Predictive values of automated blood pressure measurement: what can we learn from the Japanese population - the Ohasama study

BACKGROUND: Measurements of ambulatory blood pressure (ABP) and of home blood pressure (HBP) as an adjunct to casual/clinic blood pressure (CBP) measurements are currently widely used for the diagnosis and treatment of hypertension. We have monitored a rural cohort of people from the population of Ohasama, Japan, with respect to their prognosis and have previously reported that ABP and HBP are superior to CBP for the prediction of cardiovascular mortality. One reason that CBP is a poor predictor of prognosis is that it incorporates several biases, including the white-coat effect. METHODS AND RESULTS: We examined the prognostic significance of white-coat hypertension for mortality and found that the relative hazard for the overall mortality of patients with white-coat hypertension was significantly lower than that for true hypertension. Short-term blood pressure variability has recently attracted attention as a cause of target-organ damage and cardiovascular complications. Our results confirmed that short-term blood pressure variability (as measured every 30 min) was independently associated with cardiovascular mortality. In addition, research has recently focused on isolated systolic hypertension and pulse pressure as independent risk factors for poor cardiovascular prognosis. The Ohasama study also clearly demonstrated that isolated systolic hypertension and increased pulse pressure, as assessed by HBP, were associated with an increase in the risk of cardiovascular mortality. Circadian blood pressure variation is characterized by a diurnal elevation and a nocturnal decline in blood pressure. We therefore compared morbidity from stroke between dippers (subjects who show an ordinal nocturnal dipping of blood pressure) and non-dippers (those with a diminished nocturnal dipping or nocturnal elevation of blood pressure [inverted dippers]) in the Ohasama study. The incidence of stroke increased with an increased length of observation in dippers using antihypertensive medication but not in non-dippers using antihypertensive medication. In contrast, the relative hazard for mortality increased in non-dippers and inverted dippers. These results suggest a cause-and-effect relationship for both dippers and non-dippers. CONCLUSION: The Ohasama study showed that the level and variability of hypertension as assessed by ABP and HBP are independent predictors of cardiovascular mortality. It also demonstrated an independent association between the prognosis of hypertension and each component of ABP and HBP, indicating the prognostic significance of these blood pressure measurements.     

Disturbed circadian blood pressure rhythm and C-reactive protein in essential hypertension

We investigated the effect of the diverse definition criteria of the dipping and non-dipping status on the assessed differences in inflammatory activation between dippers and non-dippers with essential hypertension. 269 consecutive subjects (188 males, aged 50+/-7 years) with untreated stage I-II essential hypertension underwent ambulatory blood pressure (BP) monitoring and high-sensitivity C-reactive protein (hs-CRP) level determination. The population was classified into dippers and non-dippers based on the three following different definitions: true non-dippers (TND): non-dippers (nocturnal fall of systolic and diastolic BP of <10% of the daytime values, n=95) and dippers (the remaining subjects, n=174); true dippers and true non-dippers (TD-TND): non-dippers (nocturnal fall of systolic and diastolic BP<10%, n=95) and dippers (nocturnal fall of systolic and diastolic BP> or =10%, n=75); systolic non-dippers (SND): non-dippers (nocturnal systolic BP fall of <10% of the daytime values, n=145) and dippers (the remaining subjects, n=124). Non-dippers compared to dippers in the TND, TD-TND and SND classification exhibited higher levels of log hs-CRP (by 0.11 mg l(-1), P=0.02; 0.13 mg l(-1), P=0.03 and 0.14 mg l(-1), P=0.02, respectively) and 24 h pulse pressure (PP) (by 4 mm Hg, P=0.006; by 5 mm Hg, P=0.003 and by 5 mm Hg, P<0.0001, respectively). Twenty-four hour PP and nocturnal systolic BP fall were independent predictors of log hs-CRP (P<0.05 for both) in multiple regression analysis. In conclusion, essential hypertensive non-dippers compared to dippers exhibit higher hs-CRP values, irrespective of the dipping status definition. Furthermore, ambulatory PP and nocturnal systolic BP fall interrelate and participate in the inflammatory processes that accompany non-dipping state.     

Prognostic significance of ambulatory blood pressure.

Measurements of ambulatory blood pressure as an adjunct to casual/clinic blood pressure measurements are currently widely used for the diagnosis and treatment of hypertension. There have been many recent reports on the clinical significance of ambulatory blood pressure. The relationship between ambulatory blood pressure level and target-organ damage uniformly demonstrated on a cross-sectional basis that average ambulatory blood pressure is correlated to target-organ damage. The main limitation of cross-sectional studies, however, is the difficulty of drawing inferences about causality from them. We have been monitoring the prognosis of the Ohasama population and reported that ambulatory blood pressure is superior to casual blood pressure for the prediction of mortality. We also observed that the daytime ambulatory blood pressure is a better predictor for cardiovascular mortality in the general population than is the night-time ambulatory blood pressure. It is widely recognized that casual/clinic blood pressure is less representative of the true blood pressure level than is average ambulatory blood pressure. One reason that clinic blood pressure is a poor predictor of prognosis is that clinic blood pressure includes several biases, including the white-coat effect. For determining white-coat hypertension, measurement of blood pressure in a non-medical setting such as ambulatory blood pressure monitoring is indispensable. We examined the prognostic significance for mortality of white-coat hypertension and reversed white-coat hypertension (clinic blood pressure 相似文献   

Relationship between physical activity and blood pressure in dipper and non-dipper hypertensive patients

BACKGROUND : The lack of nocturnal decline in blood pressure has been associated with an increase in end-organ damage and cardiovascular events, although results remain controversial, partly because of the inability to reproduce correctly, over time, the classification of patients into dippers and non-dippers. Moreover, the non-dipping status has been frequently related to an increase in nocturnal activity, differences in quality of sleep, or both. OBJECTIVE : To assess the relationship between activity and blood pressure in patients with hypertension. METHODS : We studied 306 mild-to-moderately hypertensive patients (130 men), 53.7 +/- 14.0 years of age (mean +/- SD). Blood pressure and heart rate were measured for 48 consecutive hours, at 20-min intervals during the day and at 30-min intervals at night, using an ambulatory device, and physical activity was simultaneously evaluated at 1-min intervals by wrist actigraphy. Circadian parameters of blood pressure, heart rate and activity established by population multiple-components analysis were compared between dippers and non-dippers, by non-parametric testing. Diurnal and nocturnal means of blood pressure and activity were computed for each patient according to individual resting hours determined by actigraphy, and compared among groups by analysis of variance. RESULTS : Despite highly statistically significant differences between dippers and non-dippers with respect to nocturnal means and in each hourly nightly mean of blood pressure, there were no differences between them for the same parameters during activity, whether or not the patients were receiving medication at the time of monitoring. The average duration of sleep and the 24-h mean and standard deviation of activity were also similar between the groups. CONCLUSIONS : The highly significantly different circadian variation in blood pressure between dippers and non-dippers with essential hypertension is not related to a significant increase in nocturnal physical activity. Differences in blood pressure could, however, be related to the absence of 24-h therapeutic coverage in most non-dipper patients receiving antihypertensive medication.     

Circadian variation of blood pressure and endothelial function in patients with essential hypertension:a comparison of dippers and non-dippers

OBJECTIVES: The purpose of this study was to evaluate the relationship between the circadian blood pressure (BP) rhythm and endothelial function in patients with essential hypertension. BACKGROUND: Hypertension is associated with alterations in resistance artery endothelial function. Patients with a non-dipper circadian pattern of BP have a greater risk of cerebrovascular and cardiovascular complications than do patients with a dipper circadian pattern. METHODS: We evaluated the forearm blood flow (FBF) response to intra-arterial acetylcholine (ACh), an endothelium-dependent vasodilator, and isosorbide dinitrate (ISDN), an endothelium-independent vasodilator, infusion in 20 patients with non-dipper hypertension and 20 age- and gender-matched patients with dipper hypertension. The FBF was measured using a mercury-filled Silastic strain-gauge plethysmograph. RESULTS: The 24-h systolic BP, as well as nocturnal systolic and diastolic BPs were higher in non-dipper patients than in dipper patients. The 24-h urinary excretion of nitrite/nitrate and cyclic guanosine monophosphate was lower in non-dippers than in dippers. The response of FBF to ACh was smaller in non-dippers than in dippers (25.1 +/- 3.1 vs. 20.2 +/- 3.0 ml/min/100 ml tissue, p < 0.05). The FBF response to ISDN was similar in dippers and non-dippers. The FBF response to ACh was similar in the two groups following intra-arterial infusion of the nitric oxide (NO) synthase inhibitor N(G)-monomethyl-L-arginine. CONCLUSIONS: These findings suggest that endothelium-dependent vasodilation is blunted through a decrease in NO release in non-dippers compared with patients who have dipper hypertension.     

Predictors of mortality in patients with type 2 diabetes with or without diabetic nephropathy: a follow-up study

OBJECTIVE: To evaluate the prognostic significance of cardiovascular risk factors including 24-h ambulatory blood pressure level and rhythm for all-cause mortality in type 2 diabetic patients. METHODS: In a prospective observational study, 104 patients with type 2 diabetes were followed: 51 patients with diabetic nephropathy and 53 patients with persistent normoalbuminuria. At baseline, 24-h ambulatory blood pressure, left ventricular hypertrophy, glomerular filtration rate and cardiac autonomic neuropathy were measured. Blood samples were taken and patients answered a World Health Organization questionnaire. Dipping was calculated as the average nocturnal reduction in systolic and diastolic blood pressure. RESULTS: Mean follow-up was 9.2 years (range 0.5-12.9). During follow-up, 54 of 104 patients died. Sixteen patients (15%) had higher blood pressure at night than during the day (reversed pattern); 14 of these patients died (88%), compared to 40 of 88 patients (45%) with reduced dipping or normal dipping; log rank P = 0.001. In a Cox regression analysis, predictors of all-cause mortality were: age, male sex, presence of left ventricular hypertrophy, glycated haemoglobin A1c (HbA1c), daytime systolic blood pressure, cardiac autonomic neuropathy, glomerular filtration rate and dipping (1% increase; hazard ratio 0.97, 95% confidence interval 0.94-0.998, P = 0.033). CONCLUSION: Type 2 diabetes patients with non-dipping of night blood pressure were at higher risk of death as compared to dippers, independent of known cardiovascular risk factors. Since non-dipping has a high prevalence in patients with diabetic nephropathy, 24-h ambulatory blood pressure should be used to assess a full risk profile and blood pressure-lowering therapy in these patients.     

Impaired diurnal blood pressure variation and all-cause mortality

BACKGROUND: Most healthy people exhibit a decrease in systolic blood pressure (SBP) at night. A drop of <10% from mean daytime values, "non-dipping," is associated with kidney disease and cardiovascular events. We hypothesized that non-dipping would predict all-cause mortality. METHODS: Consecutive patients referred for ambulatory blood pressure (BP) monitoring at the Cleveland Clinic between 1994 and 2004 were included. Mean daytime (6 AM-11 PM) and nighttime (11 PM-6 AM) SBP values were calculated. We examined diurnal BP variation as a continuous variable, ((Mean daytime SBP - Mean nighttime SBP)/(Mean daytime SBP)) x 100%, and also as a categorical variable, defining "non-dipping" as a nocturnal SBP drop of <10%; subjects who exhibited non-dipping were defined as "non-dippers" and the others as "dippers." All-cause mortality was ascertained from the Social Security Death Index. RESULTS: Of the 621 patients included in the study, 261 were dippers and 360 were non-dippers. Non-dippers were older (P < 0.0001), more likely to be non-white (P < 0.05), and had higher rates of smoking, diabetes, hypertension, coronary artery disease, congestive heart failure, and renal insufficiency (P < 0.01 for all). Over a mean follow-up of 6.3 years, 61 patients died, including 10 dippers (3.8%) and 51 non-dippers (14.2%). The unadjusted hazard ratio for death based upon a decrement in the dipping percentage from the 75th to 25th percentile was 2.22 (95% confidence interval 1.64-2.95; P < 0.0001). This was attenuated after adjustment for comorbid conditions, including mean 24-h SBP and renal function: adjusted hazard ratio 1.62 (1.14-2.24; P < 0.005). CONCLUSIONS: Blunted diurnal BP variation is a strong predictor of death, but this may be accounted for, in large part, by its association with other cardiovascular risk factors.     

Sleep actigraphy in hypertensive patients with the 'non-dipper' blood pressure profile

Several prospective studies have demonstrated a higher cardiovascular complication rate in patients with a non-dipping compared with a dipping blood pressure profile. However, the extent of blood pressure reduction during sleep can be highly variable in an individual patient, and a repeat ambulatory blood pressure study commonly shows a change in category. The reasons for this variability are not clear. In general, hypertensive patients with a non-dipper blood pressure profile have higher actigraphy-measured activity during time in bed than dipper hypertensive patients but no analysis of actigraphy-determined sleep parameters has been published. We therefore prospectively studied 52 hypertensive patients who were off antihypertensive drugs for at least 3 weeks and who underwent simultaneous ambulatory and wrist actigraphy monitoring. All patients were clinically free of any sleep-related disorder. The blood pressure profile was labelled dipper when the change in mean awake blood pressure to sleep blood pressure was 10% or higher and non-dipper if less than 10%. Overall activity levels were higher during the time in bed in the non-dipper group compared with the dipper group. An inverse relationship of daytime activity with age was seen in men (r = -0.54, P = 0.001) but not in women (r = -0.06, P = 0.79). Both groups of hypertensive patients had a similar total time in bed (458 +/- 92 min, in dippers and 433 +/- 106 min in non-dippers, P = 0.39). Sleep latency (time to onset of sleep after getting into bed) was a median of 7 min in dippers and 15 min in non-dippers (P = 0.10). In addition, dipper hypertensives spent more of the time in bed asleep than non-dippers (87% vs 76%, P = 0.004). Logistic regression analysis revealed that body mass index, kg/m(2) (OR, 1.3), and night-time activity (units/min) (OR, 1.1) were predictive of a non-dipping blood pressure profile. These data show a possible disturbance of sleep in non-dipper hypertensive patients.     

Impact of nocturnal fall in blood pressure on early cardiovascular changes in essential hypertension.

OBJECTIVE: To evaluate in a selected population of subjects with a recent diagnosis of hypertension whether a blunted nocturnal fall in blood pressure is associated with more advanced cardiac and vascular damage. METHODS: One hundred and eleven recently diagnosed and never-treated patients with mild essential hypertension underwent 24-h ambulatory blood pressure monitoring (ABPM), echocardiography and carotid ultrasonography. RESULTS: The 78 patients with normal (> 10%) night-time fall in systolic blood pressure (SBP) and diastolic blood pressure (DBP) (dippers) were similar to the 33 patients with a small (< or = 10 %) fall (non-dippers) for age, sex, body surface area, smoking habit, clinic and 24-h blood pressure. There were no differences between dippers and non-dippers in left ventricular mass index (104 versus 105 g/m2), common carotid internal diameter (5.8 versus 5.9 mm), intima-media thickness (0.66 versus 0.64 mm) and carotid plaques prevalence (25 versus 29%). Furthermore, no differences were found in the correlation of daytime and night-time SBP and DBP with left ventricular mass and carotid wall thickness. When the 77 men and 34 women were analysed separately, similar results were obtained. CONCLUSION: These results suggest that a blunted reduction in night-time blood pressure does not play a major role in the development of cardiovascular changes during the early phase of essential hypertension.     

Diurnal variation of hemodynamic indices in non-dipper hypertensive patients.

The purpose of this study was to elucidate the underlying mechanisms of blunted nocturnal blood pressure reduction in non-dipper hypertensive patients. We studied the diurnal variations in systemic hemodynamic indices and baroreflex sensitivity. In 45 subjects with essential hypertension (24 men; mean age, 49+/-1 years), intra-arterial pressure was monitored telemetrically. Non-dippers were defined as those with a nocturnal reduction of systolic blood pressure of less than 10% of daytime systolic blood pressure. Stroke volume was determined using Wesseling's pulse contour method, calibrated with indocyanine green dilution. Baroreflex sensitivity was calculated as deltapulse interval/deltasystolic blood pressure on spontaneous variations. The mean values of the hemodynamic parameters were calculated every 30 min. Twenty-six subjects were classified as non-dippers. Daytime blood pressure was not significantly different between dippers (149+/-4/87+/-3 mmHg) and non-dippers (147+/-3/82+/-2 mmHg), while the nighttime blood pressure was significantly reduced in dippers (131+/-3/77+/-2 mmHg) but not in non-dippers (145+/-3/80+/-2 mmHg). Nocturnal decreases in both cardiac index and stroke index were smaller in non-dippers (-12.0+/-1.2% and 1.5+/-1.0%) than in dippers (-17.5+/-1.4% and -2.2+/-1.1%). Baroreflex sensitivity significantly increased at nighttime both in dippers (6.5+/-0.6 to 8.0+/-0.7 ms/mmHg) and in non-dippers (5.1+/-0.3 to 6.4+/-0.4 ms/mmHg). Neither daytime nor nighttime baroreflex sensitivity was significantly different between the groups. We conclude that the hemodynamics of non-dipper essential hypertension are characterized by an inadequate nocturnal decrease in cardiac index and stroke index, suggestive of relative volume expansion or malsuppressed sympathetic activity.     

Physical activity, dipping and haemodynamics

OBJECTIVE: To determine the effect of physical activity on diurnal blood pressure (BP) and haemodynamic variation. METHODS: Ambulatory measurements were performed during 24 h in 36 subjects (18 hypertensive, 13 male), aged 49.7 +/- 13.5 years. BP was recorded in the brachial artery. Physical activity and posture were measured with five acceleration sensors. RESULTS: Of the subjects 50% were dippers (nocturnal decrease in systolic or diastolic BP >/= 10%). Dippers and non-dippers had similar daytime BP, daytime, night-time, and day-night difference in physical activity, subjective sleep quality, and nocturnal cardiac output decrease (14.9 +/- 9.6 and 16.0 +/- 5.9%). In non-dippers vascular resistance increased from day to night by 9.7 +/- 8.3%, while it remained unchanged (-1.0 +/- 13.9%) in dippers. Day-night changes in heart rate and cardiac output were correlated with day-night changes in physical activity (r = 0.39 and 0.43), whereas day-night changes in systolic BP were correlated with night-time activity (r = -0.34). By selection of the active (i.e. walking) and inactive (i.e. not walking) periods during the day, we showed that physical activity has a large potential effect on dipping status and diurnal haemodynamic variation underlying BP variation. Depending on the BP taken (systolic or diastolic, respectively) the proportion of dippers increased to 81% or decreased to 25% if only the walking period was considered, whereas it decreased to 36% or increased to 53% if only the non-walking period was considered. CONCLUSIONS: Non-dippers differ from dippers by an increase of vascular resistance during the night. The degree of physical activity normally encountered during ambulatory monitoring has little influence on the diurnal BP profile or dipping status, but significantly influences underlying haemodynamics. Related to the different effects of posture and activity on systolic and diastolic BP, dipping classification may vary with the BP index taken.     

Nocturnal blood pressure decline based on different time intervals and long-term cardiovascular risk: the Ohasama Study

A diminished nocturnal decline in blood pressure (BP) represents a risk factor for cardiovascular disease. To define daytime and nighttime ambulatory BP, clock time-dependent methods are used when information on diary-based sleeping time is unavailable. We aimed to compare fixed-clock intervals with diary records to identify nocturnal BP declines as a predictor of long-term cardiovascular risk among the general population. Data were obtained from 1714 participants with no history of cardiovascular disease in Ohasama, Japan (mean age, 60.6 years; 64.9% women). We defined extreme dippers, dippers, non-dippers, and risers as nocturnal systolic BP decline ≥20%, 10–19%. 0–9%, and <0%, respectively. Over a mean follow-up period of 17.0 years, 206 cardiovascular deaths occurred. Based on diary records, multivariable-adjusted hazard ratios (HRs) for cardiovascular death compared with dippers were 1.24 (95% confidence interval [CI], 0.82–1.87) in extreme dippers, 1.21 (0.87–1.69) in non-dippers, and the highest HR of 2.31 (1.47–3.62) was observed in risers. Using a standard fixed-clock interval (daytime 09:00–21:00; nighttime 01:00–06:00), a nighttime 2 h-early shifted fixed-clock (daytime 09:00–21:00; nighttime 23:00–04:00), or a nighttime 2 h-late shifted fixed-clock (daytime 09:00–21:00; nighttime 03:00–08:00), the HR (95%CI) in risers compared with dippers was 1.57 (1.08–2.27), 2.02 (1.33–3.05), or 1.29 (0.86–1.92), respectively. Although use of diary records remains preferable, the standard and nighttime 2 h-early shifted fixed-clock intervals appear feasible for population-based studies.     

Reproducibility study of nocturnal blood pressure dipping in patients with high cardiovascular risk

It has been shown that in most people there is a physiological reduction in blood pressure during nighttime sleep, it falling by approximately 10% compared to daytime values (dippers). On the other hand, in some people, there is no nighttime reduction (non‐dippers). Various studies have found an association between being a non‐dipper and a higher risk of cardiovascular disease, but few have assessed whether the nocturnal pattern is maintained over time. From the database of the TAHPS study, data were available on 225 patients, each of whom underwent 24‐hour ambulatory blood pressure monitoring (ABPM) on four occasions over a period of 5 months. We studied the reproducibility of the nocturnal BP dipping pattern with mixed linear analysis and also calculated the concordance in the classification of patients as dippers or non‐dippers. The intraclass correlation coefficients between the different ABPM recordings were 0.482 and 0.467 for systolic and diastolic blood pressure, respectively. Two‐thirds (67%) and 70% of the patients classified, respectively, as dippers or non‐dippers based on systolic and diastolic blood pressure readings in the first ABPM recording were found to have the same classification based on the subsequent recordings. We conclude that the reproducibility of nocturnal dipping patterns and concordance of dipper vs non‐dipper status in individual patients is modest and therefore that we should be cautious about recommending treatments or interventions based on these patterns.     

Sex, cardiac hypertrophy and diurnal blood pressure variations in essential hypertension.

OBJECTIVE: To test the hypothesis of a difference between men and women in the left ventricular hypertrophic response to diurnal variations of ambulatory blood pressure in essential hypertension. DESIGN: Non-invasive ambulatory blood pressure monitoring and echocardiography in untreated hypertensive patients and healthy normotensive subjects. SETTING: Community-based ambulatory population in tertiary care centers. PATIENTS: Two hundred and sixty hypertensive patients and sixty-three healthy normotensive subjects. MAIN OUTCOME MEASURE: Patients with average daytime systolic blood pressure (SBP) and diastolic blood pressure (DBP) falling by less than 10% during the night were defined as non-dippers, the others as dippers. RESULTS: In the hypertensive group, dippers and non-dippers did not differ, in either gender, in several covariates possibly affecting left ventricular structure, including daytime ambulatory blood pressure, prevalence of white coat hypertension, age, body mass index, family history and known duration of hypertension, funduscopic changes, diabetes, alcohol consumption and renal function. Left ventricular mass (LVM) did not differ between dippers and non-dippers in hypertensive men whilst in hypertensive women it was significantly lower in dippers than in non-dippers. This sex difference held for all quartiles of the distribution of mean daytime blood pressure. In hypertensive women there was an inverse correlation between LVM and the per cent reduction of SBP and DBP from day to night, but this relationship was absent in hypertensive men. Other indices of left ventricular structure differed between dippers and non-dippers in both genders, as did LVM. CONCLUSIONS: For any level of daytime ambulatory blood pressure, a reduction of SBP and DBP by less than 10% from day to night identifies a subset of hypertensive patients at increased risk of left ventricular hypertrophy only in the female gender. These data suggest that, compared with men, hypertensive women require a longer duration of exposure to high blood pressure levels during the 24 h to develop left ventricular hypertrophy.     

Blood pressure rhythm and prevalence of vascular events in hypertensive subjects

OBJECTIVES: To evaluate the influence of age on the day-night blood pressure rhythm and on the prevalence of vascular events in those whose systolic blood pressure (SBP) fell by <10% overnight (non-dippers). DESIGN: Cross-sectional observational cohort study. SETTING: Outpatient hypertension clinic. PARTICIPANTS: 419 Hypertensive patients (214 male, 205 female). METHODS: All subjects were submitted to ambulatory blood pressure monitoring (Spacelabs 90207). The nocturnal fall of SBP was calculated from (day SBP--night SBP)/day SBP, where 'day' values were recorded between 0600 h and 2200 h and 'night' values between 2200 h and 0600 h. Dippers and non-dippers were divided in two subgroups according to age (under or over 65 years). Information on gender, smoking, diabetes mellitus and body mass index was collected and cerebrovascular and cardiovascular events, evaluated by history and medical records, were registered. RESULTS: The day-night difference in blood pressure significantly decreased with age and the prevalence of non-dippers was greater in elderly than in younger subjects (65.1% vs. 29.8%). No difference was found between groups for cerebrovascular events, irrespective of age. A relationship between non-dipping pattern and cardiovascular events was found only in younger hypertensive non-dippers (odds ratio, 2.0; 95% confidence interval, 1.20-3.21); in elderly people the prevalence of cardiovascular events was similar in dippers and non-dippers. CONCLUSIONS: Cardiovascular risk is not increased in elderly non-dipper hypertensive subjects. This contrasts with results in younger populations.     

Electronic activity-monitor-derived sleeping and awake times and diurnal variation of blood pressure

BACKGROUND: Results of a number of studies have indicated that target-organ damage is more pronounced in non-dippers, those in whom the blood pressure falls by less than 10% with the onset of sleep, than it is in dippers with comparable clinic blood pressures. However, the standard use of arbitrarily defined daytime and night-time periods, rather than precise estimates of sleeping time and awake time, could limit the accuracy of estimates of diurnal variation of blood pressure and hence of dipping status. DESIGN AND METHODS: In this study of 102 consecutive patients undergoing ambulatory blood pressure monitoring we compared activity-derived estimates of sleeping and awake blood pressures using electronic activity monitoring and diary records with estimates determined using pre-defined day and night-time periods. The dipping/non-dipping status of each subject was assessed using these three different techniques for defining the awake/asleep time periods. RESULTS: The sleeping/awake times based on the activity monitor, diary and default data were 2356 h+/-55 min/0754 h+/-50 min, 2326 h+/-61 min/0722 h+/-72 min and 2300 h and 0700 h respectively. The percentage systolic/diastolic falls in blood pressure were 18+/-6/18+/-7% with six non-dippers (activity-monitor-derived data), 16+/-6/17+/-8% and 12 non-dippers (diary data) and 13+/-7/15+/-7% and 21 non-dippers (using the pre-set daytime and night-time periods). DISCUSSION: Results of this study demonstrate that the extent of the diurnal variation in blood pressure (and hence dipping status) can differ depending on the technique used to define periods of wakefulness and sleep.     

Diurnal blood pressure variations and silent cerebrovascular damage in elderly patients with hypertension.

OBJECTIVE: To examine the effect of diurnal blood pressure changes upon cerebrovascular damage in elderly patients with hypertension. DESIGN: Fifty-four asymptomatic hypertensive and 34 normotensive elderly subjects underwent both 24-h non-invasive ambulatory blood pressure monitoring and brain magnetic resonance imaging. METHODS. Diurnal variation was defined as a difference of greater than or equal to 10 mmHg between mean awake and asleep systolic blood pressure. Hypertensives were thus classified as dippers or non-dippers. Low intense foci (lacunae) and advanced periventricular hyperintensity were identified as silent cerebrovascular damage. RESULTS: In the hypertensive group, lacunae were correlated more closely with mean asleep systolic blood pressure than with mean awake systolic blood pressure. Age, awake blood pressure, predicted whole blood viscosity, lipid profiles or quantity of sleep did not differ between the hypertensive dippers or non-dippers. The non-dippers, however, showed significantly higher grades of cerebrovascular damage as well as cardiac hypertrophy by electrocardiography than the dippers, whose results were similar to those of normotensives in this regard. CONCLUSIONS: An absent or lower nocturnal blood pressure fall in elderly hypertensives is associated with silent cerebrovascular damage. In contrast, the presence of a nocturnal fall could prevent the development of hypertensive vascular damage.     

老年高血压患者夜间血压模式短期可重复性的临床研究

目的通过分析老年高血压患者动态血压监测（ABPM）夜间血压模式的可重复性，评估其在临床应用中的实际意义。方法对入住上海交通大学附属第六人民医院老年科70名老年高血压患者[男45例，女25例，年龄（83．574-5．37）岁]于4周内进行两次24hABPM，根据夜间血压下降率分为杓型（D）、非杓型（ND）、反杓型（RD）3种血压模式，把夜间下降率分别作为连续性变量和分类变量来分析血压模式的短期可重复性，并探究可重复的不同模式间的差异。结果作为连续性变量，Bland-Altman图示夜间下降率可重复性较好；作为分类变量，第2次ABPM维持原来血压模式不变的受试者共占65．7％（46／70），其中50．0％（14／28）维持原来RD，76．5％（13／17）维持原来D，76．0％（19／25）维持原来ND，kappa值为0．482。第1次ABPM为RD、D和ND在第2次ABPM转变为其他模式的分别有20．0％，5．7％和8．6％。可重复的RD（组1）、D（组2）、ND（组3）与模式变换型（组4）两两之间比较的主要临床特点无明显差异。结论老年高血压患者的夜间血压模式无论是作为分类变量还是连续变量，可重复性都尚好，且RD血压模式相比D或ND的变异性更高，因此，临床上我们不可以仅凭一次ABPM就评定患者的血压模式。本研究尚未发现可能影响血压模式重复性的因素。     

Reduced cerebral perfusion in elderly men with silent myocardial ischaemia and nocturnal blood pressure dipping

ObjectiveKnowledge about the impact of cardiovascular disease on cerebral autoregulation and cognition in aging is sparse. The aim of our study is to examine the association between cerebral blood flow (CBF), silent ST segment depression (STDE) on ambulatory ECG (LTER) and nocturnal blood pressure variations in elderly men.MethodsIn a cross-sectional cohort study “Men born in 1914”, eighty 83-year-old men were examined by CBF, LTER and ambulatory blood pressure monitoring (ABPM). The presence and the degree of STDE were analyzed in relation to regional CBF in nocturnal blood pressure dippers/non-dippers.ResultsFourty-five (56%) study subjects had STDE, 25 at both day and night and 20 only daytime. Subjects with STDE expressed lower CBF in left frontal, temporal, inferior parietal regions and bilateral superior parietal regions compared to men without STDE. Low regional CBF was most frequent in subjects with daytime STDE. Subjects with nocturnal diastolic blood pressure dip and STDE (22 subjects; 35%) had lower mean CBF in the parietal lobe and also correlation between STDE and CBF (r = 0.31–0.44, p = 0.056–0.006) compared to non-dippers with STDE. The lowest CBF in nocturnal dippers was observed in subjects with maximal STDE daytime.ConclusionSilent myocardial ischemia may contribute to cerebrovascular disease in non-demented elderly men. Cerebral perfusion seems to be most vulnerable to myocardial ischemia in elderly with nocturnal blood pressure dipping.