Pre-ejection Period Research Articles

Neurobiological correlates of antisociality across adolescence and young adulthood: a multi-sample, multi-method study.

Antisociality across adolescence and young adulthood puts individuals at high risk of developing a variety of problems. Prior research has linked antisociality to autonomic nervous system and endocrinological functioning. However, there is large heterogeneity in antisocial behaviors, and these neurobiological measures are rarely studied conjointly, limited to small specific studies with narrow age ranges, and yield mixed findings due to the type of behavior examined. We harmonized data from 1489 participants (9-27 years, 67% male), from six heterogeneous samples. In the resulting dataset, we tested relations between distinct dimensions of antisociality and heart rate, pre-ejection period (PEP), respiratory sinus arrhythmia, respiration rate, skin conductance levels, testosterone, basal cortisol, and the cortisol awakening response (CAR), and test the role of age throughout adolescence and young adulthood. Three dimensions of antisociality were uncovered: 'callous-unemotional (CU)/manipulative traits', 'intentional aggression/conduct', and 'reactivity/impulsivity/irritability'. Shorter PEPs and higher testosterone were related to CU/manipulative traits, and a higher CAR is related to both CU/manipulative traits and intentional aggression/conduct. These effects were stable across age. Across a heterogeneous sample and consistent across development, the CAR may be a valuable measure to link to CU/manipulative traits and intentional aggression, while sympathetic arousal and testosterone are additionally valuable to understand CU/manipulative traits. Together, these findings deepen our understanding of the fundamental mechanisms underlying different components of antisociality. Finally, we illustrate the potential of using current statistical techniques for combining multiple datasets to draw robust conclusions about biobehavioral associations.

Validity of electrodermal activity-based measures of sympathetic nervous system activity from a wrist-worn device

Measuring electrodermal activity (EDA) on the wrist with the use of dry electrodes is a promising method to help identify person-specific stressors during prolonged recordings in daily life. While the feasibility of this method has been demonstrated, detailed testing of validity of such ambulatory EDA is scarce. In a controlled laboratory study, we examine SCL and ns.SCR derived from wrist-based dry electrodes (Philips DTI) and palm-based wet electrodes (VU-AMS) in 112 healthy adults (57% females, mean age = 22.3, SD = 3.4) across 26 different conditions involving mental stressors or physical activities. Changes in these EDA measures were compared to changes in the Pre-ejection period (PEP) and stressor-induced changes in affect. Absolute SCL and ns.SCR frequency were lower at the wrist compared to the palm. Wrist-based ns.SCR and palm-based ns.SCR and SCL responded directionally consistent with our experimental manipulation of sympathetic nervous system (SNS) activity. Average within-subject correlations between palm-based and wrist-based EDA were significant but modest (r SCL = 0.31; r ns.SCR = 0.42). Changes in ns.SCR frequency at the palm (r = −0.44) and the wrist (r = −0.36) were correlated with changes in PEP. Both palm-based and wrist based EDA predicted changes in affect (6.5%–14.5%). Our data suggest that wrist-based ns.SCR frequency is a useful addition to the psychophysiologist's toolkit, at least for epidemiology-sized ambulatory studies of changes in sympathetic activity during daily life.

Social observation increases the cardiovascular response of hearing-impaired listeners during a speech reception task

Certain cardiovascular measures allow for distinction between sympathetic and parasympathetic nervous system activity. Applied during listening, these measures may provide a novel and complementary insight into listening effort. To date, few studies have implemented cardiovascular measures of listening effort and seldom have these included hearing-impaired participants. These studies have generally measured changes in cardiovascular parameters while manipulating environmental factors, such as listening difficulty. Yet, listening effort is also known to be moderated by individual factors, including the importance of performing successfully. In this study, we aimed to manipulate success importance by adding observers to the traditional laboratory set-up. Twenty-nine hearing-impaired participants performed a speech reception task both alone and in the presence of two observers. Auditory stimuli consisted of Danish Hearing in Noise Test (HINT) sentences masked by four-talker babble. Sentences were delivered at two individually adapted signal-to-noise ratios, corresponding to 50 and 80% of sentences correct. We measured change scores, relative to baseline, of pre-ejection period, two indices of heart rate variability, heart rate and blood pressure (systolic, diastolic, and mean arterial pressure). After each condition, participants rated their effort investment, stress, tendency to give up and preference to change the situation to improve audibility. A multivariate analysis revealed that cardiovascular reactivity increased in the presence of the observers, compared to when the task was performed alone. More specifically, systolic, diastolic, and mean arterial blood pressure increased while observed. Interestingly, participants’ subjective ratings were sensitive only to intelligibility level, not the observation state. This study was the first to report results from a range of different cardiovascular variables measured from hearing-impaired participants during a speech reception task. Due to the timing of the observers’ presence, we were not able to conclusively attribute these physiological changes to being task related. Therefore, instead of representing listening effort, we suggest that the increased cardiovascular response detected during observation reveals increased physiological stress associated with potential evaluation.

Cardiac autonomic functioning across stress and reward: Links with depression in emerging adults

The autonomic nervous system (ANS) has received much attention as a potential low-cost, peripheral indicator of depression. Despite theoretical support, however, results have been mixed as to whether indices of the ANS reliably index depression. In response, the present study sought to clarify the relation between ANS activity and depression by examining cardiac autonomic balance (CAB) and cardiac autonomic regulation (CAR), two composite indices of the parasympathetic and sympathetic nervous system, within both a stressful and rewarding context. We hypothesized that CABStress, representing the difference between the parasympathetic and sympathetic branches in response to stress, and CARReward, representing the summation of the two branches in response to reward, will be most indicative of depressogenic risk. We examined the parasympathetic (i.e., respiratory sinus arrhythmia) and sympathetic (i.e., pre-ejection period) responses of 97 emerging adults (Mage = 18.93) for a stress (i.e., negative mood induction) and reward (i.e., probabilistic learning) task, as well as their depressive symptoms at baseline, 3-week, and 6-week follow-up. Analyses found partial support for our hypotheses, revealing greater CARReward (i.e., coactivation of both branches) was related to lower depressive symptoms. Further, exploratory analyses examining gender differences found lower CABStress (i.e., sympathetically-oriented response) was predictive of an increasing trajectory of depression, but only among males. Overall, the current study highlights the importance of simultaneously examining both branches of the ANS across various environmental contexts. Research and clinical implications of the current findings are discussed.

Reward processing and psychopathic traits in children.

Growing evidence has suggested that the mechanisms underlying the 3 dimensions of psychopathic traits, including grandiose-manipulative, callous-unemotional, and daring-impulsive, are different. As yet, the neurobiological correlates of each dimension have not been fully understood. In this study, we examined if reward processing deficits were differentially associated with these traits, and whether social adversity moderated these relationships. Pre-ejection period (PEP) was assessed in children between 8 and 10 years of age from the community (N = 340, Mage = 9.06, SD = .60; 48.2% boys) while they were completing a reward task, and the caregivers rated children's psychopathic traits. Results indicated that (a) high callous-unemotional traits were associated with less PEP shortening, reflecting reward hyporesponsivity, at low levels of social adversity, and more PEP shortening, indicating hyperresponsivity, at high levels of social adversity, (b) high daring-impulsive traits were associated with hyperresponsivity at low levels of adversity only, and (c) grandiose-manipulative traits were not linked to reward processing deficits. Findings provide further evidence that different etiologies may underlie various dimensions of psychopathic traits and highlight the important role of psychosocial factors in understanding the neurobiological mechanism of youth psychopathy. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Lagrangian-averaged vorticity deviation of spiraling blood flow in the heart during isovolumic contraction and ejection phases.

The formation of vortex rings in the left ventricular (LV) blood flow is a mechanism for optimized blood transport from the mitral valve inlet to aortic valve outlet, and the vorticity is an important measure of a well-functioning LV. However, due to lack of quantitative methods, the process of defining the boundary of a vortex in the LV and identifying the dominant vortex components has not been studied previously. The Lagrangian-averaged vorticity deviation (LAVD) can enable us to compute the trajectory integral of the normed difference of the vorticity from its spatial mean. Therefore, in this work, we have employed LAVD to identify the Lagrangian vortices and Eulerian vortices for measuring the vortex volume and vorticity in the LV blood flow. We found that during the LV ejection period, the positive (counterclockwise) and negative (clockwise) vorticity of patients are consistently stronger than those of the healthy groups, and the counterclockwise vortex volume of healthy groups (0.84+0.26ml) is greater than that of patients (0.55+0.28ml) during the pre-ejection period. Then, during the middle ejection phase, the counterclockwise vortex ring volume of patients (1.89+0.36ml) exceeds that of healthy groups (1.38+0.43ml). Finally, during the end-ejection period, the counterclockwise vortex ring volume of healthy subjects (0.61+0.17ml) is the same as that of patients (0.60+0.19ml). The results presented in this paper can provide new insights into the blood flow patterns within the LV. It can accurately indicate the role of vortices and vorticity values in intra-LV flow, and portray how cardiomyopathy (and its distorted contractile mechanism) can affect intra-LV flow patterns and mitigate adequate LV outflow.

Onset of substance use: Deviant peer, sex, and sympathetic nervous system predictors.

We evaluated whether the association between deviant peer affiliation and onset of substance use is conditional upon sex and sympathetic nervous system (SNS) reactivity as measured by pre-ejection period (PEP). Community-sampled adolescents (N = 251; M = 15.78 years; 53% female; 66% White, 34% Black) participated in three waves. PEP reactivity was collected during a mirror star-tracer stress task. Alcohol, marijuana, tobacco, or any substance use, as well as binge drinking and sexual activity involving substance use were outcomes predicted by affiliation with deviant peers and two- and three-way interactions with sex and PEP reactivity. Probability of substance use increased over time, but this was amplified for adolescents with greater deviant peer affiliation in conjunction with blunted PEP reactivity. The same pattern of results was also found for prediction of binge drinking and sexual activity involving substance use. Findings are discussed in the context of biosocial models of adolescent substance use and health risk behaviors.

SARS-CoV-2 vaccination of people living with human T leukaemia virus type 1

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A Close Examination of the Use of Systolic Time Intervals in the Calculation of Impedance Derived Cardiac Autonomic Balance and Regulation

Traditionally, impedance derived measures of cardiac autonomic balance (CAB) and regulation (CAR) are calculated using indices of heart rate variability (HRV) that primarily reflect parasympathetic nervous system activity (e.g., high-frequency HRV | HF-HRV) and pre-ejection period (PEP; a systolic time interval and measure of sympathetic activity). However, HF-HRV and PEP are considered measures of chronotropic and inotropic cardiac influence, respectively. Left ventricular ejection time (LVET) is a systolic time interval that reflects sympathetic chronotropic influence, and therefore may be a more appropriate measure for calculating CAB and CAR compared to PEP. Thus, the current study evaluates both PEP and LVET in the calculation of CAB and CAR. Data from 158 healthy participants (mean age = 19.09 years old, SD = 1.84 years) were available for analyses. CAB and CAR values were calculated using both HF-HRV and the root mean square of successive differences, in addition to both PEP and LVET, in accordance with previously established guidelines. Analyses showed that correlations were significantly weaker between CAB and CAR calculated using LVET for both HF (z = 5.12, p < 0.001) and RMSSD (z = 5.26, p < 0.001) than with PEP. These data suggest that LVET, compared to PEP, provides better “autonomic space” as evidenced by a lack of correlation between CAB and CAR computed using LVET. We stress that future research consider calculating CAB and CAR using chronotropic measures for both parasympathetic and sympathetic activity, as doing so may yield more accurate and independent measures of cardiac autonomic activity compared to a mixture of inotropic (i.e., PEP) and chronotropic (i.e., HF-HRV) measures.

Systolic and Diastolic Functions After a Brief Acute Bout of Mild Exercise in Normobaric Hypoxia.

Acute hypoxia (AH) is a challenge to the homeostasis of the cardiovascular system, especially during exercise. Research in this area is scarce. We aimed to ascertain whether echocardiographic, Doppler, and tissue Doppler measures were able to detect changes in systolic and diastolic functions during the recovery after mild exercise in AH. Twelve healthy males (age 33.5 ± 4.8 years) completed a cardiopulmonary test on an electromagnetically braked cycle-ergometer to determine their maximum workload (Wmax). On separate days, participants performed randomly assigned two exercise sessions consisting in 3 min pedalling at 30% of Wmax: (1) one test was conducted in normoxia (NORMO) and (2) one in normobaric hypoxia with FiO2 set to 13.5% (HYPO). Hemodynamics were assessed with an echocardiographic system. The main result was that the HYPO session increased parameters related to myocardial contractility such as pre-ejection period and systolic myocardial velocity with respect to the NORMO test. Moreover, the HYPO test enhanced early transmitral filling peak velocities. No effects were detected for left ventricular volumes, as end-diastolic, end-systolic, and stroke volume were similar between the NORMO and the HYPO test. Results of the present investigation support the hypothesis that a brief, mild exercise bout in acute normobaric hypoxia does not impair systolic or diastolic functions. Rather, it appears that stroke volume is well preserved and that systolic and early diastolic functions are enhanced by exercise in hypoxia.

AI-Based Estimation of End-Systolic Elastance From Arm-Pressure and Systolic Time Intervals.

Left ventricular end-systolic elastance (Ees) is a major determinant of cardiac systolic function and ventricular-arterial interaction. Previous methods for the Ees estimation require the use of the echocardiographic ejection fraction (EF). However, given that EF expresses the stroke volume as a fraction of end-diastolic volume (EDV), accurate interpretation of EF is attainable only with the additional measurement of EDV. Hence, there is still need for a simple, reliable, noninvasive method to estimate Ees. This study proposes a novel artificial intelligence—based approach to estimate Ees using the information embedded in clinically relevant systolic time intervals, namely the pre-ejection period (PEP) and ejection time (ET). We developed a training/testing scheme using virtual subjects (n = 4,645) from a previously validated in-silico model. Extreme Gradient Boosting regressor was employed to model Ees using as inputs arm cuff pressure, PEP, and ET. Results showed that Ees can be predicted with high accuracy achieving a normalized RMSE equal to 9.15% (r = 0.92) for a wide range of Ees values from 1.2 to 4.5 mmHg/ml. The proposed model was found to be less sensitive to measurement errors (±10–30% of the actual value) in blood pressure, presenting low test errors for the different levels of noise (RMSE did not exceed 0.32 mmHg/ml). In contrast, a high sensitivity was reported for measurements errors in the systolic timing features. It was demonstrated that Ees can be reliably estimated from the traditional arm-pressure and echocardiographic PEP and ET. This approach constitutes a step towards the development of an easy and clinically applicable method for assessing left ventricular systolic function.

EVALUATION OF CARDIOVASCULAR FUNCTIONAL RESPONSE TO ORTHOSTATISM IN TREATED HYPERTENSIVE PATIENTS: RESULTS OF THE IMPEDDANS STUDY

Objective: Arterial Hypertension (AHT) is one of the main causes of morbidity and mortality in the world. Generally defined as an increase in blood pressure (BP), it is characterized by hemodynamic changes that have implications for diagnosis, risk stratification and therapy. In this study we intend to characterize the hemodynamic response to orthostatism in a group of treated hypertensive patients using impedance cardiography (ICG). Design and method: Resistant hypertensive patients without heart failure, ischemic heart disease, valvular heart disease or dysrhythmia were prospectively selected. All patients underwent ICG in the supine position and in orthostatism. After ICG, they were classified into patterns: vasoconstrictor (systemic vascular resistance (SVR) &gt; 2500 dyn.s.cm-5.m2), hyperdynamic (cardiac index (CI) &gt; 4.2 l / min / m2 and / or heart rate HR &gt; 80 cycles / min), hypervolemic (thoracic fluid (CFT) &gt; 34 1 / kOhm) or balanced (hemodynamic parameters below the established limit values). All patients underwent transthoracic echocardiography to exclude major morphologic changes. Results: We included 178 patients, 56.1% males, age 63 ± 11 years, medicated with 4 ± 1 antihypertensives. In ICG, 56.5% were vasoconstrictors, 11.8% hyperdynamic, 33.4% hypervolemic and 22.9% had a balanced hemodynamic profile. In the supine position the patients had systolic blood pressure 134 ± 18, diastolic blood pressure 79 ± 11, HR 69 ± 10, indexed ejection volume 42 ± 9, pre-ejection period 95 ± 15 ms, ejection time 333 ± 17 ms, systolic time ratio 0.28 ± 0.06, RVSI 2687 ± 621, cardiac index 2.8 ± 0.4 and CFT 32 ± 5. In the orthostatic position some of these values were significantly higher: diastolic blood pressure 82 ± 12 (p &lt; 0.001), HR 73 ± 12 (p &lt; 0.001), pre-ejection period 119 ± 23 (p &lt; 0.001), systolic time ratio 0.41 ± 0.11 (p &lt; 0.001). The indexed ejection volume 39 ± 9 (p &lt; 0.001), ejection time 301 ± 46 (p &lt; 0.001) and CFT 28 ± 3 (p &lt; 0.001) were significantly lower. Conclusions: Although polymedicated, most patients had an unbalanced hemodynamic profile. The analysis of the impedance waveform with postural modification can be used to clarify the response to orthostatism and to better characterise the hemodynamic phenotype.

PTSD in veterans, couple behavior, and cardiovascular response during marital conflict.

Posttraumatic stress disorder (PTSD) is associated with strain in marriage and similar intimate relationships, and such difficulties could contribute to associations of PTSD with risk of cardiovascular disease (CVD). Heightened cardiovascular reactivity (CVR) during stressful marital interactions may be an important mechanism in this regard. This study examined dysfunctional behavior during marital conflict as a mediator of the association of PTSD with heightened CVR during these interactions. In 64 couples comprising male military veterans and female partners, participants underwent a 17-min video-recorded conflict discussion, with assessment of blood pressure and cardiac sympathetic activation (i.e. preejection period). In half of the couples, veterans met interview and questionnaire criteria for PTSD. Behavior was coded for aspects of affiliation (e.g., warmth vs. hostility) and control (e.g., dominance vs. deference), as well as blends of these broader dimensions. Extending previous reports from this study, actor-partner mediational analyses indicated that PTSD contributed to larger increases in veterans' and spouses' systolic blood pressure during the interaction through effects of the individual's own expressions of low warmth. PTSD contributed to veterans' and spouses' greater cardiac sympathetic activation through effects of the individual's own expressions of hostile control (e.g., blame, criticism). Hence, expressions of low warmth and high hostile control contribute to effects of PTSD on veterans' and spouses' heightened CVR during marital conflict discussions, suggesting a mechanism linking PTSD with CVD risk and potential targets for risk-reducing behavioral interventions. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

No Association Between Autonomic Functioning and Psychopathy and Aggression in Multi-Problem Young Adults.

BackgroundAberrant functioning of the autonomic nervous system (ANS) is an important factor in the occurrence of antisocial behavior. Baseline autonomic functioning and the responsivity of the ANS have been related to psychopathic traits and aggression. Here we investigated whether a naturalistic sample of male multi-problem young adults (age 18–27) present with similar autonomic deficits in relation to their psychopathy and aggression as previous studies observed in clinical samples.MethodsIn a sample of 112 multi-problem young adults, baseline autonomic functioning and autonomic responsivity to emotional stimuli were assessed through four physiological measures: heart rate, respiratory sinus arrhythmia, pre-ejection period, and skin conductance. 27 control participants were included primarily to assess whether the task worked appropriately. Participants watched a neutral 5 min video to assess baseline autonomic functioning and watched two sad clips to assess autonomic reactivity to sadness. We investigated the association between autonomic functioning and self-reported psychopathic traits and aggression within the multi-problem group.ResultsWe found no significant associations between autonomic functioning and psychopathy and aggression.ConclusionThese null-findings highlight the importance of research in naturalistic samples in addition to research in clinical and general populations samples and underscore the complexity of translating research findings into practical and clinical implications.

Eye Movement Desensitization (EMD) to reduce posttraumatic stress disorder-related stress reactivity in Indonesia PTSD patients: a study protocol for a randomized controlled trial

BackgroundPosttraumatic stress disorder (PTSD) may develop after exposure to a traumatic event. Eye Movement Desensitization and Reprocessing (EMDR) is an evidence-based psychological treatment for PTSD. It is yet unclear whether eye movements also reduce stress reactivity in PTSD patients. This study aims to test whether eye movements, as provided during Eye Movement Desensitization (EMD), are more effective in reducing stress reactivity in PTSD patients as compared to a retrieval-only control condition.MethodsThe study includes participants who meet criteria of PTSD of the public psychological services in Jakarta and Bandung, Indonesia. One hundred and ten participants are randomly assigned to either an (1) Eye Movement Desensitization group (n = 55) or (2) retrieval-only control group (n = 55). Participants are assessed at baseline (T0), post-treatment (T1), 1 month (T2), and at 3 months follow-up (T3). Participants are exposed to a script-driven imagery procedure at T0 and T1. The primary outcome is heart rate variability (HRV) stress reactivity during script-driven imagery. Secondary outcomes include heart rate (HR), pre-ejection period (PEP), saliva cortisol levels, PTSD symptoms, neurocognitive functioning, symptoms of anxiety and depression, perceived stress level, and quality of life.DiscussionIf the EMD intervention is effective in reducing stress reactivity outcomes, this would give us more insight into the underlying mechanisms of EMDR’s effectiveness in PTSD symptom reduction.Trial registrationISRCTN registry ISRCTN55239132. Registered on 19 December 2017.

The cardiac, vasomotor, and myocardial branches of the baroreflex in fibromyalgia: Associations with pain, affective impairments, sleep problems, and fatigue.

This study investigated the cardiac, vasomotor, and myocardial branches of the baroreflex in fibromyalgia using the spontaneous sequence method. Systolic blood pressure (SBP), interbeat interval (IBI), stroke volume (SV), pre-ejection period (PEP), and total peripheral resistance (TPR) were continuously recorded in 40 fibromyalgia patients and 30 healthy individuals during a cold pressor test and a mental arithmetic task. Sequences of covariation between SBP and IBI (cardiac branch), SV and PEP (myocardial branch), and TPR (vasomotor branch) were identified. Baroreflex sensitivity (BRS) was represented by the slope of the regression line between values in the sequences; baroreflex effectiveness (BEI) was indexed by the proportion of progressive SBP changes that elicited reflex responses. Patients exhibited lower BRS in the three branches, lower BEI in the cardiac and vasomotor branches, and reduced reactivity in cardiac BRS and BEI, SBP, IBI, SV, and PEP. Moreover, BRS and BEI were inversely related to clinical pain, cold pressor pain, depression, trait anxiety, sleep problems, and fatigue. Reduced function of the three baroreflex branches implies diminished resources for autonomic inotropic, chronotropic, and vascular regulation in fibromyalgia. Blunted stress reactivity indicates a limited capacity for autonomic cardiovascular adjustment to situational requirements. The associations of BRS and BEI with pain perception may reflect the antinociceptive effects arising from baroreceptor afferents, where reduced baroreflex function may contribute to the hyperalgesia characterizing fibromyalgia. The associations with affective impairments, sleep problems, and fatigue suggest that baroreflex dysfunctions are also involved in the secondary symptoms of the disorder.

Ventromedial Prefrontal Cortex Activity and Sympathetic Allostasis During Value-Based Ambivalence.

Anxiety is characterized by low confidence in daily decisions, coupled with high levels of phenomenological stress. Ventromedial prefrontal cortex (vmPFC) plays an integral role in maladaptive anxious behaviors via decreased sensitivity to threatening vs. non-threatening stimuli (fear generalization). vmPFC is also a key node in approach-avoidance decision making requiring two-dimensional integration of rewards and costs. More recently, vmPFC has been implicated as a key cortical input to the sympathetic branch of the autonomic nervous system. However, little is known about the role of this brain region in mediating rapid stress responses elicited by changes in confidence during decision making. We used an approach-avoidance task to examine the relationship between sympathetically mediated cardiac stress responses, vmPFC activity and choice behavior over long and short time-scales. To do this, we collected concurrent fMRI, EKG and impedance cardiography recordings of sympathetic drive while participants made approach-avoidance decisions about monetary rewards paired with painful electric shock stimuli. We observe first that increased sympathetic drive (shorter pre-ejection period) in states lasting minutes are associated with choices involving reduced decision ambivalence. Thus, on this slow time scale, sympathetic drive serves as a proxy for “mobilization” whereby participants are more likely to show consistent value-action mapping. In parallel, imaging analyses reveal that on shorter time scales (estimated with a trial-to-trial GLM), increased vmPFC activity, particularly during low-ambivalence decisions, is associated with decreased sympathetic state. Our findings support a role of sympathetic drive in resolving decision ambivalence across long time horizons and suggest a potential role of vmPFC in modulating this response on a moment-to-moment basis.

Correlation of sympathetic and parasympathetic nervous system activity during rest and acute stress tasks

Autonomic nervous system (ANS) activity is a core and central component of emotion and motivated action. The myriad social and cognitive challenges faced by humans require flexible modulation of ANS activity for different contexts. In this study, simultaneous activity of the parasympathetic and sympathetic nervous system was measured using respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP), respectively. Samples combined four previous studies (N = 325, 63% female, aged 15–55) in which RSA and PEP were collected continuously during a resting baseline and an acute stressor, the Trier Social Stress Task. The concurrent relation between RSA and PEP responses was modelled in order to determine the extent to which SNS and PNS activity is correlated across the task within and between participants, and whether this correlation was moderated by age, race, sex, or baseline RSA and PEP. Overall, RSA and PEP were reciprocally coupled. However, recovery from a stressor was characterized by coactivation. Individuals also vary in the extent to which their SNS and PNS are reciprocally coupled; women, younger adults, and individuals with higher baseline RSA showed more reciprocal coupling than men, older adults, and those with lower baseline RSA, respectively, reflecting greater coordination of physiological responding in the former groups.

Timing the opening and closure of the aortic valve using a phonocardiogram envelope: a performance test for systolic time intervals measurement

Objective. This work explored the reliability of using points on the heart sounds envelope as indicators of the opening and closure of the aortic valve (AVO, AVC) to measure the pre-ejection period (PEP) and the left ventricular ejection time (LVET). Approach. 36 phonocardiograms (PCGs) from healthy subjects and cardiovascular disease subjects were denoised using single-channel independent component analysis (SCICA) and, from the Hilbert envelopes, the positions of the S1 and S2 peaks were detected (pS1, pS2). Complementarily, the positions of the local maxima of S1 and S2 (mS1, mS2) and the points surrounding pS1 and pS2 (tS1, tS2) were obtained. Finally, the reliability of these points (and the corresponding PEP and LVET intervals) was evaluated by the calculation of three error indexes (ePEP, eLVET, and score) and by comparison to reference annotations provided by echocardiography using the Bland–Altman analysis and the paired T-test. Main results. The results indicated that, from a total of 920 and 341 heartbeats in the healthy and diseased groups, respectively, the timing points given by pS1 and pS2 (or mS1 and mS2) were unlikely to substitute for the reference annotations and, thus, are unreliable for measuring the PEP and LVET intervals in the PCG. The t-points evaluation, on the other hand, indicated that tS1 was likely to substitute for AVO and was thus reliable for measuring the PEP using the PCG, with median and interquartile ranges of 0.3(8.3) ms and −0.2(7.5) ms for each group. Future work will generate an envelope with higher temporal resolution, from where tS1 and tS2 can be more accurately detected to improve the PEP and LVET measurements on a larger dataset. Significance. The statistical tests revealed that the envelope of S1 is suitable for extracting a timing point from which the pre-ejection interval can be reliably quantified, and discarded the local maximum used in other studies.

Automativ assessment of systolic cardiac performance using PEP/LVET index

Congestive cardiac failure is one of the deadliest diseases in the world, with more than 26 million patients. Echocardiogram and angiography consider as the gold standards for heart failure diagnosis. Nevertheless, they are not commonly used for long-term follow up as they need highly skilled and experienced operator. In this paper, a simple and low-cost system for automatic assessment of systolic cardiac performance using systolic cardiac intervals is presented. The proposed system utilized electrocardiogram (ECG) and phonocardiogram (PCG) to calculate pre-ejection period (PEP) and left ventricle ejection time (LVET). The ratio between PEP and LVET was computed to assess the performance of the systolic cardiac function. ECG and PCG were acquired using a commercial stethoscope which was modified to convert PCG auscultation to electrical signals. ECG and PCG signals were digitized and transferred to a personal computer. A custom MATLAB application was designed to display the acquired ECG and PCG, and to compute PEP, LVET, and PEP/LVET ratio. The system was tested on 17 healthy subjects and results showed high agreement between the systolic heart function status assessed by the proposed system and the corresponding echocardiography results. These results imply that the proposed system could be used for long-term follow up for patients with congestive heart failure.