Sleep disturbance during ambulatory blood pressure monitoring of hypertensive patients

BACKGROUND: Hypertensive patients who fail to exhibit a normal fall in blood pressure at night may have a greater risk of target-organ damage. Sleep, with associated cessation of physical activity, is the principal determinant of nocturnal blood pressure 'dip'. OBJECTIVE: To ascertain whether hypertensive patients, who experience the discomfort of higher cuff-inflation pressures during ambulatory blood pressure monitoring, experience more interference with sleep, manifested by greater nocturnal physical activity. DESIGN: A retrospective case- control study. METHODS: Subjects were selected from a database of 475 patients who had undergone simultaneous 24 h ambulatory blood pressure monitoring and monitoring of physical activity with a wrist-mounted piezoelectric accelerometer. Sixty-one hypertensives (average daytime systolic blood pressure >/= 150 mmHg) were age matched to 61 subjects with average daytime systolic blood pressures 相似文献   

Automated blood pressure determination during exercise test. Clinical evaluation of a new automated device.

The accuracy and reproducibility of a new automatic device (P) specially designed for noninvasive blood pressure monitoring during the exercise stress test were evaluated in 50 consecutive subjects (34 normotensives and 16 hypertensives). Automatic measurements were compared with those taken by a sphygmomanometer (RR). A good agreement between systolic pressure values obtained by the two methods was found (RR 159 +/- 30 mmHg, P 158 +/- 28 mmHg, mean difference = -1.53 +/- 13 mmHg, p = 0.166, ns). On the contrary the new device significantly underestimated diastolic pressure values (RR 89.3 +/- 13 mmHg; P 84 +/- 13 mmHg, mean difference -5.37 +/- 9.3, p < 0.001). In conclusion the new device seems able to measure systolic but underestimates diastolic blood pressure both in hypertensives and in normotensives during the effort test.     

Atrial natriuretic peptide and 24 h blood pressure

BACKGROUND: Atrial natriuretic peptide (ANP) is a hormone involved in the cardiovascular modulation of blood pressure and volume homeostasis. OBJECTIVE: To compare ANP levels in normotensives and hypertensives and to correlate ANP levels with ambulatory blood pressure parameters. METHODS: Plasma samples for ANP determination (using a double-antibody radioimmunoassay Kit) were obtained from 33 consecutive subjects (24 hypertensives, nine normotensives) who had rested supine for 30 min. Afterwards, all of the subjects were subjected to 24 h non-invasive blood pressure monitoring. We found no significant difference between the two groups with regard to ANP levels (95.1+/-29 versus 96.9+/-33 pg/ml, in normotensives and hypertensives, respectively). Also, when hypertensive patients were divided according to their family history of hypertension, ANP levels were similar. There was no correlation between the ANP level and the pre-sampling blood pressure or between the ANP level and the following ambulatory blood pressure monitoring parameters: 24 h, diurnal and nocturnal systolic and diastolic blood pressures, systolic and diastolic loads, nocturnal blood pressure reduction and blood pressure variation coefficients. CONCLUSION: Both the pre-sampling blood pressure and ambulatory monitoring results (sustained blood pressures and pressure variations during the 24 h period) do not seem to influence basal ANP levels in patients with hypertension. These data do not account for a role of this peptide in cardiovascular control, in hypertension.     

The Role of Ambulatory Blood Pressure Monitoring in the Evaluation of Adolescent Hypertension

We performed 24-hour ambulatory blood pressure monitoring in a group of adolescents with hypertension induced by dynamic exercise and a group of normotensive controls. Ambulatory blood pressure monitoring was performed using a Del-Mar Avionics PIII recorder with readings taken every 7 1/2 minutes. There was little inter-individual variation in mean hourly blood pressure and the difference between mean hourly readings was not significant in hypertensives. Mean 24-hour ambulatory blood pressure was 130.2/80.7 mmHg for hypertensives and 115.2/70.8 in normotensives. Mean 24-hour variability was 18.3/12.9 mmHg in hypertensives and 14.6/11.5 in normotensives. There was no significant change in blood pressure or variability between daytime and evening for hypertensives. Normotensives showed a significant reduction in both BP and variability compared to hypertensives. In adolescents with systolic hypertension, ambulatory blood pressure monitoring confirmed a failure to reduce blood pressure following routine activity. This technique maybe used as a predictive marker of early, adult essential hypertension.     

Twenty-four hour ambulatory blood pressure in a population of elderly men

OBJECTIVES: The principal aim was to study ambulatory and office blood pressure in a population of elderly men. We also wanted to describe the prevalence of hypertension and investigate the blood pressure control in treated elderly hypertensives. DESIGN: A cross-sectional study of a population of elderly men, conducted between 1991 and 1995. SUBJECTS: Seventy-year-old men (n = 1060), participants of a cohort study that began in 1970. MAIN OUTCOME MEASURES: Office and 24 h ambulatory blood pressure. RESULTS: Average 24 h blood pressure in the population was 133 +/- 16/75 +/- 8 mmHg, and daytime blood pressure 140 +/- 16/80 +/- 9 mmHg. Corresponding values in untreated subjects (n = 685) were 131 +/- 16/74 +/- 7 and 139 +/- 16/79 +/- 8, respectively. An office recording of 140/90 mmHg corresponded to an ambulatory pressure of 130/78 (24 h) and 137/83 mmHg (daytime) in untreated subjects. In subjects identified as normotensives according to office blood pressure (n = 270), the 95th percentiles of average 24 h and daytime blood pressures were 142/80 and 153/85 mmHg, respectively. The prevalence of hypertension, defined as office blood pressure greater than or = 140/90 mmHg, was 66%. Despite treatment, treated hypertensives (n = 285) showed higher office (157/89 vs. 127/76 mmHg) and 24 h ambulatory (138/78 vs. 122/71 mmHg) pressures than normotensives (P < 0.05). Fourteen per cent of the treated hypertensives had an office blood pressure < 140/90 mmHg. CONCLUSIONS: Our results provide a basis for 24 h ambulatory blood pressure reference values in elderly men. The study confirms previous findings of a high prevalence of hypertension at older age. It also indicates that blood pressure is inadequately controlled in elderly treated hypertensives.     

Blood pressure on arising, morning blood pressure surge and blood pressure variability in white coat hypertensives and in matched normotensives and sustained hypertensives.

INTRODUCTION: It is still controversial whether subjects with white-coat hypertension (WCHT) exhibit higher cardiovascular risk compared to normotensive subjects (NT). In subjects with WCHT it is not known whether the abnormal blood pressure (BP) reaction in the office also occurs at other times of day, particularly on arising and immediately after waking, i.e. the times at which the majority of cardiovascular events are reported to occur. OBJECTIVE AND METHODS: To evaluate with 24h ambulatory BP measurement the values of morning BP surge, BP on arising and BP variability in subjects with WCHT in comparison with age-, gender- and weight-matched normotensives (BP) and untreated sustained hypertensives (BP). RESULTS: Groups of BP, WCHT and BP were matched for age, gender and body weight: BP: n=69, age 49 +/- 7 years, 54 % female, BMI 26 +/- 1, casual BP 126/79 +/- 5/4 mmHg, daytime BP 124/80 +/- 6/6 mmHg; WCHT: n=74, age 52 +/- 8 years, 57% female, BMI 26 +/- 2, casual BP 152/95 +/- 7/7 mmHg, daytime BP 126/80 +/- 5/6 mmHg; HT: n=79, age 53 +/- 7 years, 56% female, BMI 27 +/- 2, casual BP 154/97 +/- 9/8 mmHg, daytime BP 143/89 +/- 12/10 mmHg. Of the three groups, subjects with WCHT exhibited BP on arising (121/81 +/- 13/8 mmHg) similar to that of NTs (120/80 +/- 13/9 mmHg, NS), both significantly lower than that of HTs (137/92 +/- 17/10 mmHg, p < 0.01), suggesting the absence of an alerting BP reaction in WCHT at that time. By contrast, subjects with WCHT showed higher values of systolic morning BP surge vs. NTs (25 +/- 10 vs. 22 +/- 11 mmHg, p < 0.05), both lower than that observed in hypertensives (33 +/- 11 mmHg, p < 0.01 vs. NT and WCHT) and greater daytime variability (systolic BP standard variation), i.e. 12 2 vs. 10 +/- 2 mmHg, p < 0.05, both lower than that observed in hypertensives (14 +/- 3 mmHg, p < 0.01 vs. NT and WCHT). CONCLUSIONS: Although subjects with WCHT did not show any alerting blood pressure reaction on arising, morning BP surge and BP variability were greater in these subjects than in control normotensives, although lower than sustained hypertensives. Although this is still speculative, we cannot exclude the possibility that even a slight increase in morning BP surge might in the long term constitute an additional load on the circulation that could increase cardiovascular risk in subjects with WCHT compared to matched normotensives.     

Effects of exercise, diet and their combination on blood pressure

Epidemiological studies suggest an inverse relationship between physical activity or fitness and blood pressure. In a meta-analysis of 44 randomized controlled intervention trials, the weighted net change in conventional systolic/diastolic blood pressure in response to dynamic aerobic training averaged -3.4/-2.4 mmHg (P < 0.001). The effect on blood pressure was more pronounced in hypertensives than in normotensives. This type of training also lowered the blood pressure measured during ambulatory monitoring and during exercise. However, exercise appears to be less effective than diet in lowering blood pressure (P < 0.02), and adding exercise to diet does not seem to further reduce blood pressure.     

How good are standardized blood pressure recordings for diagnosing hypertension? A comparison between office and ambulatory blood pressure.

Ambulatory blood pressure monitoring was compared with office blood pressure in 48 normotensive, 81 borderline hypertensives and 35 untreated hypertensives. The studied groups were chosen from a geographically defined population of middle-aged men in southern Sweden. The mean 24-h ambulatory blood pressure values for the normotensives, borderline hypertensives and untreated hypertensives were 120/76, 127/82 and 140/92 mmHg, respectively. The diurnal mean ambulatory blood pressure in the three groups was 126/80, 134/86 and 146/96 mmHg, respectively. The percentage of 24-h diastolic blood pressure peaks greater than or equal to 95 mmHg in the groups were 7%, 22% and 53%, respectively. The corresponding values greater than or equal to 90 mmHg were 16%, 38% and 69%, respectively. In the untreated hypertensive group, there was a more pronounced (P less than 0.05) systolic blood pressure increase during the morning hours (0600-1000 h) than in the normotensive and borderline hypertensive groups. Fourteen per cent of the hypertensives showed normal blood pressure values during 24-h blood pressure monitoring. Fifteen per cent of the borderline hypertensives were normotensive during ambulatory blood pressure monitoring despite repeated office diastolic blood pressure greater than or equal to 90 mmHg. The opposite (increased blood pressure during ambulatory blood pressure monitoring and at screening but normal office blood pressure) was seen in 14% of the borderline hypertensives. Normotensives were characterized by lower mean blood pressure values, fewer blood pressure peaks and a lower systolic blood pressure increase during the morning hours than hypertensives in this study of middle-aged men. The established way of diagnosing hypertension, borderline hypertension and normotension correlated well with the results of ambulatory blood pressure monitoring.     

Evaluation of antihypertensive therapy by ambulatory blood pressure monitoring and establishment of the level of antihypertensive goal on the circadian rhythm of blood pressure

We have developed a new method for the evaluation of antihypertensive therapy on the circadian rhythm of blood pressure and attempted to determine the indications for antihypertensive therapy and the level of antihypertensive goal. Blood pressures were measured for 24 hours by the use of ambulatory blood pressure monitoring using 630 (ABPM-630) in 50 normotensives, 50 untreated hypertensives and 50 hypertensives undertreatment with various antihypertensive drugs (110 males and 40 females, with a mean age of 53.4 +/- 13.3 yrs). Blood pressure profiles were prepared for determination of the hyperbaric and hypobaric indexes. According to the WHO's definitions for blood pressure, the hyperbaric index was defined as the area above 140 mmHg in systolic blood pressure or 90 mmHg in diastolic blood pressure, and the hypobaric index, as the area below 100 mmHg or 60 mmHg, respectively. The criteria of the hypobaric index was obtained from the mean basal blood pressure (the lowest blood pressure during sleep) of the 50 normotensives. The mean hyperbaric index of the 50 normotensives was 20.4 +/- 40.2/5.5 +/- 15.3 (systole/diastole) mmHg.hour/day and the mean hypobaric index, 12.2 +/- 22.5/9.0 +/- 24.0 mmHg.hour/day. The 50 untreated hypertensives showed a mean hyperbaric index of 281.8 +/- 197.0/156.0 +/- 126.1 mmHg.hour/day and a mean hypobaric index of 0.1 +/- 0.6/0.3 +/- 1.5 mmHg.hour/day. Comparison of the indexes before and after treatment with various antihypertensives showed that a decrease in the hyperbaric index without an increase in the hypobaric index was the most optimal reduction of blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Spectral analysis of 24 h blood pressure monitoring in the assessment of trough: peak ratio. A randomized, placebo-controlled, cross-over comparison of ramipril and enalapril

BACKGROUND: The ratio between the magnitude of blood pressure reduction during the steady-state dosage interval (trough) and the maximum blood pressure reduction (peak) is an integrated in-vivo index both of the pharmacokinetic properties and of pharmacodynamic activity of an antihypertensive drug. Angiotensin converting enzyme inhibitors are often characterized by a low (often lower than 50%) trough: peak ratio but no direct drug comparisons are available. OBJECTIVE: To compare the absolute blood pressure reduction and the trough: peak ratio of daily doses of two angiotensin converting enzyme inhibitors, 5 mg ramipril and 10 mg enalapril. METHOD: After a 1-month wash-out and a 2-week placebo run-in, 25 mild hypertensives aged 47 +/- 4 years (17 men and eight women) were randomly assigned to treatments separated by a 2-week interval. Ambulatory blood pressure monitoring was performed and trough: peak ratio was calculated by the fast Fourier transform analysis of placebo-effect-subtracted data. RESULTS: After 1 month of ramipril treatment, 24 h blood pressure decreased from 139 +/- 10 to 129 +/- 11 mmHg for systolic (P < 0.05) and from 89 +/- 8 to 81 +/- 5 mmHg for diastolic blood pressure (P < 0.01). Also enalapril treatment caused a significant 24 h reduction in blood pressure both for systolic (to 132 +/- 7 mmHg, P < 0.05) and for diastolic blood pressure (to 84 +/- 5 mmHg, P < 0.05). Placebo caused a 24 h reduction in blood pressure (to 136 +/- 8 mmHg for systolic and 87 +/- 5 mmHg for diastolic blood pressure, NS, versus wash-out period). The two drugs were equally effective in reducing ambulatory blood pressure, but ramipril produced a trough: peak ratio significantly higher than that with enalapril both for systolic (48 +/- 11%, range 34-74%, versus 38 +/- 11%, range 21-67%, P < 0.005)and for diastolic blood pressure (47 +/- 11%, range 30-79 %, versus 37 +/- 12%, range 21-68%, P < 0.05). CONCLUSION: The low trough : peak ratios could have been due to the daily pattern of blood pressure of mild hypertensives, many of whom are normotensives at night-time, so that the main antihypertensive effect is exerted during daytime rather than during the night or early morning.     

Clinic and ambulatory heart rate in sustained and white-coat hypertension

BACKGROUND: Sustained and white-coat hypertensives show hypertension in the office setting but different blood pressure values outside the clinical environment. So far, only a few incomplete data on heart rate are available inside and outside the clinical setting in these groups of patient. The aim of this study was to evaluate clinic and ambulatory heart in sustained hypertensives, white-coat hypertensives and normotensives. METHODS: We selected 236 sustained hypertensives, 236 white-coat hypertensives and 236 normotensives matched for age, gender and body mass index, and with a similar occupation. The subjects had been submitted to clinic evaluation and the non-invasive monitoring of blood pressure and heart rate. White-coat hypertension was defined as clinic hypertension and a daytime blood pressure of less than 135/85 mmHg. RESULTS: The clinic heart rate was significantly higher in sustained hypertensives and white-coat hypertensives than in normotensives (76 +/- 11 versus 75.5 +/- 10 versus 70 +/- 9 beats/min [bpm], respectively, P < 0.05). The daytime heart rate was significantly higher in sustained hypertensives than in white-coat hypertensives and normotensives (79.4 +/- 10 versus 74.6 +/- 8.5 versus 74.5 +/- 8.5 bpm, respectively, P < 0.05), as were the night-time heart rate (67 +/- 8.5 versus 63 +/- 8 versus 63 +/- 8 bpm, respectively, P < 0.05) and 24 h heart rate (76.3 +/- 9 versus 72 +/- 7.8 versus 72 +/- 8 bpm, respectively, P < 0.05). When men and women were analyzed separately, the same trend was observed. CONCLUSIONS: The clinic heart rate is similar in sustained and white-coat hypertensives, but the ambulatory heart rate is lower in white-coat hypertensives. As ambulatory heart rate is more representative of 24 h heart rate load and may be a better indicator of the detrimental effect of heart rate, our findings suggest that white-coat hypertensives are at lower cardiovascular risk than sustained hypertensives.     

Effect of bedtime melatonin ingestion on blood pressure of normotensive subjects

OBJECTIVE: To determine whether the evening intake of 5 mg melatonin affects 24 h arterial blood pressure and heart-rate profiles. METHODS: Twenty-one young normotensive subjects were administered placebo or melatonin for 4 weeks, according to a cross-over double-blind design, and were subjected to ambulatory blood pressure monitoring on the first and last days of each treatment period. RESULTS: The chronic melatonin intake caused a decrease in systolic blood pressure throughout the 24 h period (109.1+/- 7.2 versus 113.6 +/- 8.15 mmHg, P < 0.05), a decrease in diastolic blood pressure (by 6.4 mmHg, P < 0.05) limited to the second half of the night, a slight lowering of the heart rate during the diurnal hours (78.6 +/- 7.6 versus 81.5 +/- 10.1 beats/min, P < 0.05) and an acceleration of a similar degree during the second half of the night. The slight hypotensive action and the diurnal heart-rate lowering may be explained theoretically in terms of various complex and synergistic mechanisms that so far have been verified only in experimental studies on animals. The etiology of the nocturnal heart-rate acceleration remains unknoiwn. Further controlled studies are needed in order to better understand the cardiovascular effects of melatonin and to evaluate possible pharmacologic interactions. CONCLUSION:     

Impaired endothelial and smooth muscle functions and arterial stiffness appear before puberty in obese children and are associated with elevated ambulatory blood pressure.

AIMS: To determine whether impaired brachial endothelial (flow-mediated dilation, FMD) and smooth muscle function (nitroglycerin-mediated dilation, NTGMD), and remodelling of the common carotid artery (CCA) develop before puberty in obese children. METHODS AND RESULTS: Arterial intima-media thickness (IMT), FMD and NTGMD were measured by high-resolution ultrasound in 48 obese and 23 lean pre-pubertal children (8.8 +/- 1.5 years old). We assessed central pulse pressure, incremental elastic modulus (Einc), casual and ambulatory systolic (SBP) and diastolic blood pressure (DBP), and body fatness by DXA. Obese children had significantly lower FMD (4.5 +/- 4.0 vs. 8.3 +/- 1.7%), NTGMD (19.0 +/- 9.0 vs. 25.8 +/- 6.1%), and increased Einc (13.9 +/- 5.2 vs. 10.4 +/- 5.2 mmHg/10(2)), ambulatory SBP (121.3 +/- 12.6 vs. 106.6 +/- 7.1, mmHg), and DBP (69.1 +/- 5.7 vs. 63.7 +/- 4.5) than lean subjects, whereas IMT was not augmented. Ambulatory systolic hypertension was present in 47% of obese subjects. FMD, NTGMD, and Einc were correlated with body fatness, body mass index, and blood pressure (BP). CONCLUSION: Impaired endothelial and smooth muscle functions and altered wall material develop before puberty in obese children, however remodelling of the CCA is not yet present. Arterial dysfunction may be considered as the first marker of atherosclerosis and is associated with elevated BP. Ambulatory blood pressure monitoring may be a potential tool to improve risk stratification in obese children.     

Twenty-four-hour ambulatory blood pressure monitoring in atrial fibrillation

BACKGROUND: Due to large beat-to-beat blood pressure variation the use of 24-h ambulatory blood pressure monitoring in patients with atrial fibrillation has been questioned. METHODS: Repeatability and variability of 24-h ambulatory blood pressure (Accutraccer II or Diasys Integra), and daily blood pressure variation was examined in 42 patients aged 51-81 (median 73.5) years admitted for elective electrocardioversion of atrial fibrillation. RESULTS: Before cardioversion 24-h ambulatory systolic blood pressure was slightly lower and nocturnal blood pressure reduction was larger in the group of patients who achieved sinus rhythm than in the group who maintained atrial fibrillation (11.5/10.5 versus 4.1/4.7 mmHg; P < 0.05). No statistically significant change was observed in ambulatory blood pressure after cardioversion in any of the two groups. Blood pressure variability (SD/mean) was 10-14% both in patients with and without conversion to sinus rhythm. Coefficient of repeatability (2 SD of difference) was 13.6 mmHg (16.6%) for diastolic blood pressure and 30.2 mmHg (24.7%) for systolic blood pressure in patients with normalized heart rhythm and 17.0 and 29.0 mmHg (21.5 and 22.4%) in patients with maintained atrial fibrillation, respectively. CONCLUSION: Ambulatory blood pressure monitoring provides data with similar variability and repeatability in patients with atrial fibrillation as in subjects with normal cardiac rhythm. Twenty-four-hour ambulatory blood pressure measurement is applicable in atrial fibrillation in the same way as during sinus rhythm.     

Obesity and left ventricular diastolic function: noninvasive study in normotensives and newly diagnosed never-treated hypertensives

OBJECTIVE: To evaluate the influence of obesity, per se or associated with hypertension, on left ventricular (LV) diastolic function. PATIENTS: Thirty-two obese newly-diagnosed never-treated hypertensives; 32 obese normotensives matched for age, sex and BMI with hypertensives; 32 lean newly diagnosed never-treated hypertensives and 32 lean normotensives, matched for age, sex and 24 h blood pressure (BP) with the obese subjects. METHODS: Twenty-four-hour ambulatory blood pressure monitoring and digitized M-mode LV echocardiograms. PARAMETERS EVALUATED: Twenty-four-hour, day-time and night-time BP and heart rate, percentage nocturnal BP fall; LV end-diastolic diameter index, septal and posterior wall thickness, LV mass index, peak shortening and lengthening rate of LV diameter, peak thinning rate of LV posterior wall. RESULTS: A main effect was found for obesity on LV diameter and LV mass and for hypertension on LV mass; LV systolic function was normal in all the subjects and similar among the four groups; LV diastolic function was significantly reduced in both obese groups with respect to lean ones. This difference persisted after correction of diastolic parameters for 24 h BP and heart rate, LV diameter and LV mass index and disappeared only after correction for body mass index. This latter was inversely related with diastolic parameters only in the obese groups. CONCLUSIONS: Obesity is associated with a preclinical impairment of LV diastolic function in both normotensives and hypertensives; the diastolic impairment is independent of haemodynamic factors, such as 24 h BP and heart rate, and bears no relation to LV geometry in normotensives and only little relation in hypertensives, having therefore to be ascribed to obesity itself.     

DASH diet lowers blood pressure and lipid-induced oxidative stress in obesity

Evidence suggests that obesity may raise blood pressure (BP) through oxidative stress-sensitive mechanisms and that the Dietary Approaches to Stop Hypertension combination diet (DASH-CD) may decrease BP by enhancing antioxidant capacity. To address this question, 12 obese patients with high-normal-to-stage 1 hypertension (hypertensives) and 12 lean normotensives were studied on their usual diets and after following the DASH-CD and a low-antioxidant diet in random sequence for 4 weeks each. Acute oxidative stress was induced by a 4-hour infusion of intralipid and heparin. Ferric-reducing activity of plasma (FRAP) and plasma F2-isoprostanes were measured as biomarkers of antioxidant capacity and oxidative stress, respectively. BP was lower in obese hypertensives on the DASH-CD than on the usual and low-antioxidant diets (-8.1+/-1.5/-7.4+/-1.6 mm Hg, P<0.05). BP did not change significantly in lean normotensives after 4 weeks on the DASH-CD but tended to rise on the low-antioxidant diet. FRAP on usual diets was higher in lean subjects than in obese subjects. FRAP increased in obese but not lean volunteers on the DASH-CD compared with usual diet, and the group difference disappeared. F2-isoprostanes increased from baseline during intralipid and heparin in both groups on the low-antioxidant diet but not in obese hypertensives on the DASH-CD. Among free-living obese hypertensives, the DASH-CD raises antioxidant capacity, lowers BP, and reduces oxidative stress induced by acute hyperlipidemia. The findings are consistent with evidence that elevated BP in obese subjects may reflect an imbalance between antioxidant capacity and oxidative stress that is improved by the DASH-CD.     

Limited (6-h) ambulatory blood pressure monitoring is a valid replacement for the office blood pressure by trained nurse clinician in the diagnosis of hypertension

OBJECTIVE: To assess the ability of limited ambulatory blood pressure monitoring as a valid replacement for office blood pressure measurement done to American Heart Association criteria in diagnosing hypertension. METHODS: In all, 105 adults, who had been referred for limited ambulatory blood pressure monitoring, participated in the study. Limited ambulatory blood pressure monitoring consisted of 6 h of blood pressure measurement while ambulatory at the Mayo Clinic, using a SpaceLabs 90207 (SpaceLabs Medical, Issaquah, Washington, USA) collecting six readings per hour for the period of observation. The study participants gave consent for three additional consecutive office blood pressure measurements, using a validated aneroid device, done to American Heart Association criteria, by a single hypertension nurse specialist. RESULTS: Mean systolic blood pressure by limited ambulatory blood pressure monitoring was 137.9+/-14.2 mmHg and for the nurse, 137.9+/-20.1 mmHg. Mean diastolic blood pressure by limited ambulatory blood pressure monitoring was 81.5+/-9.7 mmHg and for the nurse, 74.3+/-11.9 mmHg. The intermethod difference for systolic blood pressure was 0.03+/-12.5 mmHg and diastolic blood pressure, -7.2+/-8.0 mmHg. Using <140/90 as criteria factor, limited ambulatory blood pressure monitoring and the trained nurse agreed 77% of the time on whether the patient was hypertensive. This agreement increased to 81% if the participant's referral blood pressure was >or=140/90. CONCLUSIONS: Limited ambulatory blood pressure monitoring is an excellent replacement for office blood pressure, done to American Heart Association criteria, in diagnosing hypertension. This avoids issues of variability introduced by the observers, such as digit preference and bias, and increases reproducibility of blood pressure measurements. The appropriate normal value for limited ambulatory blood pressure monitoring is <140/90 mmHg compared with <135/85 mmHg used in 24-h ambulatory blood pressure monitoring.     

Relationship of systolic blood pressure with plasma homocysteine: importance of smoking status

BACKGROUND: Elevated plasma homocysteine is a risk factor for cardiovascular disease. Elevations in plasma homocysteine occur in both smokers and hypertensives, but the combined effect of smoking and hypertension on homocysteine is unknown. METHODS: Resting plasma homocysteine levels and blood pressure were determined in 56 normotensives (12 smokers) and 20 essential hypertensives (10 smokers). RESULTS: Plasma homocysteine was significantly higher in all smokers versus all non-smokers (9.46 +/- 0.5 versus 7.9 +/- 0.5 micromol/l, P = 0.041) by two-way ANOVA, and was also significantly higher in all hypertensives versus all normotensives (9.8 +/- 0.6 versus 7.6 +/- 0.4 micromol/l, P = 0.004). There was no interaction between the effects of hypertension and smoking on plasma homocysteine. Hypertensive smokers had significantly higher plasma homocysteine than either normotensive non-smokers (10.65 +/- 0.84 versus 7.05 +/- 0.26 micromol/l), hypertensive non-smokers (7.88 +/- 0.64 micromol/l) or normotensive smokers (8.36 +/- 0.5 micromol/l). In subjects overall, homocysteine levels were correlated (r = 0.306, P = 0.015) with systolic blood pressure but not with diastolic (r = 0.186). This relationship was also significant in smokers, but not non-smokers. Furthermore, subjects in the highest quintile for plasma homocysteine had significantly higher systolic BP than those in the lowest quintile. This effect was not observed when smokers were removed from the analysis. CONCLUSION: Smoking compounds the modest effect of hypertension on plasma homocysteine. The strong relationship between systolic blood pressure and homocysteine that exists only in smokers suggests that smoking-induced homocysteine elevations may raise systolic blood pressure. We speculate that smoking compounds the risk of cardiovascular disease in hypertensives, in part, by elevating homocysteine.     

The effect of crossing legs on blood pressure

OBJECTIVE: To determine whether crossing of the legs at the knee or at the ankles during blood pressure measurement in sitting position has an effect on blood pressure. METHODS: One hundred and eleven patients, 60 women, mean age 52+/-17 years (19-80): 49 chronically treated hypertensives, 28 treated diabetics and 34 normotensives were measured by one trained investigator, with an oscillometric device (Omron 705CP) on the left arm. We looked for the difference of blood pressure with the ankle or the knee crossed versus the uncrossed position. RESULTS: Leg crossing at the knee during blood pressure measurement increased systolic blood pressure significantly by 6.7 (95% confidence interval 5.0-8.4) mmHg in the hypertensives and 7.9 (4.0-11.8) mmHg in the treated diabetics. Diastolic blood pressure increased by 2.3 (0.8-3.8) mmHg in the hypertensives and 1.7 (0.1-3.4) mmHg for the treated diabetics. Normotensive participants showed a smaller, though significant, increase of systolic blood pressure 2.7 (1.2-4.2) mmHg, but not significant for diastolic blood pressure, -0.1 (-1.5-1.3) mmHg, respectively. In all groups there was no effect of crossing the ankles on blood pressure. No differences were found between men and women. No significant correlation between the increase of the blood pressure when the knees were crossed and BMI, age or baseline blood pressure was present. CONCLUSIONS: Blood pressure increased when legs were crossed at the knee in the sitting position. No significant increase of blood pressure was found when crossing the legs at the ankles. Leg position during measurement of blood pressure should be standardized and mentioned in publications.     

Blood pressure profile and variability in hypertensives treated with L-arginine infusion

BACKGROUND: The role of nitric oxide (NO) in regulation of systemic blood pressure both in normotensives and in hypertensives remains unknown. OBJECTIVE: To investigate the influence of L-arginine (the substrate for generation of NO) on blood pressure in 30 men (aged 51.5 +/- 7.3 years) with established primary arterial hypertension that was not well controlled. METHODS: The antihypertensive therapy was not discontinued and the patients were administered beta-blockers and calcium antagonists only. On day '0' the patients were administered 250 ml 0.9% NaCl during 180 min intravenously. Then we infused 250 mg/kg L-arginine diluted in 250 ml 0.9% NaCl over 180 min into the antecubital vein for four consecutive days (days 'I'-'IV'). Conventional blood pressure and heart rate measurementws were performed before infusion and every 30 min during infusion. Twenty-four-hour ambulatory blood pressure monitoring (with a SpaceLabs 90207 device) with half-hourly recordings during the daytime and during the night-time was performed on the day of NaCl infusion ('0') and repeated on the day of L-arginine infusion ('II') for all patients. As indicators of generation of NO, blood level of cyclic GMP and urinary concentration of nitrite/nitrate were measured. RESULTS: On all days of L-arginine infusion we found significant falls in systolic and diastolic blood pressures (P < 0.0001) with an accompanying significant increase in heart rate (P < 0.001). The most potent hypertensive effect during infusion of L-arginine was observed on day 'I'. Mean systolic blood pressure decreawsed from 152.1 +/- 20.0 mmHg to a minimum of 123.3 +/- 16.2 mmHg after 60 min of the infusion (by about 19%). The maximal percentage fall in systolic blood pressure was consecutively lower on each day oif L-arginine infusion. It was 14.3% on day 'II', 11.9% on day 'III' and 10.1% on day 'IV'. Similarly, the greatest reduction of diastolic blood pressure was observed during infusion of L-arginine on day 'I'. Mean diastolic blood pressure decreased from 95.9 +/- 13.6 to 80 +/- 9.7 mmHg after 120 min of infusion (by about 17%). On the consecutive days maximal falls in diastolic blood pressure compared with its initial value were 13.5% on day 'II', 10.4% on day 'III' and 9.8% on day 'IV'. Twenty-four-hour ambulatory blood pressure monitoring revealed a significant decrease in diastolic blood pressure during infusion of L-arginine compared with day 0 when 0.9% NaCl was infused. Systolic and diastolic blood pressure variabilities were significantly decreased and the day-night differences in systolic and diastolic blood pressures were increased after infusion of L-arginine. We found a significant correlation between heart rate and systolic blood pressure both during the daytime and during night-time on the day of infusion of L-arginine. An increase in urinary concentration of nitrite/nitrate was observed after administration of L-arginine.CONCLUSION: The present results demonstrate that infusion of L-arginine can influence the systemic blood pressure in hypertensives through NO synthesis. By using ambulatory blood pressure monitoring we documented that the hypotensive effect of L-arginine seems to be limited to the infusion period itself. A decrease in blood pressure variability might imply an increase in sensitivity of baroreceptors or an improvement of autonomic functioning.