Neurohormones in Vasovagal Syncope: Are They Important?

Predictive analysis of catecholamines and electrolytes for recurrence of orthostatic intolerance in children

Background

Orthostatic intolerance (OI) is usually mediated by the autonomic nerve and most often happens in the upright position. However, it can also occur in other positions and can be relieved by lying down while likely to have another attack after relief. In the current study, we aim to evaluate the predictive effect of catecholamines and electrolytes on the recurrence of OI in children.

Materials and methods

Children who were diagnosed with vasovagal syncope (VVS), postural tachycardia syndrome (POTS), and VVS combined with POTS were enrolled in this retrospective study and were followed up after 1-year physical treatment. Catecholamines in urine collected within 24 h, renin, angiotensin II, aldosterone in plasma, and electrolytes in both blood and urine collected in the morning were tested. A multivariate analysis and a receiver operating characteristic curve were used to validate the prediction effect.

Results

In the VVS cohort, the 24 h urine adrenaline (AD) and norepinephrine (NE) levels of the non-recurrence group were lower than the 24 h urine AD and NE levels of the recurrence group, with a significant difference of P < 0.05. A different content can also be witnessed in the POTS cohort that the urine of the non-recurrence group contained lower sodium and chlorine. As for the VVS + POTS cohort, the non-recurrence group has lower AD and NE levels and higher potassium and phosphorus levels in urine, the difference of which proved prominent as well.

Conclusion

The study provides further evidence that AD, NE, and electrolytes in urine are promising factors that are closely related to the recurrence of OI in children. The integrated evaluation system merging AD and NE may have better predictive ability.

Anxiety and Depression as Risk Factors for Vasovagal Syncope and Potential Treatment Targets: A Systematic Review

Vasovagal syncope (VVS) is a transient, sudden loss of consciousness followed by complete resolution, usually due to a paradoxical autonomic reaction that results in hypotension and/or bradycardia. In this study, we assessed the correlation between VVS and a patient's psychiatric status, as well as if this association could be a target in the treatment of those patients. We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched the available literature using the following databases: PubMed, Google Scholar, and ScienceDirect, with last access on July 21, 2022. The search resulted in 1691 articles, and inclusion and exclusion criteria were applied to nine remaining articles, all of which were accepted after using the quality assessment tools, four observational and four randomized controlled trials (RCTs). Four of the included studies assessed the correlation among vasovagal syncope, psychosocial impairment, and quality of life. We found a consistent correlation among VVS, psychosocial impairment, and quality of life (QoL), meaning that VVS patients usually have some degree of psychosocial impairment, especially in the form of anxiety and depression, and a poorer QoL in comparison to their healthy counterparts. The use of psychotherapy and antidepressants was proven to be effective in VVS in RCTs, but further evidence is needed.

The Role of Adenosine and Its Degradation Enzymes - Adenosinedeaminase and Adenosinekinase in Pathogenesis of Vasovagal Syncope

INTRODUCTION

Adenosine is mediator regulating physiological and pathological processes in organism. It probably plays a role in pathogenesis of vasovagal syncopes (VVS), too. Adenosine, its receptors and degradation enzymes- adenosinedeaminase (ADA) and adenosinekinase (ADK), are called the adenosinergic system.

AIM

We aimed to evaluate serum levels of adenosine, ADA and ADK in patients with tilt-induced VVS and compare them to tlit-negative controls. Secondary aim was to compare the levels between the types of VVS and correlate them with hemodynamic parameters.

SUBJECTS AND METHODS

Altogether 132 individuals were involved in this study (age 39,88±15,64 years, 51 males). All patients underwent head up tilt test (HUTT) in differential diagnosis of syncope. Blood sampling was performed before and after HUTT. Baseline and stimulated serum levels of adenosine, ADA and ADK were evaluated by ELISA method.

RESULTS

HUTT was positive in 91 patients (HUTT+), 41 individuals were negative (HUTT-). HUTT+ patients had higher baseline and stimulated adenosine levels, when compared to HUTT- population. The rise in adenosine was higher in HUTT+ group. On the other hand, the increase of ADA was significantly higher in HUTT- subjects. Among HUTT+ group, the highest adenosine was found during vasodepressoric VVS.

CONCLUSION

Adenosinergic system may play role in pathogenesis of VVS. Patients with VVS have higher adenosine levels, that may be caused by attenuated degradation. Adenosine seems to be involved predominantly in vasodepressoric type of VVS. Further research evaluating complex function of adenosinergic system in these patients is needed.

Association of Polymorphisms in Endothelin-1 and Endothelin Receptor A Genes With Vasovagal Syncope

The endothelin system may play a role in the pathogenesis of vasovagal syncope (VVS) because it is implicated in blood pressure regulation. We hypothesized that endothelin-related genetic polymorphisms might modulate susceptibility to VVS. This study aimed to evaluate the possible influence of endothelin-1 (EDN1) and endothelin receptor A (EDNRA) gene variants on the occurrence of tilt-induced VVS and autonomic nervous system activity during the head-up tilt test (HUT). Results were expressed as mean ± SEM. In 254 patients with recurrent syncope (age 45.33±1.22 years, 94 males, 160 females), heart rate variability (HRV) was measured during HUT. EDN1 rs5370 G>T and EDNRA rs5333 T>C gene polymorphisms were assessed using high-resolution melting analysis. There was no statistically significant association between polymorphisms EDN1 rs5370 and EDNRA rs5333 and positivity of HUT or hemodynamic types of VVS. Patients with GT or TT genotypes at the rs5370 locus of the EDN1 had significantly higher values of high-frequency (HF) and the standard deviation of the average NN intervals at the time of the syncope, and they tended to have lower low-frequency (LF) and LF/HF ratio when compared to homozygotes (GG). No statistically significant differences were found in HRV parameters concerning the EDNRA rs5333 genotypes. Our findings suggest the potential role of EDN1 rs5370 variants in regulating autonomic nervous activity and pathogenesis of VVS.

Neurohormones in Vasovagal Syncope: Are They Important?

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