Nocturnal cardiovascular activity in essential hypotension: evidence of differential autonomic regulation

The Effect of Sleep Quality on Coronary Lesion Severity and Prognosis in the Young Acute Coronary Syndrome Population

This study aimed to explore the effect of long-term (≥1 year) sleep quality on coronary lesion complexity and cardiovascular prognosis in young acute coronary syndrome (ACS) patients. We consecutively recruited young patients aged from 18 to 44 years old with first-episode ACS and significant epicardial stenosis on coronary angiography from January 2016 to January 2017. Coronary lesion complexity was evaluated based on SYNTAX scores. Long-term sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) (PSQI ≤ 5 and PSQI > 5 groups). The primary endpoints were major adverse cardiovascular events (MACEs). A total of 466 young ACS patients (93.13% male; median age, 41 years) were included. Poor sleepers (PSQI > 5) had higher SYNTAX scores. After adjusting for confounders, PSQI scores (continuous variables, OR: 1.264; 95%CI: 1.166-1.371; p < 0.001) and PSQI grade (binary variable, OR: 3.864; 95%CI: 2.313-6.394; p = 0.001) were significantly associated with an increased risk of complex coronary lesions. During a median follow-up of 74 months, long-term poor sleep quality (PSQI > 5) was significantly associated with an increased risk of MACEs (HR: 4.266; 95%CI: 2.274-8.001; p < 0.001). Long-term poor sleep quality was a risk factor for complex coronary lesions and has adverse effects on cardiovascular prognosis in the young ACS population.

Parasympathetic cardiac control and attentional focus in trait worry

Trait worry refers to a tendency toward increased vigilance to threat and reduced tolerance of uncertainty. While it has been established as a risk factor of general morbidity, knowledge about autonomic regulation in trait worry remains scarce. This study investigated parasympathetic cardiac control in trait worry, in the context of attentional focus. Healthy groups with high and low worry were selected using the Penn State Worry Questionnaire (n = 40 per group). Heart rate variability (HRV) was recorded in the high frequency (HF) and low frequency (LF) bands while participants performed a breathing focus task. The task included a phase of instructed worry and two phases during which participants´ ability to concentrate on their breathing was assessed. As compared to the low worry group, the high worry group exhibited lower HRV in the LF band during both breathing focus phases and smaller reduction of LF HRV during instructed worry. HF HRV did not differ between groups. High worry was associated with impaired ability to concentrate on breathing and more intrusive thoughts. In the total sample, negative intrusions correlated negatively with LF HRV during the first breathing focus phase and LF HRV reactivity. Instructed worry led to greater perceived stress and deterioration of mood in high worry participants. Reduced LF HRV reflects blunted parasympathetic cardiac control in trait worry, associated with elevated risk of poor health outcomes. In addition, it might represent a psychophysiological correlate of reduced cognitive inhibition, which interferes with attentional focus and impedes control of threat processing and perseverative thinking.

Cardiovascular autonomic profile in women with constitutional hypotension

BACKGROUND

Constitutional hypotension (CHT) is defined as a SBP below 105 mmHg. As autonomic-related symptoms are frequently reported in CHT, these symptoms suggest that the cardiovascular autonomic control is perturbed in individuals with CHT.

METHODS

We investigated the autonomic cardiovascular control of 15 women with CHT and 12 women with NBP (SBP >110 mmHg). We monitored BP and ECG for autonomic function test. Supine and head up tilt (HUT) spectral analysis of RR interval and BP variability, baroreflex sensitivity and plasma levels of plasma renin activity and aldosterone were determined. M-mode echocardiogram was used to determine the left ventricle mass.

RESULTS

SBP and DBP were lower in CHT (97 ± 1.5 and 54 ± 1.5 mmHg) than in NBP (126 ± 3 and 70 ± 4 mmHg, P < 0.001 for both), whereas heart rate was comparable (65 ± 1.5 and 63 ± 3 bpm). CHT compared with NBP had lower Valsalva's ratio and BP phase IV overshooting, 1.7 ± 0.07 vs. 2 ± 0.07 (P < 0.05) and 19 ± 2.4, and 28 ± 3 mmHg (P < 0.05), respectively. BRSseq, alpha LF and LFRR/HFRR were greater in CHT (29.2 ± 0.7 and 39.1 ± 4.7 ms/mmHg and 1.4 ± 0.2) compared with NBP (25 ± 1.6 and 20.1 ± 2.5 ms/mmHg and 0.7 ± 01, [P < 05, for all]). LFSAP was lower in CHT (0.8 ± 0.2) than in NBP (1.5 ± 0.3 mmHg, P < 0.02). HUT data were similar. Supine and HUT aldosterone and PRA were higher in CHT. Left ventricle mass was lower in CHT.

CONCLUSION

We conclude that the cardiovascular autonomic control in women with CHT is characterized by a low sympathetic vascular tone and increased baroreceptor sensitivity. Also, it seems that these women have a compensated primary hypovolemia, which warrants further investigation.

Automatic analysis of pre-ejection period during sleep using impedance cardiogram

The pre-ejection period (PEP) is a valid index of myocardial contractility and beta-adrenergic sympathetic control of the heart defined as the time between electrical systole (ECG Q wave) to the initial opening of the aortic valve, estimated as the B point on the impedance cardiogram (ICG). B-point detection accuracy can be severely impacted if ICG cardiac cycles corrupted by motion artifact, noise, or electrode displacement are included in the analyses. Here, we developed new algorithms to detect and exclude corrupted ICG cycles by analyzing their level of activity. PEP was then estimated and analyzed on ensemble-averaged clean ICG cycles using an automatic algorithm previously developed by the authors for the detection of B point in awake individuals. We investigated the algorithms' performance relative to expert visual scoring on long-duration data collected from 20 participants during overnight recordings, where the quality of ICG could be highly affected by movement artifacts and electrode displacements and the signal could also vary according to sleep stage and time of night. The artifact rejection algorithm achieved a high accuracy of 87% in detection of expert-identified corrupted ICG cycles, including those with normal amplitude as well as out-of-range values, and was robust to different types and levels of artifact. Intraclass correlations for concurrent validity of the B-point detection algorithm in different sleep stages and in-bed wakefulness exceeded 0.98, indicating excellent agreement with the expert. The algorithms show promise toward sleep applications requiring accurate and reliable automatic measurement of cardiac hemodynamic parameters.

Autonomic Cardiovascular Dysregulation at Rest and During Stress in Chronically Low Blood Pressure

Abstract. Chronic low blood pressure (hypotension) is accompanied by symptoms such as fatigue, reduced drive, faintness, dizziness, cold limbs, and concentration difficulties. The study explored the involvement of aberrances in autonomic cardiovascular control in the origin of this condition. In 40 hypotensive and 40 normotensive subjects, impedance cardiography, electrocardiography, and continuous blood pressure recordings were performed at rest and during stress induced by mental calculation. Parameters of cardiac sympathetic control (i.e., stroke volume, cardiac output, pre-ejection period, total peripheral resistance), parasympathetic control (i.e., heart rate variability), and baroreflex function (i.e., baroreflex sensitivity) were obtained. The hypotensive group exhibited markedly lower stroke volume, heart rate, and cardiac output, as well as higher pre-ejection period and baroreflex sensitivity than the control group. Hypotension was furthermore associated with a smaller blood pressure response during stress. No group differences arose in total peripheral resistance and heart rate variability. While reduced beta-adrenergic myocardial drive seems to constitute the principal feature of the autonomic impairment that characterizes chronic hypotension, baroreflex-related mechanisms may also contribute to this state. Insufficient organ perfusion due to reduced cardiac output and deficient cardiovascular adjustment to situational requirements may be involved in the manifestation of bodily and mental symptoms.

Cerebral blood flow modulations during antisaccade preparation in chronic hypotension

In addition to symptoms including fatigue, dizziness, reduced drive, or mood disturbance, individuals with chronic low blood pressure (hypotension) frequently report cognitive complaints. While attentional deficits have been empirically confirmed, it is still unknown whether the impairments also encompass executive functions. This study investigated cerebral blood flow modulations in hypotension during a precued antisaccade/prosaccade task requiring the executive function of proactive inhibition in addition to preparatory attention. Using functional transcranial Doppler sonography, bilateral blood flow velocities in the middle cerebral arteries (MCA) were recorded in 39 hypotensive and 40 normotensive participants. In the task, a stimulus appeared left or right of a fixation point 5 s after a cuing stimulus; subjects had to move their gaze to the mirror image position of the stimulus (antisaccade) or toward it (prosaccade control condition). Video-based eye tracking was used for ocular recording. A right dominant MCA blood flow increase arose during task preparation, which was smaller in hypotensive than normotensive participants. In addition, hypotensive participants exhibited lower peak velocity of the saccadic response. The extent of the reductions in blood flow and task performance in hypotension did not differ between antisaccade and prosaccade conditions. The smaller MCA flow increase may reflect reduced activity in the dorsolateral prefrontal and inferior parietal cortices during proactive inhibition and preparatory attention in hypotension. Given that group differences in blood flow and performance arose independent of task complexity and executive function load, hypotension may be characterized by basic attentional impairments rather than particular executive function deficits.

Affective impairment in chronic low blood pressure

OBJECTIVE

Physical complaints such as faintness, dizziness, cold limbs and headaches have been well-established in chronic low blood pressure (hypotension). This study investigated the occurrence of adverse emotional states and the symptoms of depression in this condition. As autonomic dysregulation, particularly diminished sympathetic tone, is believed to be involved in the etiology of hypotension, the impact of different facets of autonomic cardiovascular control on mood and depressive symptoms was also explored.

METHODS

Forty individuals with chronic hypotension and forty normotensive control persons were presented with the Mood Scale and Beck Depression Inventory. Stroke volume, cardiac output, pre-ejection period, Heather index and aortic peak blood flow velocity were recorded under resting conditions as indices of beta-adrenergic inotropic drive. Respiratory sinus arrhythmia and baroreflex sensitivity were additionally obtained.

RESULTS

Hypotensive individuals scored markedly higher on both questionnaire scales than controls, indicating an adversely affected emotional state and more severe depressive symptoms. In the entire sample, cardiac output, Heather index, and aortic peak blood flow velocity correlated negatively with the questionnaire scores; according to regression analysis, the Heather index explained the largest proportion of test score variance.

CONCLUSION

Although hypotension does not constitute a serious medical condition, the findings of an adverse affective state and increased burden with depressive symptoms corroborate the view that it can have a considerable impact on wellbeing and quality of life. The correlations of the beta-adrenergic indices with the questionnaire scales indicate that cardiac sympathetic regulation plays a key role in the psychophysiological mediation of hypotension-related mood impairment.

The Association Between Insomnia and Increased Future Cardiovascular Events: A Nationwide Population-Based Study

OBJECTIVES

Insomnia may increase the risk of cardiovascular disease (CVD), but the reported magnitude of the associations between sleep characteristics and CVD is inconsistent. We investigated the association between insomnia and the risk of developing acute myocardial infarction (AMI) and/or stroke by using a nationwide, population-based cohort database in Taiwan.

METHODS

The analyses were conducted using information from a random sample of 1 million people enrolled in the nationally representative Taiwan National Health Insurance Research Database. A total of 44,080 individuals who were 20 years or older, including 22,040 people who had diagnosis of insomnia during the study period and an age-, sex-, comorbidity-matched group of 22,040 people without insomnia, were enrolled in our study. The study end points were the occurrence of cardiovascular events including AMI or stroke during follow-up.

RESULTS

During a 10-year follow-up, 302 AMI events and 1049 stroke events were identified. The insomnia group had a higher incidence of AMI (2.25 versus 1.08 per 1000 person-years) and stroke (8.01 versus 3.69 per 1000 person-years, p < .001). Cox proportional hazard regression model analysis showed that insomnia was independently associated with a higher risk of future AMI (hazard ratio [HR] = 1.68, 95% confidence interval [CI] = 1.31-2.16, p < .001), stroke (HR = 1.85, 95% CI = 1.62-2.12, p < .001), and the composite event index (HR = 1.81, 95% CI = 1.61-2.05, p < .001), after adjusting for age, sex, and comorbidities.

CONCLUSIONS

Insomnia is associated with an increased risk of future cardiovascular events.

Reduced cerebral and cardiovascular hemodynamics during sustained affective stimulation in young women with chronic low blood pressure

Although low blood pressure has been associated with lower affect and higher depressive symptoms in the elderly, the presence of possible impairment in emotional reactivity in chronic hypotensive individuals in early adulthood remains largely unexplored. Using a combination of transcranial Doppler sonography, beat-to-beat blood pressure recording and impedance cardiography we assessed central and peripheral hemodynamic changes in 15 undergraduate women with chronic hypotension (Age: 23.9 ± 2.7 years) and 15 normotensive controls (Age: 23.7 ± 3.1 years) during sustained exposure to pleasant, unpleasant and neutral pictures. Overall, systolic blood pressure (SBP) increased in normotensives and decreased in hypotensives during picture viewing as compared to baseline. Also, compared to normotensives, in hypotensives mean cerebral blood flow velocity increased to a lesser extent during the viewing of pleasant pictures and the magnitude of this increase was negatively associated with subjective emotional arousal. In addition, in hypotensives screening SBP was positively associated with valence rating of pleasant contents. These findings indicate a close association between chronic low blood pressure and reduced processing of pleasant stimuli in young adulthood.

Hypotension and environmental noise: a replication study

Up to now, traffic noise effect studies focused on hypertension as health outcome. Hypotension has not been considered as a potential health outcome although in experiments some people also responded to noise with decreases of blood pressure. Currently, the characteristics of these persons are not known and whether this down regulation of blood pressure is an experimental artifact, selection, or can also be observed in population studies is unanswered. In a cross-sectional replication study, we randomly sampled participants (age 20–75, N = 807) from circular areas (radius = 500 m) around 31 noise measurement sites from four noise exposure strata (35–44, 45–54, 55–64, >64 Leq, dBA). Repeated blood pressure measurements were available for a smaller sample (N = 570). Standardized information on socio-demographics, housing, life style and health was obtained by door to door visits including anthropometric measurements. Noise and air pollution exposure was assigned by GIS based on both calculation and measurements. Reported hypotension or hypotension medication past year was the main outcome studied. Exposure-effect relationships were modeled with multiple non-linear logistic regression techniques using separate noise estimations for total, highway and rail exposure. Reported hypotension was significantly associated with rail and total noise exposure and strongly modified by weather sensitivity. Reported hypotension medication showed associations of similar size with rail and total noise exposure without effect modification by weather sensitivity. The size of the associations in the smaller sample with BMI as additional covariate was similar. Other important cofactors (sex, age, BMI, health) and moderators (weather sensitivity, adjacent main roads and associated annoyance) need to be considered as indispensible part of the observed relationship. This study confirms a potential new noise effect pathway and discusses potential patho-physiological routes of actions.