Family History of Hypertension and Cardiovascular Changes During High and Low Affect Provocation

The present study investigated whether subjects with a positive family history of hypertension would display differential responses in blood pressure and heart rate across different laboratory tasks. We also wanted to know whether subjects would display stable within-subject responses across different laboratory tasks. Twenty-three family history positive subjects and 23 with a negative family history participated in three tasks: 1) mental arithmetic, 2) a conversation about the weather (low affect task), and 3) a conversation about a recent upsetting, interpersonal event (high affect task). Positive family history was associated with elevated diastolic resting blood pressure and greater diastolic responsivity overall. For both groups, arithmetic was associated with the greatest heart rate changes, whereas the distressing conversation was accompanied by the greatest diastolic blood pressure response. Stability of cardiovascular activation across different tasks was present only for heart rate; it was weak for diastolic blood pressure, and completely absent for systolic blood pressure.     

Family History of Hypertension and Cardiovascular Responses to Orthostatic Stress

Cardiovascular effects of orthostatic stress (sitting to standing) were assessed in 60 healthy young male subjects according lo family history of hypertension (half with a positive and half with a negative family history' of hypertension). Systolic (SBP) and diastolic blood pressure (DBF) were recorded on each successive heart heal using a non-invasive blood pressure tracking system. Heart rate (HR) and respiration rate (RR) were also recorded. During the postural change, characteristic phasic changes were shown with an initial fall and subsequent recover of SBP and DBF and a mirror image response in MR and RR. Phasic analysis of the pre-standing sit, peak/trough, and recovery stand values indicated group differences in the initial as well as the later phases of orthostatic response. In the initial phase, subjects with a positive family history of hypertension showed an earlier trough in systolic and pulse pressure and an earlier peak in heart rate response immediately on standing up. The level of the pulse pressure trough was also higher in these subjects. In the later standing phase, these subjects showed higher levels of pulse pressure. The results were interpreted in terms of increased sympathetic nervous system activity during the initial phase and structural and neurocirculatory abnormalities in the later phase of orthostatic regulation in individuals with a positive family history of hypertension.     

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.     

Biofeedback Training of Blood Pressure: A Comparison of Three Feedback Techniques

Three biofeedback procedures were compared for their effectiveness in training subjects to modify systolic blood pressure (BP). Three groups of 6 normotensives received three training sessions using one of three types of systolic BP feedback: 1) proportional feedback at 75-sec intervals, 2) relatively continuous proportional feedback, or 3) a form of continuous binary feedback. Three subjects also completed a fourth, no-feedback, session. Each session consisted of 5 training cycles, during which the subject was first instructed to “lower” BP and then “don't lower” BP. This design permitted demonstration of subjects' ability to control BP, rather than just lowering it. Systolic and diastolic BPs were recorded, as were heart rate, respiration rate and respiration volume. The continuous binary feedback technique was most successful in producing systolic BP control, apparently due to the short feedback latency and maximal information available to subjects. Diastolic BP often increased within sessions even when systolic BP decreased. No consistent covariation between BP and other physiological responses was observed, although at times these responses varied systematically with instruction. Continued systolic BP control at diminished levels was demonstrated by subjects who completed a fourth, no-feedback, session.     

Blood Pressure Discrimination

This research concerns the ability of humans to discriminate variations in their own blood pressure in comparing two successive 5-s periods, and the effects of discrimination training (knowledge of results) on their performance. The subjects were 72 healthy male volunteers studied under various conditions. Continuous recordings were made of blood pressure, heart rate, and respiration. Without knowledge of results, discrimination of systolic blood pressure occurred at chance levels, but performance improved significantly over two sessions of discrimination training. This improvement was not maintained in a subsequent session in which no feedback was provided. Discrimination of diastolic blood pressure achieved significant levels when subjects were given knowledge of results. In general, the larger the difference to be discriminated in pressure, the better the performance. The paper also discusses relationships between blood pressure discrimination performance and simultaneous variations in heart rate and respiration, post-session subjective reports, and the role of cuff pressure changes in performance.     

Cardiovascular responses in Type A and Type B men to a series of stressors

Fifty-six healthy adult males were administered the Type A Structured Interview and assessed as exhibiting either Type A (N=42) or Type B (N=14) behavior pattern. They were monitored for systolic (SBP) and diastolic blood pressure (DBP) and heart rate (HR) responses during a series of six challenging tasks: Mental Arithmetic, Hypothesis Testing, Reaction Time, Video Game, Handgrip, and Cold Pressor. The results indicated that Type A subjects exhibited greater cardiovascular responses than did Type B subjects during some (Hypothesis Testing, Reaction Time, Video Game and Mental Arithmetic) but not all (Handgrip and Cold Pressor) of the tasks. These results are discussed in terms of previously reported findings on conditions that do and do not produce differences in Type A/B cardiovascular stress responses. This research was supported by USPHS Grant MH-31269. We would like to thank Drs. Steve Manuck, David Krantz, Ted Dembroski, Curt Sandman, David Hothersall, and Gifford Weary for their helpful comments on an earlier draft of this paper.     

Cardiovascular responses to a quantified dose of nicotine as a function of personality and nicotine tolerance

Correlations between cardiovascular effects of a quantified dose of nicotine and personality measures previously shown to predict coronary heart disease were obtained. Thirty male smokers smoked a popular brand of a regular strength cigarette (1.0 mg FTC-estimated nicotine delivery) on one occasion and a nicotine-free cigarette on another occasion by means of a quantified smoke delivery system. Partial correlations controlling for effects of body weight, questionnaire-assessed nicotine tolerance, and cardiovascular responses to the nicotine-free control cigarette showed Jenkins Activity Survey Type A scores to correlate positively with nicotine-induced increase in diastolic blood pressure but negatively with nicotine-induced increase in systolic blood pressure. Partial correlations indicated that trait anxiety and depression were significantly associated with nicotine-induced heart rate increases but not with nicotine-induced blood pressure responses.This work was supported by a grant from the Office of Research and Development Administration of Southern Illinois University at Carbondale. This article is based on the first author's thesis, which was supervised by the second author.     

Task Difficulty, Type A Behavior Pattern, and Cardiovascular Response

Forty-one young male subjects performed either an easy or moderately difficult arithmetic task with the opportunity to earn a monetary incentive if they did well. Cardiovascular (heart rate, systolic and diastolic blood pressure) and subjective responses were assessed immediately prior to and 5 min following task performance. Results indicated greater systolic (SBP) responses during the Pre-task period for subjects expecting to perform the difficult task. Behavior pattern classifications based on the Jenkins Activity Survey revealed Higher Pre-task heart rate (HR) elevations among Type As compared to Bs in the Difficult task condition, and greater Pre-task SBP responses in As compared to Bs irrespective of task difficulty. There also was some evidence of an association between SBP reactivity and scores on the Thurstone Activity scale. Change-scores reflecting SBP and HR reactivity were correlated in the Pre-task period of the Difficult but not the Easy condition. Predictions regarding the impact of motivational arousal upon goal attractiveness were not supported, possibly for methodological reasons.     

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.     

Plasma lactate levels during baseline and blood pressure conditioning in the baboon

Lactic acid in arterial blood, systolic and diastolic blood pressures, and heart rates of baboons were examined for three naive subjects, and for five experimental subjects during baseline conditions and during training to elevate diastolic blood pressure through operant conditioning methodology. Lactic acid and cardiovascular levels were determined at rest (9 a.m.), and at 12:30 and 3:00 p.m. (during conditioning sessions, for trained subjects). At rest (baseline) lactic acid levels and cardiovascular measures were similar for conditioned and naive subjects. During conditioning sessions, blood pressures but not heart rates were significantly elevated. Plasma lactate increased from morning to afternoon in both naive and trained subjects, but at three hours of conditioning, trained subjects had significantly higher lactate levels than when at rest and when compared to naive subjects at the same time of day. This study provides normative data for plasma lactate in the laboratory baboon and also indicates metabolic changes (which may be related to increased muscular work) as part of concurrent changes in multiple systems (e.g., neural, hormonal) which accompany conditioned blood pressure elevations.     

Control of Diastolic Blood Pressure in Man by Feedback and Reinforcement

When provided with external feedback of their diastolic blood pressure and incentives to respond appropriately, normal male Ss learned to raise or lower their diastolic pressure in a 35-min training session. The difference between increase and decrease groups at the end of conditioning was 7.0 mm Hg or 10% of baseline. This difference was augmented to 10.4 mm Hg or 15% of baseline during extinction when half the Ss were asked to maintain continuing “voluntary control” even though feedback and incentives were withdrawn. Heart rate was also influenced when diastolic blood pressure was reinforced, although less markedly. Further analysis indicated that when diastolic pressure is reinforced, heart rate is partially reinforced in the same direction, accounting for the coincidental conditioning of the related cardiovascular measure. No consistent changes in respiration or post-session verbal reports were obtained. These results lend support to the possibility of therapeutic application of the techniques in patients with essential hypertension.     

Psychological and Physiological Variables Associated With Large Magnitude Voluntary Heart Rate Changes

Forty subjects, given binary and proportional auditory and visual feedback and asked to raise and lower their heart rate on signal, were able to produce increases of up to 46 bpm and decreases of up to 14 bpm, with a mean increase over 5 experimental days of 11 bpm and a decrease of 5 bpm. Increases in both diastolic and systolic blood pressure and increases in skin potential level and number of skin potential responses accompanied voluntary increases in heart rate but not decreases. Subjects with the highest resting heart rate variability and skin potential level were best able to raise their heart rate. Subjects with the highest resting heart rate and highest resting heart rate variability were best able to decrease the heart rate. Subjects with high Ego Strength scores (or low Welsh's Factor A scores) on the MMPI were best able to control their heart rate. The Ego Strength score, resting heart rate, and resting heart rate variability were all significantly intercorrelated. Subjects showed marked individual differences in ability to control heart rate, although there was a significant correlation between ability to raise and ability to lower heart rate.     

Diurnal changes in blood pressure and heart rate in children with narcolepsy with cataplexy

The hypocretin neurons in the lateral hypothalamus are connected not only to brain alertness systems but also to brainstem nuclei that regulate blood pressure and heart rate. The premise is that regulation of blood pressure and heart rate is altered and affected by methylphenidate, a stimulant drug in children with narcolepsy with cataplexy. The changes in 24-hr ambulatory systolic and diastolic blood pressure and heart rate were compared among pre-treated narcolepsy with cataplexy patients (40 males, 10 females), with mean age 10.4 ± 3.5 years (M ± SD, range 5–17 years) with values from 100 archival age–sex–body mass index matched controls. Patients had a lower diurnal systolic blood pressure (−6.5 mmHg; p = 0.000) but higher heart rate (+11.0 bpm; p = 0.000), particularly evident in the waketime, while diastolic blood pressure was comparable. With methylphenidate (18 mg sustained release at 08:00 hours), patients with narcolepsy with cataplexy had higher systolic blood pressure (+4.6 mmHg, p = 0.015), diastolic blood pressure (+3.3 mmHg, p = 0.005) and heart rate (+7.1 bpm, p = 0.028) during wake time, but nighttime cardiovascular values were unchanged from pre-treated values; amplitude variation in cardiovascular values was unchanged over 24 hr. In conclusion, children with narcolepsy with cataplexy had downregulation blood pressure profile but a higher heart rate, and lesser non-dipping profiles. Daytime methylphenidate treatment increases only waketime blood pressure and further elevated heart rate values.     

Cardiovascular Responses to Stress: II. Relationships to Aerobic Exercise Patterns

A sample of 174 men aged 18–22 years were divided into thirds based on self-reported levels of weekly aerobic exercise. Heart rate, systolic and diastolic blood pressure, and pre-ejection period responses of these low, moderate, and high exercise groups were compared during a pretask rest and a later acclimated rest, a bicycle exercise task, a purported shock-avoidance reaction time task, and the cold pressor test. The low exercise subjects showed higher heart rates and marginally higher diastolic blood pressures than the high exercise subjects at rest. The low exercise subjects also showed greater myocardial responses to the mild exercise task and the reaction time task than the high exercise subjects, as reflected by group differences in heart rate, systolic blood pressure, and pre ejection period measures after covariance adjustment for baseline differences. Group differences observed in response to the cold pressor test were smaller and generally nonsignificant. These results were interpreted as evidence that aerobic exercise training may decrease beta-adrenergic myocardial responses to physical and behavioral challenges.     

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

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

Daily mood states and ambulatory blood pressure

In this study, we examined relationships between moods and both ambulatory blood pressure and heart rate in 197 men and women college students. Participants who reported frequently feeling angry during the day had higher levels of blood pressure, especially diastolic pressure during sleep. Reports of sad feelings were positively correlated and reports of pleasant or happy were negatively correlated with diastolic pressure during sleep. Participants scoring high on hostility and anxiety trait measures and low on defensiveness reported negative moods more frequently. Cluster analysis identified different mood profiles. Participants characterized by reports of all negative moods plus anger had high scores on trait hostility and consistently higher levels of blood pressure, particularly diastolic pressure during sleep. Heart rate was not related to mood reports. Hostile and anxious behavioral dispositions may play a role in sleep disturbance and high levels of blood pressure. Positive moods may counter these effects.     

Cardiovascular Responses to Mental Arithmetic and Handgrip During Different Conditions of Postural Change

Twenty healthy male subjects, aged 18–29 yrs, were studied during three sequences of four different postural trials-sitting, sitting to standing, standing, and standing to sitting. The first sequence was a baseline, without other stimulation. In the remaining two, subjects performed a mental arithmetic task and an isometric handgrip task during each trial (counterbalanced). Systolic blood pressure, diastolic blood pressure, heart rate, and skin conductance were recorded during the trials. The physiological responses to the two tasks were shown to vary as a function of the specific postural trial. Systolic and diastolic blood pressure were generally more sensitive to these effects than heart rate or skin conductance. The two tasks facilitated increases in blood pressure during the sitting to standing trials, especially during the standing phase. The increases in blood pressure were comparable to those reported previously for voluntary control and biofeedback procedures. Mental and physical strategies are effective in increasing blood pressure during postural change and may be useful in the management of orthostatic hypotension.     

The beat-to-beat blood pressure response to postural change in young and elderly healthy adult males

Heart rate and blood pressure were studied with the beat-to-beat tracking cuff system in two groups (n=20 per group) of healthy, unmedicated males, one between 60 and 75 years of age and the second between 18 and 29 years of age. The study confirms the previously reported blunted heart rate response to standing and the fact that, when blood pressure is recorded by conventional means, the response exhibited during orthostasis does not differ in healthy groups of young and elderly subjects. With the tracking cuff system, however, the elderly exhibited a smaller immediate systolic and diastolic drop in response to the change to upright posture and less variability in beat-to-beat blood pressure changes. The results have implications for cardiovascular studies, where age and posture can influence both blood pressure and heart rate.This research was supported by National Heart, Lung, and Blood Institute Research Grant HL-31184-05.     

Maternal stress responses and anxiety during pregnancy: effects on fetal heart rate

This study examined the effect of an acute maternal stress response and anxiety on fetal heart rate. Seventeen healthy, 3rd-trimester pregnant women (mean age = 26 +/- 6 years) were instrumented for continuous electrocardiography, blood pressure (BP), respiration, and fetal heart rate (HR). Subjects completed the state anxiety subscale of the State Trait Personality Inventory (STPI), then rested quietly in a semirecumbent position for a 5-min baseline period, followed by either a 5-min arithmetic or Stroop color-word task. Over the entire 5-min stress period and when averaged across all subjects, the stressors led to significant increases in maternal systolic BP and respiratory rate but changes in maternal HR, diastolic BP, and fetal HR were not significant. However, when subjects were dichotomized into groups that had above or below average anxiety scores [ANX(+) and ANX(-)], both groups had similar respiration rate increases to the stressors, but the BP and fetal heart rate (FHR) responses were significantly different. Women in the ANX(-) group had significantly greater BP responses compared to women in the ANX(+) group whereas the fetuses of ANX(+) women showed significant HR increases and the fetuses of ANX(-) women exhibited nonsignificant decreases. These findings suggest that women's acute emotional reactivity during pregnancy can influence fetal HR patterns and that a stress-induced increase in maternal BP is not the primary signal by which a women's stress response is transduced to her fetus. The results are consistent with the hypothesis that maternal psychological variables may shape the neurobehavioral development of the fetus.     

Computerized Cardiovascular Monitoring: Method and Data

This paper describes the development of a digitized, real-time, microcomputer-based signal processing system which records the following variables: systolic and diastolic blood pressure, heart rate, pulse transit time, blood volume pulse, and R-, S-, and T-wave amplitudes of EKG signals. Forty-eight healthy subjects participated in a three-task stress response study in order to gather initial data for evaluating the reliability and validity of this monitoring system. The three tasks represented replications of earlier studies: 1) reading aloud of a monotonous neutral text (Reading Only, RO); 2) mental arithmetic without vocalization (Arithmetic Quiet, AQ); and 3) mental arithmetic with vocalization (Arithmetic Aloud, AA). The findings provided support for the reliability and validity of the new monitoring system given that few data were lost, and resting values as well as differential task responses were found to be comparable with earlier data sets derived via similar experimental protocols.