Diagnosis and prevention of the vasodepressor type of neurally mediated syncope in Japanese patients

Convolutional neural network-based method for the real-time detection of reflex syncope during head-up tilt test

BACKGROUND AND OBJECTIVES

Reflex syncope (RS) is the most common type of syncope caused by dysregulation of the autonomic nervous system. Diagnosing RS typically involves the head-up tilt test (HUTT), which tracks physiological signals such as blood pressure and electrocardiograms during postural changes. However, the HUTT is time-consuming and may trigger RS symptoms in patients. Therefore, a real-time monitoring system for RS risk assessment is necessary to enhance medical efficiency and patient convenience. Although several methods have been developed, most depend on manually extracted features from physiological signals, making them susceptible to feature extraction methods and signal noise.

METHODS

This study introduces a deep learning-based method for real-time RS detection. This method removes the need for manually extracted features by employing an end-to-end architecture consisting of residual and squeeze-and-excitation blocks. The likelihood of RS occurrence was quantified using the proposed method by analyzing a raw blood pressure signal.

RESULTS

Data from 1348 patients (1291 normal and 57 with RS) were used to develop and evaluate the proposed method. The area under the receiver operating characteristic curve was 0.972 for RS detection using ten-fold cross-validation. A threshold between zero and one can adjust the performance characteristics of the proposed method. At a threshold of 0.75, the method achieved sensitivity and specificity values of 94.74 and 94.27 %, respectively. Notably, the technique detected RS 165.35 s before its occurrence, on average.

CONCLUSIONS

The proposed method outperformed conventional methods in RS detection. In addition to its excellent detection performance, this method only requires blood pressure monitoring, reducing reliance on the number of input signals and enhancing its applicability compared to procedures that require multiple signals. These advantages contribute to the development of safer, more convenient, and more efficient RS detection systems.

Association of adenylate cyclase activity in vasopressor-type neurally mediated syncope based on the α2b-AR gene

Neurally mediated syncope (NMS) arises from a neural reflex; however, its underlying cause remains unknown. Previous research has shown that variations in the Gi-α signal transduction rate led to changes in adenylate cyclase (AC) activity levels. Thus, we hypothesized that these fluctuations in AC activity could contribute to NMS. This study aimed to investigate the receptor genes associated with glutamate (Glu) repeat polymorphism sites Glu12 and Glu9 in the α2B-AR gene. A total of 50 patients with vasodepressor-type (VT)-NMS and 20 healthy volunteers were included in this study. We assessed AC activity levels and blood pressure responses during the head-up tilt (HUT) test and conducted a Glu repeat polymorphism analysis to explore its potential association with NMS. Our findings showed significantly higher AC activity in patients with the Glu12/12 homotype than healthy volunteers across all four HUT test points. Conversely, patients with the Glu9/12 heterotype exhibited a significant difference only 10 min after the test initiation, suggesting a pronounced activation effect of the β2-AR Gs-α subunit in these individuals. Both genotypes displayed the greatest blood pressure fluctuations under 70° tilt stress, with patients with Glu12/12 showing consistent cardiac load and higher values than those with Glu9/12 at two points. Notably, the frequency of NMS onset within 20 min during the tilt test varied, with one Glu12/12 patient and seven Glu9/12 patients experiencing syncope. Additionally, patients with the Glu9/12 heterotype were found to have a higher risk of syncope after prolonged standing compared to those with the Glu12/12 homotype. These results suggest that patients with the Glu12/12 homotype exhibit elevated AC activity levels, which may help increase blood pressure to prevent syncope. This study underscores that variations in AC activity among different gene types could influence the frequency of NMS onset during standing.

Factors affecting the syncopal episodes in pediatric vasovagal syncope

OBJECTIVE

To investigate factors that influence the syncopal episodes in pediatric vasovagal syncope (VVS).

METHODS

A retrospective analysis was performed on the clinical data of 2908 children who were diagnosed with VVS for the first time between January 2001 and February 2023. The study examined the linear relationships among age, sex, height, weight, heart rate (HR), blood pressure, hemodynamic type, and head-up tilt test (HUTT) mode in relation to the onset of syncope.

RESULTS

(1) Comparative analysis of intergroup differences revealed statistically significant variations in sex, age, height, weight, HR, systolic blood pressure, hemodynamic classification, and HUTT mode among syncopal episodes groups (P < 0.05); (2) Univariate analysis identified age, female, height, weight, VVS-cardioinhibited type (VVS-CI), VVS-mixed type (VVS-M) as potential risk factors for syncope episodes. Conversely, HR and sublingual nitroglycerin HUTT (SNHUT) emerged as potential protective factors against syncope episodes. (3) Multivariate analysis indicated that the frequency of syncope episodes increased by 0.27/0.02 for each unit increase in age/weight. When females compared to males and VVS-CI and VVS-M compared to VVS-vasoinhibited type (VVS-VI), the frequency of syncope episodes increased by 1.36, 0.53, and 0.66 respectively. Furthermore, SNHUT was associated with a reduction in the number of syncope episodes by 0.34 relative to basic HUTT.

CONCLUSION

Female, age, weight, VVS-CI, and VVS-M were identified as independent risk factors for syncopal episodes, while SNHUT was recognized as an independent protective factor against syncopal episodes.

Relationship between hemodynamic type and syncopal symptoms in pediatric vasovagal syncope

Vasovagal syncope (VVS) is a clinically common neurally mediated syncope. The relationship between different hemodynamic types of VVS and clinical syncopal symptoms has not been reported. The purpose of this research is to explore relationship between hemodynamic types and syncopal symptoms in pediatric VVS. Two thousand five hundred thirteen patients diagnosed with VVS at the age of 3-18 years, average age was 11.76 ± 2.83 years, including 1124 males and 1389 females, due to unexplained syncope and pre-syncope from single-center of January 2001 to December 2021 were retrospectively analyzed. Subjects were divided into two groups according to the presence or absence of syncopal symptoms: syncope group (1262 cases) and pre-syncope group (1251 cases). (1) Baseline characteristics: age, height, weight, systolic blood pressure (SBP), and diastolic blood pressure (DBP) increased in the syncope group compared with the pre-syncope group; the composition ratio of females was more than that of males in the syncope group; and the composition ratio of VVS-cardioinhibited (VVS-CI) and VVS-mixed (VVS-M) was more in the syncope group than that of the pre-syncope group (all P < 0.05). (2) Univariate analysis: age, height, weight, SBP, DBP, female, VVS-CI, and VVS-M were potential risk factors for the presence of syncopal symptoms (all P < 0.05). (3) Multivariate analysis: VVS-CI and VVS-M were independent risk factors for the presence of syncopal symptoms, with an increased probability of 203% and 175%, respectively, compared to VVS-vasoinhibited (VVS-VI) (all P < 0.01).

CONCLUSION

The hemodynamic type of pediatric VVS is closely related to the syncopal symptoms.

WHAT IS KNOWN

• There are varying probabilities of syncopal episodes in different hemodynamic types of VVS, and there is a lack of research to assess the comparative risk of syncope in children with different hemodynamic types of VVS.

WHAT IS NEW

• The probability in presence of syncopal symptoms varies greatly between different hemodynamic types of VVS. • VVS-CI and VVS-M had a 203% and 175% increased risk in presence of syncopal symptoms compared with VVS-VI, respectively.

Effects of Genetic Mutation Sites in ADR Genes on Modern Chickens Produced and Domesticated by Artificial Selection

Associations between neurotransmitters, adrenergic receptor (ADR) mutations, and behaviors in chickens produced and domesticated by artificial selection remain unclear. This study investigates the association of neurotransmitters and ADR mutations with egg laying and cockfighting-behaviors associated with significantly different breeding backgrounds-in Shaver Brown and Shamo chickens. Accordingly, the whole sequences of nine ADR genes were determined, and nine amino acid-specific mutation sites from five genes (ADRα1A: S365G, ADRα1D: T440N, ADRα2A: D273E, ADRβ1: N443S, S445N, ADRβ3: R342C, Q404L, and P406S) were extracted. Evolutionary analysis showed that these mutations were not ancestrally derived. These results confirm that the mutations at these sites were artificially selected for domestication and are breed specific. N_ST population analysis confirmed a difference in the degree of genetic differentiation between the two populations in seven genes. The results further confirm differences in the degree of genetic differentiation between the two populations in Shaver Brown (ADRA1B and ADRA1D) and Shamo (ADRA1A and ADRA2B) chickens, indicating that the ADR gene differs between the two breeds. The effects of artificial selection, guided by the human-driven selection of desirable traits, are reflected in adrenaline gene mutations. Furthermore, certain gene mutations may affect domestication, while others may affect other traits in populations or individuals.

Clinical Significance of the Head-Up Tilt Test in Improving Prognosis in Patients with Possible Neurally Mediated Syncope

Simple Summary

Several diseases can cause syncope, which is commonly known as fainting; however, syncope triggered by a reflex mechanism, also termed neurally mediated syncope (NMS), is one of the most common forms. While NMS is considered a benign disease, it can cause critical clinical events, such as severe trauma due to syncope. The head-up tilt test (HUTT) is one of the modalities for the diagnosis of NMS. The clinical significance of HUTT in the prognosis of NMS, such as recurrence rate of syncope and mortality, are still to be elucidated. This research aimed to clarify the value of HUTT for the diagnosis of NMS, and to investigate the prognosis of patients with NMS by analyzing the data of 101 patients with syncope and their close long-term (four years at the longest) follow-up. Furthermore, as insertable cardiac monitors (ICMs) are considered effective in patients with syncope, this study also aimed to evaluate the usefulness of ICM in patients with negative HUTT results. Finally, our research contributes to the improvement of the clinical management for patients with syncope.

Abstract

Syncope is commonly encountered in daily clinical practice. Depending on its etiology (benign or life-threatening conditions or environmental triggers), syncope can be neurally mediated (reflex), cardiac, or orthostatic. Furthermore, neurologic disease can cause symptoms that mimic syncope. However, there is limited research on neurally mediated syncope (NMS), which is considered a benign disorder, and close follow-ups are rarely performed. NMS can cause serious clinical events, including severe trauma and car accidents. The head-up tilt test (HUTT) is the gold standard for diagnosing NMS; however, its clinical significance remains unknown, and its relevance to NMS prognosis requires further research. This retrospective study aimed to assess the clinical significance of the HUTT for NMS. We reviewed the charts of 101 patients who underwent HUTT at Tokai University Hospital in Japan between January 2016 and March 2019. During the HUTT, 72 patients (69.2%) experienced syncope. Patients were followed up for 886.1 ± 457.7 days (interquartile range: 518–1293 days). The syncope recurrence rate was 16.9%; however, no significant difference was observed between the two groups (HUTT positive vs. negative) (13.8% vs. 18.1%, p = 0.772). Four of 29 (13.9%) and two of 72 (2.8%) patients in the negative and positive HUTT groups, respectively, experienced cardiac events (p = 0.019). Negative HUTT results may assist in anticipating unexpected clinical events within a few years. A negative HUTT result may allow us to reconsider the NMS diagnosis based on clinical information. Close outpatient follow-up of patients with negative HUTT results is warranted.