Relation between diurnal variation of blood pressure and left ventricular mass in a Chinese population

130/80 mmHg as a unifying hypertension threshold for office brachial, office central, and ambulatory daytime brachial blood pressure

The present study investigated the prognostic values for office brachial (OB), office central (OC), and ambulatory daytime brachial (AmDB) hypertension, as defined by a unifying threshold of 130/80 mmHg, and the incremental value of either OC or AmDB hypertension to OB hypertension. A total of 1219 community residents without receiving anti-hypertensive treatment (671 men and 548 women, aged ≥ 30 years old) from central Taiwan and Kinmen islands had OB, OC, and AmDB blood pressure measurements during a cardiovascular survey conducted in 1992-1993. OB hypertension, OC hypertension, and AmDB hypertension were all defined in retrospect at the threshold of 130/80 mmHg. They were followed up for nonfatal and fatal cardiovascular events until December 31, 2017, by linking the baseline database to the National Health Insurance Research dataset and the National Death Registry. During a follow-up of 25 612.5 person-years (Average event-free time: 21.0 years), there were 368 fatal and nonfatal cardiovascular events. In multivariable analyses, OB hypertension, OC hypertension, and AmDB hypertension had similar hazard ratios for cardiovascular events [2.03, 95% confidence interval: 1.47-2.80]; 1.92 (1.47-2.51); and 1.79 (1.41-2.29), respectively. Using OB normotension as the reference, either the concordant OB and OC hypertension [2.24 (1.61-3.12)], or the concordant OB and AmDB hypertension [2.52 (1.80-3.54)] was significantly associated with cardiovascular events. Moreover, OB hypertension plus AmDB normotension was also significantly associated with increased risk for cardiovascular events. We concluded that OB hypertension, OC hypertension, and AmDB hypertension defined by a unifying threshold of 130/80 mmHg may provide similar estimates of long-term risk for cardiovascular events. Cross-classification analyses suggest that addition of OC hypertension or AmDB hypertension may improve the prognostic value of OB hypertension.

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.

Guidance on ambulatory blood pressure monitoring: A statement from the HOPE Asia Network

Hypertension is an important public health issue due to its association with a number of serious diseases, including cardiovascular disease and stroke. The importance of evaluating hypertension taking into account different blood pressure (BP) profiles and BP variability (BPV) is increasingly being recognized, and is particularly relevant in Asian populations given the specific features of hypertension in the region (including greater salt sensitivity and a high rate of nocturnal hypertension). Ambulatory BP monitoring (ABPM) is the gold standard for diagnosing hypertension and assessing 24-hour BP and provides data on several important parameters that cannot be obtained using any other form of BP measurement. In addition, ABPM parameters provide better information on cardio- and cerebrovascular risk than office BP. ABPM should be used in all patients with elevated BP, particularly those with unstable office or home BP, or who are suspected to have white-coat or masked hypertension. ABPM is also an important part of hypertension diagnosis and monitoring in high-risk patients. ABPM needs to be performed using a validated device and good practice techniques, and has a role both in hypertension diagnosis and in monitoring the response to antihypertensive therapy to ensure strict BP control throughout the 24-hour period. Use of ABPM in clinical practice may be limited by cost and accessibility, and practical education of physicians and patients is essential. The ABPM evidence and practice points in this document are based on the Hypertension Cardiovascular Outcome Prevention and Evidence (HOPE) Asia Network expert panel consensus recommendations for ABPM in Asia.

2020 Consensus summary on the management of hypertension in Asia from the HOPE Asia Network

Hypertension professionals from Asia have been meeting together for the last decade to discuss how to improve the management of hypertension. Based on these education and research activities, the Hypertension, brain, cardiovascular and renal Outcome Prevention and Evidence in Asia (HOPE Asia) Network was officially established in June 2018 and includes experts from 12 countries/regions across Asia. Among the numerous research and review papers published by members of the HOPE Asia Network since 2017, publications in three key areas provide important guidance on the management of hypertension in Asia. This article highlights key consensus documents, which relate to the Asian characteristics of hypertension, home blood pressure monitoring (HBPM), and ambulatory blood pressure monitoring (ABPM). Hypertension and hypertension-related diseases are common in Asia, and their characteristics differ from those in other populations. It is essential that these are taken into consideration to provide the best opportunity for achieving "perfect 24-hour blood pressure control", guided by out-of-office (home and ambulatory) blood pressure monitoring. These region-specific consensus documents should contribute to optimizing individual and population-based hypertension management strategies in Asian country. In addition, the HOPE Asia Network model provides a good example of the local interpretation, modification, and dissemination of international best practice to benefit specific populations.

Expert panel consensus recommendations for ambulatory blood pressure monitoring in Asia: The HOPE Asia Network

Hypertension is an important public health issue because of its association with a number of significant diseases and adverse outcomes. However, there are important ethnic differences in the pathogenesis and cardio-/cerebrovascular consequences of hypertension. Given the large populations and rapidly aging demographic in Asian regions, optimal strategies to diagnose and manage hypertension are of high importance. Ambulatory blood pressure monitoring (ABPM) is an important out-of-office blood pressure (BP) measurement tool that should play a central role in hypertension detection and management. The use of ABPM is particularly important in Asia due to the specific features of hypertension in Asian patients, including a high prevalence of masked hypertension, disrupted BP variability with marked morning BP surge, and nocturnal hypertension. This HOPE Asia Network document summarizes region-specific literature on the relationship between ABPM parameters and cardiovascular risk and target organ damage, providing a rationale for consensus-based recommendations on the use of ABPM in Asia. The aim of these recommendations is to guide and improve clinical practice to facilitate optimal BP monitoring with the goal of optimizing patient management and expediting the efficient allocation of treatment and health care resources. This should contribute to the HOPE Asia Network mission of improving the management of hypertension and organ protection toward achieving "zero" cardiovascular events in Asia.

Prognostic Utility of Morning Blood Pressure Surge for 20-Year All-Cause and Cardiovascular Mortalities: Results of a Community-Based Study

Background

Morning blood pressure (BP) surge (MS), defined by the MS amplitude, is an independent prognostic factor of cardiovascular outcomes in some, but not all, populations.

Method and Results

We enrolled 2020 participants (1029 men; aged 30–79 years) with 24‐hour ambulatory BP data. During a median 19.7‐year follow‐up, 607 deaths (182 by cardiovascular causes) were confirmed from the National Death Registry. The amplitude of sleep‐trough MS (STMS) was derived from the difference between morning systolic BP (SBP) and lowest nighttime SBP. The rate of STMS was derived as the slope of linear regression of sequential SBP measures on time intervals within the STMS period. Thresholds for high STMS amplitude and rate were determined by the 95th percentiles (43.7 mm Hg and 11.3 mm Hg/h, respectively). Multivariable Cox models, adjusting for age, sex, body mass index, smoking, alcohol, low‐density lipoprotein cholesterol, 24‐hour SBP, night:day SBP ratio, and antihypertensive treatment, revealed that a high STMS rate (hazard ratio, 1.666; 95% confidence interval, 1.185–2.341), but not STMS amplitude (hazard ratio, 1.245; 95% confidence interval, 0.984–1.843), was significantly associated with a greater mortality risk. Similarly, STMS rate (hazard ratio, 2.608; 95% confidence interval, 1.554–4.375), but not STMS amplitude, was significantly associated with the risk of cardiovascular mortality (hazard ratio, 0.966; 95% confidence interval, 0.535–1.747). Moreover, the prognostic values of STMS rate were comparable in subjects with or without morning and nocturnal hypertension (P>0.05 for interaction for all). In simulation studies, STMS rate was less susceptible to measurement errors of the sleep‐trough SBP than STMS amplitude.

Conclusions

STMS rate could independently help identify subjects with an increased cardiovascular risk.

Abnormal Pulsatile Hemodynamics in Hypertensive Patients With Normalized 24-Hour Ambulatory Blood Pressure by Combination Therapy of Three or More Antihypertensive Agents

It remains uncertain whether intensive antihypertensive therapy can normalize pulsatile hemodynamics resulting in minimized residual cardiovascular risks. In this study, office and 24-hour ambulatory systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure, carotid-femoral pulse wave velocity (PWV), and forward (Pf) and reflected (Pb) pressure wave from a decomposed carotid pressure wave were measured in hypertensive participants. Among them, 57 patients whose 24-hour SBP and DBP were normalized by three or more classes of antihypertensive medications were included. Another 57 age- and sex-matched normotensive participants were randomly selected from a community survey. The well-treated hypertensive patients had similar 24-hour SBP, lower DBP, and higher PP values. The treated patients had higher PWV (11.7±0.3 vs 8.3±0.2 m/s, P<.001), Pf, Pb, Pb/Pf, and left ventricular mass index values. After adjustment for age, sex, body mass index, and office SBP, the differences for PWV, Pb, and Pb/Pf remained significant. Hypertensive patients whose 24-hour SBP and DBP are normalized may still have markedly increased arterial stiffness and wave reflection.

White coat hypertension is more risky than prehypertension: important role of arterial wave reflections

Arterial aging may link cardiovascular risk to white coat hypertension (WCH). The aims of the present study were to investigate the role of arterial aging in the white coat effect, defined as the difference between office and 24-hour ambulatory systolic blood pressures, and to compare WCH with prehypertension (PH) with respect to target organ damage and long-term cardiovascular mortality. A total of 1257 never-been-treated volunteer subjects from a community-based survey were studied. WCH and PH were defined by office and 24-hour ambulatory blood pressures. Left ventricular mass index, carotid intima-media thickness, estimated glomerular filtration rate, carotid-femoral pulse wave velocity, carotid augmentation index, amplitude of the reflection pressure wave, and 15-year cardiovascular mortality were determined. Subjects with WCH were significantly older and had greater body mass index, blood pressure values, intima-media thickness, carotid-femoral pulse wave velocity, augmentation index, amplitude of the backward pressure wave, and a lower estimated glomerular filtration rate than PH. Amplitude of the backward pressure wave was the most important independent correlate of the white coat effect in multivariate analysis (model r(2)=0.451; partial r(2)/model r(2)=90.5%). WCH had significantly greater cardiovascular mortality than PH (hazard ratio, 2.94; 95% confidence interval, 1.09-7.91), after accounting for age, sex, body mass index, smoking, fasting plasma glucose, and total cholesterol/high-density lipoprotein-cholesterol ratio. Further adjustment of the model for amplitude of the backward pressure wave eliminated the statistical significance of the WCH effect. In conclusion, the white coat effect is mainly caused by arterial aging. WCH carries higher risk for cardiovascular mortality than PH, probably via enhanced wave reflections that accompany arterial aging.

Combined effect of obstructive sleep apnea and age on daytime blood pressure

Epidemiologic studies have shown obstructive sleep apnea (OSA) is an independent risk factor for systemic hypertension. The prevalence of systemic hypertension also increases gradually with age. The purpose of this study was to assess the combined effect of OSA and age on daytime blood pressure. Patients who received nocturnal polysomnography in Tainan Municipal Hospital were invited between October 2008 and February 2010. Daytime blood pressure was measured. Participants were classified into three groups: nonapnea (n = 14, 18%) with RDI <5 episodes/h; mild to moderate OSA (n = 34, 43%) with RDI ≧ 5 and <30; and severe OSA (n = 31, 39%) with RDI ≧ 30. Seventy-nine patients (79/101, 78.2%) (63 males) completed the study. The mean of age, severity of OSA (RDI) and systolic blood pressure (SBP) was 40.3 ± 15.4 years, 28.1 ± 26.0/h and 132.6 ± 19.7 mmHg, respectively. RDI and age were significant risk factors for SBP (P < 0.05). SBP became severe when patients were older in the group of mild to moderate OSA (p = 0.0067) and diastolic blood pressure (DBP) became severe when patients were older in the group of nonapnea and mild to moderate OSA (P = 0.0042 and 0.0168, respectively). But the daytime blood pressure and age were not correlated significantly for the severe OSA subjects. This study revealed that age and RDI were risk factors in development of daytime hypertension. For patients with mild to moderate OSA, SBP was significantly worse when getting older and for patients with nonapnea and mild to moderate OSA, DBP was significantly worse with increasing age.

Central versus ambulatory blood pressure in the prediction of all-cause and cardiovascular mortalities

OBJECTIVES

Central systolic (SBP-C) and/or pulse pressure (PP-C) better predicts cardiovascular events than does peripheral blood pressure. The present study compared the prognostic significance of office central blood pressure with multiple measurements of out-of-office ambulatory peripheral blood pressure, with reference to office peripheral systolic (SBP-B) or pulse pressure (PP-B).

METHODS

In a community-based population of 1014 healthy participants, SBP-C and PP-C were estimated using carotid tonometry, and 24-h systolic (SBP-24 h) and pulse pressure (PP-24 h) were obtained from 24-h ambulatory blood pressure monitoring. Associations of SBP-B, PP-B, SBP-C, PP-C, SBP-24 h, and PP-24 h with all-cause and cardiovascular mortalities over a median follow-up of 15 years were examined by Cox regression analysis.

RESULTS

In multivariate analyses accounting for age, sex, BMI, smoking, fasting plasma glucose, and total cholesterol/high-density lipoprotein cholesterol ratio, only PP-C (hazard ratio 1.16, 95% confidence interval 1.01-1.32, per one standard deviation increment) was significantly predictive of all-cause mortality, whereas all but PP-B were significantly predictive of cardiovascular mortality. When SBP-B was simultaneously included in the models, SBP-24 h (2.01, 1.42-2.85) and SBP-C (1.71, 1.21-2.40) remained significantly predictive of cardiovascular mortality. When SBP-C was simultaneously included in the models, SBP-24 h (1.71, 1.16-2.52) remained significantly predictive of cardiovascular mortality.

CONCLUSION

Office central blood pressure is more valuable than office peripheral blood pressure in the prediction of all-cause and cardiovascular mortalities. Out-of-office ambulatory peripheral blood pressure (SBP-24 h) may be superior to central blood pressure in the prediction of cardiovascular mortality, but PP-C may better predict all-cause mortality than SBP-24 h or PP-24 h.

The importance of γ-Glutamyltransferase (GGT) activity: a potential marker of Left Ventricular (LV) diastolic function in diabetic patients with cardiovascular disease

OBJECTIVES

To examine the relation between left ventricular (LV) diastolic function and γ-glutamyltransferase (GGT) in diabetic individuals with or without previously diagnosed cardiovascular disease.

DESIGN

A cross-sectional population-based study.

SETTING

A university hospital.

SUBJECTS

A total of 205 diabetic patients were included in the study. Patients who had cardiovascular disease constituted the study group (CD group; n = 112) and patients who had no complications constituted the control group (ND group; n = 93). Left ventricular diastolic function was assessed by pulsed Doppler tissue imaging and was determined by ratio E wave/A wave.

MAIN OUTCOME MEASURES

GGT levels were higher in CD Group than ND Group (25.9 ± 2.1 vs. 20.1 ± 1.5 units/L, p = 0.023). Significant difference between mean diastolic function parameters, such as E wave/A wave (0.86 ± 0.27 vs. 1.01 ± 0.36, p = 0.015), of the diabetic patients with and without cardiovascular disease was present. In this study, E wave/A wave correlated with age, waist-to-hip ratio (WHR), systolic blood pressure, and total cholesterol. Negative correlations were also found between LV diastolic function and GGT (β = -0.009, p = 0.008).

CONCLUSION

The data showed that in type 2 diabetic patients, with evident cardiac disease, metabolic parameters affect diastolic functions more than systolic functions. Besides known cardiovascular disease risk factors, GGT might be an additional marker of diastolic dysfunction in diabetes patients with cardiovascular disease.

Is Isolated Nocturnal Hypertension a Novel Clinical Entity?

We reported previously that normotensive Chinese had higher nighttime diastolic blood pressure compared with non-Chinese. We, therefore, studied the prevalence and characteristics of isolated nocturnal hypertension (HT) and its association with arterial stiffness, an intermediate sign of target organ damage. We recorded ambulatory blood pressure, the central and peripheral systolic augmentation indexes, the ambulatory arterial stiffness index, and brachial-ankle pulse wave velocity in 677 Chinese enrolled in the JingNing population study (53.6% women; mean age: 47.6 years). Prevalence was 10.9% for isolated nocturnal HT (≥120/70 mm Hg from 10:00 pm to 4:00 am ), 4.9% for isolated daytime HT (≥135/85 mm Hg from 8:00 am to 6:00 pm ), and 38.4% for day-night HT. Patients with isolated nocturnal HT, compared with subjects with ambulatory normotension (45.8%), were older (53.7 versus 40.7 years), more often reported alcohol intake (68.9% versus 51.0%), had faster nighttime pulse rate (62.8 versus 60.7 bpm), had higher serum cholesterol (5.12 versus 4.77 mmol/L), and had higher blood glucose (4.84 versus 4.38 mmol/L). Similar to patients with isolated daytime HT or day-night HT, patients with isolated nocturnal HT had higher indexes of arterial stiffness ( P <0.05) than subjects with ambulatory normotension (central augmentation index: 140% versus 134%; peripheral augmentation index: 82.6% versus 76.5%; ambulatory arterial stiffness index: 0.40 versus 0.35 U; brachial-ankle pulse wave velocity: 16.2 versus 14.7 m/s). Of 74 patients with isolated nocturnal HT, only 4 (5.4%) had hypertension on conventional office blood pressure measurement (≥140/90 mm Hg). In conclusion, isolated nocturnal HT can only be diagnosed by ambulatory blood pressure monitoring, is prevalent among Chinese, and is associated with increased arterial stiffness.

Association Between Fasting Plasma Glucose and Left Ventricular Mass and Left Ventricular Hypertrophy over 4 Years in a Healthy Population Aged 60 and Older

OBJECTIVES

To test the association between fasting glucose level and left ventricular mass (LVM) and left ventricular hypertrophy (LVH) in people aged 60 and older.

DESIGN

Population-based prospective study with 4-year follow-up.

SETTING

Department of Internal Medicine and Family Medicine, Kaohsiung Medical University (KMU), Chung-Ho Memorial Hospital, and Graduate Institute of Medicine and Public Health, KMU.

PARTICIPANTS

Of 1,500 people screened, 105 without symptoms or signs of diabetes mellitus, hypertension, or cardiovascular disease were recruited from senior activity centers in Kaohsiung city.

MEASUREMENTS

All received two-dimensional echocardiography and fasting glucose examination at baseline and at 2- and 4-year follow-up. LVH was defined as a LVM index (LVMI) greater than 122.4 g/m(2) or 51 g/m(2.7).

RESULTS

Age ranged from 60 to 81 (mean 71.7+/-3.9). Baseline glucose ranged from 83 to 118 mg/dL (mean 99.7+/-7.9 mg/dL). LVMI was significantly higher at the 4-year follow-up (97.5+/-24.9 vs 104.5+/-27.5 g/m(2) and 44.2+/-12.1 vs 47.2+/-13.4 g/m(2.7), both P<.01), as was the occurrence of LVH (16% vs 32% and 25% vs 39%, both P<.01). Baseline glucose correlates with 4-year change in LVMI (both P<.02). In the fourth year, baseline glucose was a significant predictor of LVMI (both P<.01) and LVH (P=.03 in g/m(2) definition) using logistic regression analysis.

CONCLUSION

Because fasting glucose is an independent predictor for greater LVM and for development of LVH, it should be considered in assessment of cardiac disease and LVM in healthy older people without diabetes mellitus.

Ethnicity, sex, trait anger, and nocturnal blood pressure decline

This study examined the relationship of trait anger to nocturnal blood pressure decline among Singaporean young adults. One hundred forty-nine participants (51 Chinese, 51 Malays, 47 Indians, 49.7% men) participated in 24-h ambulatory monitoring for blood pressure and hemodynamic measures. Significant interactions were obtained between ethnicity and trait anger for systolic blood pressure and mean arterial pressure such that trait anger was significantly and negatively related to nocturnal blood pressure decline for Indians whereas this was not true for Chinese or Malays. Significant sex x trait anger interactions were obtained for systolic blood pressure, diastolic blood pressure, and mean arterial pressure in which trait anger was negatively related to blood pressure decline for men but not for women. Overall the results suggest that trait anger is a significant factor affecting nocturnal blood pressure decline particularly among Indians and men.

Optimal threshold value for left ventricular hypertrophy in blacks: the Atherosclerosis Risk in Communities study

The distribution of echocardiographic left ventricular (LV) mass differs among ethnicities. Because ethnic-specific echocardiographic criteria for LV hypertrophy (LVH) are not established, we determined whether threshold values derived from overwhelmingly white populations are appropriate for blacks, a subgroup having more LVH. Between 1992 and 1994, LV mass was measured echocardiographically in the Jackson, Mississippi, black cohort of the Atherosclerosis Risk in Communities study. Participants free of prevalent cardiovascular disease (CVD) (n=1616; mean+/-SD, age 59+/-5.7; 65% women and 57% with hypertension) were included. The optimal LVH threshold value was selected from the continuum of LV mass index (LVMI=LV mass/height(2.7)) using 3 methods: (1) the best operating point from the area under the resulting receiver-operating characteristic (ROC) curve predicting incident CVD; (2) the value with the smallest probability value associated with incident CVD; and (3) visual inspection of functions of LVMI and CVD in the general additive model (GAM) plot. At a median follow-up of 6.8 years, there were 192 events (coronary heart disease=87, stroke=62, and congestive heart failure=43; incidence=17.6/1000 person-years). The best operating point from the resulting ROC analysis was 51.2 g/m(2.7) for sensitivity (53.4%) and specificity (61.5%). The Cox and GAM models adjusted for age, gender, systolic blood pressure, hypertension, diabetes, smoking, total cholesterol-to-high-density lipoprotein ratio, LVH by ECG criterion, and socioeconomic status found 50 to 51 g/m(2.7) as the optimal threshold for LVH in middle-aged blacks, corresponding to a minimum probability value and to a log-hazard ratio of zero, respectively. Because these values are close to the 51 g/m(2.7) established from predominantly white populations, this cutpoint is appropriate for both groups.

Can brain dysfunction be a predisposing factor for metabolic syndrome?

The various mechanisms that may explain the association between brain dysfunction and the pathogenesis of metabolic syndrome (MS) leading to cardiovascular disease and type 2 diabetes have been reviewed. A Medline search was conducted until September 2003, and articles published in various national and international journals were reviewed. Experts working in the field were also consulted. Compelling evidence was found that saturated and total fat and low dietary n-3 fatty acids and other long-chain polyunsaturated fatty acids (PUFAs) in conjunction with sedentary behavior and mental stress combined with various personality traits can enhance sympathetic activity and increase the secretion of catecholamine, cortisol and serotonin, all of which appear to be underlying mechanisms involved in MS. Excess secretion of these neurotransmitters in conjunction with underlying long-chain PUFA deficiency may damage the neurons in the ventromedial hypothalamus and insulin receptors in the brain, in particular during fetal life, infancy and childhood, and lead to their dysfunction. Since 30-50% of the fatty acids in the brain are long-chain PUFAs, especially omega-3 fatty acids which are incorporated in the cell membrane phospholipids, it is possible that their supplementation may have a protective effect. Omega-3 fatty acids are also known to enhance parasympathetic activity and to increase the secretion of anti-inflammatory cytokines as well as acetylecholine in the hippocampus. It is possible that a marginal deficiency of long-chain PUFAs, especially n-3 fatty acids, due to poor dietary intake during the critical period of brain growth and development in the fetus, and later in the infant and also possibly in the child, adolescent and adult may enhance the release of tumor necrosis factor-alpha (TNF-alpha) interleukin (IL)-1, 2 and 6 and cause neuronal dysfunction. Experimental studies indicate that ventromedial hypothalamic lesions in rats induce hyperphagia, resulting in glucose intolerance and insulin resistance. Treatment with neuropeptide Y abolished hyperphagia and ob mRNA (leptin mRNA) in this animal model. Long-term infusion of norepinephrine and serotonin into the ventromedial hypothalamus impaired pancreatic islet function inasmuch as ventromedial hypothalamic norepinephrine and serotonin levels were elevated in hyperinsulinemic and insulin-resistant animals. Treatment with insulin was associated with restoration of hypothalamic neurotransmitter abnormalities, indicating that ventromedial hypothalamus dysfunction can impair pancreatic beta cells resulting in metabolic abnormalities consistent with MS. Treatment with omega-3 fatty acids, beta blockers, ACE inhibitors, estrogen, and meditation may have a beneficial effect on insulin receptors and ventromedial hypothalamic dysfunction. However, no definite or precise insight into the pathophysiological link between MS, brain function and nutrition is available. Despite this, epidemiological studies and intervention trials indicate that treatment with n-3 fatty acids may be adopted in clinical practice and used to direct therapy for prevention of type 2 diabetes, hypertension, coronary artery disease (CAD), and atherosclerosis, thereby indicating that MS may also respond to this treatment.

A comparison of awake???sleep blood pressure variation between normotensive Japanese???American and Caucasian Women in Hawaii

OBJECTIVE

To compare awake-sleep ambulatory blood pressure variation between Japanese-American and Caucasian women in Hawaii, specifically determining whether Japanese-Americans have reduced dipping of blood pressure during sleep, as is found in comparisons of Japanese and US samples.

METHODS

Normotensive school teachers from East Hawaii who were either of Japanese-American (n = 70) or Caucasian (n = 48) ethnicity were recruited. They wore an ambulatory blood pressure monitor (Spacelabs 90207) that took measurements every 15 min during waking hours and every 30 min during sleep for a 24-h period on a normal workday. All subjects provided demographic information and underwent a series of anthropometric measurements the day before monitoring. Japanese-American subjects also answered questionnaires relating to cultural identity and migration history.

RESULTS

The Japanese-American women had significantly higher mean diastolic (P < 0.01) blood pressure during sleep. These ethnic differences in sleep blood pressure persisted when analyses controlled for age, body mass index, and the waist-hip circumference ratio. There were also significant differences in the proportion by which blood pressure dipped from waking to sleeping, with the Japanese-American women dipping significantly less than the Caucasian women (P < 0.05 systolic, P < 0.001 diastolic).

CONCLUSIONS

Normotensive Japanese-American women have higher sleep pressure, and a smaller awake-sleep dip, in pressure than Caucasian women. The relative elevation of blood pressure in Japanese-American women during sleep, but not at other times of the day, is similar to the pattern seen among Japanese women in Japan.

Circadian heart rate and blood pressure variability considered for research and patient care

OBJECTIVES

To review mechanisms of circadian variations in heart rate variability (HRV) and blood pressure variability (BPV) and mortality and morbidity due to cardiovascular diseases (CVD).

METHODS

Results from 7-day/24-h HRV and BPV are interpreted by gender and age-specified reference values in the context of a Medline search.

RESULTS

Abnormal HRV and BPV measured around the clock for 7 days provides information on the risk of subsequent morbid events in subjects without obvious heart disease and without abnormality outside the conventional (in the sense of chronobiologically unquantified) physiological range. Meditation, beta-blockers, ACE inhibitors, n-3 fatty acids and estrogens may have a beneficial influence on HRV, but there is no definitive outcome-validated therapy. Low HRV has been associated with a risk of arrhythmias and arrhythmic death, unstable angina, myocardial infarction, progression of heart failure and atherosclerosis. BPV may be characterized by treatable circadian-hyper-amplitude-tension (CHAT), which can be transient '24-h CHAT' or '7-day-CHAT', MESOR-hypertension and/or an unusually-timed (odd) circadian acrophase (ecphasia), all associated with an increased risk of stroke, stroke death, myocardial infarction, and kidney disease.

CONCLUSIONS

Precise insight into the patho-physiology in time of HRV and BPV is needed with development of a consensus on best measures of HRV for clinical purposes and to determine when a 7-day record interpreted chronobiologically suffices and when it does not, for detection within as well as outside the conventional normal range, for diagnostic clinical practice and to direct therapy of risk greater than that associated with hypertension, smoking or any other risk factor.

Can nutrition influence circadian rhythm and heart rate variability?

Recent studies indicate that there is an interaction between biorhythms, the biological clock and triggers, which may be important in the pathogenesis of altered heart rate variability (HRV) and blood pressure variability (BPV). Circadian rhythms are under the influence of, and physiological variables are mediated by the activation of the adrenals, sympathetic/parasympathetic, hypothalamic and pituitary activity. Emotional stress, physical exertion, sleep deprivation and large fatty meals are major triggers of myocardial ischemia, angina, infarction, sudden cardiac death (SCD) and stroke. These events have been reported to exhibit a circadian variation with increased frequency in the second quarter of the day, which has also been observed in our studies on Indians. Recent studies indicate that altered HRV and BPV are also important in the pathogenesis and progression of heart failure, atheroma and thrombosis. Mediation via beta-blockers, oestrogens, n-3 fatty acids, vitamin E and coenzyme Q10 and fasting appears to have a beneficial influence whereas progestins, nifedipine, stress and exercise may have an adverse effect on HRV and BPV. We have reported that plasma levels of vitamin E and C are lower in the second quarter of the day than at other times, indicating their role in the pathogenesis of variability and cardiac events. Prospective studies also indicate that HRV and BPV are important and independent risk factors for cardiovascular events. However, no study has yet been conducted in patients with abnormal HRV and BPV in a randomized, placebo-controlled intervention trial to find out whether improvement in variability can cause a significant reduction in cardiovascular events. There is a need to study the role of n-3 fatty acids, coenzyme Q10, the effect of regular physical training, medication and ACE inhibitors in patients with abnormal HRV and BPV to demonstrate that improving variability can modulate cardiovascular events.

The effects of arm elevation and overnight head-up tilt on forearm and hand volume

Methods to reduce increased fluid volume, or swelling, were evaluated as short- and long-term interventions. Forearm and hand volumes were measured in 45 fit and healthy subjects using a water displacement device with previously established reliability. Volumes were measured before and after 2 hours of recumbency and before and after overnight sleep under different conditions of arm elevation or head-up tilt. No arms-at-side lying-down position, whether after 2 hours awake or after overnight sleep or with bed-head elevated or not, resulted in significant changes in forearm and hand volume. Only 2 hours in a supine lying-down position with 30 degrees of arm elevation caused a significant effect, with an average decrease of 51 ml in forearm and hand volume.

Effect of sleep/wake state on arterial blood pressure in genetically identical mice

Genetic determinants may contribute to the large variability in arterial blood pressure responses to changes in sleep/wake state in humans. In this study, we developed techniques to examine the relationship between sleep/wake state and mean arterial pressure (MAP) in unrestrained, genetically identical mice (C57BL/6J; n = 9). The left common carotid artery was catheterized, and arterial blood gases were analyzed 24-48 h postsurgery to verify normal respiratory and metabolic function. The animals were then allowed to cycle naturally through sleep/wake states over a 3- to 4-h period while continuous polysomnography and arterial pressure measurements were made. The MAP decreased from quiet wakefulness to non-rapid-eye-movement sleep (9.8 +/- 1.3 mmHg; P < 0.001) and further decreased from non-rapid-eye-movement to rapid-eye-movement sleep (9.7 +/- 1.8 mmHg; P < 0.001). We conclude that the inbred strain of C57BL/6J mice exhibits significant and consistent changes in MAP related to sleep/wake state. Future studies can compare responses in this strain of mice with those in other inbred or transgenic mice to determine whether specific genes regulate arterial blood pressure responses to sleep/wake state.

Nocturnal blood pressure fall on ambulatory monitoring in a large international database. The "Ad Hoc' Working Group

A wide range of definitions is used to distinguish subjects in whom blood pressure (BP) falls at night (dippers) from their counterparts (nondippers). In an attempt to standardize the definition of nondipping, we determined the nocturnal BP fall and night-day BP ratio by 24-hour ambulatory monitoring in 4765 normotensive and 2555 hypertensive subjects from 10 to 99 years old. In all subjects combined, the systolic/diastolic nocturnal fall and corresponding ratio averaged (+/- SD) -16.7 +/- 11.0/ -13.6 +/- 8.1 mm Hg and 87.2 +/- 8.0%/83.1 +/- 9.6%, respectively. In normotensive subjects, the 95th percentiles were -0.3/-1.1 mm Hg for the nocturnal fall and 99.7%/98.3% for the night-day ratio. Both the fall and ratio showed a curvilinear correlation with age. The smallest fall and largest ratio were observed in older (> or = 70 years) subjects. A higher BP on conventional sphygmomanometry was associated with a larger systolic (partial r = .11) and diastolic (r = .12) nocturnal BP fall. The diastolic (r = .08) but not the systolic night-day ratio increased with higher conventional BP. The nocturnal BP fall was larger and the corresponding night-day ratio smaller in oscillometric (n = 5884) than in auscultatory (n = 1436) recordings, in males (n = 3730) than in females (n = 3590), and in Europe (n = 4556) than in the other continents (n = 2764). The distributions of the nocturnal BP fall and night-day ratio showed considerable overlap among normotensive and hypertensive subjects, but the overlap tended to be larger for the ratio than for the fall. Of all subjects, 3.2% had systolic and diastolic ratios of 100% or more. With adjustments applied for confounders, the probability of being a nondipper increased 2.8 times (95% confidence interval, 2.0-4.0) from 30 to 60 years and 5.7 times (4.4-7.4) from 60 to 80 years. The odds ratios were 1.0 (0.8-1.4) for males versus females. 1.6 (1.2-2.1) for subjects with definite hypertension versus normotensive subjects, 2.4 (1.2-4.7) for Asians (n = 2213, 96% Japanese) versus inhabitants of the other continents, and 2.4 (1.5-3.8) for subjects examined with auscultatory versus oscillometric devices. In conclusion, the mathematical definition of nondipping, ie, having a night-day ratio of 100% or more for systolic and diastolic BPs, closely approximated the 95th percentiles of the night-day ratio in normotensive subjects. The ratio depends less on BP level than the nocturnal BP fall and is therefore to be preferred in the definition of dipping status. Notwithstanding the present findings, the reproducibility of nondipping and its prognostic significance need further clarification.

Prediction of cardiac structure and function by repeated clinic and ambulatory blood pressure

We performed imaging echocardiography, Doppler velocimetry, and repeated clinic and ambulatory blood pressure measurements in 74 hypertensive individuals to clarify why reports differ on the strength of the relationships of left ventricular characteristics with clinic blood pressure, on the superiority of ambulatory over clinic pressure, and on the importance of day-time and nighttime pressures. Clinic pressure was measured five times with an automated device and five times with the conventional technique on 2 different days. The partial correlation coefficients of left ventricular mass and wall thickness with the first automated systolic and diastolic clinic pressures amounted to .38 to .45 (P < .001), improved with increasing numbers of measurements, and reached .56 to .58 for the average of 10 automated pressure determinations. Similar trends were observed for conventional clinic pressures. Average 24-hour pressures were significantly related to mass and wall thickness (partial r = .50 to .61, P < .001) and explained 3% to 6% (systolic) and 5% to 12% (diastolic) of the variance of cardiac structure in addition to the first automated or conventional clinic pressure (P < .05). However, when 10 clinic measurements were averaged, only diastolic 24-hour pressure added information over and above clinic pressure (P < .05); the additional explained variance was larger with regard to the conventional (+4% for mass and +7% for wall thickness) rather than the automated (+3% for wall thickness only) pressures. Mass and wall thickness were more closely related to day-time than nighttime pressures and were not independently related to day-night differences in pressure, except when men and women were considered separately; the results were similar when four different definitions of day and night were applied. Finally, the weak association of left ventricular diastolic function with blood pressure did not improve on repeated clinic or ambulatory blood pressure measurements. In conclusion, increasing numbers of measurements strengthen the relationships of clinic pressure with left ventricular mass and wall thickness and, conversely, diminish the additional predictive power of 24-hour blood pressure. The importance of nighttime pressure and of the nighttime pressure fall does not seem to depend on the definition of day and night but differs in men and women.