Background Many cardiocirculatory mechanisms are involved in the adaptation to orthostatic stress. While these mechanisms may be impaired in Fontan patients. However, it is yet unclear how Fontan patients, who exhibit a critical fluid balance, respond to orthostatic stress. Angiotensin converting enzyme inhibitors are often prescribed to Fontan patients, but they may negatively influence orthostatic tolerance. Therefore, we evaluated the response to orthostatic stress in pediatric Fontan patients before and after treatment with enalapril. Methods Thirty-five Fontan patients (aged 14 years) with moderate-good systolic ventricular function without pre-existent enalapril treatment were included. Before and after a three-month enalapril treatment period, the hemodynamic response to head-up tilt test was evaluated by various parameters including cardiac index, blood pressure, cerebral blood flow, aortic stiffness and cardiac autonomous nervous activity. Thirty-four healthy subjects (aged 13 years) served as controls. Results Fontan patients had a decreased cerebral blood flow and increased aortic stiffness in the supine position compared to controls, while all other factors did not differ. Patients and controls showed a comparable response to head-up tilt test for most parameters. Twenty-seven patients completed the enalapril study with a mean dosage of 0.3±0.1mg/kg/day. Most parameters were unaffected by enalapril, only the percent decrease in cardiac index to tilt was higher after treatment, but the cardiac index during tilt was not lower (3.0L/min/m2 pre-enalapril versus 2.8L/min/m2 after treatment; P = 0.15). Conclusion Pediatric Fontan patients adequately respond to orthostasis with maintenance of blood pressure and cerebral blood flow and sufficient autonomic response. Enalapril treatment did not alter the response. Clinical trial information Scientific title: ACE inhibition in Fontan patients: its effect on body fluid regulation (sAFE-study). The Netherlands National Trial Register: Trail NL6415. Registered 2017-07-20. Trial information: https://www.trialregister.nl/trial/6415

STUDY OBJECTIVES: Recent work indicates that cardiac sympathetic activity is not influenced by the circadian system and instead decreases after sleep onset. However, little is known about the pattern of change in cardiac sympathetic activity during NREM/REM sleep cycles and whether this is associated with alterations in slow-wave activity (SWA). To address these questions, we examined SWA, cardiac sympathetic activity, heart rate and rectal and foot temperatures during the first three NREM/REM sleep cycles and during transitions between NREM and REM sleep.
DESIGN: Subjects were required to maintain a constant sleep-wake cycle for at least a week and have at least one adaptation night, before their night of recording.
SETTING: Individual temperature controlled bedrooms.
PARTICIPANTS: 10 young healthy males and females.
INTERVENTIONS: NA.
MEASUREMENTS AND RESULTS: All variables showed the greatest change in the first NREM cycle. Specifically, SWA, sympathetic activity, heart rate and foot temperature increased while rectal temperature decreased. After the initial increase, cardiac sympathetic activity decreased across the sleep phase, in association with a decrease in heart rate. Cardiac sympathetic activity did not significantly alter across NREM-REM cycles.
CONCLUSIONS: The results suggest that increases in heart rate and cardiac sympathetic activity early in the sleep period are, in part, a compensatory reaction to the concomitant thermoregulatory changes observed. These results also indicate that the effect of time asleep on cardiac sympathetic activity may be greater than the influence of sleep cycles. These results are discussed with reference to the recuperative value of naps.

—Work stress has repeatedly been associated with an increased risk for cardiovascular disease. This study tested whether this relationship could be explained by exaggerated cardiovascular reactivity to work or impaired recovery in leisure time. Vagal tone was assessed as a possible determinant of these work stress effects. Participants included 109 male white-collar workers (age, 47.2±5.3) who were monitored on 2 workdays and 1 nonworkday for ambulatory blood pressure, heart rate, and heart rate variability. Chronic work stress was defined according to Siegrist’s model as (1) high imbalance, a combination of high effort and low reward at work, or (2) high overcommitment, an exhaustive work-related coping style indexing the inability to unwind. All findings were adjusted for possible differences in posture and physical activity between the work stress groups. High imbalance was associated with a higher heart rate during work and directly after work, a higher systolic blood pressure during work and leisure time, and a lower 24-hour vagal tone on all 3 measurement days. Overcommitment was not associated with an unfavorable ambulatory profile. Logistic regression analysis revealed that heart rate [odds ratio 1-SD increase 1.95 (95% CI, 1.02 to 3.77)] and vagal tone [odds ratio 1-SD decrease 2.67 (95% CI, 1.24 to 5.75)] were independently associated with incident mild hypertension. Surprisingly, the values during sleep were more predictive for mild hypertension than the values during work. The results from the present study suggest that the detrimental effects of work stress are partly mediated by increased heart rate reactivity to a stressful workday, an increase in systolic blood pressure level, and lower vagal tone.

The wowing need for more advanced ambulatory monitoring has led lo the development of an ambulatory monitor for impedance cardiography (VU-AMD). This paper presents two studies addressing the validity of the VU-AMD. In the first study, the cardiovascular responses of 25 subjects during various conditions were simultaneously recorded with the VU-AMD and a standard laboratory impedance device. Correlations between the responses of the ambulatory and laboratory devices were high, both inter and intraindividually, except lot stroke volume and cardiac output during exercise In the second study, 26 subjects underwent 24-hr monitoring with the VU-AMD. The values obtained with the VU-AMD were realistic and varied in a predictable way over activity and posture. It is concluded that the VU-AMD is a valid device for the measurement of systolic time intervals in real-life situations but its applicability for absolute stroke volume and cardiac output determination remains lo he established.

Autonomous sensory meridian response (ASMR) is a warm tingling sensation which is often accompanied by feelings of calmness and relaxation. The present study examined the effects of an ASMR video on mood, attention, heart rate (HR), electrodermal activity (EDA), electroencephalography (EEG) and the interaction with personality factors in 38 young adults (33 females and 5 males). Based on the ASMR-checklist responses of having tingles during watching the ASMR video 15 participants out of 38 were classified as ASMR-experiencers. Mood, attention and personality characteristics were measured by the Profile of Mood States, the Flanker task and HEXACO. EEG, HR and EDA were recorded during the ASMR and control videos. Depressive feelings decreased after watching the ASMR video in individuals experiencing tingles relative to those not experiencing tingles. Furthermore, in all participants, irrespective of experiencing tingles, a decrease of HR during watching the ASMR video was found. In ASMR-experiencers scoring low on Conscientiousness EDA tended to increase and HR tended-relatively to the group not experiencing tingles—to decrease during watching the ASMR video. EEG recordings indicated that watching the ASMR video was associated with decreased alpha power in ASMR-sensitive participants and decreased theta as well as increased beta power in the whole group of participants. The observed ASMR-induced decrease of alpha and theta power and increase of beta power and (only in low conscientious participants) EDA may reflect that, apart from relaxation, ASMR is related to arousal and focused attention.

Associations between natural killer (NK) cell, proinflammatory cytokine stress responsivity, and cardiac autonomic responses (indexed by heart rate and heart rate variability) were assessed in 211 middle-aged men and women. Blood was drawn at baseline, immediately following color–word interference and mirror tracing tasks for the assessment of NK cell numbers, and 45 min post-stress for assessing plasma interleukin 6 (IL-6) and tumor necrosis factor alpha (TNFα) responses. Heart rate variability was measured as the root mean square of successive differences (RMSSD) in R–R intervals. Increases in NK cell counts following stress were positively associated with heart rate responses independently of age, sex, socioeconomic status, smoking, and change in hematocrit. Heart rate 45 min post-stress was positively associated with plasma IL-6 post-stress, and with TNFα changes from baseline, independently of covariates. No relationship between immune responses and heart rate variability was observed. We conclude that individual differences in sympathetically-driven cardiac stress responses are associated with NK and proinflammatory cytokine responses to psychological stress.

Previous work from our lab has used the Dutch Ambulatory Monitoring System (AMS) to assess the cardiovascular responses and motility of large free-ranging species (e.g. horses). To further examine the utility of using the AMS with non-humans, a study investigating the heart rate (HR) and heart period variability (HRV) of a large canine undergoing behavioral modification therapy was undertaken. This treatment emulated a restraint and tactile pressure technique that has previously been used in horses. Cardiovascular responses and motility were continuously measured pre-treatment (exposure to a stimulus dog), during treatment (in-box), and post-treatment. The treatment consisted of placing the dog in a 110 cm (long) by 45 cm (wide) by 102 cm (height) wooden box that only covered the animals’ torso and legs and allowed the head to be free. Once the dog was in the box, the body was covered with a lightweight material (grain product) to effect restraint and tactile pressure, which was followed by a repeat exposure to the stimulus animal. Results indicated decreased heart rate and an increased HRV during the intervention as compared to baseline with indices of motility changing in the expected directions. Estimates of respiratory frequency derived from the autoregressive spectral analysis indicated changes in respiration did not account for the cardiovascular effects. In conclusion, tactile pressure and restraint may be an important tool for behavioral modification in both humans and animals, and the AMS is a useful tool for collecting cardiovascular data on a variety of species in a great many contexts.

AIMS: Low socioeconomic status is associated with increased cardiovascular disease risk. We hypothesized that psychobiological pathways, specifically slow recovery in blood pressure and heart rate variability following mental stress, partly mediate social inequalities in risk.
METHODS AND RESULTS: Participants were 123 men and 105 women in good health aged 47-58 years drawn from the Whitehall II cohort of British civil servants. Grade of employment was the indicator of socioeconomic status. Cardiovascular measures were monitored during performance of two behavioural tasks, and for 45 min following stress. Post-stress return of blood pressure and heart rate variability to resting levels was less complete after 45 min in the medium and low than in the high grade of employment groups. The odds of failure to return to baseline by 45 min in the low relative to the high grade of employment groups were 2.60 (95% CI 1.20-5.65) and 3.85 (1.48-10.0) for systolic and diastolic pressure, respectively, and 5.19 (1.88-18.6) for heart rate variability, adjusted for sex, age, baseline levels and reactions to tasks. Subjective ratings of task difficulty, involvement and stress did not differ by socioeconomic status.
CONCLUSIONS: Lower socioeconomic status is associated with delayed recovery in cardiovascular function after mental stress. Impaired recovery may reflect heightened allostatic load, and constitute a mechanism through which low socioeconomic status enhances cardiovascular disease risk.

Shift workers encounter an increased risk of cardiovascular disease compared to their day working counterparts. To explore this phenomenon, the effects of one week of simulated night shift on cardiac sympathetic (SNS) and parasympathetic (PNS) activity were assessed. Ten (5m; 5f) healthy subjects aged 18-29 years attended an adaptation and baseline night before commencing one week of night shift (2300-0700 h). Sleep was recorded using a standard polysomnogram and circadian phase was tracked using salivary melatonin data. During sleep, heart rate (HR), cardiac PNS activity (RMSSD) and cardiac SNS activity (pre-ejection period) were recorded. Night shift did not influence seep quality, but reduced sleep duration by a mean of 52 +/- 29 min. One week of night shift evoked a small chronic sleep debt of 5 h 14 +/- 56 min and a cumulative circadian phase delay of 5 h +/- 14 min. Night shift had no significant effect on mean HR, but mean cardiac SNS activity during sleep was consistently higher and mean cardiac PNS activity during sleep declined gradually across the week. These results suggest that shiftwork has direct and unfavourable effects on cardiac autonomic activity and that this might be one mechanism via which shiftwork increases the risk of cardiovascular disease. It is postulated that sleep loss could be one mediator of the association between shiftwork and cardiovascular health.