Cardiovascular and Metabolic Activity at Rest and During Psychological and Physical Challenge in Normotensives and Subjects With Mildly Elevated Blood Pressure

Heart rate, systolic and diastolic blood pressure, and respiratory and metabolic activity were recorded prior to and during mental arithmetic and a video game task in 20 young men with mildly elevated casual systolic blood pressures. Twenty-five unambiguously normotensive young men were tested under the same protocol. For pretask baseline physiological activity, group differences emerged for all cardiovascular and metabolic variables; thus the elevated blood pressure group displayed not only higher resting cardiovascular levels than normotensive subjects, but higher levels of metabolic activity too. With regard to change in physiological activity from rest to task, the group with mildly elevated blood pressure showed reliably larger increases in heart rate to the mental arithmetic task than the normotensive subjects. These effects, however, were not paralleled by group differences in metabolic activity increase. Physiological measures were also taken prior to and during graded dynamic exercise. The subsequent calculation of individual heart rate-oxygen consumption exercise regression lines allowed the comparison of actual and predicted heart rates during psychological challenge. The subjects with mildly elevated blood pressure displayed significantly greater discrepancies between actual and predicted heart rate values than normotensives during the psychological tasks in general and menta¹ arithmetic in particular. Group differences in physiological activity during exercise largely reflected the pattern seen at rest. A possible exception here was systolic blood pressure. Not only were systolic blood pressure levels higher throughout the exercise phase for mildly elevated blood pressure subjects, but this group evidenced more of an increase from rest to exercise than the normotensives.     

Cardiovascular reactivity, Type A behavior, and coronary heart disease: Comparisons between myocardial infarction patients and controls during laboratory-induced stress

Cardiovascular responses to a series of laboratory stressors were examined in middle-aged Type A and Type B men. The subjects were 30 patients with diagnosed myocardial infarction (NYHA Class 1) and 26 age-matched healthy controls. All subjects were nonsmokers in the normotensive range, and none were on medication. Blood pressure, heart rate, forearm blood flow and resistance, and impedance cardiography-determined response variables were obtained during performance and recovery periods of both mental and physical tasks. The patients showed elevated reactivity in systolic blood pressure and cardiac output and prolonged systolic lime ratio during mental stress tasks and elevated total peripheral resistance and lower cardiac output and stroke volume during physical tasks, as compared with control subjects. Thus, the difference in blood pressure reactivity between patients and controls appeared to be primarily dependent on the vascular component during physical tasks, whereas the mental tasks promoted a hemodynamic response pattern more consistent with beta adrenergic activation. Type A men, irrespective of coronary status, showed larger systolic and diastolic blood pressure response to both mental and physical stress than did Type B men.     

Voluntary Control of Systolic Blood Pressure During Postural Change

The effects of biofeedback and voluntary control procedures on systolic blood pressure and heart rate during postural change were investigated in 30 normotensive men. Systolic pressure was measured with a continuous blood pressure tracking cuff, and blood pressure feedback was provided on a beat-to-beat basis. Postural changes in pressure, and corresponding heart rate changes, were examined in three experimental groups (N = 10 each). In two groups, subjects were given feedback training to increase or to decrease systolic blood pressure. In the third group, subjects were simply asked to increase their pressure but were not given feedback about their performance. Voluntary control of systolic pressure was attempted while subjects were seated and during postural change—sitting to standing. Subjects were also instructed to maintain voluntary blood pressure control in subsequent no-feedback test trials. During postural change, voluntary control procedures caused significant alterations in tonic levels of systolic pressure, but phasic blood pressure reactivity was unaffected. With respect to postural changes in heart rate, both tonic and phasic treatment effects were observed. Implications of the findings for basic and clinical research are discussed.     

Hypertension, erectile dysfunction, and occult sleep apnea

Sleep-related respiratory pattern was evaluated in 175 hypertensive and 110 normotensive men, none of whom reported difficulties in initiating or maintaining sleep. Patients were grouped according to sexual status (complaint of erectile problems), hypertension treatment status (treated or untreated), and blood pressure (diastolic less than 90 or greater than or equal to 90). The prevalence of sleep apnea, apnea index, duration of the longest episode of apnea, and penile rigidity were tabulated. The group with elevated blood pressure, persistent even with antihypertensive drug therapy, had the most sleep apnea. The treated hypertensive men with controlled blood pressure had significantly less apnea than those whose blood pressure remained high. Untreated hypertensive groups, however, did not differ from normotensive groups with respect to apnea. Evidence of abnormal sleep-related respiratory activity was found in both hypertensive and normotensive groups with erectile problems. Interestingly, penile rigidity was significantly lower for hypertensive men with erectile complaints than for normotensive men with erectile complaints. There was also a small, but significant, negative correlation between apnea index and penile rigidity among men with erectile complaints. These results indicate that sexual status is an important consideration in the diagnosis of hypertension and sleep apnea. Moreover, these data suggest an interrelationship among hypertension, erectile dysfunction, and sleep apnea.     

Haemodynamic Adjustments to Mental Stress in Normotensives and Subjects with Mildly Elevated Blood Pressure

Cardiac output, heart rate, stroke volume, pre-ejection period, total peripheral resistance, systolic and diastolic blood pressure, and oxygen consumption were monitored or derived in young men with mildly elevated casual blood pressures and unambiguously normotensive control subjects before, during, and after exposure to a mental arithmetic stress. Measurements were also taken while subjects underwent graded dynamic exercise. This permitted cardiac output-oxygen consumption regression equations to be calculated and, as a consequence, cardiac output during mental stress to be represented as additional cardiac output. Systolic and diastolic blood pressure were higher during all phases of the study in the mildly elevated blood pressure group. An overall groups effect during the mental stress phase of the experiment was observed for cardiac output and pre-ejection period, and the effect for stroke volume was close to significance. Significant Groups X Periods interactions were found for cardiac output and additional cardiac output, and the heart rate effect was nearly significant. Post-hoc comparisons here indicated that, in the main, group differences in these cardiac variables were more evident during the mental arithmetic stress than during the pre- and post-task baseline periods. Total peripheral resistance did not differ reliably between groups and the cardiac effects were specific to the mental stress phase of the study.     

The inverse relationship between bone status and blood pressure among Polish men

PRIMARY OBJECTIVE: An evaluation of relationships between bone density and blood pressure in healthy men. RESEARCH DESIGN: A cross-sectional population-based survey. METHODS AND PROCEDURES: An ethnically homogeneous sample of 208 men, aged 35-63, healthy and occupationally active inhabitants of the city of Wroclaw, Lower Silesia, Poland were studied. Trabecular, cortical and total bone mineral content (BMC) at the ultra-distal radius of the non-dominant hand were assessed by peripheral Quantitative Computed Tomography (pQCT: Stratec 960 apparatus). Body mass index (BMI) was used as a measure of general obesity. Systolic and diastolic blood pressure (BP) were measured using an MPC-350 sphygmomanometer. Multiple linear regression was used to evaluate the relationships between BP and BMC. A two-way analysis of covariance was carried out to test for the significance of inter-group differences in BMC with regard to age and BP with BMI as a contiuous covariable. Multiple logistic regression was used to verify whether some select factors (age, BMI, systolic and diastolic BP) could significantly predict male bone status. RESULTS: Systolic BP was not related to bone status at the ultra-distal radius. There were no differences in any BMC between systolic hyper- and normotensive subjects. Additionally, systolic hypertension did not affect the probability of an occurrence of male osteopenia (independently of age and BMI). In contrast, there were significant negative relationships between diastolic BP, and trabecular and total (but not cortical) BMC (even when controlled for age and BMI). Moreover, diastolic hypertensive men had reduced BMC at the ultra-distal radius when compared with normotensive subjects. It is noteworthy that Polish men of diastolic BP exceeding 90 mmHg had an approximately 1.50-fold increased relative risk of being osteopenic when compared with normotensive subjects (even when controlled for age, BMI and systolic BP). CONCLUSIONS: In the light of the inverse relationship between BMC and diastolic BP, Polish men with elevated diastolic BP seem to be more prone to the excessive age-related bone loss.     

Hypoalgesic effect of caffeine in normotensive men and women

Evidence from both hypertensive and normotensive individuals indicate that elevated blood pressure is associated with decreased pain sensitivity. The current study sought to experimentally raise blood pressure using 250 mg caffeine, and investigate its effects on the cold pressor pain experiences of 25 men and 25 women. In a placebo-controlled repeated-measures experiment, caffeine increased systolic and diastolic blood pressure, as well as producing more clearheaded and energetic feelings. Caffeine produced higher pain threshold and pain tolerance levels compared to placebo, and women had a lower tolerance to pain than men. Finally, a significant association was found between caffeine-related increase in systolic blood pressure and caffeine-related increase in pain tolerance. Furthermore, this association was the strongest in women. These results are discussed in light of future directions for pain and hypertension research.     

Elevated blood pressure and self-reported symptom complaints, daily hassles, and defensiveness

The association between elevated blood pressure and low rates of self-reported problems has been hypothesized to be mediated by defensiveness. In a population screening study in which 1,120 women and 903 men between 20 and 55 years of age participated, multiple resting home blood pressure measurements were performed and questionnaires were administered measuring symptom complaints, daily hassles, and defensiveness. In women, after control for potential confounders, a low number of self-reported symptoms was associated with elevated blood pressure. However, this effect was not mediated by defensiveness, although repressive defensiveness predicted independently elevated blood pressure in women. In men, no significant associations were obtained. Furthermore, no relations emerged between daily hassles and elevated blood pressure. In conclusion, although defensiveness was more prevalent among women with elevated blood pressure, it does not provide a good explanation for the low rates of self-reported symptoms found in these women.     

Biofeedback of baroreflex sensitivity in patients with mild essential hypertension

An attempt was made to reduce blood pressure by increasing the baroreflex sensitivity (BRS) via biofeedback. Six patients with mild essential hypertension and 5 normotensive participants were studied during 8 biofeedback sessions. Each session consisted of 5 trials, 5 min each. The first and the last trials served as baselines of heart rate, blood pressure, respiration, and BRS. During the3 middle trials the BRS was calculated online using the sequencing technique. The resulting value was used as a visual analogue feedback signal. Participants were asked to increase BRS. The mean BRS was 8.3 [ms/mmHg] for the hypertensive patients and 12.2 [ms/mmHg] for the normotensive participants. During biofeedback trials as well as across sessions neither the hypertensive nor the normotensive group showed a statistically significant increase of BRS, only heart rate variability increased significantly. Contrary to expectation blood pressure increased in both groups. One hypertensive subject made significant progress during the training by performing valsalva maneuvers. The data show that BRS is reduced in hypertensive subjects. The increase of the heart rate variability could be a sign of the activation of the baroreflex although the BRS itself did not increase. Despite the successful technical and organizational im plementation of this biofeedback approach, it was not effective to systematically reduce blood pressure. A further development in the direction of guiding the patient to use the valsalva breathing pattern and/or a prolonged duration of the biofeedback training might be promising.     

Increased ambulatory arterial stiffness index and blood pressure load in normotensive obese patients

ObjectivesIt has been shown that blood pressure (BP) values measured in obese subjects are higher than the individuals with normal weight, even in normotensive limits. However, data concerning the Ambulatory Arterial Stiffness Index (AASI) and blood pressure load in normotensive obese subjects is lacking. This study was aimed to compare the ambulatory arterial stiffness index and blood pressure load in normotensive obese and healthy controls.MethodsOne hundred normotensive obese and one hundred normal weight subjects were included in this study. All subjects underwent 24-hour ambulatory blood pressure monitoring. Ambulatory arterial stiffness index was calculated from 24-hour ambulatory blood pressure monitoring records. Ambulatory arterial stiffness index was defined as one minus the regression slope of unedited 24-h diastolic on systolic blood pressures. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) load values were calculated from 24-hour ambulatory blood pressure monitoring analysis.ResultsAmbulatory arterial stiffness index of the obese subjects was significantly higher than the healthy controls (0.48±0.2 vs. 0.33±0.11, p<0.001). 24-hours systolic blood pressure and diastolic blood pressure loads were significantly higher in obese subjects. Logistic regression analysis revealed that body mass index (BMI) was an independent predictor for an abnormal ambulatory arterial stiffness ındex (≥0.50) (OR: 1.137, 95% CI: 0.915-1.001, p=0.004).ConclusionBlood pressure load and ambulatory arterial stiffness index are increased in normotensive obese patients. Moreover, body mass index is an independent predictor for an abnormal ambulatory arterial stiffness index. Our results indicate that obese subjects are at higher risk for future cardiovascular events despite normal office BP levels.     

Increased beta-thromboglobulin in essential hypertension: interactions between arterial plasma adrenaline, platelet function and blood lipids

Twenty-three 50-year-old men with untreated, essential hypertension had elevated plasma concentrations of the platelet release product beta-thromboglobulin (BTG) compared to 14 age-matched control men (p less than 0.01). BTG correlated with arterial plasma adrenaline concentrations in the hypertensive (r = 0.44, p less than 0.05), normotensive (r = 0.73, p less than 0.01) and combined group (r = 0.51, p less than 0.01). Significant correlations (p less than 0.05) between BTG and cholesterol (LDL + VLDL fraction) were observed both in the hypertensive and the normotensive group. In the hypertensive group arterial adrenaline correlated with cholesterol (LDL + VLDL) (p less than 0.05). These findings are consistent with increased platelet activity in middle-aged men with essential hypertension, and may indicate that plasma adrenaline influence platelet function. The risk factors for coronary artery disease (blood pressure, lipid status, stress as evidenced by catecholamine release and platelet function) were positively related. Measurement of arterial instead of venous adrenaline is essential for the demonstration of the associations presented.     

Effect of chronic elevation of plasma calcium concentration by PTH or vitamin D3 on blood pressure and hypotensive activity of nifedipine in rats

The influence of a chronically elevated total plasma calcium concentration on blood pressure and heart rate was investigated in conscious normotensive rats. The plasma calcium concentration was elevated by continuous subcutaneous infusion with parathormone (PTH) after parathyreoidectomy, and by oral treatment with vitamin D₃. In both groups an elevated blood pressure was observed at the 1st day of treatment only. Blood pressure was returned to pretreatment values from the second day of treatments onaards. No significant changes in heart rate, due to hypercalcaemia, were observed. In hypercalcaemic rats, the calcium entry inhibitor nifedipine proved more potent in reducing blood pressure than in normocalcaemic control animals. Hydralazine was equipotent in reducing blood pressure in both groups. It is suggested, that the vasoconstrictor effects of a chronically elevated total plasma calcium concentration in conscious rats does not obviously result in a chronically elevated blood pressure, but rather in an enhanced sensitivity of the blood pressure towards calcium entry blockade.     

Time course of decrease in blood pressure and in blood pressure response to vasopressor agents during pregnancy in the rat

Summary In the unanesthetized normotensive rat blood pressure progressively decreased during the last week of pregnancy as measured with a direct and an indirect method. In renal hypertensive and desoxycorticosterone acetate (DOCA)-salt hypertensive rats blood pressure also decreased at this time. In the unanesthetized normotensive rat the blood pressure response to exogenous rat renin diminished progressively during the last week of pregnancy. Similarly, the blood pressure response to angiotensin II, noradrenaline and tyramine decreased. The decrease in blood pressure induced by acetylcholine was not affected during pregnancy. Determination of the activity of the renin-angiotensin system showed that plasma renin activity was elevated to 3–4 times the control value on day 20–21 of pregnancy, and that plasma renin substrate was decreased on day 14–15. It is suggested that the decrease in blood pressure which occurs during the last week of pregnancy in the rat is mediated through a decreased responsiveness of the cardiovascular system to vasopressor agents.     

Blood pressures of Sherpa men in modernizing Nepal

The relationship among potential risk factors (diet, adiposity, physical activity levels (PALs), and age) for elevated blood pressures (BP) was examined in 253 Sherpa men living in Kathmandu (low altitude sample: LAS) and in the Khumbu (high altitude sample: HAS) regions of Nepal. The study is based on data collected to assess nutritional status. Elevated BPs were highly prevalent among both samples of men (LAS: 21.7% and HAS: 24.8%). The highest percentage of elevated BP was found among the urban HAS (32.4%), while rural HAS had the lowest percentage (16.1%). Stepwise regression analyses showed that the BMI, age, and alcohol consumption were strong predictors of systolic blood pressure (SBP), and the BMI and age were strong predictors of diastolic blood pressure (DBP). No correlations were found among BP and intakes of sodium, calcium, potassium, or fat when all men (normotensive and elevated BP) were examined. Bivariate association between the BMI and BP showed that obese men were 8.6–9.1 times more likely to have elevated BP, and that alcohol consumers were 2.6 times more likely to have elevated BP. The results suggest that elevated BP is a problem for a large portion of male Sherpas and appears to be associated with an elevated BMI. A survey of the region only 30 years ago showed no cases of hypertension. Increasing adiposity, due primarily to decreasing PALS, places this population at risk of chronic illness in the future. Am. J. Hum. Biol. 11:469–479, 1999. © 1999 Wiley-Liss, Inc.     

Evaluation of a New Ambulatory Blood Pressure Monitor (Accutracker 102): Laboratory Comparisons With Direct Arterial Pressure, Stethoscopic Auscultatory Pressure, and Readings From a Similar Monitor (Spacelabs Model 5200)

Systolic (SBP) and diastolic (DBP) blood pressure levels generated by a new noninvasive ambulatory monitor, the Accutracker 102, were compared in the laboratory with intra-arterial pressure levels in 12 normotensive men, and with stethoscopic auscultatory determinations in 27 normotensive and hypertensive men and women over a wide range of within-subject pressure variations. In 11 subjects, its performance was also compared with another ambulatory monitor, the Spacelabs Model 5200. Highly positive correlations with both the intra-arterial (median r=+.90 for SBP, +.92 for DBP) and the stethoscopic standards (median r=+.93 for SBP, +.88 for DBP) were obtained using Accutracker's automatic readings (digital readout), while slightly higher correlations were obtained with hand-scoring of recorded data. The Spacelabs BP monitor also yielded readings that were highly correlated with stethoscopic readings (median r=+.83 for SBP, +.77 for DBP), although in 3 of the 11 subjects the Accutracker correlations were substantially higher than the Spacelabs correlations. Despite their generally good tracking of changes in pressure, both ambulatory monitors yielded absolute values in many subjects that differed by 5 mmHg or more from stethoscopic levels. The Accutracker's SBP levels were consistently too high and its DBP levels were occasionally too low, while Spacelabs' SBP and DBP values were too high and too low with equal frequency. However, mean deviation scores for each patient calculated from 5 concurrent ambulatory monitor and stethoscopic readings were shown to yield relatively stable correction factors for use when comparison with clinical standards is desired.     

Incidence of hypertension in Korea: 5-year follow-up study

Limited data are available about the incidence of hypertension over the 5-yr in non-hypertensive subjects. The study subjects were 1,806 subjects enrolled in a rural area of Daegu, Korea for a cohort study from August to November 2003. Of them, 1,287 (71.3%) individuals had another examination 5 yr later. To estimate the incidence of hypertension, 730 non-hypertensive individuals (265 males; mean age = 56.6 ± 11.1 yr-old) at baseline examination were analyzed in this study. Hypertension was defined as either a new diagnosis of hypertension or self-reports of newly initiated antihypertensive treatment; prehypertension was if the systolic blood pressure was 120-139 mmHg and/or diastolic blood pressure was 80-89 mmHg. During the 5-yr follow-up, 195 (26.7%) non-hypertensive individuals developed incident hypertension. The age-adjusted 5-yr incidence rates of hypertension were 22.9% (95% confidence interval [CI] = 19.9-29.0) in overall subjects, 22.2% (95% CI = 17.2-27.2) in men, and 24.3% (95% CI = 20.4-28.2) in women. The incidence rates of hypertension significantly increased with age. In the multivariate analysis, prehypertension (Odds ratio [OR] 2.25; P < 0.001) and older age (OR 2.26; P = 0.010) were independent predictors for incident hypertension. In this rapidly aging society, population-based preventive approach to decrease blood pressure, particularly in subjects with prehypertension, is needed to reduce hypertension.     

Neonatal chronic sympathectomy in normotensive rats affects pial arteries: enhanced stiffness and reduced capacity to dilate

The functional implication of previously shown effects on pial wall morphology by sympathectomy was tested. Following either ganglionic or pre-ganglionic denervation in 1-week-old rats the passive arterial compliance was reduced in basal cerebral arteries of 20-week-old normotensive, but not of hypertensive animals. The magnitude of the denervation induced stiffness was similar to the alteration seen in spontaneously hypertensive rats when compared with normotensive animals. No difference was seen between the two types of denervation. Following ganglionic sympathectomy in 1-week old normotensive rats – and examined 19 weeks later – the increase in cerebral blood flow (measured with the [¹⁴C]butanol sampling technique) induced by high arterial CO₂ concentration was attenuated compared with control, whereas basal cerebral blood flow of 20-week-old animals was not different from control. The results indicate a long-term role by the sympathetic nerves not only on vessel wall composition, but also on the regulatory capacity of the cerebral circulation.     

Reproducible increases in blood pressure during intermittent noise exposure: underlying haemodynamic mechanisms specific to passive coping

Summary The purpose of the present study was to investigate the reproducibility of the increases in blood pressure found in our recent study on exposure to intermittent noise, to confirm the haemodynamic mechanism raising blood pressure (via an increase in peripheral vascular resistance expected to be specific to passive coping), and to assess baroreceptor cardiac reflex sensitivity in connection with the blood pressure elevation. A group of 16 young normotensive men participated in the experiment and underwent a 10-min intermittent exposure to pink noise at 100 dB (sound pressure level). The subjects also underwent three other stresses: a 1-min cold pressor test, a 3-min isometric handgrip and 3-min of mental arithmetic. The results indicated that blood pressure was elevated reproducibly for most of the noise exposure periods and that peripheral vascular resistance increased simultaneously, as expected. Baroreflex sensitivity was not suppressed. The results, as a whole, were in agreement with our recent findings for exposure to a similar type of noise and thus the reproducibility was corroborated. The mechanism raising blood pressure was similar in the cold pressor test. Conversely, during the isometric handgrip and mental arithmetic, blood pressure elevations were attributable mainly to increases in cardiac output. The implications of the opposing haemodynamic mechanisms raising blood pressure among the four stressful tasks have been discussed in relation to active versus passive coping required for each task. Differences in the magnitude of suppression observed in baroreflex sensitivity among the tasks have also been discussed in the context of defence reactions.     

Blood pressure levels and variance assessed by ambulatory monitoring: Optimal parameters

We obtained multiple ambulatory blood pressure monitoring (ABPM) records over five years from two trained, normotensive subjects experienced in wearing the apparatus. The resulting time series data on systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were used to suggest optimal parameters for monitoring by two instruments (Colin Medical Instruments ABPM-630 and Del Mar Avionics Pressurometer) and to compare two indirect methods (auscultatory and oscillometric). A 10-min sampling interval day and night provided sufficient density of data to support spectral analysis for ultradian rhythms in the frequency range of one cycle per hour to one cycle per 9 h on a 24-h record. Rhythms with major periods of approximately 3, 6, and 9 h were variously found in 94 normotensive subjects, aged 20 to 95 years, including the two trained subjects. When the monitoring period was extended to 72 h, the circadian (∼24 h) rhythm could be more sharply defined, as well as a 12-h harmonic. In some studies the two trained subjects wore two monitors, one on each arm, set to read simultaneously. From the simultaneous measurements on both arms, it was shown that averaging across three points (30 min of record) reduced the coefficient of variation between the two simultaneous records to 6% or less. Auscultatory and oscillometric methods were equally reliable. Echocardiographic data were obtained in five normotensive subjects and compared to their ABPM data. The ABPM records provided additional information about cardiovascular function not merely duplicating that obtained by acute stress tests, such as exercise or cold pressor responses, or echocardiography. Standards for ABPM are suggested.