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International Journal of Molecular... Sep 2021Syncope, defined as a transient loss of consciousness caused by transient global cerebral hypoperfusion, affects 30-40% of humans during their lifetime. Vasovagal... (Review)
Review
Syncope, defined as a transient loss of consciousness caused by transient global cerebral hypoperfusion, affects 30-40% of humans during their lifetime. Vasovagal syncope (VVS) is the most common cause of syncope, the etiology of which is still unclear. This review summarizes data on the genetics of VVS, describing the inheritance pattern of the disorder, candidate gene association studies and genome-wide studies. According to this evidence, VVS is a complex disorder, which can be caused by the interplay between genetic factors, whose contribution varies from monogenic Mendelian inheritance to polygenic inherited predisposition, and external factors affecting the monogenic (resulting in incomplete penetrance) and polygenic syncope types.
Topics: Genetic Predisposition to Disease; Humans; Inheritance Patterns; Multifactorial Inheritance; Syncope, Vasovagal
PubMed: 34638656
DOI: 10.3390/ijms221910316 -
Frontiers in Neuroscience 2019Puberty is initiated by hormonal changes in the adolescent body that trigger physical and behavioral changes to reach adult maturation. As these changes occur, some... (Review)
Review
Puberty is initiated by hormonal changes in the adolescent body that trigger physical and behavioral changes to reach adult maturation. As these changes occur, some adolescents experience concerning pubertal symptoms that are associated with dysfunction of the autonomic nervous system (ANS). Vasovagal syncope (VVS) and Postural Orthostatic Tachycardia Syndrome (POTS) are common disorders of the ANS associated with puberty that are related to orthostatic intolerance and share similar symptoms. Compared to young males, young females have decreased orthostatic tolerance and a higher incidence of VVS and POTS. As puberty is linked to changes in specific sex and non-sex hormones, and hormonal therapy sometimes improves orthostatic symptoms in female VVS patients, it is possible that pubertal hormones play a role in the increased susceptibility of young females to autonomic dysfunction. The purpose of this paper is to review the key hormonal changes associated with female puberty, their effects on the ANS, and their potential role in predisposing some adolescent females to cardiovascular autonomic dysfunctions such as VVS and POTS. Increases in pubertal hormones such as estrogen, thyroid hormones, growth hormone, insulin, and insulin-like growth factor-1 promote vasodilatation and decrease blood volume. This may be exacerbated by higher levels of progesterone, which suppresses catecholamine secretion and sympathetic outflow. Abnormal heart rate increases in POTS patients may be exacerbated by pubertal increases in leptin, insulin, and thyroid hormones acting to increase sympathetic nervous system activity and/or catecholamine levels. Given the coincidental timing of female pubertal hormone surges and adolescent onset of VVS and POTS in young women, coupled with the known roles of these hormones in modulating cardiovascular homeostasis, it is likely that female pubertal hormones play a role in predisposing females to VVS and POTS during puberty. Further research is necessary to confirm the effects of female pubertal hormones on autonomic function, and their role in pubertal autonomic disorders such as VVS and POTS, in order to inform the treatment and management of these debilitating disorders.
PubMed: 31798399
DOI: 10.3389/fnins.2019.01197 -
Biological Psychology Jul 2022This paper reviews the many functions of the vagus nerve, to understand how they interact in daily life and what might be accomplished by therapeutical electrical... (Review)
Review
This paper reviews the many functions of the vagus nerve, to understand how they interact in daily life and what might be accomplished by therapeutical electrical stimulation. A short historical introduction on the discovery and name-giving of the cranial nerves numbers 9-12 is followed by an overview of the functions that are under lower brain stem control: heart (rate, contractility), intestine (swallowing, peristalsis and glands secretions, feeling of satiety), lungs (bronchoconstriction, lung-irritant and stretch receptor signaling), blood pressure (by vascular wall stress sensing) and blood gases by specialized receptors. Key in the review is the physiology behind beat-by-beat heart rate variations, how everyday life is reflected in its variability, from exciting moments to quiet sleep, with the 'common faint' or vasovagal collapse as extreme example. Next, the recently proposed role of the vagus nerve in limiting inflammation is discussed. This has led to adoption of an earlier developed technique for epilepsy treatment, i.e., electrical stimulation of one vagus nerve bundle in the neck, but now for immune diseases like rheumatoid arthritis and the scope is even widening to depression and cluster headache. However, the problem in application of whole vagus nerve stimulation is the lack of specificity: there is no way to titrate the stimulation to an observable effect variable. All nerves in the bundle, incoming and outgoing, can be 'hit', leading to side-effects which limit the intended application.
Topics: Blood Pressure; Electric Stimulation; Heart Rate; Humans; Vagus Nerve; Vagus Nerve Stimulation
PubMed: 35688294
DOI: 10.1016/j.biopsycho.2022.108378 -
Frontiers in Immunology 2020Neurally mediated syncope (NMS) is the most common underlying disease of pediatric syncope, which generally includes vasovagal syncope (VVS), postural tachycardia... (Review)
Review
Neurally mediated syncope (NMS) is the most common underlying disease of pediatric syncope, which generally includes vasovagal syncope (VVS), postural tachycardia syndrome (POTS), and situational syncope. Allergic diseases involving the respiratory system, digestive system, skin, and other systems are prevalent in children. In recent years, increasing attention has been paid to children with the comorbidity of NMS and allergic diseases. This article reviews the featured clinical manifestations and pathogenesis of the comorbidity according to the progress of related studies. Clinical studies have shown that the comorbidity rate of pediatric VVS and/or POTS with allergic diseases amounts to ~30-40%, referring to the whole population of children with VVS and/or POTS. Additionally, children with the comorbidity present some relatively special clinical characteristics. A series of mechanisms or regulatory factors relating to allergies, such as the imbalance of vasoactive elements, dysfunction of the autonomic nervous system (ANS), and autoimmunity may play a role in the development of the comorbidity. Moreover, 90% of children with cough syncope, a type of situational syncope, have a history of asthma, indicating a potential relationship between asthma and NMS. Further studies exploring the clinical characteristics and pathogenesis of the comorbidity are still needed to aid in the diagnosis and treatment of children with NMS.
Topics: Child; Child, Preschool; Comorbidity; Female; Humans; Hypersensitivity; Male; Syncope
PubMed: 32983103
DOI: 10.3389/fimmu.2020.01865 -
Autonomic Neuroscience : Basic &... Mar 2022Hydration with water and salt is the mainstay of treatment for autonomic nervous system disorders that impair orthostatic tolerance. The goal is to expand intravascular... (Review)
Review
Hydration with water and salt is the mainstay of treatment for autonomic nervous system disorders that impair orthostatic tolerance. The goal is to expand intravascular volume to compensate for the downward displacement of blood volume that occurs when standing and thereby sustain cerebral perfusion and restore quality of life. Despite strong consensus recommendations for salt supplementation as standard treatment of these disorders, published evidence of benefit is relatively weak, and no randomized clinical trials have occurred. This review summarizes the physiological rationale for hydration and evaluates the literature on oral and intravenous hydration in the treatment of neurogenic orthostatic hypotension, postural tachycardia syndrome, and recurrent vasovagal syncope. We conclude that oral salt replacement is indicated for treatment of neurogenic orthostatic hypotension because these patients have excessive renal sodium excretion, and for treatment of chronic orthostatic intolerance because these patients are often hypovolemic. As not all patients are able to tolerate sufficient oral hydration, there is also a role for intravenous volume-loading in severe cases of postural tachycardia syndrome. We offer guidance, based on review of the literature and the clinical judgment of a cardiologist and neurologist with experience treating autonomic disorders, regarding the option of ongoing intravenous hydration for treatment of severe, refractory cases of postural tachycardia syndrome.
PubMed: 35123367
DOI: 10.1016/j.autneu.2022.102951 -
Frontiers in Cardiovascular Medicine 2019Cerebral autoregulation is crucial for maintaining cerebral blood flow and perfusion. In recent years, the importance of cerebral oxygenation in syncope and orthostatic... (Review)
Review
Cerebral autoregulation is crucial for maintaining cerebral blood flow and perfusion. In recent years, the importance of cerebral oxygenation in syncope and orthostatic intolerance (OI) has received increased attention. Cerebral tissue oxygenation can be measured by using near-infrared spectroscopy (NIRS), which determines the ratio of oxygenated hemoglobin to total hemoglobin in cerebral tissue. NIRS is non-invasive technology using near-infrared light, which displays real-time cerebral tissue oxygenation. Normal values of cerebral tissue oxygenation in healthy subjects are 60 to 80%. Head-up tilt test (HUT) offers the opportunity to observe the haemodynamic changes precipitating syncope and is, today, the standard method for the evaluation of syncope and orthostatic intolerance syndromes. In previous studies where NIRS was applied during HUT, a significant decrease in cerebral tissue oxygenation both prior to and during loss-of-consciousness in vasovagal syncope (VVS) has been observed. Interestingly, cerebral tissue oxygenation appears to decrease even before haemodynamic changes can be observed. Apart from VVS, cerebral tissue oxygenation decreases during orthostatic provocation in patients with orthostatic hypotension (OH) and postural orthostatic tachycardia syndrome (POTS), in the latter even in the absence of hypotension. Importantly, decline of cerebral tissue oxygenation in VVS and POTS during HUT may not correlate with hemodynamic changes. In this mini review, we summarize the current knowledge of the application of cerebral oximetry in syncope and orthostatic intolerance syndromes, discuss its likely value as a clinical diagnostic tool and also emphasize its potential in the understanding of the relevant pathophysiology.
PubMed: 31824964
DOI: 10.3389/fcvm.2019.00171 -
Circulation Dec 2019This 2019 focused update to the American Heart Association and American Red Cross first aid guidelines follows the completion of a systematic review of treatments for... (Review)
Review
2019 American Heart Association and American Red Cross Focused Update for First Aid: Presyncope: An Update to the American Heart Association and American Red Cross Guidelines for First Aid.
This 2019 focused update to the American Heart Association and American Red Cross first aid guidelines follows the completion of a systematic review of treatments for presyncope of vasovagal or orthostatic origin. This review was commissioned by the International Liaison Committee on Resuscitation and resulted in the development of an international summary statement of the International Liaison Committee on Resuscitation First Aid Task Force Consensus on Science With Treatment Recommendations. This focused update highlights the evidence supporting specific interventions for presyncope of orthostatic or vasovagal origin and recommends the use of physical counterpressure maneuvers. These maneuvers include the contraction of muscles of the body such as the legs, arms, abdomen, or neck, with the goal of elevating blood pressure and alleviating symptoms. Although lower-body counterpressure maneuvers are favored over upper-body counterpressure maneuvers, multiple methods can be beneficial, depending on the situation.
Topics: American Heart Association; Cardiopulmonary Resuscitation; Consensus; Emergency Medical Services; First Aid; Humans; Out-of-Hospital Cardiac Arrest; Practice Guidelines as Topic; Red Cross; United States
PubMed: 31722559
DOI: 10.1161/CIR.0000000000000730 -
Pakistan Journal of Medical Sciences 2022To compare the levels of cortisol in patients of vasovagal syncope (VVS) and postural tachycardia syndrome (POTS).
OBJECTIVES
To compare the levels of cortisol in patients of vasovagal syncope (VVS) and postural tachycardia syndrome (POTS).
METHODS
A cross-sectional analytical study was conducted at Islamic International Medical College, Rawalpindi and Electrophysiology Department at (AFIC). This study included 80 subjects, comprising of 35 patients in each group of vasovagal syncope and postural tachycardia syndrome and 10 healthy subjects. Patients with complaint of syncope was evaluated for vasovagal syncope and postural tachycardia syndrome using Head Up Tilt Test (HUTT. Blood samples of all the participants were taken and serum cortisol was analyzed using ELISA method. Results were analyzed on SPSS Statistics 21 using ANOVA with a p value of ≤0.05 regarded as significant.
RESULTS
Hormonal analysis shows that cortisol levels in the vasovagal, postural tachycardia syndrome and in control group was 153±16.7pg/ml, 160.17±pg/ml, and 69.65± 5.8pg/ml respectively. Cortisol levels were significantly higher in both vasovagal and POTS groups as compared to controls with a p-value of 0.04 and 0.023 respectively. However, there was no significant difference between vasovagal and POTS patients with p value 0.570.
CONCLUSION
It is concluded from the study that cortisol responses of VVS and POTS were positive.
PubMed: 35035423
DOI: 10.12669/pjms.38.1.4122 -
Frontiers in Cardiovascular Medicine 2020Vasovagal syncope (VVS) is the most common cause of syncope across all age groups. Nonetheless, despite its clinical importance and considerable research effort over... (Review)
Review
Vasovagal syncope (VVS) is the most common cause of syncope across all age groups. Nonetheless, despite its clinical importance and considerable research effort over many years, the pathophysiology of VVS remains incompletely understood. In this regard, numerous studies have been undertaken in an attempt to improve insight into the evolution of VVS episodes and many of these studies have examined neurohormonal changes that occur during the progression of VVS events primarily using the head-up tilt table testing model. In this regard, the most consistent finding is a marked increase in epinephrine (Epi) spillover into the circulation beginning at an early stage as VVS evolves. Reported alterations of circulating norepinephrine (NE), on the other hand, have been more variable. Plasma concentrations of other vasoactive agents have been reported to exhibit more variable changes during a VVS event, and for the most part change somewhat later, but in some instances the changes are quite marked. The neurohormones that have drawn the most attention include arginine vasopressin [AVP], adrenomedullin, to a lesser extent brain and atrial natriuretic peptides (BNP, ANP), opioids, endothelin-1 (ET-1) and serotonin. However, whether some or all of these diverse agents contribute directly to VVS pathophysiology or are principally a compensatory response to an evolving hemodynamic crisis is as yet uncertain. The goal of this communication is to summarize key reported neurohumoral findings in VVS, and endeavor to ascertain how they may contribute to observed hemodynamic alterations during VVS.
PubMed: 32478097
DOI: 10.3389/fcvm.2020.00076 -
Italian Journal of Pediatrics Dec 2022Both vasovagal syncope (VVS) and epilepsy present with transient loss of consciousness and are often difficult to identify. Hence this study aimed to explore the value...
BACKGROUND
Both vasovagal syncope (VVS) and epilepsy present with transient loss of consciousness and are often difficult to identify. Hence this study aimed to explore the value of QT interval in the differentiation of VVS and epilepsy in children.
METHODS
One hundred thirteen children with unexplained transient loss of consciousness were selected. 56 children with VVS (VVS group), including 37 males and 19 females, the average age is 9.88 ± 2.55 years old. 57 children with epilepsy (epilepsy group), including 36 males and 21 females, the average age is 8.96 ± 2.67 years old. At the same time, the 60 healthy individuals (control group) were examined according to age and sex. The QT interval of 12-lead electrocardiogram in a basal state of three groups was measured and statistically analyzed by SPSS 24.0 software.
RESULTS
Compared with the control group, (1) QTcmax, QTcmin and QTcd were significantly longer in VVS group (P < 0.05), QTmax and QTmin were significantly shorter in VVS group (P < 0.05), and there were no significant differences in QTd between the two groups (P > 0.05). (2) The QTmax and QTmin were significantly shorter in epilepsy group (P < 0.05), and there were no significant differences in QTd, QTcmax, QTcmin, QTcd between the two groups (P > 0.05). Compared with the epilepsy group, The QTcmax, QTcmin, QTcd were significantly longer in VVS group (P < 0.05), and there were no significant differences in QTd, QTmax, QTmin between the two groups (P > 0.05). When QTcmax > 479.84 ms, QTcmin > 398.90 ms and QTcd > 53.56 ms, the sensitivity and specificity of diagnosing VVS were 62.5% and 77.19%, 82.14% and 50.88%, 82.14% and 38.60% respectively.
CONCLUSION
QTcmax, QTcmin and QTcd have certain value in differentiating VVS from epilepsy in children.
Topics: Male; Child; Female; Humans; Syncope, Vasovagal; Electrocardiography; Sensitivity and Specificity; Epilepsy
PubMed: 36510267
DOI: 10.1186/s13052-022-01388-2