Circadian rhythm of double (rate-pressure) product in healthy normotensive young subjects

Exploring the immediate effects of aerobic exercise on nocturnal blood pressure dip in medication-controlled hypertensive individuals: a randomised controlled trial

BACKGROUND

Nocturnal blood pressure dipping is crucial for cardiovascular health, but the effect of exercise on this phenomenon is not well understood. This study aims to investigate how a single session of aerobic exercise impacts nocturnal blood pressure dipping in individuals with hypertension who are on medication.

METHODS

Twenty hypertensive adults (67 ± 16 years) participated in a randomised, parallel-group clinical trial. They were randomly assigned to either an exercise or control group. Resting blood pressure was measured after a 20-minute period of comfortable seating in a calm environment. The exercise group performed 40 min of treadmill running/walking at an intensity of 60-70% of their reserve heart rate. The control group remained seated for an equivalent period with reading allowed. Ambulatory blood pressure monitoring was used to measure blood pressure over 24 h. Nocturnal dip was calculated by comparing the mean wakefulness and sleep blood pressure values.

RESULTS

No significant differences were observed between the exercise and control groups in systolic and diastolic blood pressure values at rest, during wakefulness, sleep, or over 24 h. The absolute nocturnal dip also showed no significant differences between the groups for systolic blood pressure (MD = 3.00 [95% CI: -4.77 to 10.77] p = 0.428) or diastolic blood pressure (MD = 4.60 [95% CI: -2.81 to 12.00] p = 0.208). Similarly, the relative nocturnal dip (percentage) did not differ significantly for systolic blood pressure (MD = 0.029 [95% CI: -0.039 to 0.837] p = 0.465) or diastolic blood pressure (MD = 0.047 [95% CI: -0.036 to 0.132] p = 0.250).

CONCLUSIONS

A single session of aerobic exercise does not impact the nocturnal dip in systolic and diastolic blood pressure in medication-controlled hypertensive individuals.

Findings and Methodological Shortcomings of Investigations Concerning the Relationship Between Sleep Duration and Blood Pressure: A Comprehensive Narrative Review

Cardiology and sleep societies recommend 7-9 h sleep/night for adults (7-8 h for seniors) and more for youngsters; nonetheless, short sleep duration (SSD) of <7 h/night is epidemic. We searched PubMed for representative investigations, including those cited by meta-analyses, that reported association between SSD and long sleep duration (LSD) of >9 h/night and blood pressure (BP) levels to assess shortcomings of their methods. Studies indicate both SSD and LSD negatively impact BP despite major deficiencies, such as (i) reliance mainly on cross-sectional rather than longitudinal protocols, (ii) inclusion of participants diagnosed with hypertension (HTN) and/or taking antihypertension medications, (iii) assessment of BP and diagnosis of HTN performed by single wake-time office measurement rather than multiple measurements performed by 24 h ambulatory BP monitoring (ABPM), and (iv) determination of SD by subjective recall, single-night polysomnography, or diary recordings rather than objective wrist actigraphy of sufficient duration. The limited number of ABPM-based studies, despite evidencing major shortcomings, particularly (i) assessment for 24 h rather than preferred ≥48 h and (ii) inclusion of subjects diagnosed with HTN and/or taking antihypertension medications, also report association between abnormal SD and elevated 24 h 'daytime'/wake-time diastolic and systolic (SBP) means plus 'nighttime'/sleep-time SBP mean and dipping-the latter two indices, in combination, the strongest predictors of major adverse cardiovascular events.

Critical Review of the Methodological Shortcoming of Ambulatory Blood Pressure Monitoring and Cognitive Function Studies

Growing evidence suggests that abnormal diurnal blood pressure rhythms may be associated with many adverse health outcomes, including increased risk of cognitive impairment and dementia. This study evaluates methodological aspects of research on bidirectional associations between ambulatory blood pressure monitoring (ABPM) patterns and cognitive function. By examining the 28 recent studies included in a recent systematic review on the association between ABPM patterns with cognitive function and risk of dementia, our review revealed several significant limitations in study design, sample characteristics, ABPM protocol, cognitive assessment, and data analysis. The major concerns include a lack of diversity in study populations with underrepresentation of Blacks and Latinos, a predominant focus on Alzheimer's disease or all-cause dementia without distinguishing other dementia subtypes, different and not standardized measures of cognition or dementia, prevalent use of 24 h monitoring without considering the adaption effect, inconsistent definitions of dipping status, and ignorance of individual differences in timings of daily activities such as bed and awakening times. In addition, confounding variables such as class, dose, and timing of antihypertensive medication are inadequately controlled or considered. Further, longitudinal studies were scarce examining the bidirectional relationship between ABPM patterns and cognitive decline over time. Collectively, these deficiencies undermine the reliability and generalizability of current findings. Addressing these methodological challenges is crucial for a more comprehensive understanding of diurnal blood pressure rhythms in diverse populations and for developing an evidence-based guideline for ambulatory monitoring and control of blood pressure across the sleep-wake cycle to prevent cognitive decline and dementia.

Circadian chronotherapies of coronary heart disease and its biological risk factors: A United States Prescribers' Digital Reference-based review

Chronotherapy is the timing of medications to circadian rhythms to optimize beneficial and minimize adverse outcomes. We reviewed the US Online Prescribers' Digital Reference for the specified administration schedule of medications prescribed to manage coronary heart disease (CHD) and its major risk factors. For arterial hypertension, dosing of terazosin and guanfacine is recommended in the evening and thiazide, thiazide-like, and sulfonamide diuretics morning; Verapamil (Verelan®) morning, its "PM" formulation evening, and long-acting diltiazem (Cardizem® LA), per clinical goal, morning or evening. Most hyperlipidemia medications are recommended in the evening. Many hyperglycemia medications are intended for morning ingestion, but, when indicated, some may be prescribed in unequal doses or intervals. For obesity, administration of appetite suppressant psychostimulants and sympathomimetics is stipulated for morning ingestion. Sleep insufficiency medications are to be taken before bedtime. For tobacco dependence, transdermal nicotine patch application is recommended in the morning, and bupropion early, but not late, during the wake span. For alcohol dependence, disulfiram is intended for morning ingestion. For thromboembolism prophylaxis, factor Xa inhibitor rivaroxaban is recommended at dinner and low-dose acetylsalicylic acid before bedtime. Medications for angina pectoris and edema of congestive heart failure are stipulated for morning administration. Overall, >200 medications prescribed to manage CHD and its risk factors qualify as chronotherapies.

Effect of Circadian Rhythm Modulated Blood Flow on Nanoparticle based Targeted Drug Delivery in Virtual In Vivo Arterial Geometries

Delivery of drug using nanocarriers tethered with vasculature-targeting epitopes aims to maximize the therapeutic efficacy of the drug while minimizing the drug side effects. Circadian rhythm which is governed by the central nervous system has implications for targeted drug delivery due to sleep-wake cycle changes in blood flow dynamics. This paper presents an advanced fluid dynamics modeling method that is based on viscous incompressible shear-rate fluid (blood) coupled with an advection-diffusion equation to simulate the formation of drug concentration gradients in the blood stream and buildup of concentration at the targeted site. The method is equipped with an experimentally calibrated nanoparticle-endothelial cell adhesion model that employs Robin boundary conditions to describe nanoparticle retention based on probability of adhesion, a friction model accounting for surface roughness of endothelial cell layer, and a dispersion model based on Taylor-Aris expression for effective diffusion in the boundary layer. The computational model is first experimentally validated and then tested on engineered bifurcating arterial systems where impedance boundary conditions are applied at the outflow to account for the downstream resistance at each outlet. It is then applied to a virtual geometric model of an in vivo arterial tree developed through MRI-based image processing techniques. These simulations highlight the potential of the computational model for drug transport, adhesion, and retention at multiple sites in virtual in vivo models. The model provides a virtual platform for exploring circadian rhythm modulated blood flow for targeted drug delivery while minimizing the in vivo experimentation.

Statement of Significance

A novel integration of nanoparticle-based drug delivery framework with shear-rate dependent blood flow model is presented. The framework is comprised of a unique combination of mechanics-based dispersion model, an asperity model for endothelium surface roughness, and a stochastic nanoparticle-endothelial cell adhesion model. Simulations of MRI based in vivo carotid artery system showcase the effects of vessel geometry on nanoparticle adhesion and retention at the targeted site. Vessel geometry and target site location impact nanoparticle adhesion; curved and bifurcating regions favor local accumulation of drug. It is also shown that aligning drug administration with circadian rhythm and sleep cycle can enhance the efficacy of drug delivery processes. These simulations highlight the potential of the computational modeling for exploring circadian rhythm modulated blood flow for targeted drug delivery while minimizing the in vivo experimentation.

Pioneering new frontiers in circadian medicine chronotherapies for cardiovascular health

Cardiovascular disease (CVD) is a global health concern. Circadian medicine improves cardiovascular care by aligning treatments with our body's daily rhythms and their underlying cellular circadian mechanisms. Time-based therapies, or chronotherapies, show special promise in clinical cardiology. They optimize treatment schedules for better outcomes with fewer side effects by recognizing the profound influence of rhythmic body cycles. In this review, we focus on three chronotherapy areas (medication, light, and meal timing) with potential to enhance cardiovascular care. We also highlight pioneering research in the new field of rest, the gut microbiome, novel chronotherapies for hypertension, pain management, and small molecules that targeting the circadian mechanism.

Association between Myocardial Oxygen Supply and Demand and Myocardial Injury in Patients with End-Stage Kidney Disease

AIM

In patients with end-stage kidney disease (ESKD), it is unclear whether an imbalance between myocardial oxygen supply and demand leads to myocardial injury (MI). This study clarifies the association between the balance of the rate pressure product (RPP), consisting of the systolic blood pressure multiplied by the pulse rate (PR), a marker for myocardial oxygen demand, and hemoglobin (Hb), a marker for oxygen supply, with MI.

METHODS

A total of 283 consecutive unselected patients for hemodialysis were enrolled in this retrospective, cross-sectional study, and were divided into four groups according to Hb levels (high or low) and RPP. Potential imbalances between myocardial oxygen supply and demand were defined as patients with simultaneous high RPP and low Hb levels. The odds ratio (OR) for MI, defined as cardiac troponin T (cTnT) of ≥ 0.15 ng/mL was investigated using logistic regression analysis between the four patient groups.

RESULTS

The mean age was 68.7 years, 71.3% were men, and 52.6% had diabetes. The mean Hb level was 9.0 g/dL, and 20.5% of patients were latently diagnosed with MI. The median RPP and cTnT level was 12,144 and 0.083 ng/mL, respectively. When exposed to simultaneous high RPP with low Hb, OR significantly increased compared with that of the well-balanced group (RPP ＜12,500 and Hb ≥ 9.0 g/dL; OR 3.63, p＜0.05). Similar results were obtained in multivariate analysis after adjusting for confounding variables. These associations were enhanced or weakened when the Hb cut-off level became lower (Hb=8 g/dL) or higher (Hb=10 g/dL).

CONCLUSIONS

As the myocardial oxygen supply and demand balance in patients with ESKD is potentially associated with MI, appropriate management for blood pressure, PR, and anemia may prevent MI.

Prognostic Value of Nighttime Double Product in Nondialysis Chronic Kidney Disease With Hypertension

BACKGROUND

Both nighttime systolic blood pressure and pulse rate are associated with adverse outcomes in patients with chronic kidney disease (CKD). However, nighttime double product (DP), which is the product of nighttime systolic blood pressure and pulse rate, has not yet been investigated in this context. The present study aimed to explore the prognostic value of nighttime DP for adverse outcomes in patients with CKD and hypertension.

METHODS AND RESULTS

This retrospective cohort study included a total of 1434 patients with nondialysis CKD complicated by hypertension. The patients were enrolled in Zhuhai and Guangzhou, China, with a median follow-up of 23.8 months. Patient enrollment for the high or low nighttime DP group was performed on the basis of the cutoff value determined by time-dependent receiver operator characteristic curve analysis. The primary end point was a composite of major cardiovascular and cerebrovascular events, and the secondary end point was all-cause death and composite renal end point. The 24-hour circadian DP rhythm was established via multiple-component cosinor analysis. Cox regression was used to explore the association between nighttime DP and adverse outcomes. The DP of nondialysis patients with CKD and hypertension showed a diurnal rhythm, which varied with renal function. After adjustment, high nighttime DP was associated with a higher risk for major cardiovascular and cerebrovascular events (hazard ratio [HR], 5.823 [95% CI, 2.382-14.233]), all-cause death (HR, 4.978 [95% CI, 2.205-11.240]), and composite renal event (HR, 1.661 [95% CI, 1.128-2.447]), compared with low nighttime DP. These associations were independent of nighttime systolic blood pressure and PR.

CONCLUSIONS

The present cohort study demonstrated that DP had diurnal fluctuations and nighttime DP was an important prognostic factor in nondialysis patients with CKD and hypertension, outperforming traditional risk factors, including systolic blood pressure and pulse rate.

Midday Dipping and Circadian Blood Pressure Patterns in Acute Ischemic Stroke

The purpose of this study was to investigate the alterations in blood pressure (BP) during midday and the changes in circadian BP patterns in the acute phase of ischemic stroke (AIS) with the severity of stroke and their predictive role outcomes within 3 months. A total of 228 AIS patients (a prospective multicenter follow-up study) underwent 24 h ambulatory blood pressure monitoring (ABPM). Mean BP parameters during the day (7:00-22:59), the midday (13:00-16:59), and the night (23:00-6:59), and midday and nocturnal dipping were calculated. Midday SBP dippers had less severe stroke, lower incidence of hypertension and SBP/DBP on admission, lower levels of serum glucose and WBCs, and delayed initiation of ABPM compared to risers. There was a reverse relation between midday SBP dipping and both nocturnal dipping and stroke severity. The "double dippers" (midday and nocturnal dipping) had the least severe stroke, the lowest SBP/DBP on admission, the lowest heart rate from ABPM, and a lower risk of an unfavorable outcome, while the "double risers" had the opposite results, by an approximately five-fold risk of death/disability at 3 months. These findings indicate different circadian BP patterns during the acute phase of AIS, which could be considered a marker of stroke severity and prognosis.

Rate pressure product as a novel predictor of long-term adverse outcomes in patients after percutaneous coronary intervention: a retrospective cohort study

OBJECTIVES

Previous studies have suggested that heart rate and blood pressure play important roles in the development of adverse outcomes in patients with coronary artery disease (CAD) who underwent percutaneous coronary intervention (PCI). However, the relationship between the rate pressure product (RPP) and long-term outcomes has rarely been investigated. This study investigated the effects of RPP on the clinical outcomes of patients with CAD who underwent PCI.

DESIGN

In this study, a total of 6015 patients with CAD were enrolled. All patients were from the CORFCHD-PCI (Clinical Outcomes and Risk Factors of Patients with Coronary Heart Disease after PCI) Study. They were divided into two groups according to RPP (RPP <10 269, n=4018 and RPP ≥10 269, n=1997). In addition, the median follow-up time was 32 months.

PARTICIPANTS

Data was obtained from 6050 patients with CAD who underwent PCI at the First Affiliated Hospital of Xinjiang Medical University from January 2008 to December 2016.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary endpoint was long-term mortality, including all-cause mortality (ACM) and cardiac mortality (CM). The secondary endpoints were major adverse cardiovascular events (MACEs) and major adverse cardiovascular and cerebrovascular events (MACCEs).

RESULTS

We found that there were significant differences between the two groups in the incidence of ACM, CM, MACCEs and MACEs (all p<0.05). Among the patients with CAD having ACM, CM, MACCEs and MACEs, the mean survival time of the low-value group was significantly higher than that of the high-value group. Multivariate Cox regression analyses showed that RPP was an independent predictor for ACM (HR=1.605, 95% CI: 1.215-2.120, p=0.001), CM (HR=1.733, 95% CI: 1.267-2.369, p=0.001), MACCEs (HR=1.271, 95% CI: 1.063-1.518, p=0.008) and MACEs (HR=1.315, 95% CI: 1.092-1.584, p=0.004) in patients with stable CAD. On the other hand, there was no significant correlation between the RPP and the adverse outcomes in patients with acute coronary syndrome.

CONCLUSION

In summary, RPP is an independent predictor of long-term prognosis in patients with CAD who underwent PCI. A higher baseline RPP before PCI increased the risk of adverse outcomes. Compared with heart rate and blood pressure alone, RPP has a higher predictive value for adverse clinical outcomes.

The Circadian Biology of Heart Failure

Driven by autonomous molecular clocks that are synchronized by a master pacemaker in the suprachiasmatic nucleus, cardiac physiology fluctuates in diurnal rhythms that can be partly or entirely circadian. Cardiac contractility, metabolism, and electrophysiology, all have diurnal rhythms, as does the neurohumoral control of cardiac and kidney function. In this review, we discuss the evidence that circadian biology regulates cardiac function, how molecular clocks may relate to the pathogenesis of heart failure, and how chronotherapeutics might be applied in heart failure. Disrupting molecular clocks can lead to heart failure in animal models, and the myocardial response to injury seems to be conditioned by the time of day. Human studies are consistent with these findings, and they implicate the clock and circadian rhythms in the pathogenesis of heart failure. Certain circadian rhythms are maintained in patients with heart failure, a factor that can guide optimal timing of therapy. Pharmacologic and nonpharmacologic manipulation of circadian rhythms and molecular clocks show promise in the prevention and treatment of heart failure.

The Effect of Acute Administration of the Aqueous Calyx Extract of Hibiscus sabdariffa on Blood pressure, Heart rate and Double Product of Apparently Healthy Human Subjects during Different Postures

The aqueous calyx extract of Hibiscus sabdariffa (HS) is widely consumed as a beverage in Northern Nigeria and other parts of the world. HS has been reported to lower blood pressure (BP) in animals and man. However, not much is known about the effect of HS on BP in different postures. We tested the hypothesis that HS may lower BP, heart rate (HR) and heart rate-pressure product or double product (DP) by attenuating the discharge of the autonomic nervous system in different postures. Experiments were performed in accordance with the Principles of the Declaration of Helsinki. Following ethical approval and informed consent, BP and HR were measured in different postures (supine, sitting and standing) in apparently healthy human subjects (n=20) before and after (+HS) the oral administration of 15mg/Kg HS. Mean arterial pressure (MAP; taken as representative BP) and DP were calculated. Results are expressed as mean ±SEM. Paired t test and ANOVA with a post hoc Bonferroni test were used for statistical analyses. P<0.05 was considered significant. In the supine position MAP, HR and DP were significantly (P<0.0001 each) reduced in the presence of HS (85.6±1.7mmHg, 72.1±1.1/min and 8716±320mmHg.bpm) compared to its absence (89.6±2.0mmHg, 73.7±1.6/min and 8921±444mmHg.bpm). Similar trends were observed in the sitting position in the presence of HS (85.4±2.7mmHg, 73.7±1.8/min and 9098±345mmHg.bpm vs its absence: 91.4±2.3mmHg, 77.1±1.9/min and 9388±478mmHg.bpm; P<0.0001, P<0.0001 and P=0.007 respectively) and in the standing position (+HS: 89.3±2.0mmHg,         78.1±1.8/min and 10164±230mmHg.bpm vs its absence: 94.3±2.1mmHg, 81.8±2.3/min and 10742±268mmHg.bpm; P<0.0001, P<0.0001 and P=0.007 respectively). In the absence of HS, HR and DP were significantly higher in the standing posture (81.8±2.3/min, 10742±268mmHg.bpm) compared to the sitting (77.1±1.9/min, 9388±478mmHg.bpm; P<0.05 and P<0.0001 respectively) and the supine (73.7±1.6/min, 8921±444mmHg.bpm; P<0.001 each) postures while the BP remained similar. A similar trend was observed across          the three postures in the presence of HS although the parameters were significantly lower. It is concluded that HS lowered BP, HR and DP by modulating autonomic mechanisms through the inhibition of both parasympathetic withdrawal and sympathetic nervous system discharge across the postures. Also the standing posture is associated more with a higher sympathetic nervous system discharge and a higher cardiac oxygen demand and workload than the sitting and supine postures in the absence or presence of HS.

Subjective sleep score is associated with central and peripheral blood pressure values in children aged 7-12 years

Shortened and poor-quality sleep have emerged as non-traditional risk factors for the development of hypertension in adults, and it is likely these relations extend to paediatric populations when evaluating sleep subjectively. Therefore, we aimed to evaluate subjective sleep metrics and their associations with central and peripheral blood pressure (BP) values in children. We hypothesized that poor-quality sleep and short sleep duration would be associated with elevated pressures in healthy children. Subjective sleep habits and sleep duration were evaluated using the Children's Sleep Habits Questionnaire (CSHQ) in 29 children aged 7-12 years (13 male/16 female). A total sleep score was generated by summing subscale scores: a higher score indicates poorer sleep habits. Peripheral BP was measured, and central pressures were estimated using pulse wave analysis. Pearson's r correlations were used to assess relations between total sleep score, sleep duration, and sleep score subscales with BP values. Sleep score was positively associated with central and peripheral systolic pressure (r = 0.43, p = 0.02 and r = 0.41, p = 0.03, respectively), diastolic pressure (r = 0.42, p = 0.02 and r = 0.36, p = 0.05, respectively) and mean arterial pressure (r = 0.40, p = 0.03 and r = 0.36, p = 0.03, respectively). Sleep duration was negatively associated with central and peripheral diastolic pressure (r = -0.40, p = 0.03 and r = -0.41, p = 0.03, respectively). Regarding the CSHQ subscales, daytime sleepiness and parasomnias were consistently positively associated with BP values. These findings support sleep as a primordial prevention target for hypertension and the maintenance of cardiovascular health during childhood. Consideration of a variety of sleep habits using tools such as the CSHQ may provide important insights into early-life cardiovascular risk.

Pharmacogenomics and circadian rhythms as mediators of cardiovascular drug-drug interactions

This article summarizes the current literature and documents new evidence concerning drug-drug interactions (DDI) stemming from pharmacogenomic and circadian rhythm determinants of therapies used to treat common cardiovascular diseases (CVD), such as atherosclerosis and hypertension. Patients with CVD often have more than one pathophysiologic condition, namely metabolic syndromes, hypertension, hyperlipidemia, and hyperglycemia, among others, which necessitate polytherapeutic or polypharmaceutic management. Interactions between drugs, drugs and food/food supplements, or drugs and genetic/epigenetic factors may have adverse impacts on the cardiovascular and other systems of the body. The mechanisms underlying cardiovascular DDI may involve the formation of a complex pharmacointeractome, including the absorption, distribution, metabolism, and elimination of drugs, which affect their respective bioavailability, efficacy, and/or harmful metabolites. The pharmacointeractome of cardiovascular drugs is likely operated with endogenous rhythms controlled by circadian clock genes. Basic and clinical investigations have improved the knowledge and understanding of cardiovascular pharmacogenomics and pharmacointeractomes, and additionally they have presented new evidence that the staging of deterministic circadian rhythms, according to the dosing time of drugs, e.g., upon awakening vs. at bedtime, cannot only differentially impact their pharmacokinetics and pharmacodynamics but also mediate agonistic/synergetic or antagonistic DDI. To properly manage CVD patients and avoid DDI, it is important that clinicians have sufficient knowledge of their multiple risk factors, i.e., age, gender, and life style elements (like diet, smoking, psychological stress, and alcohol consumption), and comorbidities, such as diabetes, hypertension, dyslipidemia, and depression, and the potential interactions between genetic or epigenetic background of their prescribed therapeutics.

Understanding Circadian Mechanisms of Sudden Cardiac Death: A Report From the National Heart, Lung, and Blood Institute Workshop, Part 2: Population and Clinical Considerations

Sudden cardiac death (SCD) is the sudden, unexpected death due to abrupt loss of heart function secondary to cardiovascular disease. In certain populations living with cardiovascular disease, SCD follows a distinct 24-hour pattern in occurrence, suggesting day/night rhythms in behavior, the environment, and endogenous circadian rhythms result in daily spans of increased vulnerability. The National Heart, Lung, and Blood Institute convened a workshop, Understanding Circadian Mechanisms of Sudden Cardiac Death to identify fundamental questions regarding the role of the circadian rhythms in SCD. Part 2 summarizes research gaps and opportunities in the areas of population and clinical research identified in the workshop. Established research supports a complex interaction between circadian rhythms and physiological responses that increase the risk for SCD. Moreover, these physiological responses themselves are influenced by several biological variables, including the type of cardiovascular disease, sex, age, and genetics, as well as environmental factors. The emergence of new noninvasive biotechnological tools that continuously measure key cardiovascular variables, as well as the identification of biomarkers to assess circadian rhythms, hold promise for generating large-scale human data sets that will delineate which subsets of individuals are most vulnerable to SCD. Additionally, these data will improve our understanding of how people who suffer from circadian disruptions develop cardiovascular diseases that increase the risk for SCD. Emerging strategies to identify new biomarkers that can quantify circadian health (eg, environmental, behavioral, and internal misalignment) may lead to new interventions and therapeutic targets to prevent the progression of cardiovascular diseases that cause SCD.

Circadian variations in the occurrence of first-ever intracerebral hemorrhage from different sources of income: a hospital-based cross-sectional study

BACKGROUND

The onset time of intracerebral hemorrhage (ICH) may be closely related to the working style and living habits of people, which are determined by different income sources in China. Therefore, the purpose of our study was to investigate the Circadian Variations in the occurrence of ICH from different sources of income.

METHODS

This retrospective study enrolled 4,327 patients with first-ever ICH. Based on the time of day at which the patients developed symptoms, the classifiable onset time was assigned to one of eight three-hour intervals. And based on different income sources, they were categorized into three groups: Farmers, Wage-earners, and Freelancers. Demographic and risk factors of patients were then summarized, and the circadian variation of the 3 groups of patients' known time of onset and those stratified by sex and age were analyzed.

RESULTS

The frequency of ICH onset exhibited significant circadian variation among the 3 income groups, demonstrating a bimodal distribution in the daytime, with a nadir during the night (all P < 0.001). Three groups showed a significant initial peak between 06:01 and 09:00, and the same peak was observed in their subgroups of sex and age. In the 3 income source groups, there was a smaller second peak that between 15:01 and 18:00 for Farmers and Wage-earners and 18:01 and 21:00 for Freelancers. After stratification by sex and age, the second peak was between 18:01 and 21:00 for female in Farmers, female in Freelancers, under 65 years of age in Wage-earners and 65 years or older in Freelancers, while 15:01 and 18:00 for the other groups.

CONCLUSIONS

Different circadian variations of ICH onset time are found in patients with different income sources in southwest China's Chongqing Municipality cohort. Moreover, the frequency and distribution pattern of peak hours may be closely related to the working style and living habits of people with different income sources.

The power of modelling pulsatile profiles

The quantitative description of individual observations in non-linear mixed effects models over time is complicated when the studied biomarker has a pulsatile release (e.g. insulin, growth hormone, luteinizing hormone). Unfortunately, standard non-linear mixed effects population pharmacodynamic models such as turnover and precursor response models (with or without a cosinor component) are unable to quantify these complex secretion profiles over time. In this study, the statistical power of standard statistical methodology such as 6 post-dose measurements or the area under the curve from 0 to 12 h post-dose on simulated dense concentration–time profiles of growth hormone was compared to a deconvolution-analysis-informed modelling approach in different simulated scenarios. The statistical power of the deconvolution-analysis-informed approach was determined with a Monte-Carlo Mapped Power analysis. Due to the high level of intra- and inter-individual variability in growth hormone concentrations over time, regardless of the simulated effect size, only the deconvolution-analysis informed approach reached a statistical power of more than 80% with a sample size of less than 200 subjects per cohort. Furthermore, the use of this deconvolution-analysis-informed modelling approach improved the description of the observations on an individual level and enabled the quantification of a drug effect to be used for subsequent clinical trial simulations.

Relationship between melatonin and high-risk pregnancy: A review of investigations published between the years 2010 and 2020

The purpose of this review was to search for articles on human studies investigating the relationship between melatonin and high-risk pregnancy. An electronic search was conducted in the MEDLINE and PubMed databases from September 2010 to October 2020. The initial search produced 441 articles in PubMed and 407 in MEDLINE. After sorting the titles and abstracts, and removing duplicates, we had nine articles in PubMed and three in Medline. The results of these studies mainly show that the association between melatonin receptor 1B polymorphisms and gestational diabetes mellitus is the most common physiological mechanism relating to melatonin and high-risk pregnancy in this review. In addition, the circadian rhythm, decreased melatonin production, and anti-inflammatory and antioxidant effects were explored. The findings of our review of the literature suggest that this indoleamine is essential in high-risk pregnancy for its potent anti-inflammatory and antioxidant effects, regulation of the circadian rhythm, and genic receptor expression.

Circadian rhythms of blood pressure and rate pressure product in children with postural tachycardia syndrome

OBJECTIVE

To investigate circadian rhythms of blood pressure (BP) and rate pressure product (RPP) in children with postural tachycardia syndrome (POTS) by performing 24-hour ambulatory blood pressure monitoring (24-h ABPM).

METHODS

103 POTS children and 84 age- and gender-matched healthy children were enrolled and they got 24-h ABPM under usual routine of diurnal activity and nocturnal sleep.

RESULTS

Although the mean awake systolic BP (SBP), 24-h diastolic BP (DBP), awake DBP, asleep heart rate (HR) did not differ between two groups (P > 0.05), the mean 24-h and asleep SBP, asleep DBP, 24-h and awake HR, 24-h, awake and asleep RPP were significantly higher in POTS children (P < 0.01). Non-dipping BP was more prevalent in POTS children (67.0% vs. 46%, P < 0.001). The RPP of POTS and control children showed 24-h circadian variations with peak roughly occurring approximately 2 h after waking from nocturnal sleep. Compared with controls, the RPP values of POTS children were significantly higher during 2 h before and 3 h after waking (P < 0.05). For the RPP value of 1 h after waking, a cutoff value of 8995.6 bpm·mmHg yielded a sensitivity of 75.8% and a specificity of 65.4% for predicting POTS.

CONCLUSIONS

Abnormal circadian BP regulation is prevalent in POTS children. POTS children present with daily sympathetic hyperactivity, especially during nocturnal sleep and within 3 h after waking. And the excessive morning surge in RPP parallels with the morning surge of orthostatic HR increments and OI symptoms.

The Pharmacodynamic Effects of a Dopamine-Somatostatin Chimera Agonist on the Cardiovascular System

The quantification of the effect of pharmacological treatment on the cardiovascular system is complicated because of the high level of interindividual and circadian variability. Recently, a dopamine-somatostatin chimera, BIM23B065, was under investigation to concurrently target the somatostatin and dopamine D2 receptors for the treatment of neuroendocrine tumors. However, both dopamine and somatostatin interact with different components of the cardiovascular system. This study established the response of the heart rate and the systolic blood pressure after administration of BIM23B065 in healthy male volunteers by analysis of the rate-pressure product (RPP), in a model-informed analysis. The RPP in the supine position of placebo-treated subjects showed a clear circadian component, best described by 2 cosine functions. The pharmacokinetics of BIM23B065 and its metabolite were best described using 2-compartment models with different forms of elimination kinetics. The administration of BIM23B065 gave a statistically significant reduction in the RPP, after which the effect diminished because of the tolerance to the cardiovascular effects after prolonged exposure to BIM23B065. This model provided insight in the circadian rhythm of the RPP in the supine position and the level of interindividual variability in healthy male volunteers. The developed population pharmacokinetic/pharmacodynamic model quantified the interaction between BIM23B065 and the RPP, informing on the clinical pharmacological properties of BIM23B065.

Circadian patterns of hallucinatory experiences in patients with schizophrenia: Potentials for chrono-pharmacology

The objective of this study was to investigate possible circadian pattern of psychotic symptoms in patients with schizophrenia, which could be reflected on the dosing schedule/regimen, i.e. chrono-pharmacology. Patients with schizophrenia (ICD-10) who reported having auditory hallucination, receiving monotherapy with risperidone, olanzapine or paliperidone for at least two weeks were included. The subjects were provided a diary and asked to record the time and duration of auditory hallucinations during the eight time periods (i.e. 00:00-03:00, 03:00-06:00, 06:00-09:00, 09:00-12:00, 12:00-15:00, 15:00-18:00, 18:00-21:00, and 21:00-24:00). In the diary, times of medication doses and sleep were also recorded. Time and degree of peak and trough dopamine D₂ receptor blockade with antipsychotics were estimated from 2 sparsely collected plasma drug concentrations. The prevalence and duration of auditory hallucinations were statistically examined among the eight time periods, respectively. Forty-nine patients participated in this study (mean ± SD age, 50.7 ± 14.8 years; 36 men (73.5%); 34 inpatients (69.4%)). Auditory hallucinations occurred most frequently and lasted for the longest duration in the period of 18:00-21:00 (75.5% (37/49) and 1.37 ± 1.67 h). This happened despite the fact that the difference in D₂ receptor occupancy between the peak and trough was less than 2%, indicating a stable drug delivery. Since the dopamine D₂ receptor blockade by antipsychotics was stable, the nocturnal circadian pattern found in this study may reflect intrinsic dopaminergic fluctuation or generally quieter environments at night. These circadian patterns may be considered to devise individualized treatment approach in the context of "chrono-pharmacology" for patients with schizophrenia.

The acute physiological effects of high- and low-velocity resistance exercise in older adults

The aim of the present study was to determine if workload matched, high-velocity (HVE) and low-velocity (LVE) resistance exercise protocols, elicit differing acute physiological responses in older adults. Ten older adults completed three sets of eight exercises on six separate occasions (three HVE and three LVE sessions). Systolic blood pressure, diastolic blood pressure and blood lactate were measured pre- and post-exercise, heart rate was measured before exercise and following each set of each exercise. Finally, a rating of perceived exertion was measured following each set of each exercise. There were no significant differences in blood lactate (F_(1,9) = 0.028; P = 0.872; η P 2  = 0.003), heart rate (F_(1,9) = 0.045; P = 0.837; η P 2  = 0.005), systolic blood pressure (F_(1,9) = 0.023; P = 0.884; η P 2  = 0.003) or diastolic blood pressure (F_(1,9) = 1.516; P = 0.249; η P 2  = 0.144) between HVE and LVE. However, LVE elicited significantly greater ratings of perceived exertion compared to HVE (F_(1,9) = 13.059; P = 0.006; η P 2  = 0.592). The present workload matched HVE and LVE protocols produced comparable physiological responses, although greater exertion was perceived during LVE.

Proximal and Distal Occlusion of Complex Cerebral Aneurysms-Implications of Flow Modeling by Fluid-Structure Interaction Analysis

BACKGROUND

In complex cerebral aneurysms, adequate treatment by complete occlusion is not always possible. Partial occlusion by either proximal or distal occlusion is an alternative. However, the hemodynamic consequences of these partial occlusion options are often not easily predictable.

OBJECTIVE

To assess the feasibility of fluid-structure interaction (FSI) analysis to investigate the hemodynamic changes after partial occlusion in cerebral aneurysms.

METHODS

Two patients were analyzed. One was treated by proximal occlusion and 1 by distal occlusion. In both, flow replacement bypass surgery was performed. Three-dimensional models were constructed from magnetic resonance angiography (MRA) scans and used for FSI analysis. A comparative study was done for pre- and postoperative conditions. Postoperative thrombosis was modeled and analyzed for the distal occlusion. FSI results were compared to postoperative angiograms and computed tomography (CT)-scans.

RESULTS

Proximal occlusion resulted in reduction of velocity, wall shear stresses, and disappearance of helical flow patterns in the complete aneurysm. Distal occlusion showed a decrease of velocity and wall shear stress in the dome of the aneurysm. Results were validated against postoperative CT-scans and angiograms at 1-, 7-, and 9-mo follow-up. Addition of thrombus to the distal occlusion model showed no change in velocities and luminal pressure but resulted in decrease in wall tension.

CONCLUSION

This pilot study showed hemodynamic changes in 2 patients with proximal and distal occlusion of complex cerebral aneurysms. The FSI results were in line with the follow-up CT scans and angiograms and indicate the potential of FSI as a tool in patient-specific surgical interventions.

Circadian variations in the clinical presentation of headaches among migraineurs: A study using a smartphone headache diary

Migraines occur within certain time frames. Nevertheless, information regarding circadian variation in the clinical presentation of migraine is limited. We investigated circadian variations in the clinical presentation of migraine using a smartphone headache diary (SHD). We enrolled adult participants with the diagnosis of migraine according to the third beta edition of the International Classification of Headache Disorders. Participants were asked to log in to the SHD every day for 90 days to record the occurrence of headaches. We compared the occurrence and clinical presentation of headaches during four 6-hour quadrants per day (00:00-05:59, 06:00-11:59, 12:00-17:59, and 18:00-23:59). Migraine-type headache was defined as a headache attack that fulfilled all criteria of migraine, except for the criterion regarding typical headache duration. Eighty-two participants kept a dairy for at least 50% of the study period and recorded 1491 headache attacks. Among the 1491 headache attacks, 474 (31.8%) were classified as migraine-type headaches and 1017 (68.2%) were classified as non-migraine-type headaches. All headaches, migraine-type headaches and non-migraine-type headaches occurred most frequently between 06:00 and 11:59, and least frequently between 18:00 and 23:59, and between 00:00 and 05:59. Migrainous headache characteristics, such as unilateral pain, pulsating quality, severe headache intensity, aggravation by movement, nausea, photophobia, and phonophobia presented most frequently between 06:00 and 11:59, and least frequently between 18:00 and 23:59, and 00:00 and 05:59 among 1491 all headache attacks. Headache clinical presentation as well as headache occurrence exhibited circadian periodicity among migraineurs.

ABBREVIATIONS

SHD: smartphone headache diary; ICHD-3 beta: the third edition beta version of the International Classification of Headache Disorders.

Do night and around-the-clock firefighters' shift schedules induce deviation in tau from 24 hours of systolic and diastolic blood pressure circadian rhythms?

Systolic (S) and diastolic (D) blood pressures (BP) [SBP and DBP] are circadian rhythmic with period (τ) in healthy persons assumed to be maintained at 24.0h. We tested this assumption in a sample of 30 healthy career (mean >12 yrs) 30-to-46 yr-old male Caucasian French firefighters (FFs) categorized into three groups according to work schedule and duties: Group A - 12 FFs working 12h day, 12h night, and occasionally 24h shifts and whose primary duties are firefighting plus paramedical and road rescue services; Group B - 9 FFs working mostly 12h day and 12h night shifts and whose duties are answering incoming emergency calls and coordinating service vehicle dispatch from fire stations with Group A personnel; Group C - 9 day shift (09:00-17:00h) FFs charged with administrative tasks. SBP and DBP, both in winter and in summer studies of the same FFs, were sampled by ambulatory BP monitoring every 1h between 06:00-23:00h and every 2h between 23:01-05:59h, respectively, their approximate off-duty wake and sleep spans, for 7 consecutive days. Activity (wrist actigraphy) was also sampled at 1-min intervals. Prominent τ of each variable was derived by a power spectrum program written for unequal-interval time series data, and between-group differences in incidence of τ≠24h of FFs were assessed by chi square test. Circadian rhythm disruption (τ≠24h) of either the SBP or DBP rhythm occurred almost exclusively in night and 24h shift FFs of Group A and B, but almost never in day shift FFs of Group C, and it was not associated with altered τ from 24.0h of the circadian activity rhythm. In summer, occurrence of τ≠24 for FFs of Group A and B differed from that for FFs of Group C in SBP (p=0.042) and DBP (p=0.015); no such differences were found in winter (p>0.10). Overall, manifestation of prominent τ≠24h of SBP or DBP time series was greater in summer than winter, 27.6% versus 16.7%, when workload of Group B FFs, i.e. number of incoming emergency telephone calls, and of Group A FFs, i.e. number of dispatches for provision of emergency services, was, respectively, two and fourfold greater and number of 12h night shifts worked by Group B FFs and number of 24h shifts worked by Group A FFs was, respectively, 92% and 25% greater. FFs of the three groups exhibited no winter-summer difference in τ≠24h of SBP or SDP; however, τ≠24h of DBP in Group B FFs was more frequent in summer than winter (p=0.046). Sleep/wake cycle disruption, sleep deprivation, emotional and physical stress, artificial light-at-night, and altered nutrient timings are hypothesized causes of τ≠24h for BP rhythms of affected Groups A and B FFs, but with unknown future health effects.

Bedtime Chronotherapy with Conventional Hypertension Medications to Target Increased Asleep Blood Pressure Results in Markedly Better Chronoprevention of Cardiovascular and Other Risks than Customary On-awakening Therapy

The bases for bedtime hypertension chronotherapy (BHCT) as superior chronoprevention against cardiovascular disease (CVD) are: (1) correlation between blood pressure (BP) and various risks is greater for ambulatory BP monitoring (ABPM) than office BP measurements (OBPM); (2) asleep BP mean is a better predictor of CVD risk than ABPM awake and 24-hour means and OBPM; and (3) targeting of asleep BP by BHCT with one or more conventional medications versus usual on-awakening therapy better reduces major and total CVD events. BHCT offers the most cost-effective chronoprevention against adverse CVD outcomes in regular and vulnerable renal, diabetic, and resistant hypertensive patients.

Exposure-response analyses of blood pressure and heart rate changes for methylphenidate in healthy adults

The aim of the study was to evaluate the exposure-response (E-R) relationships of blood pressure (BP) and heart rate (HR) changes in healthy adults taking methylphenidate (MPH). Intensive time profiles of BP and HR from healthy adults in placebo and MPH treatment arms of seven clinical trials from the FDA internal database were utilized for this analysis. The analysis model contains a circadian component for placebo effect and an E-R component to describe drug effect. Internal validation was performed using goodness-of-fit plots and visual predictive check. A meta-database based on a systemic literature search was constructed and used for external validation of the developed models. We found that circadian models could quantify the time profiles of BP/HR in placebo arms. Linear models could describe the correlations between MPH concentrations, and BP/HR changes. The BP and HR changes were highly dependent on the shapes of MPH pharmacokinetic (PK) profiles without an apparent time delay. MPH has the greatest effect on HR, followed by systolic BP, and diastolic BP. Internal validation revealed that the developed models could adequately describe the circadian rhythms of HR and BP in placebo arms and the E-R relationships of MPH. External validation showed the models had good predictive capability of the literature data. In conclusion, the developed models adequately characterized the circadian rhythm and the MPH induced effects on BP and HR. The changes in BP and HR were highly correlated with MPH blood levels with no apparent delay. The time courses of BP and HR are similar to the MPH PK profiles. As a result, the immediate-release formulation may yield larger maximum BP and HR effect than the extended-release formulation under similar dose.

Circadian disruption: New clinical perspective of disease pathology and basis for chronotherapeutic intervention

Biological processes are organized in time as innate rhythms defined by the period (τ), phase (peak [Φ] and trough time), amplitude (A, peak-trough difference) and mean level. The human time structure in its entirety is comprised of ultradian (τ < 20 h), circadian (20 h > τ < 28 h) and infradian (τ > 28 h) bioperiodicities. The circadian time structure (CTS) of human beings, which is more complicated than in lower animals, is orchestrated and staged by a brain central multioscillator system that includes a prominent pacemaker - the suprachiasmatic nuclei of the hypothalamus. Additional pacemaker activities are provided by the pineal hormone melatonin, which circulates during the nighttime, and the left and right cerebral cortices. Under ordinary circumstances this system coordinates the τ and Φ of rhythms driven by subservient peripheral cell, tissue and organ clock networks. Cyclic environmental, feeding and social time cues synchronize the endogenous 24 h clocks and rhythms. Accordingly, processes and functions of the internal environment are integrated in time for maximum biological efficiency, and they are also organized and synchronized in time to the external environment to ensure optimal performance and response to challenge. Artificial light at night (ALAN) exposure can alter the CTS as can night work, which, like rapid transmeridian displacement by air travel, necessitates realignment of the Φ of the multitude of 24 h rhythms. In 2001, Stevens and Rea coined the phrase "circadian disruption" (CD) to label the CTS misalignment induced by ALAN and shift work (SW) as a potential pathologic mechanism of the increased risk for cancer and other medical conditions. Current concerns relating to the effects of ALAN exposure on the CTS motivated us to renew our long-standing interest in the possible role of CD in the etiopathology of common human diseases and patient care. A surprisingly large number of medical conditions involve CD: adrenal insufficiency; nocturia; sleep-time non-dipping and rising blood pressure 24 h patterns (nocturnal hypertension); delayed sleep phase syndrome, non-24 h sleep/wake disorder; recurrent hypersomnia; SW intolerance; delirium; peptic ulcer disease; kidney failure; depression; mania; bipolar disorder; Parkinson's disease; Smith-Magenis syndrome; fatal familial insomnia syndrome; autism spectrum disorder; asthma; byssinosis; cancers; hand, foot and mouth disease; post-operative state; and ICU outcome. Poorly conceived medical interventions, for example nighttime dosing of synthetic corticosteroids and certain β-antagonists and cyclic nocturnal enteral or parenteral nutrition, plus lifestyle habits, including atypical eating times and chronic alcohol consumption, also can be causal of CD. Just as surprisingly are the many proven chronotherapeutic strategies available today to manage the CD of several of these medical conditions. In clinical medicine, CD seems to be a common, yet mostly unrecognized, pathologic mechanism of human disease as are the many effective chronotherapeutic interventions to remedy it.

Sleep-time ambulatory blood pressure as a prognostic marker of vascular and other risks and therapeutic target for prevention by hypertension chronotherapy: Rationale and design of the Hygia Project

This article describes the rationale, objectives, design and conduct of the ambulatory blood pressure monitoring (ABPM)-based Hygia Project. Given the substantial evidence of the significantly better prognostic value of ABPM compared to clinic BP measurements, several international guidelines now propose ABPM as a requirement to confirm the office diagnosis of hypertension. Nonetheless, all previous ABPM outcome investigations, except the Monitorización Ambulatoria para Predicción de Eventos Cardiovasculares study (MAPEC) study, relied upon only a single, low-reproducible 24 h ABPM assessment per participant done at study inclusion, thus precluding the opportunity to explore the potential reduction in cardiovascular disease (CVD) risk associated with modification of prognostic ABPM-derived parameters by hypertension therapy. The findings of the single-center MAPEC study, based upon periodic systematic 48 h ABPM evaluation of all participants during a median follow-up of 5.6 years, constitute the first proof-of-concept evidence that the progressive reduction of the asleep systolic blood pressure (SBP) mean and correction of the sleep-time relative SBP decline toward the normal dipper BP profile, most efficiently accomplished by a bedtime hypertension treatment strategy, best attenuates the risk of CVD, stroke and development of new-onset diabetes. The Hygia Project, primarily designed to extend the use of ABPM in primary care as a requirement for diagnosis of hypertension, evaluation of response to treatment and individualized assessment of CVD and other risks, is a research network presently composed of 40 clinical sites and 292 investigators. Its main objectives are to (i) investigate whether specific treatment-induced changes in ABPM-derived parameters reduce risk of CVD events, stroke, new-onset diabetes and/or development of chronic kidney disease (CKD); and (ii) test the hypothesis that bedtime chronotherapy entailing the entire daily dose of ≥1 conventional hypertension medications exerts better ambulatory BP control and CVD, metabolic and renal risk reduction than all such medications ingested in the morning upon awakening. Between 2007 and 2015, investigators recruited 18 078 persons [9769 men/8309 women, 59.1 ± 14.3 years of age (mean ± SD)], including 15 764 with hypertension according to ABPM criteria as participants in the prospective randomized chronotherapy trial. The initial evaluation includes 48 h ABPM, detailed medical history and screening laboratory blood and urine tests. The same evaluation procedure is scheduled annually, or more frequently when treatment adjustment is required for proper ambulatory BP control, targeting a median follow-up of >5 years. The primary CVD outcome end point is the composite of CVD death, myocardial infarction, coronary revascularization, heart failure, ischemic stroke and hemorrhagic stroke. The independent Hygia Project Events Committee periodically evaluates blinded clinical reports to ascertain and certify every documented event. Beyond the potential findings resulting from testing the main hypotheses, the Hygia Project has already demonstrated, as proof of concept, that the routine diagnosis of hypertension and individualized assessment of CVD and other risks by ABPM, as currently recommended, is fully viable in the primary care setting, where most people with either hypertension, dyslipidemia, type 2 diabetes or CKD receive routine medical attention.

Immediate Effects of Bhramari Pranayama on Resting Cardiovascular Parameters in Healthy Adolescents

INTRODUCTION

In yoga, Pranayama has a very important role in maintaining sound health. There is some strong scientific basis on constant physiological changes produced when pranayama is practiced for long duration. Still, there exists a dearth of literature on the effect of Bhramari pranayama (Bhr.p) on physiological systems.

AIM

To assess the immediate effect of Bhramari pranayama (Bhr.P) practice on the resting cardiovascular parameters in healthy adolescents.

MATERIALS AND METHODS

Sixty apparently healthy adolescents of both sex participated in the study. They were randomly divided into Bhr.P (n-30) and control (n-30) group. Informed consent was obtained after explaining the detailed procedure of the study. Bhr.P group practiced Bhramari pranayama for 45 min (5 cycles) and control group was allowed to do normal breathing (12-16 breath /min). Heart rate (HR) was assessed by radial artery palpation method and blood pressure was recorded in supine position after 5 minutes of rest by sphygmomanometer.

RESULTS

The HR reduced significantly (p-0.001) in Bhr.P group. BP indices, Pulse Pressure (PP), Mean Arterial Pressure (MAP), Rate Pressure Product (RPP) and Double Product (DoP) significantly decreased after Bhr.p practice compared with control. Pre and Post inter group analysis also showed that significant reduction in HR and BP indices in Bhr.P group.

CONCLUSION

Present study showed that Bhr.P practice produces relaxed state and in this state parasympathetic activity overrides the sympathetic activity. It suggests that Bhramari pranayama improves the resting cardiovascular parameters in healthy adolescents.

Chronotherapy with conventional blood pressure medications improves management of hypertension and reduces cardiovascular and stroke risks

Correlation between blood pressure (BP) and target organ damage, vascular risk and long-term patient prognosis is greater for measurements derived from around-the-clock ambulatory BP monitoring than in-clinic daytime ones. Numerous studies consistently substantiate the asleep BP mean is both an independent and a much better predictor of cardiovascular disease (CVD) risk than either the awake or 24 h means. Sleep-time hypertension is much more prevalent than suspected, not only in patients with sleep disorders, but also among those who are elderly or have type 2 diabetes, chronic kidney disease or resistant hypertension. Hence, cost-effective adequate control of sleep-time BP is of marked clinical relevance. Ingestion time, according to circadian rhythms, of hypertension medications of six different classes and their combinations significantly affects BP control, particularly sleep-time BP, and adverse effects. For example, because the high-amplitude circadian rhythm of the renin-angiotensin-aldosterone system activates during nighttime sleep, bedtime vs. morning ingestion of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers better reduces the asleep BP mean, with additional benefit, independent of medication terminal half-life, of converting the 24 h BP profile into more normal dipper patterning. The MAPEC (Monitorización Ambulatoria para Predicción de Eventos Cardiovasculares) study, first prospective randomized treatment-time investigation designed to test the worthiness of bedtime chronotherapy with ⩾1 conventional hypertension medications so as to specifically target attenuation of asleep BP, demonstrated, relative to conventional morning therapy, 61% reduction of total CVD events and 67% decrease of major CVD events, that is, CVD death, myocardial infarction, and ischemic and hemorrhagic stroke. The MAPEC study, along with other earlier conducted less refined trials, documents the asleep BP mean is the most significant prognostic marker of CVD morbidity and mortality; moreover, it substantiates attenuation of the asleep BP mean by a bedtime hypertension treatment strategy entailing the entire daily dose of ⩾1 hypertension medications significantly reduces CVD risk in both general and more vulnerable hypertensive patients, that is, those diagnosed with chronic kidney disease, diabetes and resistant hypertension.

Cardiovascular effects of Zumba(®) performed in a virtual environment using XBOX Kinect

[Purpose] This study evaluated the acute cardiovascular responses during a session of Zumba(®) Fitness in a virtual reality environment. [Subjects] Eighteen healthy volunteers were recruited. [Methods] The following cardiovascular variables: heart rate, systolic blood pressure, diastolic blood pressure, and double product were assessed before and after the practice of virtual Zumba(®), which was performed as a continuous sequence of five choreographed movements lasting for 22 min. The game Zumba Fitness Core(®), with the Kinect-based virtual reality system for the XBOX 360, was used to create the virtual environment. Comparisons were made among mean delta values (delta=post-Zumba(®) minus pre-Zumba(®) values) for systolic and diastolic blood pressure, heart rate, and double product using Student's t-test for paired samples. [Results] After a single session, a significant increase was noted in all the analyzed parameters (Systolic blood pressure=18%; Diastolic blood pressure=13%; Heart rate=67%; and Double product=97%). [Conclusion] The results support the feasibility of the use of Zumba Fitness Core(®) with the Kinect-based virtual reality system for the XBOX 360 in physical activity programs and further favor its indication for this purpose.

Relationship between blood pressure and physical performance

Background: Changes in blood pressure during subjects’ exercise are individually different. The reasons of these differences are unknown. Aim of the study: The aim of this paper is to investigate the rate of changes in cardiovascular system at rest and at physical load which enhance systolic blood pressure (SBP) = 200 mmHg in people with different physical performance. Material and methods: The studies included 18 soccer players and 14 students who do not practice any sport, whose age, body mass, body height and BMI have been similar, and who at baseline were measured systolic blood pressure (SBPr), diastolic blood pressure (DBPr) and heart rate (HRr). Then, the subjects performed exercise on a cycloergometer with increasing intensity in which at the level of the systolic blood pressure = 200 mm Hg (SBP200) were measured DBP200 and HR200. In terms of resting and exercise time the size of the mean arterial pressure (MAPr, MAP200), pulse pressure (PPr, PP200) and rate-pressure product (DPr, DP200) were calculated. Moreover the power achieved in PWC170 test (W and W/kg) and maximal oxygen uptake (VO2max) (ml/min and ml/min/kg) were also calculated. Results: Soccer players have reached a higher power in PWC170 and higher VO2max and lower HR200 and DP200 (p<0,001), as well as lower values of HRr (p<0,01) than students however SBP, DBP, MAP and PP registered during rest and during exercise did not differ between the groups. Among the players power reached at PWC170 (W) correlate negatively with DP200 – (p<0,05) and VO2max (ml/min; ml/min/kg) also correlated negatively with HRr (p<0,05, p<0,01). Among students power reached at PWC170 (W, W/kg) and VO2max (ml/min, ml/min/kg) correlate negatively with HR200 and DP200. Moreover VO2max (ml/min/kg) correlate negatively with HRr. Conclusions: Studies have shown that, despite differences in physical performance of both groups, there were no significant changes in blood pressure at rest or modified during exercise. However, at extremely high increase in SBP improved economization in function of the heart and circulatory system independent of the size of physical performance of the subjects were observed.

Circadian blood pressure pattern in sarcoidosis patients

OBJECTIVES

Autonomic dysfunction (AD) is frequent in sarcoidosis and considered a result of small fiber neuropathy. A non-dipper blood pressure (BP) pattern, which is also linked to AD, is associated with increased risk of cardiovascular and renal diseases. The aim of the present study was to evaluate the non-dipping BP pattern in normotensive patients with pulmonary sarcoidosis (PS).

METHODS

Sixty-three normotensive patients with PS (group 1) and 49 healthy subjects (group 2) were prospectively enrolled. Ambulatory BP monitoring was performed in all participants over a 24-h period.

RESULTS

The non-dipping BP pattern was significantly more frequent in patients with PS compared with the control group (80% vs 53%, respectively, p = 0.002). More advanced PS (grade 2) was an independent predictor of non-dipper BP pattern (odds ratio = 10.4, 95% confidence interval 1.1-95.4, p = 0.03). Masked hypertension and body mass index were also found to be other predictors of non-dipping BP pattern.

CONCLUSIONS

The present study showed that non-dipping BP pattern is frequently observed in normotensive patients with PS. The probable mechanism underlying the non-dipping BP in PS is autonomic nervous system dysfunction. PS represents an independent risk factor for non-dipping BP and these patients have increased cardiovascular risk.

Diurnal and twenty-four hour patterning of human diseases: cardiac, vascular, and respiratory diseases, conditions, and syndromes

Various medical conditions, disorders, and syndromes exhibit predictable-in-time diurnal and 24 h patterning in the signs, symptoms, and grave nonfatal and fatal events, e.g., respiratory ones of viral and allergic rhinorrhea, reversible (asthma) and non-reversible (bronchitis and emphysema) chronic obstructive pulmonary disease, cystic fibrosis, high altitude pulmonary edema, and decompression sickness; cardiac ones of atrial premature beats and tachycardia, paroxysmal atrial fibrillation, 3rd degree atrial-ventricular block, paroxysmal supraventricular tachycardia, ventricular premature beats, ventricular tachyarrhythmia, symptomatic and non-symptomatic angina pectoris, Prinzmetal vasospastic variant angina, acute (non-fatal and fatal) incidents of myocardial infarction, sudden cardiac arrest, in-bed sudden death syndrome of type-1 diabetes, acute cardiogenic pulmonary edema, and heart failure; vascular and circulatory system ones of hypertension, acute orthostatic postprandial, micturition, and defecation hypotension/syncope, intermittent claudication, venous insufficiency, standing occupation leg edema, arterial and venous branch occlusion of the eye, menopausal hot flash, sickle cell syndrome, abdominal, aortic, and thoracic dissections, pulmonary thromboembolism, and deep venous thrombosis, and cerebrovascular transient ischemic attack and hemorrhagic and ischemic stroke. Knowledge of these temporal patterns not only helps guide patient care but research of their underlying endogenous mechanisms, i.e., circadian and others, and external triggers plus informs the development and application of effective chronopreventive and chronotherapeutic strategies.

Effect of fast and slow pranayama on perceived stress and cardiovascular parameters in young health-care students

Context:

Perceived stress is higher for students in various healthcare courses. Previous studies have shown that pranayama practice is beneficial for combating stress and improve cardiovascular functions but both fast and slow pranayama practice produce different physiological responses.

Aim:

Present study was conducted to compare the effects of commonly practiced slow and fast pranayama on perceived stress and cardiovascular functions in young health-care students.

Materials and Methods:

Present study was carried out in Departments of Physiology and Advanced Centre for Yoga Therapy Education and Research, JIPMER, Pondicherry. Ninety subjects (age 18-25 years) were randomized to fast pranayama (Group 1), slow pranayama (Group 2) and control group (Group 3). Group 1 subjects practiced Kapalabhati, Bhastrika and Kukkuriya Pranayama while Group 2 subjects practiced Nadishodhana, Savitri and Pranav Paranayama. Supervised pranayama training was given for 30 min, 3 times a week for the duration of 12 weeks to Groups 1 and 2 subjects by certified yoga trainer. Following parameters were recorded at the baseline and after 12 weeks of training; perceived stress scale (PSS), heart rate (HR), respiratory rate, systolic blood pressure and diastolic blood pressure (DBP), mean arterial pressure (MAP), rate pressure product (RPP), and double product (Do P).

Results:

There was a significant decrease in PSS scores in both Group 1 and Group 2 subjects but percentage decrease was comparable in these groups. Significant decrease in HR, DBP, RPP, and Do P was seen in only Group 2 subjects.

Conclusion:

This study demonstrates that both types of pranayama practice are beneficial in reducing PSS in the healthy subjects but beneficial effect on cardiovascular parameters occurred only after practicing slow pranayama.

Twenty-four hour non-invasive ambulatory blood pressure and heart rate monitoring in Parkinson's disease

Non-motor symptoms are now commonly recognized in Parkinson's disease (PD) and can include dysautonomia. Impairment of cardiovascular autonomic function can occur at any stage of PD but is typically prevalent in advanced stages or related to (anti-Parkinsonian) drugs and can result in atypical blood pressure (BP) readings and related symptoms such as orthostatic hypotension (OH) and supine hypertension. OH is usually diagnosed with a head-up-tilt test (HUT) or an (active) standing test (also known as Schellong test) in the laboratory, but 24 h ambulatory blood pressure monitoring (ABPM) in a home setting may have several advantages, such as providing an overview of symptoms in daily life alongside pathophysiology as well as assessment of treatment interventions. This, however, is only possible if ABPM is administrated correctly and an autonomic protocol (including a diary) is followed which will be discussed in this review. A 24-h ABPM does not only allow the detection of OH, if it is present, but also the assessment of cardiovascular autonomic dysfunction during and after various daily stimuli, such as postprandial and alcohol dependent hypotension, as well as exercise and drug induced hypotension. Furthermore, information about the circadian rhythm of BP and heart rate (HR) can be obtained and establish whether or not a patient has a fall of BP at night (i.e., "dipper" vs. non-"dipper"). The information about nocturnal BP may also allow the investigation or detection of disorders such as sleep dysfunction, nocturnal movement disorders, and obstructive sleep apnea, which are common in PD. Additionally, a 24-h ABPM should be conducted to examine the effectiveness of OH therapy. This review will outline the methodology of 24 h ABPM in PD, summarize findings of such studies in PD, and briefly consider common daily stimuli that might affect 24 h ABPM.

Dipper and non-dipper blood pressure 24-hour patterns: circadian rhythm-dependent physiologic and pathophysiologic mechanisms

Neuroendocrine mechanisms are major determinants of the normal 24-h blood pressure (BP) pattern. At the central level, integration of the major driving factors of this temporal variability is mediated by circadian rhythms of monoaminergic systems in conjunction with those of the hypothalamic-pituitary-adrenal, hypothalamic-pituitary-thyroid, opioid, renin-angiotensin-aldosterone, plus endothelial systems and specific vasoactive peptides. Humoral secretions are typically episodic, coupled either to sleep and/or the circadian endogenous (suprachiasmatic nucleus) central pacemaker clock, but exhibiting also weekly, monthly, seasonal, and annual periodicities. Sleep induction and arousal are influenced also by many hormones and chemical substances that exhibit 24-h variation, e.g., arginine vasopressin, vasoactive intestinal peptide, melatonin, somatotropin, insulin, steroids, serotonin, corticotropin-releasing factor, adrenocorticotropic hormone, thyrotropin-releasing hormone, endogenous opioids, and prostaglandin E2, all with established effects on the cardiovascular system. As a consequence, physical, mental, and pathologic stimuli that activate or inhibit neuroendocrine effectors of biological rhythmicity may also interfere with, or modify, the temporal BP structure. Moreover, immediate adjustment to exogenous components/environment demands by BP rhythms is modulated by the circadian-time-dependent responsiveness of biological oscillators and their neuroendocrine effectors. This knowledge contributes to a better understanding of the pathophysiology of abnormalities of the 24-h BP pattern and level and their correction through circadian rhythm-based chronotherapeutic strategies.

Double product and end-organ damage in African and Caucasian men: the SABPA study

BACKGROUND

Increasing urbanisation in sub-Saharan African countries is causing a rapid increase in cardiovascular disease. Evidence suggests that Africans have higher blood pressures and a higher prevalence of hypertension-related cardiovascular morbidity and mortality, compared to Caucasians. We investigated double product (systolic blood pressure × heart rate), a substantial measure of cardiac workload, as a possible cardiovascular risk factor in African and Caucasian men.

MATERIAL AND METHODS

The study consisted of 101 urbanised African and 101 Caucasian male school teachers. We measured 24h ambulatory blood pressure and the carotid cross-sectional wall area, and determined left ventricular hypertrophy electrocardiographically by means of the Cornell product. Urinary albumin and creatinine were analysed to obtain the albumin-to-creatinine ratio.

RESULTS

Africans had higher 24h, daytime and nighttime systolic- and diastolic blood pressure, heart rate and resultant double product compared to the Caucasians. In addition, markers of end-organ damage, albumin-to-creatinine ratio and left ventricular hypertrophy were higher in the Africans while cross-sectional wall area did not differ. In Africans after single partial and multiple regression analysis, 24h systolic blood pressure, but not double product or heart rate, correlated positively with markers of end-organ damage (cross-sectional wall area: β=0.398, P=0.005; left ventricular hypertrophy: β=0.455, P<0.001; albumin-to-creatinine ratio: β=0.280, P=0.012). No associations were evident in Caucasian men.

CONCLUSIONS

Double product may not be a good marker of increased cardiovascular risk when compared to systolic blood pressure in African and Caucasian men.

REM-related bradyarrhythmia syndrome

Cardiac arrhythmias during sleep are relatively common and include a diverse etiology, from benign sinus bradycardia to potentially fatal ventricular arrhythmias. Predisposing factors include obstructive sleep apnea and cardiac disease. Rapid eye movement (REM)-related bradyarrhythmia syndrome (including sinus arrest and complete atrioventricular block with ventricular asystole) in the absence of an underlying cardiac or physiologic sleep disorder was first described in the early 1980s. Although uncertain, the underlying pathophysiology likely reflects abnormal autonomic neural-cardiac inputs during REM sleep. The autonomic nervous system (ANS) is a known key modulator of heart rate fluctuations and rhythm during sleep and nocturnal heart rate reflects a balance between the sympathetic-parasympathetic systems. Whether the primary trigger for REM-related bradyarrhythmias reflects abnormal centrally mediated control of the ANS during REM sleep or anomalous baroreflex parasympathetic influences is unknown. This review focuses on the salient features of the REM-related bradyarrhythmia syndrome and explores potential mechanisms with a particular assessment of the relationship between the ANS and nocturnal heart rate fluctuations.

"Smart" liposomal nanocontainers in biology and medicine

The perspectives of using liposomes for delivery of drugs to desired parts of the human body have been intensively investigated for more than 30 years. During this time many inventions have been suggested and different kinds of liposomal devices developed, and a number of them have reached the stages of preclinical or clinical trials. The latest techniques can be used to develop biocompatible nano-sized liposomal containers having some abilities of artificial intellect, such as the presence of sensory and responsive units. However, only a few have been clinically approved. Further improvements in this area depend on our knowledge of the interactions of drugs with the lipid bilayer of liposomes. Further studies on liposomal transport through the human body, their targeting of cells requiring therapeutic treatment, and finally, the development of techniques for controlled drug delivery to desired acceptors on cell surfaces or in cytoplasm are still required.