3,470 research outputs found

    History of concussion and lowered heart rate variability at rest beyond symptom recovery: a systematic review and meta-analysis

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    IntroductionConcussion is a growing concern in worldwide sporting culture. Heart rate variability (HRV) is closely tied with autonomic nervous system (ANS) deficits that arise from a concussion. The objective of this review was to determine if a history of concussion (HOC) can impact HRV values in the time-domain in individuals at rest. This review works to add to the literature surrounding HRV testing and if it can be used to check for brain vulnerabilities beyond the recovery of concussion symptoms.Materials and methodsThe systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) method. A computer based systematic review scanned articles dating from 1996 to June 2023 through PubMed, Cochrane Library, Google Scholar, and EMBASE databases. A risk of bias assessment was conducted using the ROBINS-E tool. The average difference in time between heartbeats (MeanNN), the standard deviation of the differences (SDNN), and the root mean squared of the successive intervals (RMSSD) were measured.ResultsSix total studies were found that fit the inclusion criteria including a total of 242 participants (133 without HOC, 109 with HOC). The average age of the control group was 23.3 ± 8.2, while the average age of the history of TBI group was 25.4 ± 9.7, with no significant difference between the groups (p = 0.202). Four of the studies reported no significant difference in any of the three measures, while two of the studies reported significant difference for all three measures. The meta-analysis was conducted and found that MeanNN (p = 0.03) and RMSSD (p = 0.04) reached statistical significance, while SDNN did not (p = 0.11).ConclusionThe results of this meta-analysis showed significant difference in two of the three HRV time-domain parameters evaluated. It demonstrates that there can be lowered HRV values that expand beyond the recovery of symptoms, reflecting an extensive period of ANS susceptibility after a concussion. This may be an important variable in determining an athlete’s return to play (RTP). Lack of homogenous study populations and testing methods introduces potential for bias and confounding factors, such as gender or age. Future studies should focus on baseline tests to compare individuals to themselves rather than matched controls

    Effects of Mirror Therapy in Patients with Chronic Somatoform Pain Disorders on Psychometric Parameters and Heart Rate Variability

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    Patients with chronic somatoform pain disorders often report impaired quality of life and high symptom burden, often responding inadequately to available treatment options. Mirror therapy has been shown to be effective in treating phantom limb pain following limb amputation and has been used successfully for other disorders, such as complex regional pain syndrome (CRPS). This pilot study examined the efficacy of mirror therapy in patients with chronic somatoform pain disorder, specifically whether and to what extent it can reduce symptom severity and modulate associated autonomic dysregulation. Fifteen patients (n = 15) diagnosed with a chronic somatoform pain disorder (F45.40, F45.41) were enrolled in the study and received four weeks of tablet-based mirror therapy including exercises for the upper and lower limb. Symptom severity was assessed with established questionnaires. In addition, heart rate variability (HRV) was recorded. After mirror therapy, there was a significant reduction in pain intensity (z = -2.878, p = .004). In addition, a reduction in absolute power in the low- frequency band of HRV (t(13) = 2.536, p = .025) was also found. The present pilot study was the first to examine the effect of mirror therapy in individuals with chronic somatoform pain disorders. The results suggest that this intervention may reduce pain intensity and influence associated dysfunctional HRV. Because this is a pilot study, these results and their explanatory power are limited by several factors, such as a small sample size and lack of a control group. Nevertheless, these promising results should be validated in further studies to pave the way for this new additional therapeutic option for these patients

    Pathophysiology of myocardial infarction with non-obstructive coronary arteries and Takotsubo syndrome

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    Introduction: The working diagnosis myocardial infarction with non-obstructive coronary arteries (MINOCA), with the subgroup myocardial infarction with normal coronary arteries (MINCA), encompasses conditions of diverse aetiological origin. One of them is Takotsubo syndrome (TTS), a reversible and often stress-induced condition of acute heart failure, predominantly affecting postmenopausal women. Both MINOCA and TTS are associated with substantial morbidity and mortality, yet evidence-based treatment is lacking. The overall aim of this thesis was to expand the knowledge on pathophysiological mechanisms of MINOCA and TTS, with a view to guide future clinical management. The study specific aims were I) to characterise MINCA patients regarding risk factors and markers for endothelial function and atherosclerosis, II) to improve the diagnostics of MINOCA, III) to study if coronary microvascular dysfunction (CMD) is a prominent feature of acute TTS, and whether CMD in TTS is associated with clinical parameters, and IV) to determine whether sympathetic activity and reactivity are enhanced in the early recovery phase of TTS. Methods and results: In study I, the first Stockholm Myocardial Infarction with Normal Coronaries (SMINC) study, we included 100 MINCA patients together with two age- and sexmatched control groups of MI patients with coronary heart disease, respectively healthy volunteers. Endothelial function was evaluated with peripheral arterial tonometry measuring reactive hyperaemia index. Atherosclerosis was evaluated with carotid ultrasound measuring intima-media thickness. MINCA was associated with many established cardiovascular risk factors and female sex. Measures of endothelial function and atherosclerosis did not differ between study groups. One out of four MINCA patients received a clinical diagnosis of TTS. In study II, the SMINC-2 study, 148 MINOCA patients were examined by comprehensive cardiovascular magnetic resonance (CMR) imaging at median 3 days after admission. 150 patients from the screening phase of the SMINC-1 study, examined by standard CMR imaging at median 12 days after admission, served as historical controls. The underlying diagnosis was identified in 77% of patients in the SMINC-2 study, compared to 47% of patients in SMINC-1. The improved diagnostic yield was mainly due to increased detection of myocarditis and TTS. In study III, the Sympathetic And vascular Function in Takotsubo syndrome (SAFT) study, we included 27 female TTS patients together with age- and sexmatched controls with ischemia and no obstructive coronary arteries (INOCA). CMD was assessed invasively with thermodilution technique during index coronary angiography. Cardiac function was determined by echocardiography and CMR imaging in TTS patients. CMD was more common in TTS patients than in INOCA controls (78% vs. 44%). CMD was related to left ventricular function in TTS and more pronounced in the apical than midventricular phenotype. In study IV, muscle sympathetic nerve activity (MSNA) was determined by microneurography of the peroneal nerve at rest and during stress in 18 TTS patients from the SAFT study together with 13 age- and sex-matched healthy controls. Cardiac specific sympathetic activity was depicted by 123Imetaiodobenzylguanidine scintigraphy in 10 TTS patients. Despite signs of increased cardiac sympathetic activity in TTS, MSNA at rest and in response to stress did not differ between TTS patients and controls. Conclusions: MINCA is associated with many cardiovascular risk factors, female sex, and TTS, but not with markers of endothelial function and atherosclerosis. Early and comprehensive CMR imaging significantly improves the diagnostic yield in MINOCA and is therefore strongly suggested as a standard diagnostic tool. CMD is highly prevalent in the acute phase of TTS, associated with left ventricular function, and thus proposed as a key mediator in TTS pathophysiology. An altered cardiac response to sympathetic activation, rather than an underlying sympathetic hyperactivity or hyperreactivity, is likely central for TTS development

    The role of the autonomic nervous system in polycystic ovary syndrome

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    This article reviewed the relationship between the autonomic nervous system and the development of polycystic ovary syndrome (PCOS). PCOS is the most common reproductive endocrine disorder among women of reproductive age. Its primary characteristics include persistent anovulation, hyperandrogenism, and polycystic ovarian morphology, often accompanied by disturbances in glucose and lipid metabolism. The body’s functions are regulated by the autonomic nervous system, which consists mainly of the sympathetic and parasympathetic nervous systems. The autonomic nervous system helps maintain homeostasis in the body. Research indicates that ovarian function in mammals is under autonomic neural control. The ovaries receive central nervous system information through the ovarian plexus nerves and the superior ovarian nerves. Neurotransmitters mediate neural function, with acetylcholine and norepinephrine being the predominant autonomic neurotransmitters. They influence the secretion of ovarian steroids and follicular development. In animal experiments, estrogen, androgens, and stress-induced rat models have been used to explore the relationship between PCOS and the autonomic nervous system. Results have shown that the activation of the autonomic nervous system contributes to the development of PCOS in rat. In clinical practice, assessments of autonomic nervous system function in PCOS patients have been gradually employed. These assessments include heart rate variability testing, measurement of muscle sympathetic nerve activity, skin sympathetic response testing, and post-exercise heart rate recovery evaluation. PCOS patients exhibit autonomic nervous system dysfunction, characterized by increased sympathetic nervous system activity and decreased vagal nerve activity. Abnormal metabolic indicators in PCOS women can also impact autonomic nervous system activity. Clinical studies have shown that various effective methods for managing PCOS regulate patients’ autonomic nervous system activity during the treatment process. This suggests that improving autonomic nervous system activity may be an effective approach in treating PCOS

    Sex Differences in Physiological Responses after Cardiac Rehabilitation

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    Background and Purpose: Heart disease (HD) is one of the leading causes of death in men and women in Canada. Many HD patients are referred for cardiac rehabilitation (CR) which is a multidisciplinary outpatient supervised exercise program consisting of aerobic and resistance training to improve cardiovascular health. Previous studies have shown that healthy men and women respond differently to aerobic and resistance training. The purpose of this systematic review is to discover any physiological differences in male and female HD patient responses to a CR program. Methods and Results: A search strategy was generated to investigate at the relationships between heart disease patients, a supervised exercise program, physiological outcomes, and gender differences. Conclusions: This review presents that HD patients respond similarly in most physiological variables regardless of sex. Though, many studies discussing maximal oxygen consumption, functional capacity, six-minute walk distances, and grip strength strongly suggest that men benefit more

    Angiotensin-converting Enzyme Inhibitors Decrease the Risk of Cardiac Rupture after Acute Myocardial Infarction: A Meta-analysis of Randomized Controlled Trials

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    Background: ACEI therapy decreases mortality in patients with acute MI. However, the effects of ACEIs on CR are unclear. Methods: A comprehensive search of PUBMED, EMBASE, ISI Web of Science, MEDLINE and the Cochrane Register of Controlled Trials before July 2022 was conducted to identify all RCTs on ACEIs that recorded CR as an outcome. Review Manager 5.3 was used to analyze the data. Results: Five RCTs including 26,383 patients with MI were identified; 71 of the 13,159 patients receiving ACEIs and 107 of the 13,224 control patients were verified to have CR. ACEI therapy started within 24 hours after the onset of acute MI significantly decreased the risk of CR, by 33% (RR: 0.67, 95% CI: 0.50–0.90, P=0.008). Conclusions: Early administration of ACEIs (within 24 hours after the onset of acute MI) decreased the incidence of CR in patients with acute MI

    A novel strategy to fit and validate physiological models: a case study of acardiorespiratory model for simulation of incremental aerobic exercise

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    Applying complex mathematical models of physiological systems is challenging due to the large number of parameters. Identifying these parameters through experimentation is difficult, and although procedures for fitting and validating models are reported, no integrated strategy exists. Additionally, the complexity of optimization is generally neglected when the number of experimental observations is restricted, obtaining multiple solutions or results without physiological justification. This work proposes a fitting and validation strategy for physiological models with many parameters under various populations, stimuli, and experimental conditions. A cardiorespiratory system model is used as a case study, and the strategy, model, computational implementation, and data analysis are described. Using optimized parameter values, model simulations are compared to those obtained using nominal values, with experimental data as a reference. Overall, a reduction in prediction error is achieved compared to that reported for model building. Furthermore, the behavior and accuracy of all the predictions in the steady state were improved. The results validate the fitted model and provide evidence of the proposed strategy’s usefulness.Peer ReviewedPostprint (published version

    Information-Theoretic Analysis of Cardio-Respiratory Interactions in Heart Failure Patients: Effects of Arrhythmias and Cardiac Resynchronization Therapy

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    The properties of cardio-respiratory coupling (CRC) are affected by various pathological conditions related to the cardiovascular and/or respiratory systems. In heart failure, one of the most common cardiac pathological conditions, the degree of CRC changes primarily depend on the type of heart-rhythm alterations. In this work, we investigated CRC in heart-failure patients, applying measures from information theory, i.e., Granger Causality (GC), Transfer Entropy (TE) and Cross Entropy (CE), to quantify the directed coupling and causality between cardiac (RR interval) and respiratory (Resp) time series. Patients were divided into three groups depending on their heart rhythm (sinus rhythm and presence of low/high number of ventricular extrasystoles) and were studied also after cardiac resynchronization therapy (CRT), distinguishing responders and non-responders to the therapy. The information-theoretic analysis of bidirectional cardio-respiratory interactions in HF patients revealed the strong effect of nonlinear components in the RR (high number of ventricular extrasystoles) and in the Resp time series (respiratory sinus arrhythmia) as well as in their causal interactions. We showed that GC as a linear model measure is not sensitive to both nonlinear components and only model free measures as TE and CE may quantify them. CRT responders mainly exhibit unchanged asymmetry in the TE values, with statistically significant dominance of the information flow from Resp to RR over the opposite flow from RR to Resp, before and after CRT. In non-responders this asymmetry was statistically significant only after CRT. Our results indicate that the success of CRT is related to corresponding information transfer between the cardiac and respiratory signal quantified at baseline measurements, which could contribute to a better selection of patients for this type of therapy
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