Family history of hypertension and cardiovascular responses to orthostatic stress

Orthostatic hypertension in normotensive type 2 diabetics: What characteristics?

AIM OF THE STUDY

We aimed to determine the prevalence of orthostatic hypertension (OHT) in normotensive, newly diagnosed type 2 diabetics, to assess clinical, biological characteristics of those patients and evaluate the evolution of their blood pressure, after one year of follow-up.

MATERIALS AND METHODS

It is an observational, prospective, cohort study, on 108 normotensive, newly diagnosed diabetics, 40 men and 68 women aged from 40 to 70 ans. OHT was defined as an increase of systolic blood pressure (SBP) ≥20mmHg and/or diastolic blood pressure (DBP) ≥10mmHg, after 1 and 2min of standing from supine position. Arterial hypertension and metabolic syndrome were respectively defined according to WHO and AHA 2009 guidelines. Clinical and biological data were collected for all patients. They had a screening for diabetic complications and a follow-up during one year. Statistical analysis was performed with Epi-Info 6.04.

RESULTS

We found OHT in 22 patients (20.4%). Patients with OHT had a higher SBP at lying position (P=0.029), a higher waist circumference (P=0.022) and LDL (P=0.041). They had more frequently obesity (P=0.036) left ventricular hypertrophy (P=0.024), metabolic syndrome (P=0.042) and cerebrovascular events (P=0.050) when compared with those with normal blood pressure response to orthostasis. One year after follow-up, the prevalence of permanent hypertension was significantly higher in the OHT group (P=0.0008).

CONCLUSION

Our study suggests that OHT is associated with insulin resistance syndrome and onset of sustained arterial hypertension in normotensive, newly diagnosed diabetics.

Medial prefrontal cortex damage affects physiological and psychological stress responses differently in men and women

The ability to produce appropriate physiological and psychological responses to stressful situations depends on accurate recognition and appraisal of such situations. Such ability is also important for proper emotion regulation. A number of studies have suggested that the medial prefrontal cortex (mPFC) plays a significant role in emotion regulation, as well as in the control of physiological endpoints of emotion regulation such as the hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS). Further, recent work has suggested that men and women may differ in these mechanisms of neural control of emotion regulation. Here, we examined the role of the human mPFC in self-report, ANS, and HPA stress reactivity by testing a group of participants with damage to this region (9 women and 9 men), a brain damaged comparison group (6 women and 6 men), and healthy comparison participants (27 women and 27 men) on an orthostatic challenge and the Trier Social Stress Test (TSST). The mPFC participants showed heightened self-reported stress in response to the TSST. In women, mPFC damage led to an increased cortisol response to the TSST. By contrast, in men, greater volume of mPFC damage was correlated with a decreased cortisol response. Finally, men with mPFC damage showed altered autonomic control of the heart (higher heart rate and lower high frequency heart rate variability) during an orthostatic challenge. These findings support the idea that the mPFC is involved in the regulation of physiological and psychological responses to stress and that this regulation may differ between men and women.

Cardiovascular reactivity and family history of hypertension: A meta-analysis

A regression-based meta-analysis examined the degree to which the effects of a family history of hypertension on cardiovascular reactivity are moderated by the magnitude of cardiovascular responses elicited in challenge/task conditions. Mean change scores for negative family history groups were regressed on mean change scores for positive family history groups. The slopes of separate regression lines obtained for systolic and diastolic blood pressure and heart rate were significantly less than 1.0 and the y-intercepts for these regression lines were significantly greater than zero. This pattern indicates that family history differences in cardiovascular reactivity to stress are greatest in situations that elicit the smallest baseline-stressor change scores in non-family-history groups.

The Computation of Evoked Heart Rate and Blood Pressure

Abstract For many years psychophysiologists have been interested in stimulus related changes in heart rate and blood pressure. To represent these evoked heart rate and blood pressure patterns, heart rate and blood pressure data have to be transformed into equidistant time series. This paper presents an extensive comparison between two methods. The most often used method is based on linear interpolation, also known as weighted averaging. The low pass filtering method presented here is based on a well-known model for the generation of heart beats, the integral pulse frequency modulation model (IPFM). The comparison shows that the results of the filtering and interpolation procedures are virtually identical. Practically, small differences between the methods disappear in the averaging process. Therefore, the interpolation method is a suitable practical alternative to the computationally complex filtering method.

The relation between event-related brain potential, heart rate, and blood pressure responses in an S1-S2 paradigm

Event-related brain potential (ERP), heart rate (HR), and blood pressure (BP) responses were examined during the 6 s foreperiod of a choice-reaction task. Low and high trait-anxious males were required to make same/different judgements based on the similarity of two successively presented visual patterns. The pitch of a warning tone, presented at the beginning of the foreperiod, indicated whether speed or accuracy was to be emphasized on that trial. In different conditions, subjects received either a monetary reward or aversive noise, depending on their performance. Two clusters of parallel variations were observed in the foreperiod: (1) speed/accuracy instructions affected the amplitude of the CNV and, in interaction with anxiety group, the initial decreases in HR and diastolic BP; (2) type of reward, in interaction with speed/accuracy instructions, affected the amplitude of the P300 and PSW, the mid-interval HR acceleration, and subsequent increases in diastolic and systolic BP. A correlational analysis showed a close relationship between changes in HR and BP, whereas no relationship was evident between changes in ERPs and changes in HR and BP.

The cardiovascular response to postural change as a function of race

Little is known about racial differences in cardiovascular responses to postural change. The immediate and delayed change from sitting to standing was studied in 207 healthy young Asian, black, and white men and women by means of a noninvasive blood pressure tracking system. Whereas Asians and whites had decreased mean arterial pressure (MAP) 32-41 s after standing, blacks had an increase. During the delayed response (3 min after standing), compared to Asians and whites, blacks had greater increases in diastolic blood pressure and MAP. Their heart rate increase was also greater than Asians. For systolic blood pressure and pulse pressure there were Race x Family History interactions for the immediate response to orthostasis and Race x Gender interactions for the delayed response. Blacks generally displayed different cardiovascular patterns from the other two racial groups, possibly reflecting increased peripheral resistance and altered baroreceptor function.

Hypnotic susceptibility, mood state, and cardiovascular reactivity

In this study we explored the relationship between hypnotic susceptibility measured with the Harvard Group Scale of Hypnotic Susceptibility (HGSHS) and cardiovascular parameters. After assessing their degree of hypnotic susceptibility, we induced 21 female students into happy mood states and into sad mood states. During the mood state induction we monitored blood pressure, heart rate, and cardiac vagal tone continuously. The study demonstrated a strong relationship between hypnotic susceptibility and both cardiac vagal tone and heart rate reactivity. Subjects with lower heart rate and greater vagal tone during baseline and greater heart rate increases during mood induction were more susceptible to hypnosis. Multiple regression analyses indicated that approximately 40% of the individual difference variance of hypnotic susceptibility was accounted for by baseline cardiac vagal tone and heart rate reactivity during mood state. The data demonstrate that autonomic tone, assessed by cardiac vagal tone and heart rate reactivity, are related to hypnotic susceptibility as measured by the HGSHS.

Cardiac autonomic mechanisms associated with borderline hypertension under varying behavioral demands: evidence for attenuated parasympathetic tone but not for enhanced beta-adrenergic activity

Elevated blood pressure in psychophysiological studies of borderline hypertension is frequently attributed to the effects of increased sympathetic tone, and with few exceptions, the potential parasympathetic contributions have not been considered. Furthermore, of the investigations that have addressed vagal influences upon blood pressure, most have employed invasive pharmacological assessment of parasympathetic tone. In this study, cardiac parasympathetic and beta-adrenergic influences in borderline hypertension were evaluated noninvasively employing respiratory sinus arrhythmia as a vagal index and preejection period as a sympathetic index of cardiac functioning. Subjects were 30 borderline hypertensive and 23 normotensive males (age range, 24-45 years). The ECG, blood pressure, impedance cardiography, and respiration were measured during two baselines (initial and post-task), a memory-comparison reaction time task, the cold pressor, and CO2-rebreathing. Results indicated tonic differences between groups in all cardiovascular variables across tasks, with the exception of pre-ejection period, which showed no group effects at all. Hypertensives additionally manifested somewhat heightened systolic blood pressure reactivity and attenuated cardiac parasympathetic responsivity to specific tasks. Our findings provide no support for an exaggerated cardiac beta-adrenergic tonic level or reactivity in borderline hypertensives. On the other hand, the consistently lower magnitude of respiratory sinus arrhythmia in our hypertensives suggests that reduced parasympathetic control may be involved in the pathophysiology of hypertension.

Plotting systolic, diastolic, and pulse pressure on a real time scale

Since a valid non-invasive method for continuously measuring blood pressure is available for the psychophysiological laboratory, a procedure must be found for depicting blood pressure characteristics (systolic, diastolic, pulse pressure) on a real time scale, that is not simply from one heartbeat to the next. Values for blood pressure characteristics are actualized by heartbeats and thus occur at discrete points in time only, quite like values for heart rate. It is being assumed that the conditions for the blood pressure characteristics vary continuously, however, and that a value, actualized by a heartbeat, is representative for a time interval extending halfway before and after the point in time where it occurs. For computing a value for a real time interval it is proposed to weight the blood pressure values according to the amount of time their respective time intervals extend within the real time interval.