Altered Heart Rate Variability Research Articles

Using heart rate variability to predict neurological outcomes in preterm infants: a scoping review.

Infants born preterm are at higher risk of neurological complications, including intraventricular haemorrhage and white matter injury. After discharge, these infants may experience adverse neurodevelopmental outcomes and exhibit lower educational attainment. Early detection of brain injury and accurate prediction of neurodevelopmental impairment would allow early intervention and support. Heart rate variability (HRV) describes the variation of time intervals between each subsequent heartbeat. HRV is controlled by the autonomic nervous system, which may be affected by hypoxia and compromised blood flow. While HRV has primarily been investigated in neonatal sepsis, the association between HRV, brain injury and neurodevelopmental outcomes in preterm infants is less established. The present scoping review examines the utility of HRV monitoring for predicting short-term and long-term neurological outcomes in preterm infants. Following systematic search of Medline, Embase, Web of Science and the Cochrane Library, 15 studies were included. Nine studies examined the relationship between HRV and brain injury, with all but two showed an association. Eight studies examined the relationship between HRV and long-term outcomes and all eight found an association. This scoping review suggests that decreased HRV in the neonatal period is associated with short- and long-term neurodevelopmental outcomes in preterm infants. IMPACT: Changes in heart rate variability correlate with the occurrence of intraventricular haemorrhage in preterm infants. A decrease in heart rate variability may precede the development of intraventricular haemorrhage. Alterations in heart rate variability correlate with long-term neurodevelopmental outcomes. Significant variability exists in metrics used in assessing heart rate variability.

Heart rate variability activity in soccer athletes after a musculoskeletal injury.

The aim of this study is to analyse the adaptations of the autonomic nervous system after a musculoskeletal injury, obtained by measuring heart rate variability in athletes. It was hypothesized that there is an alteration in heart rate variability after a musculoskeletal injury. Cohort study. 15 semi-professional soccer players from three football teams, aged between 21 and 33 (mean age: 29.4 ± 3.31 years), with a recent musculoskeletal injury. Heart rate variability was collected using the Polar m200 and the chest strap H10 in two moments: within 72 h after the injury and between 5 and 7 days after full return-to-play. Results show differences between T1 and T2 (p ≤ 0.05) in low-frequency power (n.u.) (p = 0.001) and high-frequency power (n.u.) (p = 0.001), in low-frequency/high-frequency ratio (p = 0.001) and in high-frequency power (ms2) (p = 0.017) measures. No statistical differences were found in low-frequency power (ms2) (p = 0.233). The low frequency power (n.u.) was significantly lower after injury compared with LF power (n.u.) values after full return-to-play. In high-frequency power there was a significant difference between both moments with high values after injury. The use of heart rate variability therefore seems to be promising to detect an imbalance in the autonomic nervous system and help clinical departments to identify a possible non-traumatic musculoskeletal injury. Further research should be performed considering a wide range of musculoskeletal injuries and to establish baseline values of the athletes.

Analysis of heart rate variability and anthropometric measurements to compare obesity classes II and III in patients undergoing bariatric surgery

Introduction: obesity is an important public health problem worldwide. It is believed that obese candidates for bariatric surgery present cardiac autonomic dysfunction and that weight reduction achieved through surgical treatment of obesity may promote improvement in autonomic nervous system activity, minimizing cardiovascular risks. Objective: thus, the objective of this study is to assess the impact of surgical bariatric weight reduction on HRV and on anthropometric measurements (BMI, WHtR, and WC) comparing obesity classes II and III. Method: the study included 25 obese individuals who underwent a preoperative assessment. Anthropometric measurements and heart rate varability (HRV) were collected preoperatively. The participants were then divided into two groups: obesity class II and obesity class III (class II: BMI from 35 to 39 k/m2, and class III: BMI from > 40 kg/m2). Thirty days after surgery, a postoperative assessment was performed and the data were compared. Results: our results confirm that both class II and III obesity groups presented altered HRV preoperatively and that the participants in the obesity II group showed a statistically significant increase in the HRV index when compared to the obesity III group, through the mean RR, PNN50, SNS, and stress index. Conclusion: the findings confirmed the important contribution that bariatric surgery makes to improving metabolic health and lowering important obesity indices. The varying alterations in heart rate variability indicate subtle advantages concerning autonomic function, especially for individuals classified as obese II

Heart rate variability and cognitive functions in adolescents with complex congenital heart disease.

Heart Rate Variability (HRV) originates from the interplay between parasympathetic/sympathetic inputs to the heart, thus serving as an indicator of Autonomic Nervous System regulation. Prior research indicates that decreased HRV, marked by reduced autonomic balance, is related to poorer cognitive performance. While the population with congenital heart disease (CHD) show changes in HRV linked with the heart defect, the association between HRV and cognitive functions in CHD remains unexplored. 46 adolescents with CHD who went through infant open-heart surgery and 64 healthy controls (50.9% males, 12.8 ± 1.4 years) underwent neurodevelopmental testing and photoplethysmograph acquisition. Group differences and associations with cognitive functions were analysed with linear regression. P values were FDR-corrected. Adolescents with CHD showed lower HRV (quantified by high-frequency power) compared to controls (p < 0.001). Lower HRV was correlated with worse executive function (β = 0.24, p = 0.044) and lower IQ (β = 0.26, p = 0.010) in the whole sample and with lower IQ (β = 0.35, p = 0.014) in the CHD group. These associations were robust to confounders, including age, sex, and socioeconomic status. Our findings demonstrate an association between HRV and cognitive functions in adolescents with complex CHD. Early detection of alterations in HRV/autonomic regulation may help to identify children with CHD at risk for cognitive impairments. Adolescents with congenital heart disease (CHD) showed lower heart rate variability (HRV), indicating an imbalanced autonomic nervous system. Lower HRV was associated with lower IQ and executive function (EF) in the whole sample. The association between HRV and IQ was significantly stronger in CHD than in healthy controls. This study provides the first evidence of a link between altered HRV and cognitive impairments in the CHD population. Neurodevelopmental impairments seen in adolescents with CHD could be linked to their altered cardiac autonomic nervous activity, marked by low HRV.

Altered Heart Rate Variability During Mobile Game Playing and Watching Self-Mobile Gaming in Individuals with Problematic Mobile Game Use: Implications for Cardiac Health.

The surge in mobile gaming, fueled by smartphone and internet accessibility, lacks a comprehensive understanding of physiological changes during gameplay. This study, involving 93 participants (average age 21.75 years), categorized them into Problematic Mobile Gaming (PMG) and non-problematic Mobile Gaming (nPMG) groups based on Problematic Mobile Gaming Questionnaire (PMGQ) scores. The PMGQ is a 12-item scale developed in Taiwan to assess symptoms of problematic mobile gaming. The research delved into heart rate variability (HRV) alterations during real-time mobile gaming and self-gaming video viewing. Results showed that the PMG group significantly presents a lower root mean square of successive differences (RMSSD), and High Frequency (lnHF) than does the nPMG group (F=4.73, p=0.03; F=10.65, p=0.002, respectively) at the baseline. In addition, the PMG group significantly displayed elevated HF and low-frequency to high-frequency (LF/HF) in the mobile-gaming (F=7.59, p=0.007; F=9.31, p=0.003) condition as well as in the watching self-gaming videos (F=9.75, p=0.002; F=9.02, p=0.003) than did the nPMG. The study suggests targeted interventions to mitigate autonomic arousal, offering a potential avenue to address adverse effects associated with problematic mobile gaming behavior. The PMG group displayed increased craving scores after real-time mobile gaming and watching self-gaming video excerpts, unlike the nPMG group. Elevated LF/HF ratios in frequent gaming cases heightened autonomic arousal, presenting challenges in relaxation after mobile gaming. These findings contribute to a nuanced understanding of the complex interplay between mobile gaming activities, physiological responses, and potential intervention strategies.

Hypothyroidism and Heart Rate Variability: Implications for Cardiac Autonomic Regulation.

Thyroid hormones have a pivotal role in controlling metabolic processes, cardiovascular function, and autonomic nervous system activity. Hypothyroidism, a prevalent endocrine illness marked by inadequate production of thyroid hormone, has been linked to different cardiovascular abnormalities, including alterations in heart rate variability (HRV). The study included 110 patients with hypothyroid disorder. Participants underwent clinical assessments, including thyroid function tests and HRV analysis. HRV, a measure of the variation in time intervals between heartbeats, serves as an indicator of autonomic nervous system activity and cardiovascular health. The HRV values were acquired using continuous 24-h electrocardiogram (ECG) monitoring in individuals with hypothyroidism, as well as after a treatment period of 3 months. All patients exhibited cardiovascular symptoms like palpitations or fatigue but showed no discernible cardiac pathology or other conditions associated with cardiac disease. The findings of our study demonstrate associations between hypothyroidism and alterations in heart rate variability (HRV) parameters. These results illustrate the possible influence of thyroid dysfunction on the regulation of cardiac autonomic function.

Vago-splenic signal transduction of cardioprotection in humans.

The spleen serves as an important relay organ that releases cardioprotective factor(s) upon vagal activation during remote ischaemic conditioning (RIC) in rats and pigs. The translation of these findings to humans was attempted. Remote ischaemic conditioning or electrical auricular tragus stimulation (ATS) were performed in 10 healthy young volunteers, 10 volunteers with splenectomy, and 20 matched controls. Venous blood samples were taken before and after RIC/ATS or placebo, and a plasma dialysate was infused into isolated perfused rat hearts subjected to global ischaemia/reperfusion. Neither left nor right RIC or ATS altered heart rate and heart rate variability in the study cohorts. With the plasma dialysate prepared before RIC or ATS, respectively, infarct size (% ventricular mass) in the recipient rat heart was 36 ± 6% (left RIC), 34 ± 3% (right RIC) or 31 ± 5% (left ATS), 35 ± 5% (right ATS), and decreased with the plasma dialysate from healthy volunteers after RIC or ATS to 20 ± 4% (left RIC), 23 ± 6% (right RIC) or to 19 ± 4% (left ATS), 26 ± 9% (right ATS); infarct size was still reduced with plasma dialysate 4 days after ATS and 9 days after RIC. In a subgroup of six healthy volunteers, such infarct size reduction was abrogated by intravenous atropine. Infarct size reduction by RIC or ATS was also abrogated in 10 volunteers with splenectomy, but not in their 20 matched controls. In humans, vagal innervation and the spleen as a relay organ are decisive for the cardioprotective signal transduction of RIC and ATS.

ECG screening and Sudden Cardiac Death prevention in endurance athletes

Abstract Introduction Sudden cardiac death (SCD) is the leading cause of mortality in athletes during sport activity. Identifying non-invasive and repeatable risk markers during annual athletes screening remains a crucial goal for the scientific community for the prevention of cardiovascular disease. The ECG, exercise test and spirometry are part of the annual screening program in the sport population over 40 years of age. The Heart Rate Variability (HRV) has been shown to be an independent predictor of mortality in populations with CV disease, but its relationship with SCD has been little explored in those at low risk, including athletes. This study aims to use a 5 minute ECG screening in a specific population of athletes practicing endurance sports and evaluate its clinical repercussions. Aims The primary aim of the study is to assess whether morphological and spectral ECG analysis in endurance athletes by the 5-minute 'mini Holter ECG' can add information to the annual screening for the prevention of CV diseases and SCD. Materials The study population were selected from Endurance Marathon athletes. A control group was also collected for comparison. The 5 minutes ECG was recorded at rest with the Kardia Mobile 6L™ device that use three electrodes, which allows 6 leads recording. HRV indices were obtained using the Kubios software. A morphological analysis was performed and the HRV parameters were analyzed in the time and frequency domains. Results A total of 554 subjects (220 athletes-334 controls, 325 male-229 women) were analyzed. A higher incidence of sinus arrhythmias, LAFB, 1stdegree AVB, J point/ST-segment abnormalities in athletes compared to controls was observed. Athletes had a significantly shorter QTc than the control group (394.87±30.55 ms vs. 407.01±29.09 ms), suggestive of greater protection from malignant ventricular arrhythmias. The HRV PNS (-0.73±1.25 vs -0.21±1.45) and SNS (1.71±1.91 vs 0.58 ± 1.43) indices were also higher and lower in the athlete group than in the control group, suggestive for higher vagal tone. Given the absence of a normality range of standard HRV parameters in the athlete population, values in the normal range of the 5th to 95th percentile were extrapolated in the whole population for the main HRV parameters. The project, therefore, is to evaluate patients with HRV values higher or lower than 5-95 percentile to identify those deserving further clinical investigations and closer follow-up for suspected increased risk of CV disease and SCD. Conclusions The 5-minute cardiac Holter, combining a more accurate analysis in terms of morphology and arrhythmias than the 12-lead ECG, allows a greater number of static and dynamic alterations to be detected; moreover, the analysis of HRV could provide even more information, such that it could be considered as a complementary tool during the examination and FUP of athletes. Further long-term prospective studies are needed to correlate alterations in HRV and clinical events.

Intrinsic cardiac neurons as the consulate general of the brain in the heart: A review

Contrary to the prevailing understanding about one-way communication from brain to heart, recent research has unveiled a two-way communication pathway between these two organs, featuring the delivery of signals from the cardiac afferents to the brain. While the medulla oblongata is known to send autonomic signals for cardiac function regulation, 80% of the vagal afferents send signals to the brain for cardiac regulation. The vagus nerve receives these signals from the intrinsic cardiac neurons, often referred to as &amp;ldquo;the little brain of the heart.&amp;rdquo; Intrinsic cardiac neurons are neuronal structures with the same biochemical profile as neurons, communicating with the vagus nerve through acetylcholine and expresses markers of neuronal function such as tyrosine hydroxylase and others. Intrinsic cardiac neurons also influence the autonomic system, which can be studied through heart-rate variability measures. Heart rate variability (HRV) is altered in many types of cardiac disorders and is a well-known measure for studying short- and long-term disease-related variations in cardiac function. Some psychiatric disorders such as post-traumatic stress disorder, schizophrenia, and major depression also exhibited alterations in HRV. HRV is related to heartbeat-evoked potentials (HEPs) and electrical potentials in the brain that are influenced by the heart. HEPs are altered in disease states and can be impacted by environmental factors. This paper reviews the existing literature concerning intrinsic cardiac neurons and their possible role in heart-brain communication.

Maternal Injection with Dexamethasone Results in Female-Biased Autonomic Dysregulation in Rat Offspring

Autonomic dysfunction is an underlying risk factor for cardiovascular disease (CVD). Maternal injection of the synthetic GC dexamethasone (DEX) during the last 4 days of gestation results in female-biased increases in stress-responsive pressor (MAP), heart rate (HR) and altered heart rate variability (HRV) in adult rat offspring, suggesting a role for GC-mediated programming of autonomic function. The present study used pharmacological antagonists for adrenergic (SYM) or cholinergic (PS) receptors to investigate the degree to which changes in SYM or PS activity underlie the autonomic dysfunction in offspring of dams injected with DEX during late gestation. Naïve breeders were injected with DEX (0.4mg/kg/day, s.c.) or vehicle (hydroxypropyl beta cyclodextrin; Veh) on gestation days 18-21. Radiotelemetry was used in adult offspring for recording HR, MAP, and HRV (root mean square of successive differences: RMSSD). At 10-11 weeks rats were randomly assigned to receive SYM antagonists, α-adrenoceptor (prazosin; 0.5mg/kg, i.p.) + β-adrenoceptor (atenolol; 1mg/kg, i.p.), a PS antagonist (homatropine methylbromide; 0.2mg/kg, i.p), or saline (SAL, i.p.). Evaluations were made over 20 min following injection and then during a 20 min restraint. Females were tested on diestrus. In utero DEX exposure resulted in significantly lower RMSSD, an index of vagal tone, in DEX-exposed females and males. PS blockade significantly reduced RMSSD in Veh-, but not DEX-exposed female offspring. SYM blockade did not influence RMSSD in females. In males, PS blockade reduced in RMSSD in both DEX- and Veh-exposed offspring. SYM blockade only reduced RMSSD in males exposed to DEX. Area under the curve (AUC) analysis revealed that in female offspring, SYM blockade resulted in a greater reduction in HR in DEX-exposed offspring, compared to Veh (DEX-SYM: −220 bpm vs. DEX-SAL; Veh-SYM: −197 bpm vs. VEH-SAL) and during restraint (DEX-SYM: −535 bpm vs. DEX-SAL; Veh-SYM: −342 bpm vs. VEH-SAL). PS blockade resulted in a greater increase in HR in Veh-exposed females both following the injection (Veh-PS: −187 bpm vs. VEH-SAL; DEX-PS: −101 bpm vs. DEX-SAL) and during restraint (Veh-PS: −161 bpm vs. VEH-SAL; DEX-PS: −61 bpm vs. DEX-SAL). AUC analysis for MAP showed similar responses to those for HR with SYM blockade having a greater impact in DEX-exposed females and PS blockade having a greater effect in Veh-exposed females. By contrast, in male offspring in utero DEX exposure did not influence HR or MAP responses to SYM or PS blockade. Overall, these findings suggest that maternal DEX injections alter autonomic development primarily in in female offspring and is characterized by a shift from PS to SYM predominance. Better understanding of the mechanisms involved in this programming are important for identifying individuals at risk for CVD and development of interventional strategies for prevention of CVD. Funding: NIH U54 MH118919. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Ivabradine in Septic Shock: A Narrative Review.

In patients with septic shock, compensatory tachycardia initially serves to maintain adequate cardiac output and tissue oxygenation but may persist despite appropriate fluid and vasopressor resuscitation. This sustained elevation in heart rate and altered heart rate variability, indicative of autonomic dysfunction, is a well-established independent predictor of adverse outcomes in critical illness. Elevated heart rate exacerbates myocardial oxygen demand, reduces ventricular filling time, compromises coronary perfusion during diastole, and impairs the isovolumetric relaxation phase of the cardiac cycle, contributing to ventricular-arterial decoupling. This also leads to increased ventricular and atrial filling pressures, with a heightened risk of arrhythmias. Ivabradine, a highly selective inhibitor of the sinoatrial node's pacemaker current (If or "funny" current), mitigates heart rate by modulating diastolic depolarization slope without affecting contractility. By exerting a selective chronotropic effect devoid of negative inotropic properties, ivabradine shows potential for improving hemodynamics in septic shock patients with cardiac dysfunction. This review evaluates the plausible mechanisms and existing evidence regarding the utility of ivabradine in managing patients with septic shock.

Analysis of Heart Rate Variability in Individuals Affected by Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) produces alterations in the autonomic nervous system (ANS), which explains the cardiac manifestations observed in patients. The assessment of heart rate variability (HRV) is what best reflects the activity of the ANS on heart rate. The Polar H7 Bluetooth® device proves to be a non-invasive and much faster technology than existing alternatives for this purpose. The goal of this study is to determine HRV using Polar H7 Bluetooth technology in ALS patients, comparing the obtained measurements with values from healthy individuals. The sample consisted of 124 participants: 68 diagnosed with ALS and 56 healthy individuals. Using Polar H7 Bluetooth technology and the ELITE HRV application, various HRV measurements were determined for all participants, specifically the HRV index, RMSSD, RMSSD LN, SDNN index, PNN50, LF, HF, LF/HF ratio, HR average, and HF peak frequency. Statistically significant differences were observed between ALS patients and healthy individuals in the HRV index, RMSSD, RMSSD LN, SDNN index, PNN50, HF, and LF, where healthy individuals exhibited higher scores. For the HR average, the ALS group showed a higher value. Values were similar when comparing men and women with ALS, with only a higher HF peak frequency observed in women. The Polar H7 Bluetooth® device is effective in determining heart rate variability alterations in ALS, being a promising prognostic tool for the disease.

Heart rate and heart rate variability in obsessive-compulsive disorder: Evidence from patients and unaffected first-degree relatives

Altered heart rate (HR) and heart rate variability (HRV) are common observations in psychiatric disorders. Yet, few studies have examined these cardiac measures in obsessive-compulsive disorder (OCD). The current study aimed to investigate HR and HRV, indexed by the root mean square of successive differences (RMSSD) and further time domain indices, as putative biological characteristics of OCD. Electrocardiogram was recorded during a five-minute resting state. Group differences between patients with OCD (n = 96), healthy participants (n = 112), and unaffected first-degree relatives of patients with OCD (n = 47) were analyzed. As potential moderators of group differences, we examined the influence of age and medication, respectively. As results indicated, patients with OCD showed higher HR and lower HRV compared to healthy participants. These group differences were not moderated by age. Importantly, subgroup analyses showed that only medicated patients displayed lower HRV compared to healthy individuals, while HR alterations were evident in unmedicated patients. Regarding unaffected first-degree relatives, group differences in HRV remained at trend level. Further, an age-moderated group differentiation showed that higher HRV distinguished relatives from healthy individuals in young adulthood, whereas at higher age lower HRV was indicative of relatives. Both the role of familial risk and medication in HRV alterations need further elucidation. Pending future studies, alterations in HR and potentially HRV might serve as useful indices to characterize the pathophysiology of OCD.

Vagal predominance correlates with mood state changes of winter-over expeditioners during prolonged Antarctic residence.

Winter-over expeditioners in Antarctica are challenged by various environmental and psycho-social stress factors, which may induce psychophysiological changes. The autonomic nervous system (ANS) plays a crucial role in the adaptation process under stress. However, the relationship between ANS activity and the mood states of expeditioners remains largely unexplored. This study aims to uncover the pattern of ANS adjustment under extreme Antarctic environments and provide new insights into the correlations between ANS activity and mood state changes, which may provide scientific data for medical interventions. Fourteen expeditioners at Zhongshan Station participated in this study. The study was conducted during four representative periods: pre-Antarctica, Antarctica-1 (pre-winter), Antarctica-2 (winter), and Antarctica-3 (summer). The heart rate variability (HRV) of the expeditioners was continuously measured for 24 hours to evaluate ANS activity. Plasma levels of catecholamines were tested by ELISA. Mood states were assessed by the Profile of Mood States (POMS) scale. HRV analysis showed a disturbance of ANS during winter and summer periods. For frequency domain parameters, very low frequency (VLF), low frequency (LF), high frequency (HF), and total power (TP) significantly increased during the second half of the mission. Especially, LF/HF ratio decreased during summer, indicating the predominance of vagal tone. Results of the time domain analysis showed increased heart rate variability during the austral winter and summer. Plasma epinephrine (E) significantly increased during residence in Antarctica. Compared with pre-Antarctica, the vigor, depression, and anger scores of the expeditioners decreased significantly during the austral summer. Notably, the depression score showed a moderate positive correlation with LF/HF, while weak negative correlations with other HRV indicators, including TP, VLF, and LF. Anger score showed a moderate positive correlation with LF/HF and weak negative correlations with the average normal-to-normal (NN) interval, and the root mean square of differences between adjacent RR intervals (RMSSD). Plasma E level weakly correlated with the average NN interval. Prolonged residence in Antarctica increased the ANS activities and shifted the cardiac autonomic modulation towards vagal predominance. The alteration of HRV correlated with mood states and plasma epinephrine levels.

Brain connectivity networks underlying resting heart rate variability in acute ischemic stroke

Acute strokes can affect heart rate variability (HRV), the mechanisms how are not well understood. We included 42 acute stroke patients (2–7 days after ischemic stroke, mean age 66 years, 16 women). For analysis of HRV, 20 matched controls (mean age 60.7, 10 women) were recruited. HRV was assessed at rest, in a supine position and individual breathing rhythmus for 5 min. The coefficient of variation (VC), the root mean square of successive differences (RMSSD), the powers of low (LF, 0.04–0.14 Hz) and high (HF, 0.15–0.50 Hz) frequency bands were extracted. HRV parameters were z-transformed related to age- and sex-matched normal subjects. Z-values < -1 indicate reduced HRV. Acute stroke lesions were marked on diffusion-weighted images employing MRIcroN and co-registered to a T1-weighted structural volume-dataset. Using independent component analysis (ICA), stroke lesions were related to HRV. Subsequently, we used the ICA-derived lesion pattern as a seed and estimated the connectivity between these brain regions and seven common functional networks, which were obtained from 50 age-matched healthy subjects (mean age 68.9, 27 women). Especially, LF and VC were frequently reduced in patients. ICA revealed one covarying lesion pattern for LF and one similar for VC, predominantly affecting the right hemisphere. Activity in brain areas corresponding to these lesions mainly impact on limbic (r = 0.55 ± 0.08) and salience ventral attention networks (0.61 ± 0.10) in the group with reduced LF power (z-score < -1), but on control and default mode networks in the group with physiological LF power (z-score > -1). No different connectivity could be found for the respective VC groups. Our results suggest that HRV alteration after acute stroke might be due to affecting resting-state brain networks.

Heart rate variability alterations in takotsubo syndrome and related association with psychological factors: a systematic review and meta-analysis

Psychological factors may have a precipitant role in takotsubo syndrome (TS). Aberrant Heart Rate Variability (HRV) has been reported in TS, suggesting inflexibility of the autonomous nervous system. Nevertheless, results on HRV alterations and their link with psychological factors in TS are conflicting. This work aimed to systematically explore whether TS may be associated with HRV alterations and their association with specific psychological profiles in TS patients. A literature search was conducted across databases (Pubmed, Scopus, PsycInfo, Web of Science) and empirical studies including TS patients which were evaluated in one or more HRV indices were retrieved. HRV and psychological outcomes were extracted. 10 empirical studies with 194 TS patients were included. Results showed significant alteration of HRV in TS patients, with indices compared to controls, and a progressive increase over time. Nevertheless, retrieved data presented mixed results, as also shown by a large heterogeneity in the meta-analytic findings. 2 studies found significant relationships between HRV alterations and trait—rather than state—psychological outcomes (i.e., coping strategies and emotional arousal), pointing to the need to explore the role of psychological vulnerabilities, rather than single traumatic stressors, in the association between HRV and TS.

Preeclampsia-exposed children's heart rate variability 8-12 yr after index pregnancy: FINNCARE study.

Preeclampsia is related with elevated systolic blood pressure (SBP) in children. We studied if preeclampsia-exposed (PE) children develop alterations in heart rate variability (HRV) and if this is reflected in their blood pressure (BP), as well as overall associations with body size and composition, gestational and perinatal factors. We examined 182 PE (46 early-onset PE) and 85 unexposed (non-PE) children 8-12 yr after preeclampsia exposure. HRV monitoring was performed 5 min in supine followed by 5 min in standing position and compared with office, 24-h ambulatory, and central BPs in relation to body anthropometrics and composition, gestational, and perinatal data. There were no major differences in HRV between PE and non-PE children. HRV in supine position was strongly associated with office and ambulatory heart rates (HRs), and HR was independently associated with office BPs. However, HRV was not related with office or 24-h SBP and PP, nor with elevated SBP in PE compared with non-PE children [adjusted mean differences for office and 24-h SBP 4.8 (P < 0.001) and 2.5 mmHg (P = 0.049), respectively]. In supine position, high-frequency (HF) power [β, -0.04 (95% CI -0.06 to -0.01)], root mean square of successive differences in R-R intervals (rMSSD) [-0.015 (-0.028 to -0.002)], and the ratio of low-frequency (LF) to HF power [0.03 (0.01-0.04)] were independently associated with child fat mass. LF and HF power and rMSSD displayed independent inverse associations with child age. There were no significant associations between child HRV and gestational and perinatal factors. During prepuberty, the HRV in children with PE is similar to that in non-PE children. Elevated SBP following preeclampsia exposure is not related with HRV. Child adiposity could be related to decreased cardiac vagal tone.NEW & NOTEWORTHY Heart rate variability in preadolescent children exposed to preeclampsia in utero is no different from age-matched controls. Preeclampsia-exposed children's elevated SBP is not related to alterations in heart rate variability, which is a noninvasive measure of the modulation of heart rate by autonomic tone. However, childhood adiposity might be coupled with diminished cardiac vagal tone.

Heart Rate Variability, Autonomic Reactivity, and Emotion Regulation during Sadness Induction in Somatic Symptom Disorder.

Preliminary evidence suggests altered heart rate variability (HRV) and impaired emotion regulation (ER) in somatic symptom disorder (SSD). Moreover, HRV can be considered an index of ER. Yet, to date, research on HRV and emotional reactivity in SSD is scarce and findings are inconsistent. Thus, this study aimed to examine ER differences, HRV at rest, and in response to emotion induction in persons with SSD compared to controls. The sample comprised 44 persons with SSD (DSM-5; 79.5% female, Mage = 45.7, SD = 14.7) and 41 persons without SSD (non-SSD; 78% female, Mage = 44.2, SD = 14.7). We assessed the participants' somatic symptom severity, ER, and control variables (e.g., depressive symptoms). Frequency and time domain HRV by ECG and subjective emotional states were measured at rest, under sadness induction, and during recovery periods. We evaluated baseline between-group differences with t-tests, and HRV and emotional reactivity and recovery with repeated measures ANOVAs. We found no significant differences in resting state HRV between persons with and without SSD. Regarding reactivity and recovery, SSD group showed lower reactivity in SDNN (standard deviation of NN interval) than non-SSD group. Moreover, SSD group reported more maladaptive ER techniques (e.g. rumination) and a higher effort to regulate their emotions during the experiment than non-SSD group. The study indicated impaired ER in persons with SSD. This finding showed more clearly in self-report than in HRV. Further research on HRV reactivity including tasks evoking other negative emotions in persons with SSD is required.

Salt-sensitive trait of normotensive individuals is associated with altered autonomous cardiac regulation: a randomized controlled intervention study.

Blood pressure (BP) responses to sodium intake show great variation, discriminating salt-sensitive (SS) from salt-resistant (SR) individuals. The pathophysiology behind salt sensitivity is still not fully elucidated. We aimed to investigate salt-induced effects on body fluid, vascular tone, and autonomic cardiac response with regard to BP change in healthy normotensive individuals. We performed a randomized crossover study in 51 normotensive individuals with normal body mass index and estimated glomerular filtration rate. Subjects followed both a low-Na+ diet (LSD, <50 mmol/day) and a high-Na+ diet (HSD, >200 mmol/day). Cardiac output, systemic vascular resistance (SVR), and cardiac autonomous activity, through heart rate variability and cross-correlation baroreflex sensitivity (xBRS), were assessed with noninvasive continuous finger BP measurements. In a subset, extracellular volume (ECV) was assessed by iohexol measurements. Subjects were characterized as SS if mean arterial pressure (MAP) increased ≥3 mmHg after HSD. After HSD, SS subjects (25%) showed a 6.1-mmHg (SD 1.9) increase in MAP. No differences between SS and SR in body weight, cardiac output, or ECV were found. SVR was positively correlated with Delta BP (r = 0.31, P = 0.03). xBRS and heart rate variability were significantly higher in SS participants compared to SR participants after both HSD and LSD. Sodium loading did not alter heart rate variability within groups. Salt sensitivity in normotensive individuals is associated with an inability to decrease SVR upon high salt intake that is accompanied by alterations in autonomous cardiac regulation, as reflected by decreased xBRS and heart rate variability. No discriminatory changes upon high salt were observed among salt-sensitive individuals in body weight and ECV.NEW & NOTEWORTHY Extracellular fluid expansion in normotensive individuals after salt loading is present in both salt-sensitive and salt-resistant individuals and is not discriminatory to the blood pressure response to sodium loading in a steady-state measurement. In normotensive subjects, the ability to sufficiently vasodilate seems to play a pivotal role in salt sensitivity. In a normotensive cohort, differences in sympathovagal balance are also present in low-salt conditions rather than being affected by salt loading. Whereas treatment and prevention of salt-sensitive blood pressure increase are mostly focused on renal sodium handling and extracellular volume regulation, our study suggests that an inability to adequately vasodilate and altered autonomous cardiac functioning are additional key players in the pathophysiology of salt-sensitive blood pressure increase.

Autonomic dysregulation in long-term patients suffering from Post-COVID-19 Syndrome assessed by heart rate variability

Post-COVID-19 Syndrome (PCS) is a condition with multiple symptoms partly related to dysregulation of the autonomic nerve system. Assessment of heart rate variability (HRV) using 24 h Holter-ECG may serve as a surrogate to characterize cardiac autonomic activity. A prospective study including 103 PCS patients (time after infection = 252 days, age = 49.0 ± 11.3 years, 45.7% women) was performed and patients underwent detailed clinical screening, cardiopulmonary exercise testing, and 24 h Holter monitoring. Data of PCS patients was compared to 103 CAD patients and a healthy control group (n = 90). After correction for age and sex, frequency-related variables differed in PCS patients compared to controls including LF/HFpower, LF/HFnu, and LF/HF ratio (24 h; p ≤ 0.001). By contrast, these variables were largely comparable between PCS and CAD patients, while sympathetic activation was highest in PCS patients during the 24 h period. Overall, PCS patients showed disturbed diurnal adjustment of HRV, with impaired parasympathetic activity at night. Patients hospitalized during acute infection showed an even more pronounced overactivation of sympathetic activity compared to patients who underwent ambulant care. Our data demonstrate persistent HRV alterations in PCS patients with long-term symptom duration, suggesting a sustained impairment of sympathovagal balance. Moreover, sympathetic overstimulation and diminished parasympathetic response in long-term PCS patients are comparable to findings in CAD patients. Whether HRV variables have a prognostic value in PCS and/or might serve as biomarkers indicating a successful interventional approach warrants further longitudinal studies.