Blood pressure response to stress tests does not reflect blood pressure variability and degree of cardiovascular involvement in young hypertensives

Inverse Association between Exercising Blood Pressure Response and Left Ventricular Chamber Size and Mass in Women Who Habitually Resistance Train

Exercise is a major modifiable lifestyle factor that leads to temporarily increased systolic blood pressure (SBP), which is thought to influence left ventricular mass normalized to body surface area (LVM/BSA). This relationship has never been studied in women who habitually perform resistance exercise.

PURPOSE

To determine if a direct correlation exists between the SBP response to resistance exercise (change from rest; eSBP) and LVM/BSA in young healthy women who habitually resistance train.

METHODS

Leg extension resistance exercise was performed while continuously monitoring blood pressure using finger plethysmography. LVM was estimated using echocardiography. Data are shown as mean ± SD.

RESULTS

Thirty-one women participated (age 23 ± 3 years, height 164 ± 7 cm, body mass 63.7 ± 10.3 kg). Resting SBP (110 ± 8 mmHg, r = 0.355, p = 0.049) was shown to be directly correlated to LVM/BSA (72.0 ± 28.4 g/m2). Conversely, eSBP (30.8 ± 14.6 ∆mmHg, r = -0.437, p = 0.014) was inversely related to LVM/BSA. eSBP was not correlated to interventricular septum width (0.88 ± 0.12 cm, r = -0.137, p = 0.463) or posterior wall thickness (0.91 ± 0.15 cm, r = -0.084, p = 0.654). eSBP was inversely related to left ventricle internal diameter during diastole (LVIDd) (4.25 ± 0.33 cm, r = -0.411, p = 0.021).

CONCLUSION

Counter to the hypothesis, these data suggest an inverse association between eSBP during resistance exercise and LVM/BSA in healthy young women who resistance train. This relationship is due to a smaller LVIDd with greater eSBP.

High Home Blood Pressure Variability Associates With Exaggerated Blood Pressure Response to Cold Stress

BACKGROUND

Exaggerated sympathetic cardiovascular (CV) reactivity to stress associates with elevated risk for clinical and preclinical end points of CV disease. It would be useful to identify these individuals, preferably from feasible measurements commonly used in health care. Our study examined the association between home blood pressure (BP) variability and cardiac workload response to whole-body cold exposure.

METHODS

Seventy-five men (55-65 years, 46 hypertensive) measured BP at home twice in the morning and evening for a week. We computed systolic home BP variability as SD of daily means and divided the subjects into groups demonstrating either high or low BP variability. They were exposed to whole-body cold exposure (-10 °C, wind 3 m/second, 15 minutes, winter clothes, standing). BP and heart rate were measured at 3-minute intervals during, and 15 minutes before and after the exposure. Rate-pressure product (RPP) was calculated to represent cardiac workload.

RESULTS

Subjects with high systolic home BP variability demonstrated a greater RPP increase in cold conditions compared to those with low BP variability [mean change from baseline (95% CI): 1,850 (1,450 to 2,250) bpm × mm Hg vs. 930 (610, 1,250) bpm × mm Hg, P < 0.01]. This was related to the augmented systolic BP change [31(28, 35) mm Hg vs. 23(20, 26) mm Hg, P < 0.01]. Home BP variability correlated with cold-related RPP (rS = 0.34, P = 0.003) and systolic BP (rS = 0.38, P < 0.001) responses.

CONCLUSIONS

Moderate whole-body cold exposure increased BP and cardiac workload more among those with higher systolic home BP variability, independently of home BP level. Elevated home BP variability may indicate augmented sympathetically mediated vascular reactivity for environmental stressors.

PUBLIC TRIALS REGISTRY NUMBER

Trial Number NCT02007031.

The effects of acute stress exposure on striatal activity during Pavlovian conditioning with monetary gains and losses

Pavlovian conditioning involves the association of an inherently neutral stimulus with an appetitive or aversive outcome, such that the neutral stimulus itself acquires reinforcing properties. Across species, this type of learning has been shown to involve subcortical brain regions such as the striatum and the amygdala. It is less clear, however, how the neural circuitry involved in the acquisition of Pavlovian contingencies in humans, particularly in the striatum, is affected by acute stress. In the current study, we investigate the effect of acute stress exposure on Pavlovian conditioning using monetary reinforcers. Participants underwent a partial reinforcement conditioning procedure in which neutral stimuli were paired with high and low magnitude monetary gains and losses. A between-subjects design was used, such that half of the participants were exposed to cold stress while the remaining participants were exposed to a no stress control procedure. Cortisol measurements and subjective ratings were used as measures of stress. We observed an interaction between stress, valence, and magnitude in the ventral striatum, with the peak in the putamen. More specifically, the stress group exhibited an increased sensitivity to magnitude in the gain domain. This effect was driven by those participants who experienced a larger increase in circulating cortisol levels in response to the stress manipulation. Taken together, these results suggest that acute stress can lead to individual differences in circulating cortisol levels which influence the striatum during Pavlovian conditioning with monetary reinforcers.

Orthostatic hypertension-a new haemodynamic cardiovascular risk factor

Orthostatic hypertension-a condition characterized by a hyperactive pressor response to orthostatic stress-is an emerging risk factor for cardiovascular disease and is associated with hypertensive target-organ damage (resulting in silent cerebrovascular disease, left ventricular hypertrophy, carotid atherosclerosis and/or chronic kidney disease) and cardiovascular events (such as coronary artery disease and lacunar stroke). The condition is also considered to be a form of prehypertension as it precedes hypertension in young, normotensive adults. Orthostatic blood pressure changes can be assessed using orthostatic stress tests, including clinic active standing tests, home blood pressure monitoring and the head-up tilting test. Devices for home and for ambulatory blood pressure monitoring that are equipped with position sensors and do not induce a white-coat effect have increased the sensitivity and specificity of diagnosis of out-of-clinic orthostatic hypertension. Potential major mechanisms of orthostatic hypertension are sympathetic hyperactivity (as a result of hypersensitivity of the cardiopulmonary and arterial baroreceptor reflex) and α-adrenergic hyperactivation. Orthostatic hypertension is also associated with morning blood pressure surge and extreme nocturnal blood pressure dipping, both of which increase the pulsatile haemodynamic stress of central arterial pressure and blood flow in patients with systemic haemodynamic atherothrombotic syndrome.

A novel system for continuous peripheral arterial pressure-volume loop measurement

This study develops a system to obtain continuous blood pressure signal and impedance plethysmography (IPG) signal, simultaneously. Based on the principle of impedance measurement, the peripheral vessel volume change can be computed from the IPG signal. Equipped with simultaneous information of pressure and volume, a pressure-volume (PV) loop can be constructed. It is well known that the left ventricular pressure-volume loop contains a number of feature points indicating the performance of cardiac function. Therefore, in this study, the same principle is used to try to discuss the peripheral vessel pressure-volume loop. Ten volunteers were recruited for this study. Subjects went through the cold pressor test by immersing their left foot into ice water. Blood pressure signal and impedance changed were recorded using a custom-made system. The results illustrated that the pressure-volume loop, as it was expected, demonstrated a contraction phenomenon after stimulation in five out of ten subjects. The areas of those pressure-volume loops reduced as much as 70% in some subject. However, loop responses to stressors varied from subject to subject and the slope of the loop did not alter significantly. In conclusion, the proposed system is a potential way to measure and to investigate the compliance and characteristic of peripheral blood vessel.

Ambulatory arterial stiffness index is not correlated with the pressor response to laboratory stressors in normotensive humans

BACKGROUND

Ambulatory arterial stiffness index (AASI) is a novel estimate of arterial stiffness, which independently predicts cardiovascular mortality, even in normotensive individuals. Additionally, other markers derived from ambulatory blood pressure (BP) monitoring, including variability, pulse pressure, nocturnal dipping, and morning BP surge, have all been shown to be predictive of end-organ damage and cardiovascular disease. Exaggerated cardiovascular reactivity to sympathoexcitatory stimuli may also predict future incidence of hypertension. The purpose of this investigation was to test the hypothesis that AASI and other derivations of ambulatory BP, including pulse pressure, 24-h blood pressure variability, dipping, and morning surge, would be correlated with the pressor response to common physiological stress maneuvers.

METHOD

We measured continuous heart rate and arterial BP during head-up tilt, mental stress, cold pressor test, and isometric handgrip to fatigue in 67 healthy, normotensive, nonobese individuals (43 women, 24 men, mean age +/- SD: 28 +/- 6 years). Then, 24-h ambulatory BP was obtained, and AASI was defined as 1 minus the slope of diastolic on systolic BP in individual 24-h ambulatory BP recordings.

RESULTS

Although all measures were widely variable among patients, there was no relationship between AASI, pulse pressure, blood pressure variability, dipping, and morning surge with the pressor responses.

CONCLUSION

We conclude that in the absence of aging, cardiovascular, or autonomic disease, the novel stiffness index (AASI) or other ambulatory BP indices are either poorly correlated with or mechanistically unrelated to the complex pressor response to common provocations of sympathoexcitation.

Cardiovascular reactivity and left ventricular mass: An integrative review

Left ventricular hypertrophy has been shown to be an independent predictor of risk for cardiovascular morbidity and mortality. Behavioral scientists have focused on how hemodynamic factors influenced by psychosocial stress may be associated with left ventricular mass (LVM). We reviewed existing studies examining stress-related cardiovascular reactivity (CVR) and LVM, with a goal of examining the moderating role of population (age and hypertensive status) and methodological factors (task type, sample size, and study design) explaining the observed results. Twenty-one studies met the criteria for this review. Results showed only a modestly consistent relationship between CVR and LVM. Forty-three percent of the studies reported 1 or more significant results linking systolic blood pressure reactivity with LVM, and 14% of the studies showed that diastolic blood pressure reactivity was significantly related to LVM. Hypertensive status, task type, and sample size did not play a major role in moderating the relationship between LVM and CVR. A somewhat larger percentage of positive results was shown in prospective and adult studies. The association between CVR and LVM may be real, although the effect size is modest, and we discuss methodological strategies for enhancing statistical power in future investigations. Additional sampling factors (e.g., race, gender) may also impact this relationship. Finally, greater attention is warranted to the role of the psychosocial environment, as this may interact with reactivity to influence LVM.

Exercise blood pressure response is related to left ventricular mass

An exaggerated SBP response to exercise has been associated with increased left ventricular (LV) mass in some but not all studies. A total of 43 women and 34 men, aged 55-75 years, without evidence of cardiovascular disease, with a mean resting BP of 142+/-9/77+/-8 mmHg had their BP measured at rest and during maximal treadmill exercise. LV mass was measured using magnetic resonance imaging. LV mass was adjusted for lean body mass, which was assessed by dual energy X-ray absorptiometry. LV mass was within the normal range for the majority of the subjects. Among the resting and exercise BP indices, maximal SBP was the strongest correlate of LV mass (r=0.41, P<0.05). In multivariate analysis, maximal SBP was independently associated with LV mass after adjustment for lean body mass and gender, explaining 3% of the variance (P<0.05). Maximal exercise SBP is a modest but still independent predictor of LV mass in older persons with normal LV mass. These results raise the possibility that the SBP response to maximal exercise is an early marker of LV hypertrophy.

Pulse pressure responses to psychological tasks improve the prediction of left ventricular mass: 10 years of follow-up

OBJECTIVES

To examine the role of casual blood pressure measurements and blood pressure responses to psychological tasks in the prediction of future left ventricular mass index (LVMI), and to determine the importance of different components of blood pressure, and the predictive value of an individual's personal characteristics and antihypertensive medication on future LVMI.

METHODS

At baseline, blood pressure was recorded by casual measurements; during tests it was recorded by intra-arterial monitoring. The participants were healthy, untreated 35-45-year old men. Echocardiography data both at baseline and after 10 years of follow-up were available from 65 individuals, of whom 49 (75%) were not taking antihypertensive medication at follow-up. Those not taking antihypertensive medication were included in the prediction of LVMI (g/m2).

RESULTS

Baseline LVMI correlated significantly with future LVMI only among the 49 unmedicated individuals (r = 0.52, P < 0.0001). The predictive value of baseline LVMI on future LVMI among them (adjusted coefficient of determination = 0.26) was not improved by the inclusion of casual blood pressure. In contrast, blood pressure responses to the psychological tasks improved the prediction of future LVMI by 4-13%. Pulse pressure was the blood pressure variable that entered the final prediction models; the correlations with future LVMI were best for pulse pressure response to habituation task (r = 0.43, P < 0.05) and to relaxation (r = 0.37, P < 0.05).

CONCLUSIONS

To our knowledge, this is the longest prospective follow-up to show that blood pressure responses to psychological tasks improve the prediction of LVMI compared with casual blood pressure measurements. The pulse pressure, which reflects the properties of the arterial wall, is the most significant blood pressure variable in predicting future LVMI.

Pulse pressure in tests improves the prediction of left ventricular mass: 10 years of follow-up

Literature does not agree with the usefulness of exercise blood pressure (BP) in predicting hypertension or target organ damage. In this prospective 10 years of follow-up, we evaluated if exaggerated BP responses to tests may improve the prediction of left ventricular mass index (LVMI). At baseline, BP was recorded by casual measurements, and during tests using intra-arterial monitoring. The subjects were 97 healthy, untreated 35- to 45-year-old-men (34 normotensive, 29 borderline hypertensive, and 34 mild hypertensive). At 10-year follow-up, echocardiography was performed to 86 (89%) of them. Subjects not taking antihypertensive medication (n = 66) were included in the prediction of LVMI(g m-2). Echocardiography data at baseline was available from 70 (72%) of the subjects, of whom 52 did not use antihypertensive medication at follow-up. Pulse pressure (PP) at supine test (r = 0.337, P = 0.006), PP at dynamic exercise last work load (r = 0.332, P = 0.006), and PP after dynamic exercise (r = 0.316, P = 0.010) were the best BP variables achieved in tests in predicting future LVMI of the 66 subjects. Casual BP did not significantly correlate with future LVMI. The best model in predicting LVMI included PP achieved after dynamic exercise, family history of hypertension, and body mass index (BMI) (adj.R2 = 0.207). Baseline LVMI correlated significantly with future LVMI only among the 52 unmedicated subjects (r = 0.508, P<0.0001). The predictive value of baseline LVMI on future LVMI among them (adj.R2 = 0.243) was best improved by PP achieved in supine test and age (adj.R2 = 0.350). In conclusion, BP measurements during tests improved the prediction of LVMI compared with casual BP. For the first time, the pulsatile component of BP in tests was found to be the most significant BP parameter in predicting future LVMI.

Anticipatory blood pressure responses to exercise are associated with left ventricular mass in Finnish men: Kuopio Ischemic Heart Disease Risk Factor Study

BACKGROUND

Exaggerated cardiovascular reactivity to psychological demands may contribute to the development of left ventricular (LV) hypertrophy. We examined the cross-sectional association between anticipatory blood pressure (BP) responses to bicycle exercise and LV mass in the Kuopio Ischemic Heart Disease Risk Factor Study, a population-based epidemiological sample.

METHODS AND RESULTS

Among 876 men from 4 age cohorts (ages 42, 48, 58, and 64 years), we collected echocardiographic assessments of LV mass along with measures of BP response taken before bicycle ergometry testing. Anticipatory BP responses were positively associated with LV mass, with significant associations only among younger (age <50 years) subjects with elevated resting pressures (3-way interactions for anticipatory BP x age x resting pressure for systolic and diastolic BP, all P:<0.05; for younger subjects with elevated systolic BP, P:<0. 01; and for younger subjects with elevated diastolic BP, P:<0.001). Among these subgroups, exaggerated anticipatory BP responses (top quartile) were associated with an incremental increase in LV mass of 10% or greater, corrected for body surface area. Results remained significant after adjusting for age, education, salt consumption, and resting BP, and the pattern of findings was maintained among men with no previous history of cardiovascular disease.

CONCLUSIONS

The tendency to show exaggerated pressor responses to psychological demands may be a significant independent correlate of LV mass, especially among young men with high resting pressures. This is the first study to examine such associations in a middle-aged population sample.

Reproducibility of the cold pressor test: studies in normal subjects

The reproducibility of the cold pressor test was studied in healthy subjects. A non-invasive method was utilized for estimating beat-to-beat arterial blood pressure (BP) and heart rate (HR). The study population of 17 healthy volunteers consisted of two groups. In the first group (Group 1, n = 11), a 1-min test was performed three times during the same day. In the second group (Group 2, n = 6), a 2-min test was repeated at the same time of the day on three consecutive days. In both groups, the test response was defined as the 46- to 60-s mean, minus the prestimulus 15 s baseline mean. In Group 1, a fair test-retest reliability was observed for the systolic BP response (intraclass correlation coefficient R = 0.57). Large intraindividual HR and diastolic BP variabilities were found. The intraindividual testretest difference in Group 1 ranged from -8 to 11 beats/min (SD = 4.3, R = 0.49) for the HR, from -16 to 13 mmHg (SD = 6.3) for systolic BP, and form -21 to 20 mmHg (SD = 9.7, R = 0.23) for diastolic BP. Even larger variability was observed when the test was repeated on different days (Group 2). Thus, the maxim that the response pattern to the cold pressor test is fairly constant for each individual may not be true. It does not seem to be advisable to use the results from one solitary cold pressor test. The use of replicated measurements and large sample sizes in comparative studies to compensate for the low to moderate reliability of the cold pressor test is recommended.