Heart Rate Biofeedback and Cold Pressor Pain

This study addressed the relative contributions of self-regulated heart rate change and belief that heart rate is changing in an instructed direction to the perception of cold pressor pain. Forty male volunteers were each assigned to one of four combinations of increase or decrease heart rate instructions and increase or decrease feedback conditions. Subjects were given an initial 45-sec cold pressor test, 25 feedback trials, and a final cold pressor in which they were told to change their heart rate in the instructed direction, but without the aid of feedback. Subjects were instructed specifically that increased heart rate was associated with increased pain and decreased heart rate with decreased pain. The veridical groups (consistent instructions and feedback) showed appropriate heart rate changes during biofeedback training and parallel changes in heart rate and pain perception during the final cold pressor. The non-veridical (reverse) feedback groups showed no heart rate change during biofeedback training and no relationship between heart rate and pain perception changes during the final cold pressor test. EMG, respiration, and skin conductance data are presented, and several mechanisms are proposed to explain the physiological and subjective changes.     

Patterns and stability of cardiovascular responses to variations of the cold pressor test

Test-retest reliabilities and patterns of heart rate and blood pressure responses were examined using variations in the cold pressor test in 113 normotensive white college men. Comparisons were made of stimulus site (forehead vs. foot) and bodily posture (seated vs. supine) across four separate groups of men. The stability of cardiovascular responses was examined over a 2-week test-retest interval. Different cardiovascular response patterns emerged as a function of stimulation site and posture. Systolic and diastolic blood pressure increases were accompanied by bradycardia in the forehead cold pressor task but by tachycardia in the foot cold pressor task. Systolic blood pressure increases were larger for foot than for forehead stimulation. Heart rate increases were larger for supine than for seated men. Effects on response were independent of postural differences at baseline, and there were no stimulation site by posture interactions. The cardiovascular responses to stimulation did not attenuate across sessions in any experimental condition but were more reliable for foot than for forehead stimulation and for supine than for seated posture. Short-term stability for changes to the task approached that for baseline and task and was higher than has been reported elsewhere.     

How Many Blood Pressure Measurements are Enough?: An Application of Generalizability Theory to the Study of Blood Pressure Reliability

Generalizability theory was applied to blood pressure measurements collected under various designs in order to determine the number of readings needed to attain reliable estimates. The designs assessed variation within the same day in the laboratory, home, and work; variation across days in the laboratory; and variation across measuring devices. Two samples of normotensive (n=40 and n=79) subjects participated in the study. Blood pressure was measured using either a mercury sphygmomanometer, a Dinamap Adult/Pediatric monitor, or a Spacelabs Ambulatory monitor. The results showed that only one reading is necessary whenever generalizations are restricted to the same day in the laboratory. At least six readings of systolic blood pressure are needed at home and at work, and 6 to 10 diastolic blood pressure readings may be required from work and home, respectively. To generalize across days, one or two readings from each of two days for systolic blood pressure and from more than three days for diastolic blood pressure may be required. At least one replication with each of two instruments is necessary in order to generalize across instruments in the laboratory.     

The Relation Between Rhythmic Cardiovascular Variability and Reactivity to Orthostatic, Cognitive, and Cold Pressor Stress

Two groups of normotensive, male subjects having either a positive or negative parental history of essential hypertension were exposed to passive body tilt from horizontal to a 70° head-up posture, while systolic and diastolic blood pressure, heart period, and respiration amplitude were sampled on a beat-by-beat basis. Subjects also performed mental arithmetic and cold pressor tasks, and cardiovascular reactivity was expressed as change from baseline levels. The body tilt data were analyzed by cross-spectral analysis focusing on two frequency bands, one between .06-.1 Hz, and the other at the predominant breathing frequency. The two groups did not differ significantly in their basal levels of physiological activity or in their response to the tasks. Cross-spectral analysis identified tilt induced changes in the power spectra and coherence spectra within the two frequency bands. These changes differed between the two frequency bands and among the various physiological response systems investigated. Larger rhythmic oscillations in heart period within both frequency bands predicted greater cardiovascular reactivity to the mental arithmetic task but not the cold pressor task. The results are discussed in terms of neural control mechanisms (e.g., vagal tone) implicated in the dynamic regulation of cardiovascular function during psychophysiological states such as stress.     

Stimulus dimensions of the cold pressor test and the associated patterns of cardiovascular response

Hemodynamics of the cold pressor response in relation to its pain and nonpain stimulus components were investigated in normotensive college men using the foot and forehead cold pressor tasks. Mechanisms of pain- and non-pain-related increases in blood pressure were analyzed as residual effects of concurrent changes in total peripheral resistance and cardiac output. The identified partial relationships suggested that the response pattern associated with pain included positive change both in cardiac output and in total peripheral resistance, whereas the nonpain-related response was limited to an increase in total peripheral resistance. Analyses of individual differences in car-diovascular responses to pain further indicated that pain-related increments in blood pressure were mediated by a steeper rise in total peripheral resistance, an increase in heart rate, and an apparent increase in preload. At baseline, high reactors to pain manifested relatively elevated total perpheral resistance, diminished cardiac output, and an indication of a reduced inotropic state, suggesting that altered basal homeostasis may discriminate normotensive individuals displaying heightened cardiovascular reactivity to aversive cold stimulation.     

Evaluation of Myocardial and Peripheral Vascular Responses During Reaction Time, Mental Arithmetic, and Cold Pressor Tasks

The primary purpose of this study was to examine the covariation of cardiac output and forearm blood flow during reaction time, mental arithmetic, and cold pressor tasks. Cardiac output was indexed using impedance cardiography, whereas impedance venous occlusion plethysmography was used lo index forearm blood flow. Cardiac output increased significantly over resting values in all three tasks, hut the pattern of these increases differed. Large heart rate increases during mental arithmetic and cold pressor tasks more than offset stroke volume decreases; the increases in the reaction time task were due to relatively smaller heart rate increases with stroke volume augmentation. For forearm blood flow, all task levels were higher than resting levels, but only mental arithmetic levels were statistically higher. The correlation between cardiac output and forearm blood flow change was significant for the reaction time task, but not for the mental arithmetic or cold pressor tasks.     

Cardiovascular Responses to the Combination of Caffeine and Mental Arithmetic, Cold Pressor, and Static Exercise Stressors

The present study examined cardiovascular responses to the combination of caffeine (250mg) and mental arithmetic, cold pressor, and static exercise stressors in 48 healthy males. Subjects were tested in a within-subject, placebo-controlled, double-blind design. Repeated measurements of heart rate, finger temperature, respiratory sinus arrhythmia, forearm blood flow, and blood pressure were obtained during a pre-drug resting baseline, a post-drug resting baseline, the three stressor tasks, and a recovery baseline. The primary analyses were 2(Drug) x 5(Period) x 6(Stress Order) MANCOVAs using pre-drug baseline values as covariates. Significant period main effects were observed for all measures. Significant drug main effects were observed for blood pressure, finger temperature, respiratory sinus arrhythmia, and forearm blood flow. The significant changes in blood pressure and finger temperature produced by caffeine combined in an additive fashion with the effects produced by the stressors. Significantly greater increases in forearm blood flow and heart rate during mental arithmetic on the caffeine day suggested a potentiation of sympathetic, beta-adrenergic activity. Questionnaires administered during baseline periods to assess psychological responses to stress and caffeine revealed a potentiation of anxiety and anger responses to stress on the caffeine day.     

Relationships between Venous Return and Blood Pressure in Caval Veins and Right Atrium During Pressor Stimulation

The dynamics of changes in blood flow and pressure in the superior and inferior vena cava, total venous return, and right atrial pressure in response to pressor stimuli were studied in acute experiments on cats. It was shown that blood flow and pressure in caval veins changed synchronously and unidirectionally, while shifts in the right atrial pressure did not depend on direction and magnitude of changes in caval flow and pressure and total venous return. Our results suggest that right atrial pressure does not play a role in the regulation of venous return.     

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.     

Children''s Cardiovascular Reactivity: Stability of Racial Differences and Relation to Subsequent Blood Pressure over a One-Year Period

After measuring blood pressure and heart rate at rest and during a video game procedure in 477 children enrolled in 3rd grade, 434 (91%) children had these measurements repeated a year later in 4th grade. Black children demonstrated greater blood pressure and heart rate reactivity than White children in both years, and an increase in heart rate reactivity from 3rd to 4th grade. Gender effects were inconsistent. Systolic and diastolic blood pressures during the video game were more highly correlated from year-to-year than were the resting measures. Regression analysis indicated that systolic reactivity was significantly related to subsequent systolic pressure at rest, particularly among Black girls. Diastolic reactivity was associated with subsequent resting diastolic pressure only among White children. Associations between reactivity and future blood pressure were independent of initial resting blood pressure. This study suggests that cardiovascular reactivity to psychological stress may be one important factor in future level of blood pressure and that the increased heart rate reactivity of Black children may be associated with the prevalence of hypertension among Black adults.     

Hemodynamic Reactivity to Laboratory Stressors in Healthy Subjects: Influence of Gender and Family History of Cardiovascular Diseases

Although laboratory stressor tests have been applied as a preliminary protocol in some cardiovascular studies, there is a lack of data comparing the pressor and chronotropic responses among the main stressor tests. Therefore, the aim of this study was to evaluate the variability in hemodynamic responsiveness to the main stressor tests, establish a hyperresponsiveness cutoff criterion and analyze the influence of gender and family history of cardiovascular diseases (CVDs) in healthy subjects. We examined hemodynamic responses to physical (cold pressor and handgrip tests) and mental (Stroop color-word test) stressors in 98 subjects (48 males and 50 females) without CVDs. All stressor tests resulted in increased blood pressure (BP) levels, which were lower and less dispersed in the handgrip test compared to the cold pressor test. Adopting the 75^th percentile as the cutoff in our data, we classified subjects exhibiting absolute pressor changes equal to or higher than 14, 24 and 36 mmHg in systolic and 9, 13 and 24 mmHg in diastolic BP during the handgrip, Stroop and cold pressor test, respectively, as hyperresponsives. Males exhibited greater (p<0.05) increases in systolic BP in the handgrip (11% vs. 8%) and cold pressor (25% vs. 21%) tests and in diastolic BP in the handgrip (12% vs. 7%) and Stroop (22% vs. 19%) tests than females. A positive association between family history of CVDs and pressor hyperreactivity to stressor tests was observed. We propose using the 75^th percentile of hemodynamic sample values as a cutoff criterion to classify individuals as pressor or chronotropic hyperreactives. We conclude that hemodynamic responsiveness to stressor tests in healthy subjects is positively influenced by male gender and family history of CVDs.     

Heart Rate Acceleration and its Relationship to Total Serum Cholesterol, Triglycerides, and Blood Pressure Reactivity in Men with Mild Hypertension

This study investigated heart rate (HR) acceleration and its relationship to serum cholesterol, triglycerides, and blood pressure reactivity in a group of men with unmedicated mild hypertension. Each man's cardiovascular responses were monitored as he performed the Stroop Color Word Interference test and played the Pac Man Videogame. In comparison to their low HR accelerator counterparts, high HR accelerators manifested greater systolic and diastolic blood pressure responses during behavioral challenge. Moreover, high HR accelerators exhibited higher levels of serum cholesterol and triglycerides than low HR accelerators, even though these determinations were made from blood drawn during the clinic visit that preceded the clinic visit where cardiovascular reactivity was assessed. Heart rate acceleration and its positive association with serum lipids, as well as its role as a potential individual difference relevant to the profiling of persons at greater risk for the development of atherosclerosis were discussed.     

The combined effect of the cold pressor test and isometric exercise on heart rate and blood pressure

Summary The purpose of this study was to determine if the cold pressor test during isometric knee extension [15% of maximal voluntary contraction (MVC)] could have an additive effect on cardiovascular responses. Systolic and diastolic blood pressures, heart rate and pressure rate product were measured in eight healthy male subjects. The subjects performed the cold pressor tests and isometric leg extensions singly and in combination. The increases of systolic and diastolic blood pressure during isometric exercise were of almost the same magnitude as those during the cold pressor test. The responses of arterial blood pressure, and heart rate to a combination of the cold pressor test and isometric knee extension were greater than for each test separately. It is suggested that this additional effect of cold immersion of one hand during isometric exercise may have been due to vasoconstriction effects in the contralateral unstressed limb. In summary, the circulatory effects of the local application of cold during static exercise at 15% MVC were additive.     

高血压病患者血脂、血糖与血压关系的研究

目的:探讨高血压病患者血脂、血糖与血压的相关性。方法:测定482例高血压病患者和100例健康人Cho-C、TG、LDL-C、HDL-C、apoA、apoB、血糖(BS)以及血压(SBP、DBP),并进行统计学分析。结果:高血压组Cho-C、TG、LDL-C、BS明显升高(P<0.05~0.01);Cho-C与BS呈明显正相关(P<0.05);TG与BS、SBP、DBP呈明显正相关(P<0.05~0.01);BS与SBP呈明显正相关(P<0.05)。结论:高血压病患者存在脂代谢及糖代谢异常。TG与血糖水平及血压均呈正相关。     

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.     

Association of Type D personality with the autonomic and hemodynamic response to the cold pressor test

Mechanisms relating Type D personality to poor health are largely unknown, with autonomic nervous system function being a candidate. This study examined the physiologic response to cold stress. Undergraduates (N = 101, 84% female) underwent a cold pressor test. An electrocardiogram, impedance cardiogram, and blood pressure were recorded. Type D personality was assessed by self‐report questionnaire. Type D was associated with increased systolic and diastolic blood pressure reactivity. Exploratory analyses showed Type D men to respond with increased respiratory sinus arrhythmia (i.e., higher parasympathetic activity), and decreased pre‐ejection period (i.e., larger sympathetic activity), while Type D women showed a reciprocal response pattern. In conclusion, Type D personality was associated with an exaggerated hemodynamic response to cold stress, which may contribute to an increased risk of hypertension in Type D individuals.     

Cardiovascular and perceptual effects of reporting pain during the foot and forehead cold pressor tests

In research involving the cold pressor test, a tacit presumption is often made that reporting pain during stimulation is not in itself reactive. This study examined whether, for the foot and forehead cold pressor tests, activities involved in reporting pain may affect (a) the evoked pattern of cardiovascular response, and (b) the magnitude of self-perceived pain. In 40 normotensive college men, increases in systolic blood pressure were greater during test sessions that included verbal ratings of pain, as compared to sessions in which pain was not reported. In contrast to its effect on physiological activation, reporting pain did not significantly alter the participant’s perception of the painfulness of the test, on recollection shortly after the test. We conclude, therefore, that reporting pain during the cold pressor test may impose significant additional demands on the cardiovascular system, but it docs not interfere significantly with the processing of nociceptive information. This research was supported by Grants HL 07426 and HL 36588 from the National Heart, Lung and Blood Institute of the National Institutes of Health     

Hemodynamics of Blood Pressure Responses During Active and Passive Coping

This laboratory study was designed to address a number of interrelated issues regarding cardiovascular reactivity to psychological stress. One objective was to extend the previous research comparing cardiovascular responses during active versus passive coping, by comparing responses to two task conditions designed to be similar in all ways except the opportunity to make a response influencing the task's outcome. A second objective was to compare responses to two different passive film tasks, which differed in outcome uncertainty and the degree of vicarious active coping achieved through identification with the role portrayed by the actors. A third objective was to evaluate whether individuals are predisposed to exhibit a particular hemodynamic pattern underlying their blood pressure adjustments, independently of the task demands imposed. Ninety healthy young adult male subjects were tested in pairs on a series of tasks that included a competitive reaction-time task, an active as well as a passive phase of a team reaction-time task, and passive viewing of two film segments. The tasks demanding active coping responses tended to raise blood pressure due primarily to an increase in cardiac output, while vascular resistance fell. During passive coping demands cardiac output increased to a lesser extent, but vascular resistance also tended to increase, thereby raising blood pressure by their synergistic effects. However, these patterns were not typical of all participating subjects. On the basis of their cardiac output and vascular resistance responses to the competitive reaction-time task, one third of the subjects were categorized as being high myocardial reactors (n = 30) and another third high vascular reactors (n = 31). Post-hoc analyses of responses to the other tasks, based on these categorizations, indicated that the hemodynamic basis of reactivity is an individual characteristic only partially modified by coping demands. The active/passive coping dimension is discussed both conceptually and in relation to the role of stress in the etiology of hypertension.     

Reliable Measures of Behaviorally-Evoked Cardiovascular Reactivity from a PC-Based Test Battery: Results from Student and Community Samples

This paper describes efforts to reduce measurement error in the assessment of cardiovascular reactivity by standardizing task requirements and by aggregating data across tasks and testing sessions. Using these methods, reliable measures of reactivity (.80 or greater) were obtained on five different measures of cardiovascular function (heart rate, systolic blood pressure, diastolic blood pressure, stroke volume, pre-ejection period) in samples of college students and community volunteers. Methodological limitations may have hampered previous efforts in this area. Current findings are consistent with a dispositional model of cardiovascular reactivity, and they suggest productive future strategies for obtaining reliable assessments.     

Relationship between Blood Pressure Variability and the Quality of Life

Purpose

Blood pressure variability (BPV) is emerging as an important cardiovascular prognostic factor in addition to average blood pressure level. While there have been some suggestions for the determinants of the blood pressure variability, little is known about the relationship between the blood pressure variability and health-related quality of life (QOL).

Materials and Methods

Fifty-six men and women with mild hypertension were enrolled from local health centers in Republic of Korea, from April to October 2009. They self-monitored their blood pressure twice daily for 8 weeks. Pharmacological treatment was not changed during the period. Standard deviation and coefficient of variation of blood pressure measurements were calculated as indices of BPV. Measurements of QOL were done at initial and at 8-week follow-up visits.

Results

Study subjects had gender ratio of 39:41 (male:female) and the mean age was 64±10 years. The mean home blood pressure''s at week 4 and 8 did not differ from baseline. Total score of QOL at follow-up visit and change of QOL among two measurements were negatively correlated to BPV indices, i.e., higher QOL was associated with lower BPV. This finding persisted after adjustment for age, gender and the number of antihypertensive agents. Among dimensions of QOL, physical, mental and hypertension-related dimensions were associated particularly with BPV.

Conclusion

QOL may be a significant determinant of BPV. Improvement of QOL may lead to favorable changes in BPV.