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

Rosiglitazone lowers resting and blood pressure response to exercise in men with type 2 diabetes: A 1-year randomized study

AIMS

We aimed to determine the effect of 1-year treatment with the insulin sensitizer peroxisome proliferator-activated receptor (PPAR)-γ agonist rosiglitazone on exercise capacity and blood pressure (BP) response to exercise in men with coronary artery disease (CAD) and type 2 diabetes (T2D).

MATERIALS AND METHODS

A total of 116 men (age, 64 ± 7 years; body mass index, 30.0 ± 4.4 kg/m² ) with CAD and T2D were randomized to receive rosiglitazone or placebo for 1 year. Exercise capacity (VO_2peak ) and BP response to exercise were assessed with a maximal treadmill test, prior to the intervention and at 1-year follow-up. Exercise-induced hypertension (EIH) was defined as maximal systolic BP ≥ 220 mm Hg and/or diastolic BP ≥ 100 mm Hg.

RESULTS

PPAR-γ agonist-treated patients showed improvements in fasting glucose, HbA1c and insulin sensitivity (Homeostasis model assessment of insulin resistance [HOMA-IR]) (all P < .05). Resting BPs, maximal exercise diastolic BP and resting rate-pressure product (RPP) were all reduced in the PPAR-γ agonist group (P < .05). Maximal exercise duration was unchanged. T2D patients who displayed the greatest improvement in insulin sensitivity (HOMA-IR) under PPAR-γ agonist treatment experienced a greater reduction in exercise BP and RPP (P < .05). The proportion of men with EIH decreased in the PPAR-γ agonist group during follow-up (39.00% ± 0.06% vs 21.00% ± 0.05%). In the subgroup with EIH that was treated with a PPAR-γ agonist, resting and exercise diastolic BP, as well as resting RPP, were all reduced at 1-year follow-up (P < .05).

CONCLUSIONS

The insulin sensitizer rosiglitazone has a beneficial effect on resting and BP response to exercise in men with CAD and T2D, especially in those with an exaggerated BP response to exercise.

High trait rumination is associated with blunted nighttime diastolic blood pressure dipping

Background

Blunted blood pressure (BP) dipping during nighttime sleep has been associated with an increased risk of cardiovascular events. Psychological traits have been associated with prolonged cardiovascular activation and a lack of cardiovascular recovery. This activation may extend into nighttime sleep and reduce BP dipping.

Purpose

This study aims to evaluate the association between trait rumination and nighttime BP dipping.

Methods

Sixty women scoring either high or low on trait rumination underwent one 24-h ambulatory BP monitoring session. Self-reported wake and sleep times were used to calculate nighttime BP.

Results

High trait rumination was associated with less diastolic blood pressure (DBP) dipping relative to low trait rumination. Awake ambulatory BP, asleep systolic blood pressure (SBP) and DBP, and asleep SBP dipping were not associated with trait rumination.

Conclusions

In a sample of young women, high trait rumination was associated with less DBP dipping, suggesting that it may be associated with prolonged cardiovascular activation that extends into nighttime sleep, blunting BP dipping.

Left ventricular mass and the risk of sudden cardiac death: a population-based study

BACKGROUND

Left ventricular (LV) mass ascertained using echocardiography may enhance risk stratification for sudden cardiac death. The objective of this study was to assess the association between left ventricular mass and the risk of sudden cardiac death in a population-based cohort and determine its incremental value beyond conventional risk predictors.

METHODS AND RESULTS

Assessment of LV mass was based on echocardiography in a sample of 905 middle-aged men representative of the general population (aged 42 to 61 years). During the follow-up period of 20 years, there were a total of 63 sudden cardiac deaths. In a comparison of the top versus the bottom quartile of LV mass adjusted by body surface area (>120 versus <89 g/m(2)), the multivariable adjusted hazard ratio was 2.57 (95% CI 1.24 to 5.31, P=0.010). Further adjustment for LV function only modestly attenuated the risk of sudden cardiac death among men with LV mass of >120 g/m(2) (hazard ratio 2.29, 95% CI 1.10 to 4.74, P=0.026). Addition of LV mass adjusted by body surface area to a conventional risk factor model for sudden cardiac death improved the integrated discrimination index by 0.033 (95% CI 0.009 to 0.057, P=0.007) and the category-free net reclassification index by 0.501 (95% CI 0.092 to 0.911, P=0.016).

CONCLUSIONS

Indexed LV mass by body surface area is an independent predictor of sudden cardiac death and may help improve the risk prediction of sudden cardiac death beyond conventional cardiovascular risk factors.

Usefulness of blood pressure rise prior to exercise stress testing to predict the risk of future hypertension in normotensive Korean men

The aim of this study was to test the hypothesis that blood pressure (BP) increase before exercise stress testing is associated with the incidence of hypertension in a prospective study of 3,805 normotensive men without hypertension at baseline. Changes in BP were defined as the difference between seated BP at rest and BP measured immediately before exercise stress testing. Hypertension was defined as systolic and diastolic BP ≥ 140/90 mm Hg or hypertension diagnosed by a physician at the second examination. During 18,923 patient-years of follow-up, 371 new cases of hypertension developed (incidence rate 19.6 per 1,000 patient-years). Men with systolic BP changes >0 mm Hg and diastolic BP changes >7 mm Hg had 1.70 times (95% confidence interval [CI] 1.37 to 2.12) and 2.23 times (95% CI 1.76 to 2.82) increased relative risk for incident hypertension compared with men whose systolic BP changes were <0 mm Hg and diastolic BP changes were <7 mm Hg after adjustment for confounders. Men in the highest quartile of mean BP change (>10 mm Hg) had a higher incidence of hypertension (relative risk 2.98, 95% CI 2.19 to 4.06) compared with those in the lowest quartile (<0 mm Hg), and each 1 mm Hg increment in mean BP was associated with a 6% (95% CI 1.05 to 1.09) higher incidence of hypertension after adjustment for risk factors. In conclusion, BP increase before exercise stress testing is associated with incident hypertension, independent of risk factors in normotensive men. The assessment of BP immediately before exercise testing may be a useful addition to the standard exercise stress testing procedures.

Cardiovascular and psychological reactivity and recovery from harassment in a biracial sample of high and low hostile men and women

BACKGROUND

This study emphasizes the importance of studying the emotional, motivational, and cognitive characteristics accompanying and the potential hemodynamic mechanisms underlying cardiovascular reactivity to and recovery from interpersonal conflict.

PURPOSE

The relation of dispositional hostility to cardiovascular reactivity during a frustrating anagram task and post-task recovery was investigated.

METHODS

The sample was composed of 99 healthy participants (age, 18-30 years; 53% women; 51% Caucasian; 49% African American)-half randomly assigned to a harassment condition. High and low hostility groups were created by a median split specific to sex and race subgroup score distributions on the Cook-Medley Hostility Scale. It was hypothesized that hostility would interact with harassment such that harassed, high hostile individuals would display the greatest cardiovascular and emotional reactivity and slowest recovery of the four groups. Participants completed a 10-min baseline, a 6-min anagram task, and a 5-min recovery period with blood pressure, heart rate, pre-ejection period, stroke index, cardiac index, and total peripheral resistance index measured.

RESULTS

Harassed participants displayed significantly greater cardiovascular responses and lower positive affect to the task and slower systolic blood pressure (SBP) recovery than did nonharassed participants. The high hostile group, irrespective of harassment, showed blunted cardiovascular responses during the task and delayed SBP recovery than the low hostile group.

CONCLUSION

Although the predicted interaction between hostility and harassment was not supported in the context of cardiovascular responses, such an interaction was observed in the context of blame attributions, whereby harassed hostile participants were found to blame others for their task performance than the other subgroups.

Arterial pulsatile hemodynamic load induced by isometric exercise strongly predicts left ventricular mass in hypertension

Although resting hemodynamic load has been extensively investigated as a determinant of left ventricular (LV) hypertrophy, little is known about the relationship between provoked hemodynamic load and the risk of LV hypertrophy. We studied central pressure-flow relations among 40 hypertensive and 19 normotensive adults using carotid applanation tonometry and Doppler echocardiography at rest and during a 40% maximal voluntary forearm contraction (handgrip) maneuver. Carotid-femoral pulse wave velocity (CF-PWV) was measured at rest. Hypertensive subjects demonstrated various abnormalities in resting and induced pulsatile load. Isometric exercise significantly increased systemic vascular resistance, aortic characteristic impedance (Zc), induced earlier wave reflections, increased augmentation index, and decreased total arterial compliance (TAC; all P < or = 0.01). In hypertensive subjects, CF-PWV was the strongest resting predictor of LV mass index (LVMI) and remained an independent predictor after adjustment for age, gender, systemic vascular resistance, reflection magnitude, aortic Zc, and TAC (beta = 2.52 m/s; P < 0.0001). Age, sex, CF-PWV, and resting hemodynamic indexes explained 48% of the interindividual variability in LVMI. In stepwise regression, TAC (beta = -17.85; P < 0.0001) during handgrip, Zc during handgrip (beta = -150; P < 0.0001), and the change in the timing of wave reflections during handgrip (beta = -0.63; P = 0.03) were independent predictors of LVMI. A model that included indexes of provoked hemodynamic load explained 68% of the interindividual variability in LVMI. Hemodynamic load provoked by isometric exercise strongly predicts LVMI in hypertension. The magnitude of this association is far greater than for resting hemodynamic load, suggesting that provoked testing captures important arterial properties that are not apparent at rest and is advantageous to assess dynamic arterial load in hypertension.

White coat hypertension in childhood: evidence for end-organ effect

OBJECTIVE

To evaluate the hypothesis that white coat hypertension (WCH) represents a prehypertensive state by correlating ambulatory blood pressure monitoring (ABPM) results with BP response to treadmill exercise (TE) and echocardiographic measurement of left ventricular mass index (LVMI) in children with high blood pressure (HBP).

STUDY DESIGN

We evaluated 119 consecutive children age 6 to 18 years (mean = 13.3 years; 65% male) referred for HBP. Office systolic BP (SBP) exceeded the 95th percentile for age/sex/height in all of the children; 10% also had elevated diastolic BP (DBP). WCH was defined as elevated office SBP +/- elevated DBP with normal mean awake ABPM-SBP. ABPM classified 62 subjects as having WCH and 57 as having HBP.

RESULTS

Office BP did not differ between the 2 groups. As defined, awake ABPM-SBP was lower in the WCH group (males: HBP, 142 +/- 12 vs WCH, 124 +/- 5; females: HBP, 137 +/- 8 vs WCH, 121 +/- 5). Awake and asleep DBP and asleep SBP were significantly lower in the WCH group. On TE, maximal SBP exceeded norms for age/sex/body surface area in 63% of the HBP group and 38% of the WCH group. LVMI exceeded the 95th percentile for age/sex in 59% of the males and 90% of the females in the HBP group and in 33% of the males and 36% of the females in the WCH group.

CONCLUSIONS

Exaggerated exercise BP and/or increased LVMI in 62% of those subjects with WCH suggest that this diagnosis in children may represent a prehypertensive state.

Programming of the stress response: a fundamental mechanism underlying the long-term effects of the fetal environment?

There is a large body of evidence which suggests that an adverse fetal environment results in a heightened biobehavioral response to stress, with increased activity of the classical mediators of the stress response, including the hypothalamic-pituitary adrenal axis and autonomic nervous system. Although this has been amply demonstrated in animal experiments, several recent studies suggest that the same processes operate in human populations and may have important consequences for health. The evidence suggests that an adverse early environment or markers of an adverse environment such as low birth weight are linked with long-term alterations in these neuroendocrine systems. However, these studies also demonstrate that there is a considerable degree of heterogeneity in the responses observed which appear to depend on a variety of factors such as the nature or timing of the adverse exposure as well as the gender of the offspring. The mediators of these classical neuroendocrine responses such as cortisol and catecholamines are biologically potent and may directly influence disease susceptibility by means of their effects on metabolism and the vasculature. However, lifelong changes in the set point of these neuroendocrine systems in response to the early environment may also direct the course of development during fetal life, infancy and childhood towards the generation of a phenotype adapted for the adult environment predicted by the clues available during fetal life. This has biological advantages if the actual adult environment turns out to be appropriate for the phenotype. However, ill health may occur if the phenotype is not well matched to the actual environment encountered in adult life.

Birth weight, stress, and the metabolic syndrome in adult life

There is now widespread agreement that small size at birth is associated with an increased risk of the metabolic syndrome (glucose intolerance, high blood pressure, and dyslipidemia) and related pathologies, including cardiovascular disease in later life. Evidence is emerging that suggests that programming of hormonal systems in response to an adverse fetal environment may be one of the mechanisms underlying these long-term consequences of growth restriction in early life. In particular, alterations in neuroendocrine responses to stress may be important. Recent research suggests that increased adrenocortical and sympathoadrenal responses are associated with small size at birth. Epidemiological studies show that such physiological alterations in these neuroendocrine systems may have potent effects on risk of cardiovascular disease through their influence on risk factors, such as plasma glucose and lipid concentrations and blood pressure.

Azelnidipine Attenuates Cardiovascular and Sympathetic Responses to Air-Jet Stress in Genetically Hypertensive Rats

Azelnidipine is a new dihydropyridine calcium channel blocker that causes minimal stimulation of the sympathetic nervous system despite its significant depressor effect. In the present study, we examined the effects of oral or intravenous administration of azelnidipine on cardiovascular and renal sympathetic nerve activity (RSNA) responses to air-jet stress in conscious, unrestrained stroke-prone spontaneously hypertensive rats. Oral administration of high-dose azelnidipine (10 mg/kg per day) or nicardipine (150 mg/kg per day) for 10 days caused a significant and comparable decrease in blood pressure, but low-dose azelnidipine (3 mg/kg per day) did not. Air-jet stress increased mean arterial pressure (MAP), heart rate (HR) and RSNA. High-dose azelnidipine significantly attenuated the increases in MAP, HR and RSNA in response to air-jet stress while nicardipine did not. Low-dose azelnidipine significantly attenuated the pressor response with a trend of decrease in RSNA. Intravenous injection of azelnidipine induced a slowly developing depressor effect. To obtain a similar time course of decrease in MAP by azelnidipine, nicardipine was continuously infused at adjusted doses. Both drugs increased HR and RSNA significantly, while the change in RSNA was smaller in the azelnidipine group. In addition, intravenous administration of azelnidipine attenuated the responses of MAP, HR, and RSNA to air-jet stress; by comparison, the inhibitory actions of nicardipine were weak. In conclusion, oral or intravenous administration of azelnidipine inhibited cardiovascular and sympathetic responses to air-jet stress. This action of azelnidipine may be mediated at least in part by the inhibition of the sympathetic nervous system.

Aortic Elastic Properties in Patients With Hypertensive Response to Exercise

BACKGROUND

The aim of this study was to evaluate whether there is a relationship between aortic elastic properties in patients with a suggestive response to treadmill exercise testing.

METHODS AND RESULTS

The study group comprised 32 patients suggesting hypertensive response to exercise and 20 patients suggesting normal blood pressure response to treadmill exercise testing. Baseline demographic characteristics were similar in both groups. However, the mean aortic stiffness index of patients suggesting hypertensive response to treadmill exercise testing was significantly higher (4.8+/-1.26 vs 2.36+/-1.09; p=0.001) whereas aortic distensibility was significantly lower (12.82 +/-5.84 vs 22.64+/-14.54; p=0.001) than the control group. The aortic strain of patients with hypertensive response to exercise was lower than the control group (12+/-3% vs 19.2+/-5%, p<0.001). The left ventricular mass (LVM) of these patients was also higher than control group (206.5+/-46.3 vs 134.2+/-19.97; p=0.01). A negative correlation between LVM and distensibility was found (r=-0.64; p=0.001) well as a positive correlation between LVM and aortic stiffness index (r=0.51; p=0.004) in patients suggesting hypertensive response to exercise. Pressure--rate product was also found to be correlated with LVM (r=0.47; p=0.006).

CONCLUSION

Elastic properties of the aorta may be impaired in subjects showing exaggerated blood pressure response to exercise long before clinically manifest hypertension, particularly if the LVM is increased.

Plasma N-terminal fragments of natriuretic propeptides predict the risk of cardiovascular events and mortality in middle-aged men

AIMS

The prognostic significance of N-terminal pro-A-type (NT-proANP) and pro-B-type natriuretic peptides (NT-proBNP) is not well documented in population-based prospective studies. We, therefore, studied if both NT-proANP and NT-proBNP are predictive for overall death, cardiovascular events, and atrial fibrillation (AF) among middle-aged men without heart failure or AF at baseline.

METHODS AND RESULTS

Plasma NT-proANP and NT-proBNP were measured in a representative population-based sample of 905 men (age 46-65 years) from eastern Finland. There were 110 deaths [58 cardiovascular and 40 coronary heart disease (CHD)] and 59 cases of AF during a follow-up of 10 years. The multivariable adjusted risk for overall was 1.35-fold (95% CI 1.15-1.57) and 1.52-fold (95% CI 1.21-1.91) for CHD death for each SD (160.8 pmol/L) increment in NT-proANP. The respective risks were 1.26-fold (95% CI 1.12-1.42) and 1.44-fold (95% CI 1.22-1.60) for each SD (58.9 pmol/L) increment in NT-proBNP. The adjusted risks for future AF were 1.46 (P<0.001) and 1.72-fold (P<0.001) for each SD increment in NT-proANP and NT-proBNP, respectively.

CONCLUSION

The main finding of the present study is that NT-proANP and NT-proBNP are strong predictors of death from cardiovascular and other causes including AF. These natriuretic peptides add to the prognostic value of conventional risk factors and provide a non-invasive measure for identifying men with high risk of death and its co-morbidities.

Prolonged stress-related cardiovascular activation: Is there any?

BACKGROUND

Prolonged physiological activation before or after stressors has gained recognition as a decisive element in theories that explain the link between stress and disease, specifically cardiovascular (CV) disease. This view is opposed to the conventional reactivity hypothesis that emphasizes responses during stressors.

PURPOSE

Prolonged activity has not often been an explicit research goal of real-life stress studies. Nevertheless, a growing number of these studies have provided evidence for prolonged activity, often as a secondary research goal.

METHODS

An overview of this evidence is lacking and is provided in this article.

RESULTS

The combined data from the reviewed studies suggest that discrete and chronic stress sources, as well as negative emotional episodes and dispositions, are related to prolonged CV activity of various durations, including sleep periods. On the other hand, evidence supporting the assumption that prolonged stress-related activation predicts disease is still very modest.

CONCLUSIONS

In this article we suggest that future research of prolonged activation should give priority to (a) the establishment of clear beginnings and endings of stressful events, (b) the prediction of disease by prolonged activation, and (c) potential psychological mediators of stress-related prolonged activation. These mediators may include, for example, worry and rumination, or other processes characterized by perseverative cognition, including unconscious processes.

Blood pressure stress reactivity and left ventricular mass in a random community sample of African-American and caucasian men and women

Exaggerated blood pressure (BP) reactivity to stress may contribute to left ventricular (LV) hypertrophy, a major risk factor for cardiovascular morbidity. This study examined the extent to which BP responses to acute stress are associated with LV mass and relative wall thickness in a community sample of African-American and white men and women. BP was measured at rest and in response to 2 acute challenges (mental arithmetic and handgrip). Systolic BP at rest was positively associated with LV mass and relative wall thickness (p < 0.001). The associations between the responses to the stressors and LV mass were not significant. African-American and white men who exhibited high BP responses to the arithmetic stressor had greater relative wall thickness than those with low reactivity (p < 0.05). In conclusion, BP reactivity is not related to LV mass, but may be related to concentric remodeling.

Hostility and distraction have differential influences on cardiovascular recovery from anger recall in women

This study investigated the relation of dispositional hostility to cardiovascular reactivity during an anger-recall task and of hostility and distraction to posttask recovery in 80 healthy women (ages 18-30). Half were randomly assigned to distraction during recovery. Hostility predicted slower systolic blood pressure and preejection period during recovery. Distraction was related to faster cardiac recovery, higher high-frequency (HF) power, lower low-frequency (LF) power and LF:HF ratios, and lower state anger and rumination during recovery. These results indicate deleterious influences of hostility on cardiovascular recovery but not during anger recall. The findings also show beneficial effects of distraction in expediting cardiovascular recovery, possibly through reducing rumination and anger.

Exercise blood pressure, cardiac structure, and diastolic function in young normotensive patients with polycystic kidney disease: a prehypertensive state

BACKGROUND

Increased left ventricular mass (LVM) and left ventricular hypertrophy have been found in early stages of autosomal dominant polycystic kidney disease (ADPKD). The mechanisms that lead to an increase in LVM in this population are unknown. The aim of this study is to evaluate blood pressure (BP) response to exercise and very early alterations in cardiac structure and diastolic function in young normotensive patients with ADPKD.

METHODS

Color Doppler echocardiography and exercise treadmill testing according to the Bruce protocol were performed in 18 young normotensive patients with ADPKD and 18 healthy subjects.

RESULTS

LVM index was greater and isovolumic relaxation time (IVRT) was longer in patients with ADPKD than controls (93.3 +/- 21.4 versus 77.5 +/- 18.6 g/m2; P = 0.02; 100 +/- 20.2 versus 80 +/- 9.7 milliseconds; P = 0.001, respectively). Exercise capacity in metabolic equivalents was similar in both groups. Systolic BP response during exercise and recovery were similar in both groups. Diastolic BP decreased during exercise, but the magnitude of decrease was lower in patients with ADPKD than controls (P = 0.01). During recovery, patients with ADPKD showed a greater sustained diastolic BP than controls (P = 0.02). Patients with ADPKD with an exaggerated systolic BP response had a greater LVM index than those with a normal response (112.1 +/- 10.4 versus 84 +/- 19.2 g/m2; P = 0.001). Multivariate regression analysis showed that exercise systolic BP and diastolic BP were independent predictors of LVM index and IVRT, respectively.

CONCLUSION

Young normotensive patients with ADPKD showed increased LVM index and prolonged IVRT, which are related to exercise BP response. Exaggerated diastolic BP response during exercise suggests an impaired capacity for exercise-induced vasodilatation and may indicate a greater risk for the development of future hypertension.

The Latin American Social Medicine database

Background

Public health practitioners and researchers for many years have been attempting to understand more clearly the links between social conditions and the health of populations. Until recently, most public health professionals in English-speaking countries were unaware that their colleagues in Latin America had developed an entire field of inquiry and practice devoted to making these links more clearly understood. The Latin American Social Medicine (LASM) database finally bridges this previous gap.

Description

This public health informatics case study describes the key features of a unique information resource intended to improve access to LASM literature and to augment understanding about the social determinants of health. This case study includes both quantitative and qualitative evaluation data. Currently the LASM database at The University of New Mexico brings important information, originally known mostly within professional networks located in Latin American countries to public health professionals worldwide via the Internet. The LASM database uses Spanish, Portuguese, and English language trilingual, structured abstracts to summarize classic and contemporary works.

Conclusion

This database provides helpful information for public health professionals on the social determinants of health and expands access to LASM.

Search strategies for population and social subjects in a medical school curriculum

This case study describes strategies developed for medical students to conduct Specific (as opposed to Sensitive) searches in PubMed so they can quickly locate several relevant references to articles on the population and social aspects of medicine. The Specific search strategy protocol for population and social aspects of medicine involves use of the MeSH Database, certain features of the Detailed Display in the MeSH Database, and applying Limits. By teaching the Specific form of search strategy, busy users can learn a handful of basic techniques that should yield a useful proportion of references, thereby ensuring these users' frequent success.

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.

Allelic variation in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) and cardiovascular reactivity in young adult male and female twins of European-American descent

OBJECTIVE

To examine the effect of length variation in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) on individual differences in cardiovascular response to psychological challenge.

METHODS

Heart rate (HR) and systolic and diastolic blood pressure (SBP, DBP) responses to computerized versions of two psychological challenges, the Stroop Color-Word Interference Test and mental arithmetic, were measured among 131 monozygotic (MZ) and 60 dizygotic (DZ) male or female (same-sex) European-American twin pairs. Among the 382 participants, 140 were homozygous for the "long" allele (l/l) at 5-HTTLPR, 61 were homozygous for the "short" allele (s/s), and 181 participants had one long and one short allele (l/s). Association and sib-pair analyses were performed to characterize genetic associations.

RESULTS

In the full sample, 5-HTTLPR was associated with HR reactivity to psychological challenge, albeit in interaction with sex. Task-elicited HR responses of women homozygous for the short allele were significantly greater than among: a) men of the same genotype; and b) women having either one (l/s) or two (l/l) long alleles at 5-HTTLPR. SBP and DBP responsivity was unrelated to genotype. These results were corroborated on reanalysis in two genetically independent subsamples. Variability at 5-HTTLPR also predicted HR reactivity in sib-pair analyses among DZ twins.

CONCLUSIONS

These results suggest that the commonly observed sex difference in HR reactivity may be, in part, genetically mediated and perhaps occur only among individuals homozygous for the short allele at 5-HTTLPR.

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.

Cardiovascular reactivity to psychological challenge: conceptual and measurement considerations

OBJECTIVE AND METHODS

This article is a selective review of recent findings bearing on the conceptualization and measurement of cardiovascular reactivity to psychological challenge, with a focus on several issues relevant to the reliability, content validity, construct validity, and criterion validity of these measures.

RESULTS AND CONCLUSIONS

With respect to reliability, use of standardized task demands and aggregated scores are associated with enhanced short-term reliability, but the long-term reliability of cardiovascular reactivity has not been sufficiently documented. With respect to content validity, existing evidence suggests that "vascular" or "cardiac" tasks may evoke responses that reflect similar distributions of individual difference, whereas associations between responses to "physical" and "psychological" tasks are modest. The evidence is not clear at present with respect to the importance of including affective or interpersonal stimuli as part of trait reactivity assessments. With respect to construct validity, existing data show that cardiovascular reactivity to psychological challenge is largely independent of standard measures of autonomic function. With respect to criterion validity, recent studies point to a number of methodological limitations that may have restricted our ability to detect lab-to-life generalizability of reactivity measures in the past. Continued progress in understanding and measuring reactivity as an individual difference dimension is essential in helping us to evaluate emerging evidence examining the relationship between reactivity and disease risk.

Psychophysiological reactivity: mechanisms and pathways to cardiovascular disease

OBJECTIVE

This article examines possible sources of heightened psychophysiological reactivity in relation to risk for hypertension and coronary artery disease. The idea that exaggerated reactions to psychological stress may predict greater risk for future disease has some support in the psychosomatic and behavioral medicine literature. However, the pathways by which exaggerated reactivity could arise in a given person and the implications of different sources of reactivity for potential disease relationships have received little attention.

METHODS

This topic is approached through a selective literature review and by means of a neurophysiologically based model of individual differences in physiological reactivity. Temperament characteristics, cognitive processes, neurophysiology, and peripheral physiology are used to indicate three levels that could contribute to exaggerated physiological reactivity.

RESULTS

At the top level in the model, activity of the frontal cortex and limbic system establish cognitive-emotional sources of activation that may underlie exaggerated physiological reactivity. In the absence of these influences, large responses may be more likely when exaggerated subcortical response tendencies are present via the hypothalamus or brain stem. Finally, peripheral alterations may account for larger reactions in persons who have otherwise normal emotional and hypothalamic and brainstem response tendencies. Cognitive-emotional and hypothalamic-brainstem sources of altered reactivity may cause or aggravate disease. In contrast, altered peripheral reactivity suggests that a pathophysiologic process may be present, serving as a marker for disease.

CONCLUSIONS

These three levels of analysis allow for organization of existing data in the area of cardiovascular reactivity and for planning future studies in a hypothesis-building framework.

Cardiovascular reactivity and development of preclinical and clinical disease states

OBJECTIVE

The objective of this review is to evaluate the evidence for the hypothesis that cardiovascular reactivity can predict the development of preclinical (elevated blood pressure, ventricular remodeling, carotid atherosclerosis) and/or clinical cardiovascular disease states.

METHODS

A review of the literature was conducted examining prospective studies.

RESULTS

Three large epidemiological studies with long-term follow-up periods (20 years or more) have found blood pressure responses to the cold pressor task to be predictive of subsequent essential hypertension in initially normotensive samples. Studies showing less consistent results have tended to use shorter-term follow-up periods. A larger body of literature demonstrates consistent associations between stress-related cardiovascular reactivity and blood pressure elevations in youth over the course of 1 to 6 years; such relationships have not been consistently shown among adult samples. Moderately consistent evidence points to a positive relationship between reactivity and other measures of subclinical disease (increased left ventricular mass and carotid atherosclerosis) among the few prospective studies that have examined these issues to date. A number of additional factors, however, such as baseline levels of disease risk and exposure to psychosocial stress, seem to moderate these relationships. Health status at baseline also seems to moderate the association between reactivity and clinical coronary heart disease in recent reports: two of three existing studies in initially healthy samples show no evidence of a relationship between reactivity and clinical outcomes, whereas three of four studies in samples with preexisting coronary heart disease or essential hypertension show a positive relationship between reactivity and subsequent disease states.

CONCLUSIONS

There is reasonable evidence to suggest that cardiovascular reactivity can predict the development of some preclinical states (eg, increased left ventricular mass and blood pressure) states and perhaps even new clinical events in some patients with essential hypertension or coronary heart disease. However, much more information is needed concerning moderating and potentially confounding variables before the robustness of the positive relationships can become clinically useful.

Cannabis, tobacco, and caffeine use modify the blood pressure reactivity protection of ascorbic acid

Cannabis, caffeine, and tobacco use are associated with increased mesolimbic dopamine activity. Ascorbic acid (AA) modulates some dopaminergic agent effects, and was recently found to decrease systolic blood pressure (SBP) stress reactivity. To examine how AA SBP stress reactivity protection varies by use of these substances, data from an AA trial (Cetebe, 3000 mg/day for 14 days; N=108) were compared by substance use level regarding SBP reactivity to the anticipation and actual experience phases of a standardized psychological stressor (10 min of public speaking and arithmetic). Self-reported never users of cannabis, persons not currently smoking tobacco, and persons consuming three or more caffeine beverages daily all exhibited AA SBP stress reactivity protection to the actual stressor, but not during the anticipation phase. Conversely, self-reported ever cannabis users, current tobacco smokers, and persons consuming less than three caffeine beverages daily exhibited the AA SBP protection during the anticipation phase, but only the lower caffeine consumption group exhibited AA protection during both phases. Covariates (neuroticism, extraversion, and depression scores, age, sex, body mass index) were all nonsignificant. Results are discussed in terms of dopaminergic effects of these substances, modulation of catecholaminergic and endothelial activity, and AA support of coping styles.

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.

Relationship of clinic, ambulatory, and laboratory stress blood pressure to left ventricular mass in overweight men and women with high blood pressure

OBJECTIVE

This study was designed to evaluate the relationship between left ventricular (LV) mass and blood pressure (BP) recorded in the following contexts: in the clinic, using standard auscultatory procedures, during a typical day using ambulatory BP monitoring, and in the laboratory environment during behavioral stress testing.

METHODS

Ninety-seven men and women with clinic systolic blood pressure (SBP) of 130 to 180 mm Hg and/or diastolic blood pressure (DBP) of 85 to 110 mm Hg and mild to moderate obesity were included in the study. Laboratory stressors included the following tasks: Public Speaking; Anger Interview; Mirror Trace; and Cold Pressor. LV mass was measured using echocardiography and adjusted for body size by dividing by height(2.7) to yield LV mass index (LVMI).

RESULTS

LVMI was positively correlated with clinic SBP (r = 0.24, p <.05), ambulatory SBP (r = 0.34, p <.01), and aggregated laboratory stress SBP (r = 0.28, p <.01). Of the individual stressors, only SBP responses to the Mirror Trace and Cold Pressor tasks were independently correlated with LVMI (r = 0.35 and 0.34, respectively, p values <.01). Hierarchical regression analyses revealed that laboratory stress SBP remained a significant predictor of LVMI, after controlling for BMI and clinic pressure.

CONCLUSIONS

These findings suggest that cardiovascular responses to behavioral stress are associated with individual differences in LVMI in men and women with high blood pressure who are overweight. Laboratory studies of behavioral stress may help promote our understanding of the pathophysiology of LVH.