Hemodynamic response patterns: responder type differences in reactivity and recovery

We examined whether responder type groups reflecting patterns of hemodynamic reactivity might also differ in recovery responses. Cardiac output (CO), total peripheral resistance (TPR), systolic and diastolic blood pressure, heart rate, and Heather index were assessed at rest and during speech and cold pressor tasks in young adults. Participants (n = 152) were classified as myocardial, vascular, or mixed-mild responders based on CO and TPR responses to speech presentation. Vascular responders exhibited slower CO and TPR speech recovery than the myocardial and/or mixed-mild groups. Responder type differences in reactivity showed limited task-generalizability. The sustained vascular response pattern of the vascular group is consistent with that seen in hypertension. In light of associations of heightened TPR with markers of disease risk, this suggests potentially negative health implications for vascular responders.     

Hemodynamic profile, compensation deficit, and ambulatory blood pressure

This study hypothesized that physiologically grounded patterns of hemodynamic profile and compensation deficit would be superior to traditional blood pressure reactivity in the prediction of daily-life blood pressure. Impedance cardiography-derived measures and beat-to-beat blood pressure were monitored continuously in 45 subjects during baseline and four tasks. Ambulatory blood pressure measures were obtained combining data from one work day and one off day. The mediating effects of gender and family history of hypertension were considered. Only gender was significantly associated with hemodynamic profile. Regression analysis indicated that typical reactivity measures failed to predict everyday life blood pressure. After controlling for gender and baseline blood pressure, hemodynamic patterns during specific tasks proved to be strong predictors, overcoming limitations of previous reactivity models in predicting real-life blood pressure.     

Stability of individual differences in cardiovascular reactivity

Examining the stability of individual differences in cardiovascular reactivity, 42 male subjects were presented a difficult cognitive task to perform at each of two experimental sessions, scheduled 1 week apart, and recordings of hear rate and systolic and diastolic blood pressure obtained during periods of rest and task performance on each occasion of testing. Measures of task-related arousal (reactivity) across the two experimental sessions revealed substantial and reliable individual differences on all three response variables, as evidenced by (1) subsets of subjects representing clearly differentiated groups of Reactors and NonReactors on each measure and (2) correlation of reactivity scores of all subjects between the first and second sessions. While individual differences in systolic blood pressure and heart rate reactivity correlated positively, magnitude of systolic and diastolic blood pressure responses did not covary reliably among subjects. It was concluded that the present data demonstrate consistency, or reproducibility, of idiosyncratic cardiovascular reactivity and suggested that the variability of relationships among response measures may reflect more basic dimensions of individual differences involving neuroregulatory mechanisms underlying cardiovascular adjustments.     

Stress reactivity and the Hemodynamic Profile-Compensation Deficit (HP-CD) Model of blood pressure regulation

Considering the central role of the concept of blood pressure reactivity to explanations of the influence of life stress in the pathogenesis of cardiovascular disease, it is important that the underlying psychophysiological determinants of blood pressure change are elucidated. Empirical evidence is reviewed concerning the utility of the Hemodynamic Profile-Compensation Deficit (HP-CD) Model (Gregg et al., 2002), which draws on physiological theory that explains blood pressure regulation as a dynamic compensatory relation between cardiac output and total peripheral resistance. Core constructs and quantitative features of the Model are explained, accompanied by a focussed review of the Model's application in reactivity studies of stress, lifestyle behaviours, laboratory-to-field generalisability, and personality differences. Although the available studies are relatively few in number, evidence of the Model's utility is promising. Application of the Model in further research could help to elucidate cardiovascular pathogenesis in ways not achievable through the study of blood pressure reactivity alone.     

Stability of individual differences in cardiovascular reactivity: A thirteen month follow-up

This study concerns the stability of individual differences in cardiovascular reactivity among nineteen male subjects who had participated in a similar investigation thirteen months earlier. In the previous study (Year I), subjects were presented a frustrating task in concept formation to perform at each of two experimental sessions, scheduled one week apart, and recordings of heart rate (HR) and systolic and diastolic blood pressure (SBP, DBP) obtained during periods of rest and task performance on each occasion of testing. Under the current procedure (Year II), subjects were exposed to the same experimental stressor as on year I, as well as a second cognitive task involving a difficult problem in “mental arithmetic”; HR, SBP and DBP were again recorded both at rest and while subjects performed the instructed tasks. Measures of task-related cardiovascular arousal across the two years of observation revealed reproducible individual differences with respect to the magnitude of subjects' HR and SBP, but not DBP, reactivity. Although individual differences in HR and SBP responses correlated positively, neither HR nor SBP reactivity covaried reliably with DBP changes. It was suggested that concomitant response differences in HR and SBP, as observed under these experimental conditions, may reflect an underlying dimension of individual differences in beta-adrenergic reactivity.     

The acute post-exercise response of blood pressure varies with time of day

The reactivity of ambulatory blood pressure following a given change in everyday physical activities is highest in the morning. Whether the acute response of blood pressure following a controlled bout of steady-state exercise is influenced by time of day is examined in this study. After 45 min of supine rest, 12 male normotensives completed 30 min of cycling at 70% [Formula: see text] which began at either 0800 or 1600 hours. Arterial blood pressure, cardiac output, total peripheral resistance, cutaneous blood flow and temperature were determined before, and up to 90 min after, exercise. Mean +/- SE arterial pressure, averaged over the acute (20-min) period, reduced by 7 +/- 2 mmHg following exercise at 1600 hours but increased by 3 +/- 3 mmHg following exercise at 0800 hours (P = 0.03). Total peripheral resistance fell by 4.2 +/- 0.8 mmHg l(-1) min(-1) after exercise at 1600 hour, but increased slightly by 0.1 +/- 0.5 mmHg l(-1) min(-1) after morning exercise (P = 0.02). We conclude that the acutely hypotensive effects following 30 min of steady state exercise are less marked in the morning, probably because the exercise-mediated decrease in peripheral resistance is not as apparent at this time of day.     

Shifting hemodynamics of blood pressure control during prolonged mental stress

The present study examined the hemodynamics underlying blood pressure elevations for evidence of a shift in the control of blood pressure during prolonged mental stress. Mean arterial pressure (MAP), cardiac output (CO), and total peripheral resistance (TPR) were measured at rest, during a 28-min mental arithmetic stress task, and during recovery, in 30 young healthy men and women. The stress task elicited a sustained increase in MAP: CO rose during the first half of the task but returned to baseline levels during the last quarter of the task, whereas TPR increased as the task progressed. When participants' hemodynamic reactions were classified as cardiac, vascular, or neither, there were more cardiac reactors early relative to late in the task, whereas there were more vascular reactors late relative to early. Thus, the sustained pressor response was initially supported mainly by cardiac mechanisms but subsequently by predominantly vascular mechanisms.     

A twin study of cardiac reactivity and its relationship to parental blood pressure

The cardiac reactivity of 40 monozygotic and 40 dizygotic pairs of young male twins was monitored during psychological challenge, as afforded by a video game. The observed pattern of variation could not be accounted for solely by environmental factors. In fact, a simple genetic model that implicated additive genetic effects, along with those stemming from individual environments, best fitted the data. In addition, cardiac reactions were substantially greater for subjects whose parents both had relatively elevated blood pressure. Overall, these data suggest individual differences in cardiac reactivity have a heritable component, and that high reactivity may be a precursor of elevated blood pressure.     

Reproducibility of blood pressure and heart rate reactivity: A meta-analysis

Reproducibilities of blood pressure and heart rule (HR) reactivity reported in studies assessing responses to the same laboratory stressors across occasions were reviewed with meta-analytic techniques. Changes in HR had the greatest reproducibility (r =.555), followed by systolic blood pressure (SBP) (.407) and diastolic blood pressure (DBF) (.348), Both SBP and HR response reproducibility was higher at shorter lest-retest intervals, whereas DBP values varied unsystematically with length of test-retest interval Older samples exhibited higher SBP and DBP reproducibility to stressors. SBP and DBP reproducibilities were better for tasks that did not make speech demands. The reliability of reactivity assessment was higher when based on three or more measurements, On the basis of able evidence, the drop in stress reproducibility, as test-retest interval increases, places limits on the viability of BP reactivity as a strong marker or risk factor for coronary heart disease.     

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.     

Influence of population and exercise protocol characteristics on hemodynamic determinants of post-aerobic exercise hypotension

Due to differences in study populations and protocols, the hemodynamic determinantsof post-aerobic exercise hypotension (PAEH) are controversial. This review analyzedthe factors that might influence PAEH hemodynamic determinants, through a search onPubMed using the following key words: “postexercise” or “post-exercise” combined with“hypotension”, “blood pressure”, “cardiac output”, and “peripheral vascularresistance”, and “aerobic exercise” combined only with “blood pressure”. Forty-sevenstudies were selected, and the following characteristics were analyzed: age, gender,training status, body mass index status, blood pressure status, exercise intensity,duration and mode (continuous or interval), time of day, and recovery position. Dataanalysis showed that 1) most postexercise hypotension cases are dueto a reduction in systemic vascular resistance; 2) age, body massindex, and blood pressure status influence postexercise hemodynamics, favoringcardiac output decrease in elderly, overweight, and hypertensive subjects;3) gender and training status do not have an isolated influence;4) exercise duration, intensity, and mode also do not affectpostexercise hemodynamics; 5) time of day might have an influence,but more data are needed; and 6) recovery in the supine positionfacilitates systemic vascular resistance decrease. In conclusion, many factors mayinfluence postexercise hypotension hemodynamics, and future studies should directlyaddress these specific influences because different combinations may explain theobserved variability in postexercise hemodynamic studies.     

Influence of control and physical effort on cardiovascular reactivity to a video game task

This study investigated the influences of both perceived control and physical effort on cardiovascular reactivity. Undergraduates (N = 32) played a video game task interrupted by aversive noise. Perceived control of the noise was manipulated by instructions indicating the presence or absence of a contingency between performance and noise presentations. Physical effort was manipulated by controlling the physical force required to perform the task. There was a significant main effect of control on systolic blood pressure (SBP) and total peripheral resistance (TPR), with both increasing more during low than high control conditions. The results suggest that high perceived control over aversive noise in an effortful task reduces SBP and TPR reactivity relative to low perceived control. The results are consistent with the idea that control buffers the reactivity associated with task performance under aversive conditions.     

Cardiovascular reactivity and resistance to opposing viewpoints during intragroup conflict

This study examined how the outcomes of joint decision making relate to cardiovascular reactions when group members disagree about the decision to be taken. A conflict was experimentally induced during a joint decision‐making task, while cardiovascular markers of challenge/threat motivational states were assessed following the biopsychosocial model of challenge and threat (BPSM; J. Blascovich, 2008 ). Results show that individuals were less likely to adjust their initially preferred decision alternative the more they exhibited a cardiovascular pattern indicative of threat (i.e., relatively high total peripheral resistance and low cardiac output) compared to challenge. This finding extends the BPSM by showing a link between threat and rigidity, and emphasizes the importance of psychophysiological processes for studying intragroup conflict and decision making.     

Systemic overperfusion and resting blood pressure

During psychosocial stressors, individuals with mildly elevated resting blood pressures (BP) exhibit cardiac output (CO) that is in excess of metabolic demand (i.e., systemic overperfusion). The present study used the "additional" CO method to assess whether individuals in the high average BP range also exhibit systemic overperfusion at rest. Healthy young adult males (N = 48), divided into "high average" and "low average" groups using resting BP, participated in an active coping task. Consistent with past research, the high average group evidenced higher levels of additional CO than did the low average group during both baseline and task periods. More importantly, the high average group also exhibited significant amounts of additional CO at rest, whereas the low average group did not. These results may help to advance our understanding of the process by which systemic overperfusion may contribute to the development of elevated BP.     

Postural stability of hemodynamic responses during mental challenge

Laboratory stress testing is typically conducted while subjects are seated, whereas real-life stressors may often be encountered while standing. The present study of 20 healthy young men evaluated blood pressure and underlying hemodynamic adjustments to a standardized mental arithmetic task performed twice while seated and twice while standing. Blood pressure increased during mental arithmetic in both postures, but the underlying hemodynamic determinants of the pressor responses were different for the two postures. Augmented cardiac output was responsible for increasing blood pressure during seated task performance, whereas increased vascular resistance was the mechanism for the pressor response to the task performed while standing. Blood pressure and hemodynamic responses were reproducible subject characteristics for a given posture; test-retest correlations were significant for all cardiovascular measures. However, seated blood pressure responses were not significantly correlated with standing blood pressure responses. In contrast, significant between-posture correlations were found for cardiac output and vascular resistance responses. This preliminary evidence of postural stability of the hemodynamic determinants of blood pressure responses during stress is consistent with growing evidence that hemodynamic response tendencies are robust characteristics of reactivity. Ambulatory monitoring of hemodynamic response patterns during real-life stress may reveal more idiosyncratic profiles of stress reactivity than are displayed by blood pressure responses alone.     

Blood pressure changes highlight gender differences in emotional reactivity to arousing pictures

The current study was aimed at investigating the effects of gender on the magnitude and patterning of blood pressure responses to specific pleasant and unpleasant, arousing visual stimuli. Systolic and diastolic blood pressure (SBP and DBP), as well as heart rate (HR) and skin conductance (SCR) responses were investigated during picture viewing in 21 female and 25 male students. The pattern of SCR and HR reactivity across emotional categories was found to be similar for men and women. Gender was found to be an effective moderator of BP responses specifically to sexual stimulus content, which prompted greater reactivity in men than in women. These findings extend prior research on gender differences in autonomic responding to emotional visual stimuli and suggest that BP changes might reflect sexual peripheral arousal more than other autonomic measures.     

Ethnic differences in cardiovascular-somatosensory interactions and in the central processing of noxious stimuli

Ethnic differences in central sensitization of pain processing and stress-relevant endogenous pain regulatory mechanisms were examined. Forty-four African Americans (AAs; 50% women) and 44 non-Hispanic Whites (nHWs; 50% women) matched for socioeconomic status, were tested for pain responses to the temporal summation of heat pulses and ischemic and cold pain. Resting and stress blood pressure (BP) and norepinephrine (NE) were assessed. AAs had heightened pain responses to all 3 pain tasks relative to nHWs. In nHWs, higher BP and NE were related to reduced pain. In AAs, there was no relationship between BP and pain, but higher NE was related to increased pain. This study provides evidence for ethnic differences in centrally mediated pain and extends prior research demonstrating ethnic differences in endogenous pain regulatory mechanisms. These results have implications for understanding biobehavioral factors contributing to ethnic disparities in clinical pain.     

Central and peripheral hemodynamics during maximal leg extension exercise

Summary The purpose of this study was to examine the central and peripheral hemodynamic adaptations to maximal leg extension exercise. Seventeen men (¯X=25 years, 84 kg) performed leg extension exercise (Universal equipment) for 12 repetitions (90s) to fatigue. Each repetition consisted of a 3s lifting motion, 1s pause, and 3s lowering motion. Impedance cardiography was used to measure stroke volume (SV), cardiac output ( ), systolic time intervals, and impedance contractility indices on a beat-by-beat basis. There were significant increases in systolic, diastolic, mean arterial pressure, total peripheral resistance, and HR during exercise. The mean remained similar throughout the protocol. SV decreased even though indices of myocardial performance indicated an enhancement of contractility. The magnitude of and SV were dependent upon the phase of leg extension. SV and during the lifting portions of the exercise were smaller than the lowering portions. The differences in SV and during the concentric and eccentric phases of the exercise most likely reflect the large static forces in exercising muscle which impeded venous return and increased afterload.     

Piecewise latent growth curve modeling of systolic blood pressure reactivity and recovery from the cold pressor test

Latent growth curve methodology was used to model systolic blood pressure reactivity and recovery from the cold pressor test. A piecewise regression approach permitted the separate but simultaneous modeling of the two components (reactivity and recovery) of the stress process. Data came from a study of 99 participants classified on the basis of gender, ethnicity, and family history of hypertension. Their systolic blood pressure was assessed at rest, during the cold pressor test, and during a task recovery period. A measure of task appraisal and readings from ambulatory blood pressure monitoring during a workday were also examined. The article illustrates a step-by-step approach to modeling reactivity and recovery. Results indicated that both reactivity and recovery were associated with subsequent systolic blood pressure at work.     

Etiology of individual differences in reading performance: A test of sex limitation

To test the hypothesis that the etiology of individual differences in reading performance differs in males and females, reading performance data from twin pairs tested in the Colorado Learning Disabilities Research Center were fitted to structural equation models of sex limitation. The sample included 513 pairs of twins in which at least one member of each pair has a positive school history of reading problems [228 monozygotic (MZ), 176 same-sex dizygotic (DZ), and 109 opposite-sex DZ pairs] and 302 matched control pairs [148 MZ, 98 same-sex DZ, and 56 opposite-sex DZ pairs]. Estimates of the genetic correlation between performance in males and females were obtained by analysis of data from both same-sex and opposite-sex twin pairs (Neale and Cardon, 1992). The full model fit the data well ²=17,74, df=16,p=0.340), and the resulting genetic parameter estimates were highly similar in males and females in both the proband and the control samples. The correlations between genetic influences in males and females do not differ among groups (change in ²=0.95, df=1,p0.25), and the resulting pooled estimate is about .5. Thus, results of this analysis suggest that the etiology of individual differences in reading performance may differ to some extent in males and females.