Epidemiology of reflex syncope

Clinical and Autonomic Profile, and Modified Calgary Score for Children and Adolescents with Presumed Vasovagal Syncope Submitted to the Tilt Test

BACKGROUND

In the pediatric population, syncope is mainly from vasovagal (VVS) origin. Its evaluation must be done by clinical methods, and the tilt test (TT) can contribute to the diagnosis.

OBJECTIVES

To analyze the clinical profile, Calgary and modified Calgary scores, response to TT and heart rate variability (HRV) of patients aged ≤ 18 years with presumed VVS. To compare the variables between patients with positive and negative responses to TT.

METHOD

Observational and prospective study, with 73 patients aged between 6 and 18 years, submitted to clinical evaluation and calculation of scores without previous knowledge of the TT. It was done at 70º under monitoring for HRV analysis. P-value < 0.05 was the statistical significance criterion.

RESULTS

Median age was 14.0 years; 52% of participants were female, 72 had Calgary ≥ -2 (mean 1.80), and 69 had modified Calgary ≥ -3 (mean 1.38). Prodromes were observed in 59 patients, recurrence in 50 and trauma in 19. The response to TT was positive in 54 participants (49 vasovagal, with 39 vasodepressor responses), with an increase in the low frequency (LF) component and a decrease in the high frequency (HF) component (p < 0,0001). In the supine position, LF was 33.6 in females and 47.4 in normalized units for males (p = 0.02). When applying the operating characteristic curve for positive TT, there was no statistical significance for HRV and scores.

CONCLUSION

Most children and adolescents with a presumed diagnosis of VVS presented a typical clinical scenario, with a Calgary score ≥ -2, and a predominant vasodepressor response to TT. Greater sympathetic activation was observed in the supine position in males. Calgary scores and sympathetic activation did not predict the response to TT.

Decision-Making in Patients with Vasovagal Syncope: A Preliminary Study

The aim of this study was to evaluate the differences in performance during a decisional conflict task between subjects with emotional/blood phobia and those with an orthostatic vasovagal syncope. A total of 332 young subjects were included, from which 99 were excluded because of their condition or treatment. The subjects were classified into four groups depending on their responses to a questionnaire: 98 in a control group, 10 in an emotional/blood phobia syncope group, 38 in an orthostatic syncope group, and 87 in an unclear status group. This former group was excluded. The subjects performed a decisional conflict task to quantify their conflict-management ability. The task was the computer version of the Simon Task. Emotional/blood phobia syncope subjects showed a delayed reaction time when faced with decisional conflict in comparison with the control and orthostatic syncope subjects (55.8 ± 17.7 ms, 20.5 ± 4.9 ms, and 13.4 ± 9.2 ms, respectively, p ≤ 0.05). Our result suggests that emotional/blood phobia and orthostatic syncope are two clinical entities. Decisions could be a target of management in patients with emotional/blood phobia syncope. The altered decision-making of subjects with emotion/blood phobia syncope emphasized the role of higher cerebral functions in blood pressure control.

Cerebral Oxygenation Responses to Standing in Young Patients with Vasovagal Syncope

Vasovagal syncope (VVS) is common in young adults and is attributed to cerebral hypoperfusion. However, during active stand (AS) testing, only peripheral and not cerebral hemodynamic responses are measured. We sought to determine whether cerebral oxygenation responses to an AS test were altered in young VVS patients when compared to the young healthy controls. A sample of young healthy adults and consecutive VVS patients attending a Falls and Syncope unit was recruited. Continuous beat-to-beat blood pressure (BP), heart rate, near-infrared spectroscopy (NIRS)-derived tissue saturation index (TSI), and changes in concentration of oxygenated/deoxygenated Δ[O₂Hb]/Δ[HHb] hemoglobin were measured. BP and NIRS-derived features included nadir, peak, overshoot, trough, recovery rate, normalized recovery rate, and steady-state. Multivariate linear regression was used to adjust for confounders and BP. In total, 13 controls and 27 VVS patients were recruited. While no significant differences were observed in the TSI and Δ[O₂Hb], there was a significantly smaller Δ[HHb] peak-to-trough and faster Δ[HHb] recovery rate in VVS patients, independent of BP. A higher BP steady-state was observed in patients but did not remain significant after multiple comparison correction. Young VVS patients demonstrated a similar cerebral circulatory response with signs of altered peripheral circulation with respect to the controls, potentially due to a hyper-reactive autonomic nervous system. This study sets the grounds for future investigations to understand the role of cerebral regulation during standing in VVS.

Arrhythmic syncope: From diagnosis to management

Syncope is a concerning symptom that affects a large proportion of patients. It can be related to a heterogeneous group of pathologies ranging from trivial causes to diseases with a high risk of sudden death. However, benign causes are the most frequent, and identifying high-risk patients with potentially severe etiologies is crucial to establish an accurate diagnosis, initiate effective therapy, and alter the prognosis. The term cardiac syncope refers to those episodes where the cause of the cerebral hypoperfusion is directly related to a cardiac disorder, while arrhythmic syncope is cardiac syncope specifically due to rhythm disorders. Indeed, arrhythmias are the most common cause of cardiac syncope. Both bradyarrhythmia and tachyarrhythmia can cause a sudden decrease in cardiac output and produce syncope. In this review, we summarized the main guidelines in the management of patients with syncope of presumed arrhythmic origin. Therefore, we presented a thorough approach to syncope work-up through different tests depending on the clinical characteristics of the patients, risk stratification, and the management of syncope in different scenarios such as structural heart disease and channelopathies.

Correlation between percutaneous patent foramen ovale closure and recurrence of unexplained syncope

Background

The relationship between patent foramen ovale (PFO) and unexplained syncope remains to be illustrated. Therefore, this study aimed to explore the outcomes and prognostic factors for syncope recurrence after PFO closure.

Methods

Patients with both large right-to-left shunting (RLS) PFO and unexplained syncope who visited the cardiovascular department of Xiangya Hospital Central South University from 1 January 2017 to 31 December 2021 were consecutively enrolled in our study. The recurrence rate of syncope was compared between the non-closure group (n = 20) and the closure group (n = 91).

Results

A total of 111 patients were finally included. After 31.11 ± 14.30 months of follow-up, only 11% of patients in the closure group had recurrent syncope, which was much lower than that of the non-closure group (11.0 vs. 35%, P = 0.018). We further investigated the possible prognostic factors for syncope recurrence in the closure group and found syncope occurring more than five times preoperatively, hypertension, and residual RLS at 12-month follow-up were significantly correlated with a higher number of recurrences.

Conclusions

PFO closure reduced the recurrence rate of unexplained syncope. The efficacy of prevention was prognosticated by factors including the presence or absence of syncope induction, the frequency of syncope episodes, and the presence or absence of hypertension. Syncope recurrence was also related to residual shunts post closure.

COVID-19 vaccines associated with vasovagal malaise: A retrospective study in two mass vaccination centers and analysis of the WHO pharmacovigilance database

The association between COVID-19 vaccines and vasovagal malaise (VVM) has recently been reported in the literature. Our study aimed to describe COVID-19 vaccines associated VVM cases and to identify risk factors of COVID-19 vaccines associated VVM. To this end, we performed a descriptive study of VVM reports associated with COVID-19 vaccines from two French mass COVID-19 vaccination centers. We also extracted reports of VVM associated with all-COVID-19 vaccines in VigiBase®, the World Health Organization (WHO) pharmacovigilance database to analyze demographic data. In the two French mass vaccination center database, 408 entries reported VVM after the standard administration of tozinameran - Pfizer® (1.63/1,000 vaccinated persons). Of these cases, 213 (52.2%) occurred in women, and 193 (47.3%) occurred in the 18-29 year-old (yo) age group. In 232 cases (56.8%), patients had a history of anxiety related to needles or medical visits, 213 (52.2%) reported a fear of COVID-19 vaccination in particular, and 233 (57.1%) had a history of VVM. In VigiBase®, 336,291 notifications of COVID-19 vaccines associated with VVM were identified in the adult population during the period of analysis. The most reported age class was 18-44 years (52.4%), and women represented 71.7% of the reports. Reporting widely differed depending on the country. This study, performed in real-life conditions, highlights that VVM is associated with all-COVID-19 vaccines. Young age and history of anxiety related in young adults could be a triggering factor of vaccines-associated VVM. Further studies are needed to confirm our results.

Assessment of Canadian Syncope Risk Score in the prediction of outcomes of patients with syncope at the Emergency Department of Suez Canal University: STROBE compliant

Syncope is a temporary loss of consciousness usually related to insufficient blood flow to the brain. It's also called fainting or "passing out." Syncope is responsible for 3% to 5% of emergency department visits, with a hospitalization rate in about 40% of cases, with an average stay of 5.5 days. The Canadian Syncope Risk Score showed good discrimination and calibration for 30-day risk of serious adverse events after disposition from the emergency department.The aim was to assess Canadian Syncope Risk Score in predicting outcomes and mortality at the emergency department of Suez Canal University Hospitals.A prospective observational cohort study was carried out in emergency department in Suez Canal University Hospital. After approval by the Ethical and Research Committee of Faculty of Medicine, Suez Canal University, 60 patients with syncope attending to emergency department were included to this study. All included participants were assessed by history taking and they also assessed by the Canadian Syncope Risk Score.The Canadian Syncope Risk Score's mean of the study group was 4.9 and the range of the scores was from -2 to 11. The mean of the percentage of risk of serious events at 30 days in the study group was 29.17% and it ranged from 0.7% to 83.6%.There was a statistically significant difference between means Canadian Syncope Risk Score's score regarding complication occurrence. Cases which showed complications had a mean score of 7.33 compared to a mean score of 1.25 in case of no complication occurrence P-value <.001. At a cut-off point of more than 3 for the Canadian Syncope Risk Score's, sensitivity of that score in complication's occurrence prediction was 100% and the specificity was 87.5% P-value <.001.The Canadian Syncope Risk Score's is strong predictor for risk of serious adverse events and a good indicator for admission, with 100% sensitivity and 87.5% specificity at cut off point more than 3.

Stress and the baroreflex

The stress response to emotions elicits the release of glucocorticoids from the adrenal cortex, epinephrine from the adrenal medulla, and norepinephrine from the sympathetic nerves. The baroreflex adapts to buffer these responses to ensure that perfusion to the organs meets the demands while maintaining blood pressure within a within a narrow range. While stressor-evoked autonomic cardiovascular responses may be adaptive for the short-term, the recurrent exaggerated cardiovascular stress reactions can be maladaptive in the long-term. Prolonged stress or loss of the baroreflex's buffering capacity can predispose episodes of heightened sympathetic activity during stress leading to hypertension, tachycardia, and ventricular wall motion abnormalities. This review discusses 1) how the baroreflex responds to acute and chronic stressors, 2) how lesions in the neuronal pathways of the baroreflex alter the ability to respond or counteract the stress response, and 3) the techniques to assess baroreflex sensitivity and stress responses. Evidence suggests that loss of baroreflex sensitivity may predispose heightened autonomic responses to stress and at least in part explain the association between stress, mortality and cardiovascular diseases.

Unexplained syncope in a young athlete: the diagnostic process to find the diagnosis—a case report

Background

Differential diagnosis of recurrent syncope is a routine procedure in clinical practice. Most of these syncopes are benign reflex syncopes but identifying patients with cardiac syncope is crucial to prevent fatal outcomes.

Case summary

In this case report, we present the case of a young athlete with recurrent unexplained syncope referred to us for a second opinion. Despite normal resting-electrocardiography and echocardiography, he developed frequent polymorphic and bidirectional premature ventricular contractions during exercise. Genetic testing confirmed a mutation in the RyR2-gene and the diagnosis of catecholaminergic polymorphic ventricular tachycardia was made. A medical therapy with betablockers was initiated but poorly tolerated, so that an implantable cardioverter-defibrillator was implanted. Furthermore, family screening revealed his mother and his sister to be genetic carriers as well. Implantable cardioverter-defibrillator implantation was performed in both family members. The patient did not experience any syncope or arrhythmic episodes during the follow-up period.

Discussion

This case report highlights the importance of thorough diagnostic and potential pitfalls in patients with unexplained syncope. Sometimes, the diagnostic steps need to be extended or repeated to detect rare or potential malignant causes of syncope.

Recent Updates and Technological Developments in Evaluating Cardiac Syncope in the Emergency Department

Syncope is a commonly encountered problem in the emergency department (ED), accounting for approximately 3% of presenting complaints. Clinical assessment of syncope can be challenging due to the diverse range of conditions that can precipitate the symptom. Annual mortality for patients presenting with syncope ranges from 0-12%, and if the syncope is secondary to a cardiac cause, then this figure rises to 18-33%. In ED, it is paramount to accurately identify those presenting with syncope, especially patients with an underlying cardiac aetiology, initiate appropriate management, and refer them for further investigations. In 2018, the European Society of Cardiology (ESC) updated its guidelines with regard to diagnosing and managing patients with syncope. We highlight recent developments and considerations in various components of the workup, such as history, physical examination, investigations, risk stratification, and novel biomarkers, since the establishment of the 2018 ESC guidelines. We further discuss the emerging role of artificial intelligence in diagnosing cardiac syncope and postulate how wearable technology may transform evaluating cardiac syncope in ED.

OUP accepted manuscript

Aims

Methods and results

Conclusion

Unexplained Syncope: The Importance of the Electrophysiology Study

Syncope of cardiac origin may be associated with an increased risk of sudden cardiac death if not treated in a timely and appropriate manner. The diagnostic approach of syncope imposes a significant economic burden on society. The investigation and elucidation of the pathogenetic mechanism of syncope are of great clinical importance, as both prognosis and appropriate therapeutic approaches depend on these factors. The responsible mechanism of presyncope or syncope can only be revealed through the patient history, baseline clinical examination and electrocardiogram. The percentage of patients who are diagnosed with these tests alone exceeds 50%. In patients with a history of organic or acquired heart disease or/and the presence of abnormal findings on the electrocardiogram, a further diagnostic electrophysiology inclusive approach should be followed to exclude life threatening arrhythmiological mechanism. However, if the patient does not suffer from underlying heart disease and does not show abnormal electrocardiographic findings in the electrocardiogram, then the probability in the electrophysiology study to find a responsible cause is small but not absent. The role of a two-step electrophysiology study inclusive risk stratification approach for the effective management of the former is thoroughly discussed in this review.

Venous capacitance and venous return in young adults with typical vasovagal syncope: a cross-sectional study

Vasovagal syncope (VVS) has a high prevalence in the general population and is associated with potential complications. There is limited information on the possible association between venous capacitance (VC) and venous return (VR), important determinants of preload and VVS. Since the tilt test was reported to yield a high rate of false positive results, the aim of this study was to evaluate whether abnormal VC and VR at baseline could predispose individuals to VVS.To this end, 88 young, healthy volunteers were recruited and classified to 26 (29.5%) who experienced typical VVS and 62 (70.5%) who did not. VC and VR were evaluated with a commercial device and plethysmography applied to the elevated legs. Maximum venous outflow (MVO), segmental venous capacitance (SVC) and MVO/SVC ratio were calculated and averaged.No significant differences between MVO (5.0±0.5 vs 5.6±0.8, p>0.05), SVC (6.0±0.5 vs 6.3±0.8, p>0.05) or MVO/SVC ratio (0.83±0.02 vs 0.86±0.03, p>0.05) were observed for the non-VVS and VVS volunteers, respectively. There was a significant association between a higher MVO and SVC values and a larger decrease in diastolic blood pressure with standing, although correlations were weak (R²=0.0582 and 0.0681, respectively).In conclusion, at baseline, VC and VR are not impaired in healthy volunteers with a history of VVS. It remains unknown if similar results would be found in patients with cardiovascular comorbidities. Also, the sensitivity of VC and VR evaluations to identify a predisposition for VVS following physiological provocations merits further study.

Genetic markers of vasovagal syncope

Vasovagal syncope may have a genetic predisposition. It has a high prevalence in some families, and children of a fainting parent are more likely to faint than those without a parent who faints. Having two fainting parents or a fainting twin increases the likelihood even further. Several genotypes appear to associate with the phenotype of positive tilt tests, but the control subjects are usually those who faint and have negative tilt tests. Twin studies, highly focused genome-wide association studies, and copy number variation studies all suggest there are loci in the genome that associate with vasovagal syncope, although the specific genes, pathways, and proteins are unknown. A recent multigenerational kindred candidate gene study identified 3 genes that associate with vasovagal syncope. The best evidence to date is for central signaling genes involving serotonin and dopamine. Genome-wide association studies to date have not yet been helpful. Our understanding of the genetic correlates of vasovagal syncope leaves ample opportunity for future work.

Syncope in Commercial Pilots and New Regulatory Guidance

INTRODUCTION: Syncope is both incapacitating and unpredictable, presenting a significant challenge in aircrew assessment. Previous UK Civil Aviation Authority (CAA) guidance lacked transparency and relied heavily on specialist in-house cardiology and neurology opinion. A new algorithm was developed which elaborated and formalized the decision-making process. An analysis of its impact on historic cases was undertaken to ensure it aligned with previous certificatory outcomes.METHODS: The medical literature on syncope and the approaches of other national aviation authorities were reviewed to help inform the development of a new algorithm. Using syncope cases in the CAA database, regulatory outcomes generated using the new algorithm were compared with previous decisions in terms of time off from flying (TOF) and Operational Multi-Crew Limitation (OML) duration.RESULTS: There were 40 historic syncope cases (25 existing certificate holders,15 initial applicants) which were reassessed using the new algorithm. The mean TOF for existing pilots using the new algorithm was 7.1 9.8 (mean SD) vs. 4.2 3.5 mo under the old guidance with an OML duration of 21.4 34.9 vs. 24.5 25.2 mo. One less initial applicant experienced a delay to certification. Four cases with underlying pathology were detected using old and new guidance.DISCUSSION: The reassessment of cases showed no statistically significant difference in TOF and OML duration; this is a positive finding from a regulatory perspective, enabling algorithm-led decision-making with less reliance on in-house expertise. A similar approach may be useful in future updates to other areas of regulatory practice.Anderton RA, Mitchell SJ, ONunain SS. Syncope in commercial pilots and new regulatory guidance. Aerosp Med Hum Perform. 2021; 92(8):642649.

New hemodynamic criteria to separate classical orthostatic hypotension from vasovagal syncope

OBJECTIVE

To define and evaluate hemodynamic criteria to distinguish between classical orthostatic hypotension (cOH) and vasovagal syncope (VVS) in tilt table testing (TTT).

METHODS

Inclusion criteria for VVS were a history of VVS and tilt-induced syncope defined as a blood pressure (BP) decrease and electroencephalographic changes during syncope with complaint recognition. Criteria for cOH were a history of cOH and a BP decrease meeting published criteria. Clinical diagnoses were established prior to TTT. We assessed (1) whether the decrease of systolic BP accelerated, "convex," or decelerated, "concave"; (2) the time from head-up tilt to when BP reached one-half its maximal decrease; (3) the difference between baseline heart rate (HR) and HR at BP nadir. We calculated the diagnostic yield of optimized thresholds of these features and their combinations.

RESULTS

We included 82 VVS cases (40% men, median age 44 years) and 65 cOH cases (66% men, median age 70 years). BP decrease was concave in cOH in 79% and convex in VVS in 94% (p < 0.001). The time to reach half the BP decrease was shorter in cOH (median 34 sec, interquartile range (IQR) 19-98 sec) than in VVS (median 1571 sec, IQR 1381-1775 sec, p < 0.001). Mean HR increased by 11 ± 11 bpm in cOH and decreased by 20 ± 19 bpm in VVS (p < 0.001). When all three features pointed to VVS, sensitivity for VVS was 82% and specificity was 100%. When all three pointed to cOH, sensitivity for cOH was 71% and specificity was 100%.

INTERPRETATION

These new hemodynamic criteria reliably differentiate cOH from VVS.

The association between the biometeorological indicators and emergency interventions due to fainting: A retrospective cohort study

The association of fainting with specific situations and circumstances, such as the sight of blood, response to pain, prolonged standing position and fatigue, is well recognized and described in medical literature. Clinical experience also indicates that specific, local physical conditions, such as exposure to heat or remaining in a small, stuffy room may also trigger fainting. This paper verifies the hypothesis concerning the association between atmospheric conditions and the incidence of fainting. This is a retrospective cohort study of data relating to fainting collected in the city of Olsztyn (Poland). In total, 10,449 emergency service interventions in the period 2012-2019 that concluded with the R55 (syncope and collapse) diagnosis according to the ICD 10 were analyzed. The obtained data were matched with meteorological data, including basic parameters (temperature, humidity, atmospheric pressure) and complex parameters, with special attention given to the Universal Thermal Climate Index (UTCI). This index is derived from an analysis of human thermal balance and is particularly useful for describing the organism's response to thermal stress. Statistically significant differences in the occurrences of fainting depending on the season were revealed (more in the summer), but only for women. Among the analyzed meteorological and biometeorological parameters, statistical significance was found for parameters relating to temperature, with the greatest usefulness revealed for the UTCI. Periods with heat stress were more conducive to fainting, whereas the result for the general population was influenced by women in two age groups: 25-45 and 46-60. To our best knowledge, this is the first attempt worldwide to utilize the UTCI as a predictor of fainting. Our results confirmed the applicability of the UTCI as a universal biometeorological tool for the assessment of relationships between atmospheric conditions and the incidence of fainting.

Efficient syncope prediction from resting state clinical data using wavelet bispectrum and multilayer perceptron neural network

Neurally mediated syncope (NMS) is the most common type of syncope, and head up tilt test (HUTT) is, so far, the most appropriate tool to identify NMS. In this work, an effort to predict the NMS before performing the HUTT is attempted. To achieve this, the heart rate variability (HRV) at rest and during the first minutes of tilting position during HUTT was analyzed using both time and frequency domains. Various features from HRV regularity and complexity, along with wavelet higher-order spectrum (WHOS) analysis in low-frequency (LF) and high-frequency (HF) bands were examined. The experimental results from 26 patients with history of NMS have shown that at rest, a time domain entropy measure and WHOS-based features in LF band exhibit significant differences between positive and negative HUTT as well as among 10 healthy subjects and NMS patients. The best performance of multilayer perceptron neural network (MPNN) was achieved by using an input vector consisted of WHOS-based HRV features in the LF zone and systolic blood pressure from the resting period, yielding an accuracy of 89.7%, assessed by 5-fold cross-validation. The promising results presented here pave the way for an early prediction of the HUTT outcome from resting state, contributing to the identification of patients at higher risk NMS. The HRV analysis along with systolic blood pressure at rest predict NMS using a multilayer perceptron neural network.

Long-Term Effects of Ivabradine on Cardiac Vagal Parasympathetic Function in Normal Rats

Background: The complex interactions that exist between the pacemaker current, I _f, and the parasympathetic nervous system could significantly influence the course of patients undergoing chronic therapy with the I _f blocker ivabradine. We thus aimed to assess the effects of chronic ivabradine therapy on autonomic modulation and on the cardiovascular response to in situ and in vitro parasympathetic stimulation. The right atrial expression of HCN genes, encoding proteins for I _f, was also evaluated. Methods: Sympathetic and parasympathetic heart rate variability parameters and right atrial HCN(1-4) RNA levels were analyzed in 6 Control and 10 ivabradine-treated male Wistar rats (IVA; 3 weeks, 10 mg/kg/day). The heart rate (HR) and systolic blood pressure (SBP) responses to in situ electrical stimulation of the vagus nerve (2-20 Hz) were assessed in 6 additional Control and 10 IVA rats. The spontaneous sinus node discharge rate (SNDR) response to in vitro cholinergic receptors stimulation using carbamylcholine (10^-9-10^-6 mol/L) was also assessed in these later rats. Results: Ivabradine significantly increased vagal modulation and shifted the sympatho-vagal balance toward vagal dominance. In Control, in situ vagus nerve stimulation induced progressive decrease in both the SBP (p = 0.0001) and the HR (p< 0.0001). Meanwhile, in IVA, vagal stimulation had no effect on the HR (p = 0.16) and induced a significantly lower drop in SBP (p< 0.05). IVA also displayed a significantly lower SNDR drop in response to carbamylcholine (p< 0.01) and significantly higher right atrial HCN4 expression (p = 0.02). Conclusion: Chronic ivabradine administration enhanced vagal modulation in healthy rats. In addition, ivabradine reduced the HR response to direct muscarinic receptors stimulation, canceled the cardioinhibitory response and blunted the hemodynamic response to in situ vagal stimulation. These data bring new insights into the mechanisms of ivabradine-related atrial proarrhythmia and suggest that long-term I _f blockade may protect against excessive bradycardia induced by acute vagal activation.

Factors facilitating and hindering the implementation of the European Society of Cardiology Syncope Guidelines at the Emergency Department: A nationwide qualitative study

AIMS

Syncope care is often fragmented and inefficient. Structuring syncope care through implementation of guidelines and Syncope Units has been shown to improve diagnostic yield, reduce costs and improve quality of life. We implemented the European Society of Cardiology (ESC) 2018 syncope guidelines at the Emergency Departments (ED) and established Syncope Units in five Dutch hospitals. We evaluated the implementation process by identifying factors that hinder ('barriers') and facilitate ('facilitators') the implementation.

METHODS AND RESULTS

We conducted, recorded and transcribed semi-structured interviews with 19 specialists and residents involved in syncope care from neurology, cardiology, internal medicine and emergency medicine. Two researchers independently classified the reported barriers and facilitators, according to the framework of qualitative research (Flottorp), which distinguished several separate fields ('levels'). Software package Atlas.ti was used for analysis. We identified 31 barriers and 22 facilitators. Most barriers occurred on the level of the individual health care professional (e.g. inexperienced residents having to work with the guideline at the ED) and the organizational context (e.g. specialists not relinquishing preceding procedures). Participants reported most facilitators at the level of innovation (e.g. structured work-flow at the ED). The multidisciplinary Syncope Unit was welcomed as useful solution to a perceived need in clinical practice.

CONCLUSION

Implementing ESC syncope guidelines at the ED and establishing Syncope Units facilitated a structured multidisciplinary work-up for syncope patients. Most identified barriers related to the individual health care professional and the organizational context. Future implementation of the multidisciplinary guideline should be tailored to address these barriers.

A comparison of health-related quality of life in autonomic disorders: postural tachycardia syndrome versus vasovagal syncope

PURPOSE

Postural tachycardia syndrome (POTS) and vasovagal syncope (VVS) are two disorders of orthostatic intolerance which are often misdiagnosed as the other. In each case, patients experience a reduced health-related quality of life (HRQoL) compared to healthy populations. This study was conducted to test the hypothesis that HRQoL is worse in POTS.

METHODS

POTS patients were recruited from the Dysautonomia International Annual Patient and Caregiver Conference. VVS patient data came from those enrolled in the Second Prevention of Syncope Trial. Participants aged ≥ 18 years (177 POTS and 72 VVS) completed the RAND 36-Item Health Survey, a generic and coherent health-related quality of life survey.

RESULTS

POTS patients reported reduced HRQoL compared to VVS patients in physical functioning (42.5 ± 1.7 vs. 76.5 ± 2.9, p < 0.001), role limitations due to physical health (11.4 ± 1.9 vs. 33.0 ± 5.0, p < 0.001), energy and fatigue (27.2 ± 1.3 vs. 50.7 ± 2.6, p < 0.001), social functioning (45.2 ± 1.8 vs. 71.2 ± 2.9, p < 0.001), pain (48.8 ± 1.9 vs. 67.7 ± 2.9, p < 0.001), and general health (31.2 ± 1.5 vs. 60.5 ± 2.6, p < 0.001) domains. Scores did not differ significantly in the role limitations due to emotional health (p = 0.052) and emotional well-being (p = 0.271) domains. Physical and general health composite scores were lower in the POTS population, while mental health composite scores were not different.

CONCLUSION

Differences in HRQoL exist between these patient populations. POTS patients report lower scores in physical and general health domains than VVS patients, but emotional health domains do not differ significantly. Targeting physical functioning in these patients may help improve quality of life.

[Syncope in children and adolescents: are the current guidelines being followed?]

BACKGROUND

Syncope in childhood and adolescence is frequent and in most cases benign. A thorough history taking, complete physical examination, electrocardiography and further diagnostic work-up as indicated should rule out possible cardiac syncope.

OBJECTIVE

To evaluate whether the diagnosis of syncope was performed according to the currently valid S2k guideline.

MATERIAL AND METHODS

Retrospective study (January 2015-December 2017), University Children's Hospital of Saarland, Homburg, Germany. All patients aged 1-18 years presenting with the primary complaint of syncope were included.

RESULTS

In this study 262 patients presented with a history of syncope (161 female (61.5%), 101 male (38.5%), median age 12.5 ± 3.9 years). Of these, 183 (69.8%) were reflex syncopes, 36 (13.7%) presyncopes, 35 (13.4%) undefined and 8 (3.1%) cardiac syncope. Out of 262 patients, 43 (16.4%) were diagnosed in accordance with the published guidelines and 13/43 (30.2%) correctly received further diagnostic work-up. In 219/262 patients (83.6%) basic diagnostic testing was not sufficient and 135/219 (61.6%) were submitted to further unnecessary diagnostic tests.

CONCLUSION

Better adherence to the syncope guidelines bears the potential to avoid unnecessary and costly auxiliary medical tests while correctly diagnosing patients with syncope.

Clinical Characteristics of Personality and Conduct Disorders in Child Patients With Vasovagal Syncope: A Clinical Case-Control Study

Objective: To analyze the clinical characteristics of abnormal personality and conduct disorders (CDs) in pediatric patients with vasovagal syncope (VVS). Methods: In this study, we recruited patients diagnosed with VVS at Children's Heart Center from January 2018 to December 2020. Healthy children were recruited as controls. The Eysenck Personality Questionnaire-Child edition (EPQ-C) and Achenbach Child Behavior Checklist (CBCL) were used for the assessment. Results: One hundred and fifty-one VVS patients and 151 healthy controls were included in this study. Compared with the control group, patients in the VVS group had a higher incidence of abnormal personality and were more prone to suffer from CDs. Moreover, pediatric patients with VVS suffered more events of syncope recurrence if they had CDs. Conclusion: Abnormal personality and CDs are common clinical characteristics in pediatric patients with VVS.

Pacing Therapies for Vasovagal Syncope

Vasovagal Syncope (VVS) is mediated by a cardiac autonomic reflex with resultant bradycardia and hypotension, precipitating syncope. While benign and mostly well controlled, recurrent VVS can be debilitating and warrants intervention. Non-pharmacological management of VVS have had variable success. In patients with recurrent cardioinhibitory VVS, permanent pacing can be effective. The utility of pacing to preempt the syncopal depends on the prominent temporal role of bradycardia during the vasovagal reflex. Current guidelines recommend pacing as a therapy to consider in older patients with recurrent VVS. Although younger patients can benefit, one should be cautious given the long-term risk of complications. Available data appears to favor a dual chamber pacemaker with closed loop stimulation algorithm to prevent recurrent cardioinhibitory VVS. Several aspects, including mechanistic understanding of VVS and appropriate patient selection, remain unclear, and require further study.

A novel strategy to treat vaso-vagal syncope: Cardiac neuromodulation by cryoballoon pulmonary vein isolation

Background

Clinical management of vaso-vagal syncope (VVS) remains challenging since no therapy has proven to completely prevent VVS recurrence.

Objective

The purpose of this study was to analyze the mid-term outcome of cryoballoon (CB) cardioneuroablation achieved by pulmonary vein isolation (PVI) in patients with VVS.

Methods

Patients who underwent CB cardioneuroablation in our centers between January 2014 to June 2018 were included. All patients had a history of VVS or pre-syncope despite therapeutic attempts with medical and/or pacing treatments. Patients were excluded in case of structural heart diseases, cerebrovascular diseases or suspected drug-related syncope. Both heart rate (HR) and atrio-ventricular (AV) interval were analyzed on the 12-lead electrocardiogram (ECG) the day before the procedure, the day after, and in the follow-up.

Results

In total, 26 patients (76.9% males, 37.5 ± 9.0 years old) were included. All patients underwent a successful procedure with the 28 mm second-generation Arctic Front Advance CB. No major complication occurred. At a mean follow-up of 20.1 ± 11.6 months the freedom from VVS or reflex pre-syncope was 83,7%, with 22 patients free from any clinical recurrence. Basal HR significantly increased the day after the procedure (57.2 bpm vs 78.3 bpm, p < 0.001), while at the final follow-up it stabilized at a value halfway between the 2 previous ones (69.8 bpm, p = 0.0086). The AV interval didn’t modify significantly after the procedure.

Conclusion

Endocardial autonomic denervation achieved by CB PVI appears to be an effective and safe treatment option for patients with refractory VVS and reflex pre-syncope.

Postural Tachycardia Syndrome and Neurally Mediated Syncope

PURPOSE OF REVIEW

This article reviews the diagnosis and management of the most common disorders of orthostatic intolerance: postural tachycardia syndrome (POTS) and neurally mediated syncope.

RECENT FINDINGS

POTS is a heterogeneous syndrome caused by several pathophysiologic mechanisms that may coexist (limited autonomic neuropathy, hyperadrenergic state, hypovolemia, venous pooling, joint hypermobility, deconditioning). Neurally mediated syncope occurs despite intact autonomic reflexes. Management of orthostatic intolerance aims to increase functional capacity, including standing time, performance of daily activities, and exercise tolerance. Nonpharmacologic strategies (fluid and salt loading, physical countermaneuvers, compression garments, exercise training) are fundamental for patients with POTS, occasionally complemented by medications to raise blood pressure or slow heart rate. Neurally mediated syncope is best managed by recognition and avoidance of triggers.

SUMMARY

Significant negative effects on quality of life occur in patients with POTS and in patients with recurrent neurally mediated syncope, which can be mitigated through targeted evaluation and thoughtful management.

A higher proportion of men than of women fainted in the phase without nitroglycerin in tilt-induced vasovagal syncope

Purpose

Vasovagal syncope (VVS) affects more women than men. We determined whether this sex ratio affects tilt table test (TTT) results.

Methods

We retrospectively studied TTT outcomes in suspected VVS. TTT consisted of supine rest, a maximum 20 min of head-up tilt without and, if nitroglycerin was needed, a further maximum 20 min after nitroglycerin administration. TTT was terminated if VVS occurred. We used binary logistic regression for the entire TTT and for each phase, with VVS as outcome and age and sex as predictors.

Results

TTT provoked vasovagal (pre)syncope in 494 out of 766 tests (64%). The proportion of men and women who fainted during the entire TTT did not differ significantly between the sexes (p = 0.13, corrected for age). A lower proportion of women than men had VVS in the phase without nitroglycerin (odds ratio 0.54; 95% confidence interval 0.37–0.79; p = 0.002, corrected for age), whereas a higher proportion of women than men fainted after nitroglycerin (odds ratio 1.58; 95% confidence interval 1.13–2.21; p = 0.008, corrected for age). These sex differences remained significant after correction for a history of orthostatic versus emotional triggers. The effect of sex on TTT outcome was closely associated with differences of blood pressure change upon tilt-up (lower in men in both TTT phases: without nitroglycerin p = 0.003; with nitroglycerin p = 0.05), but not with heart rate changes.

Conclusion

Men were more susceptible to induction of VVS without nitroglycerin and women after it. The unexpected findings may be due to sex-specific pathophysiological differences.

Electronic supplementary material

The online version of this article (10.1007/s10286-020-00666-5) contains supplementary material, which is available to authorized users.

The Search for the Genes of Vasovagal Syncope

Only humans faint, and not all do so. Syncope tends to recur, and the predisposition to syncope can persist over many decades. Observations such as these have suggested that there may be a genetic predisposition to vasovagal syncope. It seems to have a high prevalence in some families; having a parent who faints increases the likelihood of an offspring fainting, and this is increased even further if both biological parents faint. Numerous studies have correlated a number of genotypes with positive tilt tests. However, the control subjects are usually those who faint, but have negative tilt tests, making the conclusions about association with the clinical phenotype less certain. Twin studies, highly focused genome-wide association studies, and gene duplicate studies all suggest there are sites in the genome that associate with vasovagal syncope, although the specific genes, pathways, and proteins are unknown. A recent large, candidate gene study of kindreds with high, multigenerational prevalence of the vasovagal syncope identified 3 genes that associate with vasovagal syncope. Our understanding of the genetic correlates of vasovagal syncope is in its infancy, with much to be understood.

Increased expression of blood muscarinic receptors in patients with reflex syncope

AIMS

Pathophysiology of reflex syncope is not fully understood but a vagal overactivity might be involved in this syncope. Previously, overexpression of muscarinic M2 receptors and acetylcholinesterase was found in particular in the heart and in lymphocytes of rabbits with vagal overactivity as well as in hearts of Sudden Infant Death Syndromes. The aim of this present study was to look at M2 receptor expression in blood of patients with reflex syncope. The second objective was to measure acetylcholinesterase expression in these patients.

METHODS AND RESULTS

136 subjects were enrolled. This monocenter study pooled 45 adults exhibiting recurrent reflex syncope compared with 32 healthy adult volunteers (18-50 years) and 38 children exhibiting reflex syncope requiring hospitalization compared with 21 controls (1-17 years). One blood sample was taken from each subject and blood mRNA expression of M2 receptors was assessed by qRT-PCR. Taking into account the non-symmetric distributions of values in both groups, statistical interferences were assessed using bayesian techniques. A M2 receptor overexpression was observed in adult and pediatric patients compared to controls. The medians [q1;q3] were 0.9 [0.3;1.9] in patients versus 0.2 [0.1;1.0] in controls; the probability that M2 receptor expression was higher in patients than in controls (Pr[patients>controls]) was estimated at 0.99. Acetylcholinesterase expression was also increased 0.7 [0.4;1.6] in patients versus 0.4 [0.2;1.1] in controls; the probability that acetylcholinesterase expression was higher in patients than in controls (Pr[patients>controls]) was estimated at 0.97. Both in adults and children, the expression ratio of M2 receptors over acetylcholinesterase was greater in the patient group compared with the control group.

CONCLUSION

M2 receptor overexpression has been detected in the blood of both, adults and children, exhibiting reflex syncope. As in our experimental model, i.e. rabbits with vagal overactivity, acetylcholinesterase overexpression was associated with M2 receptor overexpression. For the first time, biological abnormalities are identified in vagal syncope in which only clinical signs are, so far, taken into account for differential diagnosis and therapeutic management. Further work will be needed to validate potential biomarkers of risk or severity associated with the cholinergic system.

Did This Patient Have Cardiac Syncope?: The Rational Clinical Examination Systematic Review

IMPORTANCE

Syncope can result from a reduction in cardiac output from serious cardiac conditions, such as arrhythmias or structural heart disease (cardiac syncope), or other causes, such as vasovagal syncope or orthostatic hypotension.

OBJECTIVE

To perform a systematic review of studies of the accuracy of the clinical examination for identifying patients with cardiac syncope.

STUDY SELECTION

Studies of adults presenting to primary care, emergency departments, or referred to specialty clinics.

DATA EXTRACTION AND SYNTHESIS

Relevant data were abstracted from articles in databases through April 9, 2019, and methodologic quality was assessed. Included studies had an independent comparison to a reference standard.

MAIN OUTCOMES AND MEASURES

Sensitivity, specificity, and likelihood ratios (LRs).

RESULTS

Eleven studies of cardiac syncope (N = 4317) were included. Age at first syncope of at least 35 years was associated with greater likelihood of cardiac syncope (n = 323; sensitivity, 91% [95% CI, 85%-97%]; specificity, 72% [95% CI, 66%-78%]; LR, 3.3 [95% CI, 2.6-4.1]), while age younger than 35 years was associated with a lower likelihood (LR, 0.13 [95% CI, 0.06-0.25]). A history of atrial fibrillation or flutter (n = 323; sensitivity, 13% [95% CI, 6%-20%]; specificity, 98% [95% CI, 96%-100%]; LR, 7.3 [95% CI, 2.4-22]), or known severe structural heart disease (n = 222; range of sensitivity, 35%-51%, range of specificity, 84%-93%; range of LR, 3.3-4.8; 2 studies) were associated with greater likelihood of cardiac syncope. Symptoms prior to syncope that were associated with lower likelihood of cardiac syncope were mood change or prodromal preoccupation with details (n = 323; sensitivity, 2% [95% CI, 0%-5%]; specificity, 76% [95% CI, 71%-81%]; LR, 0.09 [95% CI, 0.02-0.38]), feeling cold (n = 412; sensitivity, 2% [95% CI, 0%-5%]; specificity, 89% [95% CI, 85%-93%]; LR, 0.16 [95% CI, 0.06-0.64]), or headache (n = 323; sensitivity, 3% [95% CI, 0%-7%]; specificity, 80% [95% CI, 75%-85%]; LR, 0.17 [95% CI, 0.06-0.55]). Cyanosis witnessed during the episode was associated with higher likelihood of cardiac syncope (n = 323; sensitivity, 8% [95% CI, 2%-14%]; specificity, 99% [95% CI, 98%-100%]; LR, 6.2 [95% CI, 1.6-24]). Mood changes after syncope (n = 323; sensitivity, 3% [95% CI, 0%-7%]; specificity, 83% [95% CI, 78%-88%]; LR, 0.21 [95% CI, 0.06-0.65]) and inability to remember behavior prior to syncope (n = 323; sensitivity, 5% [95% CI, 0%-9%]; specificity, 82% [95% CI, 77%-87%]; LR, 0.25, [95% CI, 0.09-0.69]) were associated with lower likelihood of cardiac syncope. Two studies prospectively validated the accuracy of the multivariable Evaluation of Guidelines in Syncope Study (EGSYS) score, which is based on 6 clinical variables. An EGSYS score of less than 3 was associated with lower likelihood of cardiac syncope (n = 456; range of sensitivity, 89%-91%, range of specificity, 69%-73%; range of LR, 0.12-0.17; 2 studies). Cardiac biomarkers show promising diagnostic accuracy for cardiac syncope, but diagnostic thresholds require validation.

CONCLUSIONS AND RELEVANCE

The clinical examination, including the electrocardiogram as part of multivariable scores, can accurately identify patients with and without cardiac syncope.

Neurally mediated syncope diagnosis based on adenylate cyclase activity in Japanese patients

The study aims to clarify the mechanism in patients with neurally mediated syncope (NMS), focusing on the adenylate cyclase (AC) activity level in lymphocytes. This study included 40 subjects: 22 healthy volunteers and 18 NMS patients. We investigated the changes in AC activity that occur during of syncope at rest and during the head-up tilt (HUT) test. We obtained 8 mL of blood at rest time and four times during the HUT test. Then, we measured the AC activity and the test reagent was added to the lymphocytes (10,000) and reacted for 30 min at room temperature. We were able to determine the standard value of AC activity when adrenaline (AD) and isoproterenol (IP) were added to lymphocytes. The results of our study showed one of the causes of NMS has a difference in AC activity level and classification of the patients into two different types of NMS was possible: either the vasodepressor type (VT) or mixed type (MT). At rest time, VT patients showed significantly higher AC activity (AD; 100 μM: p = 0.005, IP; 50 μM: p = 0.02) and MT patients showed significantly lower AC activity (AD; 10 μM: p = 0.02, IP; 50 μM: p = 0.004) than the average AC activity in healthy volunteers. Moreover, VT patients had significantly higher AC activity than healthy volunteers at the four points of the HUT test. MT patients had significantly lower AC activity (AD: p = 0.04 and IP: p = 0.04) than healthy volunteers at the rest time of HUT. Our study showed a significant difference in AC activities between NMS patients and healthy volunteers at rest. Therefore, a detailed NMS diagnosis can be made by examining AC activity levels in blood taken at rest time.

Acceleration Index Predicts Efficacy of Orthostatic Training on Vasovagal Syncope in Children

OBJECTIVE

To explore the value of the acceleration index as a predictor of therapeutic response to orthostatic training in children with vasovagal syncope (VVS).

STUDY DESIGN

Thirty-three children with VVS were recruited and treated with orthostatic training. The therapeutic response of each patient was evaluated after 3 months of treatment. A Pearson correlation was calculated between the acceleration index and the severity of VVS. The value of the acceleration index in predicting the therapeutic response to orthostatic training was assessed by analysis of the receiver operating characteristic curve.

RESULTS

Among the 33 children with VVS, 20 were found to be responders and the remaining were nonresponders. The mean acceleration index was significantly lower in responders compared with nonresponders (21.10 ± 6.61 vs 31.36 ± 9.00; P = .001) and it was negatively correlated with positive response time in the head-up tilt test, with systolic blood pressure and with diastolic blood pressure at positive response time in the head-up tilt test (P < .05). The receiver operating characteristic curve for the predictive value of the acceleration index showed that the area under the curve was 0.827 (95% CI, 0.676-0.978; P = .002), and a cutoff value of the acceleration index of 26.77 yielded a sensitivity of 85.0% and a specificity of 69.2%.

CONCLUSIONS

The acceleration index may be useful for predicting the efficacy of orthostatic training on VVS in children.

Adrenergic agonist induces rhythmic firing in quiescent cardiac preganglionic neurons in nucleus ambiguous via activation of intrinsic membrane excitability

Cholinergic vagal nerves projecting from neurons in the brain stem nucleus ambiguus (NAm) play a predominant role in cardiac parasympathetic pacemaking control. Central adrenergic signaling modulates the tone of this vagal output; however, the exact excitability mechanisms are not fully understood. We investigated responses of NAm neurons to adrenergic agonists using in vitro mouse brain stem slices. Preganglionic NAm neurons were identified by ChAT-tdTomato fluorescence in young adult transgenic mice, and their cardiac projection was confirmed by retrograde dye tracing. Juxtacellular recordings detected sparse or absent spontaneous action potentials (AP) in NAm neurons. However, bath application of epinephrine or norepinephrine strongly and reversibly activated most NAm neurons regardless of their basal firing rate. Epinephrine was more potent than norepinephrine, and this activation largely depends on α₁-adrenoceptors. Interestingly, adrenergic activation of NAm neurons does not require an ionotropic synaptic mechanism, because postsynaptic excitatory or inhibitory receptor blockade did not occlude the excitatory effect, and bath-applied adrenergic agonists did not alter excitatory or inhibitory synaptic transmission. Instead, adrenergic agonists significantly elevated intrinsic membrane excitability to facilitate generation of recurrent action potentials. T-type calcium current and hyperpolarization-activated current are involved in this excitation pattern, although not required for spontaneous AP induction by epinephrine. In contrast, pharmacological blockade of persistent sodium current significantly inhibited the adrenergic effects. Our results demonstrate that central adrenergic signaling enhances the intrinsic excitability of NAm neurons and that persistent sodium current is required for this effect. This central balancing mechanism may counteract excessive peripheral cardiac excitation during increased sympathetic tone.

NEW & NOTEWORTHY Cardiac preganglionic cholinergic neurons in the nucleus ambiguus (NAm) are responsible for slowing cardiac pacemaking. This study identified that adrenergic agonists can induce rhythmic action potentials in otherwise quiescent cholinergic NAm preganglionic neurons in brain stem slice preparation. The modulatory influence of adrenaline on central parasympathetic outflow may contribute to both physiological and deleterious cardiovascular regulation.

Hemodynamics of tonic immobility in the American alligator (Alligator mississippiensis) identified through Doppler ultrasonography

American alligators (Alligator mississippiensis) held inverted exhibit tonic immobility, combining unresponsiveness with flaccid paralysis. We hypothesize that inverting the alligator causes a gravitationally promoted increase in right aortic blood flowing through the foramen of Panizza, with a concurrent decrease in blood flow through the primary carotid, and thereby of cerebral perfusion. Inverting the alligator results in displacement of the liver, post-pulmonary septum, and the heart. EKG analysis revealed a significant decrease in heart rate following inversion; this decrease was maintained for approximately 45 s after inversion which is in general agreement with the total duration of tonic immobility in alligators (49 s). Doppler ultrasonography revealed that following inversion of the alligator, there was a reversal in direction of blood flow through the foramen of Panizza, and this blood flow had a significant increase in velocity (compared to the foraminal flow in the prone alligator). There was an associated significant decrease in the velocity of blood flow through the primary carotid artery once the alligator was held in the supine position. Tonic immobility in the alligator appears to be a form of vasovagal syncope which arises, in part, from the unique features of the crocodilian heart.

Pacing for Vasovagal Syncope

Vasovagal syncope (VVS) is due to a common autonomic reflex involving the cardiovascular system. It is associated with bradycardia (cardioinhibitory response) and/or hypotension (vasodepressor response), likely mediated by parasympathetic activation and sympathetic inhibition. While generally a situational, isolated and/or self-limited event, for some, VVS is recurrent, unpredictable and debilitating. Conservative, non-pharmacological management may help, but no specific medical therapy has been proven widely effective. Permanent pacing may have specific benefit, but its value has been debated. The temporal causative association of bradycardia with syncope in those with VVS may help identify which patient could benefit from pacing but the timing and type of pacing in lieu of blood pressure changes may be critical. The mode, rate, pacing algorithm and time to initiate dual-chamber pacing preferentially with respect to the vasovagal reflex may be important to prevent or ameliorate the faint but completely convincing data are not yet available. Based on available data, DDD pacing with the closed loop stimulation algorithm appears a viable, if not the best, alternative presently to prevent recurrent VVS episodes. While several knowledge gaps remain, permanent pacing appears to have a role in managing select patients with VVS.

Implantable loop recorders in patients with unexplained syncope: Clinical predictors of pacemaker implantation

BACKGROUND

Implantable loop recorders (ILR) are a valuable tool for the investigation of unexplainedsyncopal episodes. The aim of this retrospective single center study was to identify predictive factors for pacemaker implantation in patients with unexplained syncope who underwent ILR insertion.

METHODS

One hundred six patients were retrospectively analyzed (mean age 59.1 years; 47.2% male) with unexplained syncope and negative conventional testing who underwent ILR implantation. The pri- mary study endpoint was detection of symptomatic or asymptomatic bradycardia requiring pacemaker implantation.

RESULTS

The average follow-up period after ILR implantation was 20 ± 15 months. Pacemaker im- plantation according to current guidelines was necessary in 22 (20.8%) patients, mean duration until index bradycardia was 81 ± 88 (2-350) days. Ten (45.5%) patients received a pacemaker due to sinus arrest, 7 (31.8%) patients due to third-degree atrioventricular block, 2 (9.1%) patients due to second- degree atrioventricular block and 1 (4.5%) patient due to atrial fibrillation with a slow ventricular rate. Three factors remained significant in multivariate analysis: obesity, which defined by a body mass index above 30 kg/m2 (OR: 7.39, p = 0.014), a right bundle branch block (OR: 9.40, p = 0.023) and chronic renal failure as defined by a glomerular filtration rate of less than 60 mL/min (OR: 6.42, p = 0.035).

CONCLUSIONS

Bradycardia is a frequent finding in patients undergoing ILR implantation due to un- explained syncope. Obesity, right bundle branch block and chronic renal failure are independent clinical predictors of pacemaker implantation.

[Syncope, falls and vertigo]

Dizziness/vertigo, falls and syncope are among the most common reasons for seeking medical care. As clinical entities they share common pathogenetic and clinical features and differences. The diagnostic work-up can often be initiated in a general practitioner's or internist's practice and, if necessary, completed in an interdisciplinary emergency unit. Simple diagnostic tools can be used in an outpatient setting to obtain valuable diagnostic information. First and foremost, it is important to differentiate between prognostically favorable clinical events and potentially serious disease. In younger patients diagnostic procedures should primarily focus on potential structural cardiac disease and/or primary arrhythmia. The same applies to elderly patients in whom, however, multicausal clinical symptoms and severe complications in the case of falls are characteristic. Elderly patients frequently require the involvement of various clinical specialties to investigate a broad spectrum of potential differential diagnoses in an interdisciplinary diagnostic approach, which is not always available in practice. In the emergency unit, decisions regarding inpatient care need to be made individually. In elderly patients, inpatient care is sometimes necessary not only due to acute disease, but also in order to ensure social care. Geriatric day hospitals may be a suitable option for some of these patients.

Typical vasovagal syncope as a "defense mechanism" for the heart by contrasting sympathetic overactivity

Many observations suggest that typical (emotional or orthostatic) vasovagal syncope (VVS) is not a disease, but rather a manifestation of a non-pathological trait. Some authors have hypothesized this type of syncope as a "defense mechanism" for the organism and a few theories have been postulated. Under the human violent conflicts theory, the VVS evolved during the Paleolithic era only in the human lineage. In this evolutionary period, a predominant cause of death was wounding by a sharp object. This theory could explain the occurrence of emotional VVS, but not of the orthostatic one. The clot production theory suggests that the vasovagal reflex is a defense mechanism against hemorrhage in mammals. This theory could explain orthostatic VVS, but not emotional VVS. The brain self-preservation theory is mainly based on the observation that during tilt testing a decrease in cerebral blood flow often precedes the drop in blood pressure and heart rate. The faint causes the body to take on a gravitationally neutral position, and thereby provides a better chance of restoring brain blood supply. However, a decrease in cerebral blood flow has not been demonstrated during negative emotions, which trigger emotional VVS. Under the heart defense theory, the vasovagal reflex seems to be a protective mechanism against sympathetic overactivity and the heart is the most vulnerable organ during this condition. This appears to be the only unifying theory able to explain the occurrence of the vasovagal reflex and its associated selective advantage, during both orthostatic and emotional stress.

Renal nerve stimulation for treatment of neurocardiogenic syncope: a review from perspective of commercialization potential

A strong evidence of outcomes for vasovagal syncope is not easily identified. It would seem reasonable that the proposed Mayo Clinic technology would be reserved for cases with severe recurrent or refractory syncope. However, recurrence levels are relatively low, and while some predictive methods have been proposed, recurrence is also influenced by the interaction that occurs during screening and examinations, i.e. recurrence diminishes once an initial diagnosis has been made. Finally, a key factor in being able to identify suitable patients relates to understanding the relative significance of the vasodepression and cardioinhibitory components-the therapy is best suited to patients that have a significant level of both components. It is probably not needed in patients with mainly cardioinhibitory involvement-data from ISSUE 2 and ISSUE 3 studies suggest that this is a relatively large proportion, particularly with asystolic involvement. The challenge remains in having suitable screening tests to identify the best patients. Tilt table testing has questions concerning its ability to replicate clinical syncope-implantable loop recorders (ILRs) may provide more accurate data but their usage is not yet widely accepted given the costs and invasive nature of the monitor.