Changes In Ambulatory Blood Pressure Research Articles

A longitudinal study of job strain and ambulatory blood pressure: results from a three-year follow-up.

This study was conducted to investigate the hypothesis that exposure to "job strain" is related to increased ambulatory blood pressure (ABP). Participants were 195 men who wore an ABP monitor for 24 hours on two occasions 3 years apart. Job strain status, evaluated at each assessment, was used to identify four groups: those not having job strain at either assessment (N = 138), those having job strain at both times (N = 15), and two crossover groups. Regression analysis was used to examine the cross-sectional associations of ABP with job strain, controlling for other known risk factors. Repeated-measures analysis of variance was used to examine the association of ABP change with the category of job strain change. The cross-sectional analysis of the Time 2 data yielded almost identical, highly significant effects of job strain on ABP as was shown in our previously published Time 1 analysis. Those in high strain jobs at both times had systolic/diastolic ABPs at work and at home that were, on average, 11/7 mm Hg higher than those with no job strain at both times; the crossover groups had intermediate levels of ABP. The longitudinal analysis showed that those with a high strain job at Time 1, but not at Time 2, had a significant decrease in work and home ABP of approximately 5/3 mm Hg. The previously reported cross-sectional association between job strain and ABP was replicated at follow-up. The group repeatedly exposed to job strain had higher levels of ABP at Time 2 than either crossover group. Furthermore, change in job strain status partially predicted change in ABP. These results provide new evidence supporting the hypothesis that job strain is an occupational risk factor in the etiology of essential hypertension.

Reply to Editorial

We agree with Professor Bulpitt (1) that if a study on antihypertensive treatment is not placebo controlled, clinic blood pressure and side-effect data have a limited scientific value. For this reason, we reported them briefly (to characterize our population by a commonly used set of values) and focused on ambulatory blood pressure measurements (2), which we thought were scientifically valid because (a) the number of patients in whom ambulatory blood pressure monitoring could be performed was rather large; (b) patients' age extended to the so-called "old-elderly" range, in which information on ambulatory blood pressure changes during antihypertensive treatment is still limited; and (c) ambulatory blood pressure is substantially devoid of a placebo effect. On this crucial third point, we disagree with Professor Bulpitt's considerations. There is now a large body of evidence that, unlike clinic blood pressure, 24-h, daytime, and nighttime average blood pressures are not significantly less when placebo is administered for weeks or months (3,4). It is also clear that the data from Staessen et al. (5) should not be interpreted as at variance with these results. One, in the study by Staessen et al. (5), the "placebo" patients showed a reduction in 24-h average systolic blood pressure that was not only small (2.4 mm Hg) but also about a third the concomitant reduction in clinic systolic blood pressure (6.6 mm Hg). Two, whereas in the placebo group, clinic diastolic blood pressure was significantly reduced (1.4 mm Hg), ambulatory diastolic blood pressure was not. Three, and most important, in the study by Staessen et al. (5) statistically significant blood pressure reductions were seen only after administration of placebo for 1 year. This makes the results somewhat irrelevant for antihypertensive drug studies, in which only short- or medium-term placebo administration is ethically acceptable. It also makes interpretation of the data difficult because it is conceivable that in elderly patients with systolic hypertension [i.e., the patients involved in the study by Staessen et al. (5)], a small long-term reduction in systolic blood pressure is caused by a decline in cardiac function. We have also some reservations on Professor Bulpitt's definition of a "controlled" study. To us this does not mean that a study has to answer all or most of the important points concerning an issue, but that its design allows the results to be interpreted according to the original hypothesis, even if single and simple. For us the hypothesis was whether a combination of a low-dose thiazide and an ACE inhibitor (a treatment largely used as first line in the clinical practice) effectively reduced blood pressure over the 24 h in aged patients (i.e., in patients in whom suboptimal or undesirable blood pressure effects of treatment cannot be easily excluded). We believe our study allowed this to be obtained. It did not allow, of course, determination of the role of the combination components in the ambulatory blood pressure effect, an interesting question that would have required, as Professor Bulpitt emphasizes, a parallel design involving three groups of patients or a cross-over design on a single group of patients studied with the three different treatments.

Seasonal changes in ambulatory blood pressure in employees under different indoor temperatures.

The effect of indoor temperature control on summer and winter ambulatory blood pressure levels at work was studied. Ambulatory systolic blood pressure (SBP) and diastolic blood pressure (DBP) were monitored once in summer and once in winter in 101 healthy normotensive subjects aged 28-63 years, engaged in similar physical work, from two plants with and three without air conditioning. Subjects were interviewed about health related habits, and measurements of environmental and occupational conditions were obtained. After controlling for possible confounders, mean SBP and DBP during work were significantly higher in winter than in summer (delta SBP = 3.4 mm Hg, P = 0.035; delta DBP = 3.3 mm Hg, P < 0.003). The seasonal change in SBP and DBP showed an independent association with the presence or absence of air conditioning of the industrial plants (SBP: beta = 0.194, P < 0.0001; DBP: beta = 0.054, P = 0.038). The percentage of subjects with increases of more than 10 mm Hg from summer to winter was higher in plants without than with air conditioning. (1) In normotensive subjects ambulatory working BP varies by season, with higher values in winter. If validated for hypertensive subjects, it may be necessary to tailor drug treatment to these variations. (2) The findings make it clear that drawing valid conclusions from comparisons of BPs between groups requires controlling for several factors, particularly season of the year. (3) Climatic conditions in the industrial plant influence the magnitude of seasonal variations in BP. Work in plants without air conditioning places a considerable added load on the employee's cardiovascular system.

Effects of amlodipine on 24-hour ambulatory blood pressure profiles, electrocardiographic monitoring, and left ventricular mass and function in black patients with very severe hypertension.

In a 3-month, open-label study, 54 consecutive black patients with very severe hypertension were treated with amlodipine. Very severe hypertension was defined as an average sitting diastolic blood pressure (BP) > or = 115 mmHg and < or = 140 mmHg as a mean of 10 readings over a 30-minute period using an automatic BP measuring device and a mean 24-hour diastolic ambulatory blood pressure (ABP) > or = 110 mmHg and < or = 140 mmHg). Serial changes in 24-hour ABP and electrocardiographic monitoring, left ventricular (LV) mass index, and LV systolic function were evaluated. Mean 24-hour ABP was reduced from 181 +/- 14/119 +/- 6 to 140 +/- 15/92 +/- 9 mmHg at 3 months (P < 0.0001). Target BP (mean 24-hour diastolic ABP < 90 mmHg) was achieved in 35% of the patients. The reduction in BP was sustained for 24 hours after drug administration. Simultaneous BP measurements using the automatic BP measuring device were significantly different from the ABP measurements before and after treatment, suggesting a marked "white coat" pressor effect. At baseline, frequent or complex ventricular arrhythmias (> 30 ventricular extrasystoles per hour, ventricular couplets) were present in 2 (4%) patients, with no significant change after treatment. Left ventricular mass index regressed from 140 +/- 50 to 111 +/- 30 g/m2 at 3 months (P < 0.03); LV performance was not adversely affected. Adverse effects were few and tended to disappear during the treatment period. All of the clinical laboratory parameters tested remained unchanged. In this group of patients, treatment with amlodipine showed a marked and sustained antihypertensive action as demonstrated by 24-hour ABP monitoring, and was well tolerated and associated with LV mass regression without adverse effect on systolic cardiac function. Further, a low rate of complex ventricular arrhythmias was documented.

Ambulatory blood pressure in patients with occult recurrent coarctation of the aorta.

The hypothesis that mild recurrent aortic obstruction produces subtle changes in ambulatory blood pressure was investigated by performing 24-hour monitoring on 11 postoperative coarctation patients. Patients (age 16.1 +/- 2.7 years) were compared with normal controls (age 15.7 +/- 2.5 years, n = 15). Surgery (end-to-end anastomosis) was performed at 6.0 +/- 1.0 years of age. There were no significant differences between patients and controls in terms of baseline blood pressure (right arm 123/78 +/- 4/3 mmHg versus 120/75 +/- 3/2 mmHg) or right leg systolic pressure (125 +/- 6 mmHg versus 123 +/- 4 mmHg). Of the 11 patients 8 had recoarctation by Doppler study (mean gradient 25.3 +/- 2.1 mmHg), 5 of 11 had a postexercise arm-leg pressure difference of > 30 mmHg, and 6 patients had aortic diameters at the site of surgery < 70% of the descending aortic diameter (by magnetic resonance imaging). There were no significant differences between the coarctation and control groups in terms of mean ambulatory systolic (125 +/- 3 mmHg versus 119 +/- 2 mmHg) or diastolic (69 +/- 2 mmHg versus 72 +/- 2 mmHg) pressures throughout the day. However, coarctation patients had a larger number of systolic pressures that exceeded the 95th percentile (18.2 +/- 5.6% versus 6.8 +/- 1.2%). These labile increases in systolic pressure correlated with residual coarctation (r = 0.642, p = 0.003). Ambulatory monitoring is a useful tool for detecting and monitoring subtle abnormalities of blood pressure control after coarctation repair.

Test-retest reliability of 24-hour ambulatory blood pressures

The test-retest reliability of 24-hour ambulatory blood pressures (ABP) was examined using correlational analyses as well as idiographic and nomothetic time-series regression analyses. Thirty normotensives (equal males and females) underwent ABP monitoring on three occasions, each of which was separated by a week. When analyzing the data, various postural positions, activities, and locations were controlled for in order to differentially assess the effects of these variables independently. Correlational analyses found the overall test-retest reliability of the ABPs to be quite good (SBP r = .84-.88, DBP r = .83-.86, HR r = .91-.95). Correlations examined within specific postural positions, activities, and locations were also significant. The time-series regression analyses used confirmed the reproducibility of the ABPs, with no greater than 20% of the subjects showing significant changes in ABPs over the three monitoring periods. Gender effects were also examined. In general, males had significantly higher systolic ABPs overall, although there was no influence of gender in terms of the test-retest reliability of the ABPs.

Ambulatory Blood Pressure Changes and Effect on Cerebral Perfusion in Amlodipine Treated Elderly Hypertensives

Ambulatory Blood Pressure Changes and Effect on Cerebral Perfusion in Amlodipine Treated Elderly Hypertensives

Ambulatory Blood Pressure Changes in the Menstrual Cycle of Hypertensive Women Significance of Plasma Renin Activity Values

Blood pressure (BP) changes during the menstrual cycle (MC) have not been studied in hypertensive women in relationship to changes in sex hormone levels and plasma renin activity (PRA). We therefore carried out 24 h ambulatory BP recordings and hormonal measurements in 34 hypertensive and 27 matched normotensive women during the follicular ovulatory and luteal phases of the menstrual cycle. Plasma renin activity was similar in the two groups and rose significantly during the luteal phase only in the hypertensives (P < .01). There were no differences in plasma estradiol or progesterone between the normotensives and hypertensives, but testosterone was higher in the hypertensives during the ovulatory (P < .01) and luteal (P < .001) phases. Blood pressure did not change in the normotensives throughout the cycle, but it increased in the hypertensives during ovulation (P < .01). When patients were divided according to mean menstrual cycle PRA, only those with relatively low PRA (< 2 ng/mL/h) had a significant BP rise during ovulation and it primarily occurred at night (P < .05). The results demonstrate that premenopausal hypertensive women have increased testosterone during ovulation and increased testosterone and PRA during the luteal phase of the cycle. Like normotensives, hypertensives with relatively high PRA exhibit no change in BP during the cycle, whereas those with relatively low PRA have a nighttime increase in BP during ovulation.

Relation of regression of left ventricular hypertrophy to changes in ambulatory blood pressure after long-term therapy with perindopril versus nifedipine

Casual as well as ambulatory 24-hour blood pressure (BP) and echocardiographic parameters were studied in 40 patients with untreated or insufficiently treated mild to moderate essential hypertension. Left ventricular (LV) hypertrophy was assessed before and after 24 weeks of therapy with either the converting enzyme inhibitor perindopril or the calcium antagonist nifedipine. The design was a double-blind parallel study with a placebo run-in period. Patients received a daily oral dosage of either 4 to 8 mg of perindopril or 40 to 80 mg of nifedipine in slow-release form. A diuretic (25 mg/day of hydrochlorothiazide) was added in nonresponders (>90 mm Hg casual diastolic BP). Once-daily perindopril and twice-daily nifedipine comparably reduced both casual and ambulatory BP throughout 24 hours (p <0.01) without affecting 24-hour heart rate. Six subjects withdrew from the nifedipine group and 4 from the perindopril group. After 12 and 24 weeks of therapy, LV hypertrophy was significantly reduced by both agents. Before active treatment was begun, LV mass index was more closely correlated to 24-hour (p <0.001) than to casual BP. This correlation disappeared after treatment with both agents. The correlation between ambulatory systolic daytime BP and LV mass was only still present (r = 0.54; p <0.05) after 24 weeks of treatment with nifedipine. It is concluded that regression of LV hypertrophy during converting enzyme inhibition or calcium antagonism may be partly independent of dosage and magnitude of 24-hour BP decrease.