatory BP monitoring (ABPM). Secondary outcomes include several CVD risk biomarkers, including clinic BP, lipid profile, vascular endothelial function, arterial stiffness, and sympathetic nervous system (SNS) activity. Data analysis will evaluate the association between improvements in insomnia and sleep with primary and secondary CVD risk biomarker outcomes. The SLEEPRIGHT trial (ClinicalTrials.Gov NCT04009447) will utilize CBT-I, the current gold standard treatment for insomnia disorder, to evaluate whether reducing insomnia severity and improving sleep are accompanied by improved biomarkers of CVD risk in patients with untreated hypertension.

Diurnal cardio-respiratory changes in ambulatory individuals deciphered using a multi-parameter wearable device

Background

Recent technological developments enable big data-driven insights on diurnal changes. This study aimed to describe the trajectory of multiple and advanced parameters using a medical-grade wearable remote patient monitor.

Methods

Parameters were monitored for 24 h in 256 ambulatory participants who kept living their normal life. Parameters included heart rate, blood pressure, stroke volume, cardiac index, systemic vascular resistance, blood oxygen saturation, and respiratory rate. Diurnal variations were evaluated, and analyses were stratified based on sex, age, and body mass index.

Results

All parameters showed diurnal changes (p < 0.001). Females demonstrated higher heart rate and cardiac index with lower systemic vascular resistance. Obese participants had a higher blood pressure, and lower stroke volume and cardiac index. Systemic vascular resistance was higher among the elderly. Diurnal changes corresponded with awake-sleep hours and differed between sex, age, and body mass index groups.

Conclusion

Wearable monitoring platforms could decipher hemodynamic changes in subgroups of individuals, and might help with efforts to provide personalized medicine, pre-symptomatic diagnosis and prevention, and drug development.

Heart rate turbulence measurements in patients with dipper and non-dipper hypertension: the effects of autonomic functions

Background/aim

Hypertensive patients have shown autonomic dysfunction that is closely associated with the measurements of heart rate variability (HRV) and heart rate turbulence (HRT). We aimed to show the alterations of HRV and HRT measurements in patients with both dipper and non-dipper hypertension.

Materials and methods

This was a retrospective study consisting of one hundred and twenty-three participants (mean age ± SD, 55.7 ± 14.8 years; range, 18–90 years). The participants were divided into two groups: Group1: The patients with dipper hypertension, Group2: The patients with non-dipper hypertension. Two cardiologists performed HRV and HRT using 24-h electrocardiography (ECG) Holter and ambulatory blood pressure monitoring (ABPM) of patients.

Results

The results indicated that patients in group 2 had higher low frequency power/high frequency power ratio (LF/HF), lower high frequency power (HF) , root mean square of standard deviation (RMSSD) values than group 1 (p = 0.007, p = 0.008, and p = 0.002, respectively). Group 2 also showed higher heart rate turbulence onset (HRTTO) and lower heart rate turbulence slope (HRTTS) values than Group 1 (p = 0.004, p = 0.001, respectively). We performed multivariate analysis and observed that HRTTS and HRTTO have statistically significant associations with the presence of dipper or non-dipper hypertension [F = 7.755, p = 0.001], LF/HF [F = 7.868, p = 0.001], and HF [F = 4.081, p = 0.020].

Conclusion

This study shows a statistically significant difference in HRT measurements between dipper and non-dipper hypertensive patients. Deteriorated autonomic circadian rhythm and autonomic functions may contribute to these results.

Ethnic Differences in Resting Total Peripheral Resistance: A Systematic Review and Meta-Analysis

OBJECTIVE

Decades of research suggest that there may be important ethnic differences in the hemodynamic mechanisms that co-determine arterial blood pressure, the primary diagnostic index of hypertension. In general, studies have observed that, compared with European Americans (EAs), African Americans (AAs) exhibit higher total peripheral resistance (TPR), an important summative index of peripheral vascular constriction. In contrast, EAs have been reliably shown to exhibit greater cardiac output (CO), which is directly linked to left ventricle and overall cardiac blood flow. We have previously proposed that elevated basal TPR, in particular, represents one component of the cardiovascular conundrum, characterized, paradoxically, by elevated resting heart rate variability among AAs relative to EAs. The present meta-analysis and systematic review of the literature sought to extend this previous work by establishing the magnitude of the empirically implied ethnic differences in resting TPR and CO.

METHODS

A search of the literature yielded 140 abstracts on differences in TPR between AAs and EAs; 40 were included. Sample sizes, means, and standard deviations for baseline TPR with samples that included EAs and AAs were collected, and Hedges g was computed.

RESULTS

Findings indicated that AAs had higher baseline TPR than did EAs (Hedges g = 0.307, SE = 0.043, confidence interval= 0.224 to 0.391, p < .001). In addition, EAs had higher resting CO than did AAs (Hedges g = -0.214, SE = 0.056, confidence interval = -0.324 to -0.104, p < .001).

CONCLUSIONS

We discuss the present findings in the context of the role of elevated TPR in the deleterious effects of high blood pressure specifically for AAs.

Prognostic value of nocturnal blood pressure dipping on cardiovascular outcomes in Chinese patients with hypertension in primary care

Meta‐analyses showed that non‐dipping of nocturnal blood pressure on ambulatory blood pressure monitoring (ABPM) was associated with adverse cardiovascular prognosis. However, these prognostic studies were mainly conducted in Caucasian and Japanese populations. Whether this association applies to Chinese patients remained uninvestigated. A total of 1199 Chinese patients with hypertension undergoing ABPM between January 2012 and December 2014 were recruited retrospectively from five public hypertension referral clinics in Hong Kong. Patients were followed up for a mean 6.42 years for cardiovascular morbidity and mortality and all‐cause mortality. Time to event of different dipping patterns was compared by Kaplan‐Meier curves. Hazard ratios (HR) were obtained by Cox proportional hazard models with patient demographics and confounding factors adjusted in multivariate regression. A total of 163 end point events occurred in the period. Normal dipping was observed in 446 patients (37.2%), non‐dipping in 490 (40.9%), reverse dipping in 161 (13.4%), and extreme dipping in 102 (8.5%). Kaplan‐Meier analyses showed inferior survival in non‐dippers and reverse dippers for total cardiovascular events and coronary events but not cerebrovascular events. After adjusting for confounding factors, Cox regressions showed HRs 1.166 (CI 0.770‐1.764) and 1.173 (CI 0.681‐2.021) in non‐dippers and reverse dippers for total cardiovascular events, and HRs 1.320 (CI 0.814‐2.141) and 1.476 (CI 0.783‐2.784) for coronary events. Nocturnal blood pressure non‐dipping, and to a greater extent reverse dipping, demonstrated adverse cardiovascular prognosis in a cohort of Chinese patients with hypertension in Hong Kong. Further focused studies on cerebrovascular events and reverse dippers were warranted to refine risk stratification.

Higher cardiac vagal activity predicts lower peripheral resistance 6 years later in European but not African Americans

African American (AA) individuals are at a greater risk for the development of cardiovascular complications, such as hypertension, compared with European Americans (EAs). Higher vagally mediated heart rate variability (HRV) is typically associated with lower blood pressure (BP) and total peripheral resistance (TPR). However, research has yet to examine the differential impact of HRV on longitudinal hemodynamic activity between AAs and EAs. We sought to rectify this in a sample of 385 normotensive youths (207 AAs, 178 EAs; mean age 23.16 ± 2.9 yr). Individuals participated in two laboratory evaluations spanning approximately 6 yr. Bioimpedance was used to assess HRV at time 1 and cardiac output at both time 1 and time 2. Mean arterial pressure (MAP) was measured at both time points via an automated BP machine. TPR was calculated as MAP divided by cardiac output. Results showed AAs to have higher BP and higher TPR at time 2 compared with EAs, independent of several important covariates. Also, higher HRV at time 1 significantly predicted both lower TPR and BP at time 2 among EAs only; these associations were attenuated and not significant in AAs. HRV did not significantly predict cardiac output at time 2 in the full sample or split by ethnicity. Our findings highlight that AAs show TPR mediated long-term increases in BP irrespective of resting HRV, providing a physiological pathway linking AAs with a greater risk for mortality and morbidity from hypertension and potentially other cardiovascular disease.NEW & NEWSWORTHY African Americans and European Americans differ in hemodynamics underlying long-term blood pressure regulation. Over 6 yr, African Americans show total peripheral resistance-mediated increases in blood pressure compared with European Americans. Higher heart rate variability predicts lower blood pressure and total peripheral resistance 6 yr later in European Americans but not African Americans.

Actigraphy-Derived Sleep Efficiency Is Associated With Endothelial Function in Men and Women With Untreated Hypertension

BACKGROUND

Poor sleep quality is increasingly recognized as an important and potentially modifiable risk factor for cardiovascular disease (CVD). Impaired endothelial function may be 1 mechanism underlying the association between poor sleep and CVD risk. The present study examined the relationship between objective measures of sleep quality and endothelial function in a sample of untreated hypertensive adults.

METHODS

Participants were 127 men (N = 74) and women (N = 53), including 55 African Americans and 72 White Americans, aged 40-60 years (mean age, 45.3 ± 8.5 years), with untreated hypertension (systolic blood pressure 130-159 mm Hg and/or diastolic blood pressure 85-99 mm Hg). Noninvasive brachial artery flow-mediated dilation (FMD) was assessed by ultrasound. Sleep parameters, including sleep efficiency (SE), total sleep time (TST), and subjective sleep quality, were assessed over 7 consecutive days by wrist actigraphy.

RESULTS

Participants averaged 7.76 ± 1 hours in bed, with an average SE of 78 ± 9%, and TST of 6 ± 1 hours. Brachial FMD averaged 3.5 ± 3.1%. In multivariate analyses controlling for sex, race, body mass index, clinic blood pressure, income, smoking, alcohol use, and baseline arterial diameter, SE was positively associated with FMD (β = 0.28, P = 0.012). Subjective sleep quality (β = -0.04, P = 0.63) and TST (β = -0.11, P = 0.25) were unrelated to FMD.

CONCLUSIONS

Poor sleep as indicated by low SE was associated with impaired FMD. These findings for SE are consistent with previous observations of other measures implicating poor sleep as a CVD risk factor. Interventions that improve sleep may also help lower CVD risk.

Neurohumoral and ambulatory haemodynamic adaptations following isometric exercise training in unmedicated hypertensive patients

OBJECTIVE

Hypertension remains the leading modifiable risk factor for cardiovascular disease. Isometric exercise training (IET) has been shown to be a useful nonpharmacological intervention for reducing resting blood pressure (BP). This study aimed to measure alterations in office BP, ambulatory BP, cardiac autonomic modulation and inflammatory and vascular biomarkers following a programme of IET in unmedicated hypertensive patients.

METHODS

Twenty-four unmedicated stage 1 hypertensive patients (age 43.8 ± 7.3 years; height, 178.1 ± 7 cm; weight 89.7 ± 12.8 kg) were randomly assigned in a cross-over study design, to 4-weeks of home-based IET and control period, separated by a 3-week washout period. Office and ambulatory BP, cardiac autonomic modulation, and inflammatory and vascular biomarkers were recorded pre and post-IET and control periods.

RESULTS

Clinic and 24-h ambulatory BP significantly reduced following IET by 12.4/6.2 and 11.8/5.6 mmHg in SBP/DBP, respectively (P < 0.001 for both), compared with the control. The BP adaptations were associated with a significant (P = 0.018) reduction in the average real variability of 24-h ambulatory BP following IET, compared with control. Cardiac autonomic modulation improved by 11% (P < 0.001), baroreceptor reflex sensitivity improved by 47% (P < 0.001), and IL-6 and asymmetric dimethylarginine reduced by 10% (P = 0.022) and 19% (P = 0.023), respectively, which differed significantly to the control period.

CONCLUSION

This is the first evidence of durable BP reduction and wider cardiovascular disease risk benefits of IET in a relevant patient population. Our findings support the role of IET as a safe and viable therapeutic and preventive intervention in the treatment of hypertension.

The Autonomic Nervous System and Hypertension: Ethnic Differences and Psychosocial Factors

PURPOSE OF THE REVIEW

In the present paper, we overview emerging research examining the autonomic nervous system (ANS), especially the parasympathetic nervous system as indexed by heart rate variability (HRV), and the impact of psychosocial factors on hypertension-related disease in African Americans.

RECENT FINDINGS

A growing corpus of studies has shown that (1) usual patterns of compensatory sympathetic-parasympathetic regulation differ between African Americans and European Americans; (2) despite their enhanced cardiovascular disease risk profile, African Americans tend to exhibit higher HRV relative to European Americans; and (3) racial discrimination and other forms of psychosocial stress are associated with diminished HRV among African Americans. Significant disparities in hypertension-related disease exist such that African Americans have greater risk. The underlying factors associated with this increased risk are, to date, not fully understood. The present review provides evidence for a unique pattern of ANS regulation in African Americans and shows that psychosocial factors such as racial discrimination may contribute to this paradoxical situation.

OSA and Cardiovascular Risk in Pediatrics

OSA occurs in approximately 1% to 5% of children in the United States. Long-term cardiovascular risks associated with OSA in the adult population are well documented. Although changes in BP regulation occur in children with OSA, the pathways leading to chronic cardiovascular risks of OSA in children are less clear. Risk factors associated with cardiovascular disease in adult populations could carry the same future risk for children. It is imperative to determine whether known mechanisms of cardiovascular diseases in adults are like those that lead to pediatric disease. Early pathophysiologic changes may lead to a lifetime burden of cardiovascular disease and early mortality. With this perspective in mind, our review discusses pathways leading to cardiovascular pathology in children with OSA and provides a comprehensive overview of recent research findings related to cardiovascular sequelae in the pediatric population.

Hemodynamic profile and compensation deficit in African and European Americans during physical and mental stress

Increased vascular reactivity to stress has been suggested to contribute to the greater risk for developing hypertension in African Americans. Here, we examined the way (hemodynamic profile) and the extent to which (compensation deficit) cardiac output and total peripheral resistance compensate for each other in determining blood pressure responses to a physical (orthostasis) and a mental (anger recall) stress task, in normotensive African American (AA, n = 30) and European American (EA, n = 48) college students. Blood pressure stress reactivity did not differ as a function of race. However, AAs showed a prominent vascular hemodynamic profile and a significant compensation deficit in response to both tasks, while EAs showed no hemodynamic response to orthostasis and a mixed profile in response to anger recall. The present findings demonstrate a more prominent vascular hemodynamic reactivity to stress in AAs, which could contribute to the pathogenesis of hypertension in this ethnic group.

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.

Impact of Racial Discrimination and Hostility on Adrenergic Receptor Responsiveness in African American Adults

OBJECTIVE

Racial discrimination is increasingly recognized as a contributor to increased cardiovascular disease (CVD) risk among African Americans. Previous research has shown significant overlap between racial discrimination and hostility, an established predictor of CVD risk including alterations in adrenergic receptor functioning. The present study examined the associations of racial discrimination and hostility with adrenergic receptor responsiveness.

METHODS

In a sample (N = 57) of young to middle-aged African American adults (51% female) with normal and mildly elevated blood pressure, a standardized isoproterenol sensitivity test (CD25) was used to evaluate β-AR responsiveness, whereas the dose of phenylephrine required to increase mean arterial pressure by 25 mm Hg (PD25) was used to assess α1-AR responsiveness. Racial discrimination was measured using the Perceived Racism Scale and hostility was assessed using the Cook-Medley Hostility Scale.

RESULTS

In hierarchical regression models, greater racial discrimination, but not hostility, emerged as a significant predictor of decreased β-adrenergic receptor responsiveness (β = .38, p = .004). However, moderation analysis revealed that the association between racial discrimination and blunted β-adrenergic receptor responsiveness was strongest among those with higher hostility (β = .49, 95% confidence interval = .17-.82, p = .004). In addition, hostility, but not racial discrimination, significantly predicted α1-AR responsiveness.

CONCLUSIONS

These findings suggest racial discrimination was associated with blunted β-adrenergic receptor responsiveness, providing further evidence of the potential contribution of racial discrimination to increased CVD risk among African Americans. The adverse effects of discrimination on cardiovascular health may be enhanced in individuals with higher levels of hostility.