Is there any point to vasovagal syncope?

Adult vasovagal syncope with abdominal pain diagnosed by head-up tilt combined with transcranial doppler: a preliminary study

BACKGROUND

Syncope is a common condition that increases the risk of injury and reduces the quality of life. Abdominal pain as a precursor to vasovagal syncope (VVS) in adults is rarely reported and is often misdiagnosed.​.

METHODS

We present three adult patients with VVS and presyncopal abdominal pain diagnosed by synchronous multimodal detection (transcranial Doppler [TCD] with head-up tilt [HUT]) and discuss the relevant literature.

RESULTS

Case 1: A 52-year-old man presented with recurrent decreased consciousness preceded by six months of abdominal pain. Physical examinations were unremarkable. Dynamic electrocardiography, echocardiography, head and neck computed tomography angiography, magnetic resonance imaging (MRI), and video electroencephalogram showed no abnormalities. Case 2: A 57-year-old woman presented with recurrent syncope for 30 + years, accompanied by abdominal pain. Physical examination, electroencephalography, and MRI showed no abnormalities. Echocardiography showed large right-to-left shunts. Case 3: A 30-year-old woman presented with recurrent syncope for 10 + years, with abdominal pain as a precursor. Physical examination, laboratory analysis, head computed tomography, electrocardiography, and echocardiography showed no abnormalities. Syncope secondary to abdominal pain was reproduced during HUT. Further, HUT revealed vasovagal syncope, and synchronous TCD showed decreased cerebral blood flow; the final diagnosis was VVS in all cases.

CONCLUSIONS

Abdominal pain may be a precursor of VVS in adults, and our findings enrich the clinical phenotypic spectrum of VVS. Prompt recognition of syncopal precursors is important to prevent incidents and assist in treatment decision-making. Abdominal pain in VVS may be a sign of sympathetic overdrive. Synchronous multimodal detection can help in diagnosing VVS and understanding hemodynamic mechanisms.

Endocardial ablation of epicardial ganglionated plexi: history, open questions and future prospects of cardioneuroablation

Neurocardiogenic syncope is the most common cause of transient loss of consciousness and considerably reduces quality of life. Pharmacological and pacing therapy may not be fully efficacious and complications related to implanted hardware must be considered. In this context, cardioneuroablation (CNA) has been proposed to attenuate the vagal reflex with elimination of cardioinhibition. It has been shown that CNA is able to eliminate recurrences of syncope in over 90% of cases and no major complications are reported in the current literature. Despite these encouraging findings, CNA is only mentioned in current guidelines as a possible alternative treatment and has no real indication class. The diversity of mapping techniques, the absence of direct denervation control, the lack of a precise endpoint, the possible placebo effect, the short follow-up, and the question of the learning curve represent the major limitations of this promising procedure. The aim of this review was to look over the existing literature, analysing the novelties, the limitations, the unresolved issues and the outcome of CNA.

An ethologically based view into human fear

The quality of the defensive response to a threat depends on the elements that trigger the fear response. The current classification system of phobias does not account for this. Here, we analyze the fear-eliciting elements and discern the different types of fears that originate from them. We propose Pain, Disgust, Vasovagal response, Visual-vestibular and postural interactions, Movement and Speed, Distance and Size, Low and mid-level visual features, Smell, and Territory and social status. We subdivide phobias according to the fear-eliciting elements most frequently triggered by them and their impact on behavior. We discuss the implications of a clinical conceptualization of phobias in humans by reconsidering the current nosology. This conceptualization will facilitate finding etiological factors in defensive behavior expression, fine-tuning exposure techniques, and challenging preconceived notions of preparedness. This approach to phobias leads to surprising discoveries and shows how specific responses bear little relation to the interpretation we might later give to them. Dividing fears into their potentially fear-eliciting elements can also help in applying the research principles formulated by the Research Domain Criteria initiative.

The pathophysiology of vasovagal syncope: Novel insights

The pathophysiology of vasovagal syncope (VVS) is reviewed, focusing on hemodynamic aspects. Much more is known about orthostatic than about emotional VVS, probably because the former can be studied using a tilt table test (TTT). Recent advances made it possible to quantify the relative contributions of the three factors that control blood pressure: heart rate (HR), stroke volume (SV) and total peripheral resistance (TPR). Orthostatic VVS starts with venous pooling, reflected in a decrease of SV. This is followed by cardioinhibition (CI), which is a decrease of HR that accelerates the ongoing decrease of BP, making the start of CI a literal as well as fundamental turning point. The role of hormonal and other humoral factors, respiration and of psychological influences is reviewed in short, leading to the conclusion that a multidisciplinary approach to the study of the pathophysiology of VVS may yield new insights.

Gender Matters: Nonlinear Relationships Between Heart Rate Variability and Depression and Positive Affect

Vagally mediated heart rate variability (vmHRV), a measure of the parasympathetic nervous system's control over the heart, is often negatively related to maladaptive emotional outcomes. Recent work suggests that quadratic relationships involving these factors may be present; however, research has not investigated gender differences in these nonlinear functions. To address this gap, the current study tested for quadratic relationships between resting vmHRV and depression and positive affect while investigating gender differences in these relationships. Significant quadratic effects were found between resting vmHRV and reports of both depression symptoms and positive affect in women but not men. Specifically, the lowest levels of depression and the highest levels of positive affect were found at moderate vmHRV in women. These results suggest that examinations of vmHRV's nonlinear associations require the consideration of gender. Our findings are interpreted based on proposed differential neuropsychological mechanisms of vmHRV in men versus women.

Usefulness of post-procedural heart rate response to predict syncope recurrence or positive head up tilt table testing after cardioneuroablation

Aims

Previous reports have suggested that cardioneuroablation (CNA) can be effective in reducing syncopal recurrences in patients with vasovagal syncope (VVS). This study assessed the efficacy of CNA in preventing a positive response to head-up tilt testing (HUT).

Methods and results

This is a single-centre retrospective study reviewing prospectively collected data. Fifty-one consecutive patients with VVS were included in the study. After confirmation of >3 s asystole on HUT, all patients underwent CNA. Head-up tilt testing was repeated 1 month after CNA. The main outcome measures were recurrence of syncope episode and positive response on HUT. During a median follow-up period of 11 months (interquartile range 3–27 months), all but 3 (5.8%) of 51 patients were free of syncope. Repeated HUTs were negative in 44 (86.2%) patients. When patients with recurrent syncope were excluded, vasodepressor response was seen in three cases and cardioinhibitory response in one case, respectively. Cardioneuroablation caused significant and durable shortening of RR interval in all cases. This effect was significantly higher in patients without positive HUT responses.

Conclusion

This pilot study shows that CNA can effectively prevent recurrent syncopal episodes in patients with refractory VVS. Head-up tilt testing seems as a valuable diagnostic tool not only to select suitable candidates and but also to evaluate success of CNA.

The clinical characteristics of situational syncope in children and adults undergoing head-up tilt testing

OBJECTIVE

Situational syncope is a subtype of neurally mediated syncope and associated with specific circumstances. This paper is to assess the clinical characteristics and underlying causes of situational syncope.

METHODS

This is a retrospective study of patients who underwent head-up tilt testing (HUTT). Medical records including age at HUTT, gender, number of syncopal episodes, family history of syncope, triggers before the syncopal episode, position during the syncopal episode and the responses to HUTT were reviewed.

RESULTS

Among 3140 patients, 354 patients (mean age 28.3 ± 16.6 years old, with 184 males and 170 females) were diagnosed with situational syncope. The causes of situational syncope included micturition (50.85%), defecation (15.82%), bathing (10.45%), swallowing (6.50%), cough (4.80%), post-dinner (3.95%), singing (3.11%), teeth brushing (2.26%), and hair grooming (2.26%). Patients with syncope triggered by micturition, cough, post-dinner were more likely to be men, while those caused by bathing, swallowing, singing, teeth brushing and hair grooming were more likely to be women. 34.75% of patients with situational syncope were between the ages of 10-19 years old, and 20.34% were between the ages of 40-49 years old. 74.01% of situational syncopal events occurred in an upright position. 47.74% of patients had positive responses to HUTT.

CONCLUSIONS

These findings show that micturition was the most common cause of situational syncope in both children and adults. There were significant gender and age differences among situational syncope triggered by different causes. Most of situational syncope occurred in the upright position and nearly half of the patients had positive responses to HUTT.

Indications for permanent pacing in dogs and cats

Pacemaker implantation is considered as a standard procedure for treatment of symptomatic bradycardia in both dogs and cats. Advanced second-degree and third-degree atrioventricular blocks, sick sinus syndrome, persistent atrial standstill, and vasovagal syncope are the most common rhythm disturbances that require pacing to either alleviate clinical signs or prolong survival. Most pacemakers are implanted transvenously, using endocardial leads, but rarely epicardial leads may be necessary. To decide whether a patient is a candidate for pacing, as well as which pacing modality should be used, the clinician must have a clear understanding of the etiology, the pathophysiology, and the natural history of the most common bradyarrhythmias, as well as what result can be achieved by pacing patients with different rhythm disturbances. The goal of this review was, therefore, to describe the indications for pacing by evaluating the available evidence in both human and veterinary medicine. We described the etiology of bradyarrhythmias, clinical signs and electrocardiographic abnormalities, and the choice of pacing modality, taking into account how different choices may have different physiological consequences to selected patients. It is expected that this review will assist veterinarians in recognizing arrhythmias that may require permanent pacing and the risk-benefit of each pacing modality and its impact on outcome.

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.

Prophylactic Atropine Administration Prevents Vasovagal Response Induced by Cryoballoon Ablation in Patients with Atrial Fibrillation

BACKGROUND

Cryoballoon (CB) ablation of pulmonary vein ostia often induces a vagal response. This prospective study was designed to assess the effectiveness of prophylactic intravenous administration of atropine on hemodynamic impairment induced by CB ablation in patients with atrial fibrillation.

METHODS

Twenty-five patients with paroxysmal atrial fibrillation undergoing CB ablation were prospectively enrolled and assigned to one of two groups. First 12 patients (trial group) were administered 1 mg of atropine before deflation of the CB, while the following 13 patients (control group) were given atropine only after the onset of the hemodynamic variation (decrease in heart rate and/or blood pressure). Treatment was considered effective when the hemodynamic variations were restored.

RESULTS

In the trial group, three patients with transient hypotension did not require supportive care throughout the procedures, and one patient with hypotension required supportive care. In the control group, hypotension, bradycardia, and mixed bradycardia with hypotension requiring supportive care occurred in six, three, and three patients, respectively. Overall, the rate of marked vagal responses was significantly lower when prophylactic atropine was administrated (4/12 patients vs 12/13 patients, respectively; P < 0.01).

CONCLUSIONS

Atropine is significantly effective in the prevention of all types of vasovagal responses induced by CB ablation in patients with atrial fibrillation.

[Syncope: electrocardiogram and autonomic function tests]

Syncope represents one of the most frequent reasons for consultation in the emergency department. A proper identification will allow a precise etiologic approach and the optimization of delivery of health resources.
Once knowing the classification of syncope; it is the clinical interrogatory what enables to discriminate which of these patients present with a neurogenic mediated syncope or a cardiac mediated syncope. The use of diagnostic methods such as the tilt test, will clarify what type of neurally mediated syncope predominates in the patient.
The electrocardiogram is the cornerstone in the identification of those patients who had a true episode of self-limited or aborted sudden death as the first manifestation of their syncope, a fact which provides prognostic and therapeutic information that will impact the morbidity and mortality.

Tilt table test today - state of the art

A tilt table test (TTT) is an inexpensive, noninvasive tool for the differential diagnosis of syncope and orthostatic intolerance and has good diagnostic yield. The autonomic system malfunction which underlines the reflex syncope is manifested as either hypotension or bradycardia, while an orthostatic challenge is applied. The timing of the response to the orthostatic challenge, as well as the predominant component of the response help to differentiate between various forms of neurocardiogenic syncope, orthostatic hypotension and non-cardiovascular conditions (e.g., pseudosyncope). Medications, such as isoproterenol and nitrates, may increase TTT sensitivity. Sublingual nitrates are easiest to administer without the need of venous access. TTT can be combined with carotid sinus massage to evaluate carotid sinus hypersensitivity, which may not be present in supine position. TTT is not useful to access the response to treatment. Recently, implantable loop recorders (ILR) have been used to document cardioinhibitory reflex syncope, because pacemakers are beneficial in many of these patients, especially those over 45 years of age. The stepwise use of both TTT and ILR is a promising approach in these patients. Recently, TTT has been used for indications other than syncope, such as assessment of autonomic function in Parkinson's disease and its differentiation from multiple system atrophy.

Vasovagal Syncope: Hypothesis Focusing on Its Being a Clinical Feature Unique to Humans

Humans live primarily in the upright position; as a result, there is a constant struggle between gravity and needed supply of blood flow to the brain. In certain circumstances brain blood supply may become temporarily insufficient, resulting in syncope. Among the numerous causes of syncope in humans, vasovagal syncope (VVS) is by far the most common. However, despite intensive research, many aspects of the pathophysiology of VVS remain unknown; among these, one of the least well understood is the basis for why VVS is restricted, among vertebrates, to Homo sapiens. In this manuscript we review proposals that have been offered in an attempt to address the issue of the origin of VVS and, although highly speculative, we suggest a new hypothesis (the "brain theory") to try to address the question of why humans, to the exclusion of other species, remain susceptible to VVS. This theory suggests that VVS evolved to offer protection to the brain's functional integrity under certain conditions of severe threat. Although seemingly a disadvantageous evolutionary adaptation, the faint causes the body to take on a gravitationally neutral position, and thereby provides a better chance of restoring brain blood supply and preserving long-term brain function.

Managing the military patient with syncope

Syncope is a relatively common occurrence in military populations. It is defined as a transient loss of consciousness due to global cerebral hypoperfusion, characterised by a rapid onset, short duration and a spontaneous and complete recovery. While the symptom of syncope is easily elicited, discovering the mechanism can be more problematic and may require a plethora of diagnostic tests. The aim of this paper is to review current evidence pertaining to the classification, investigation and management of syncope, from a military perspective. Emphasis is placed on assisting primary healthcare professionals in the assessment and management of syncope, in the UK and on operations, while providing explicit guidance on risk. The occupational limitations required in safely managing patients with syncope are stressed along with the potential long-term limitations.

Different haemodynamic patterns in head-up tilt test on 400 paediatric cases with unexplained syncope

OBJECTIVE

To assess haemodynamic patterns in head-up tilt testing on 400 paediatric cases with unexplained syncope.

METHODS

Medical records of 520 children who underwent head-up tilt testing in the preceding year were retrospectively evaluated, and 400 children, 264 (66%) girls and 136 (34%) boys, aged 12.6±2.6 years (median 13; range 5-18), with unexplained syncope were enrolled in the study. Age, sex, baseline heart rate, baseline blood pressure, frequency of symptoms, and/or fainting attacks were recorded. The test protocol consisted of 25 minutes of supine resting followed by 20 minutes of 70° upright positioning. Subjects were divided into nine groups according to their differing haemodynamic patterns.

RESULTS

There were no statistically significant differences between the groups with regard to age, gender, baseline blood pressure, and frequency of syncope (p>0.05). The response was compatible with orthostatic intolerance in 28 cases (7.0%), postural orthostatic tachycardia syndrome in 24 cases (6.0%), asymptomatic postural orthostatic tachycardia syndrome in 26 cases (6.5%), orthostatic hypotension in seven cases (1.7%), vasovagal syncope in 38 cases (9.5%), and negative in 274 cases (69.2%). Vasovagal syncope response patterns were of type 3 in nine cases (2.2%), type 2A in 10 cases (2.5%), type 2B in two cases (0.5%), and type 1 (mixed) in 17 cases (4.25%).

CONCLUSIONS

In the 400 paediatric cases with unexplained syncope, nine different haemodynamic response patterns to head-up tilt testing were discerned. Children with orthostatic intolerance syndromes are increasingly referred to hospitals because of difficulty in daily activities. Therefore, there is need for further clinical trials in these patient groups.

Sub-Lingual Spray Versus Pearl of TNG as A Provocative Agent for Tilt Table Test

OBJECTIVE

The aim of this study was to determine the false positive ratio of Tilt Table Test (TTT) result by using TNG spray (Sub-lingual; SL) as compared to TNG pearl in patients referred to military service.

MATERIAL AND METHODS

This was a prospective study. It was conducted on 110 cases referred for military service, expressed vasovagal symptoms. We divided the subjects into three groups; first Group (60 cases) used TNG pearl for provoking syncope in TTT, Group 2 (50 cases) and Group 3 (control cases) used TNG spray in the same dose (0.4 mg).

RESULTS

In the first step of tilt study, 10%, and 8% of subjects had fainted on not using provoking drug in cases and controls, respectively. After using the drugs, 36.6%, 96% and 18% showed positive results in pearl, spray and the control groups, respectively (p<0.05).

CONCLUSION

Rather than pearl group, a 40 minute tilt using TNG spray showed significant higher positive results, which may be incorrectly positive. Using this form of TNG seems not useful for distinguishing and diagnosing vasovagal shocks, especially in subjects referred for military service capacity. For constant evidence, a cross-over clinical trial study is required, involving suspected cases divided into two groups, who both will be examined with spray and pearl.

Carotid artery stiffness in patients with neurally mediated syncope

OBJECTIVES

Neurally mediated syncope is defined as a transient loss of blood flow to the brain, resulting in vasodilatation, bradycardia, or both. The pathophysiologic mechanisms of neurally mediated syncope are not clear. In this study, we investigated carotid artery elasticity parameters in patients with neurally mediated syncope.

METHODS

The study was conducted on 41 patients who were examined by the tilt table test. Group 1 constituted of 21 patients who had a positive response to the tilt table test. Clinical and hemodynamic parameters were compared with patients in a negative tilt table test group (group 2). The systolic and diastolic diameters of the carotid arteries, carotid distensibility, carotid strain, carotid stiffness index, and carotid elastic modulus of the left carotid arteries were calculated by a high-resolution ultrasound device.

RESULTS

No differences in hemodynamic variables or clinical parameters were detected between the groups. Carotid distensibility (mean ± SD, 1.6 ± 0.6 versus 2.2 ± 0.8 cm(2) × dyne(-1) × 10(-6); P = .044) and strain (6.8% ± 1.7% versus 8.2% ± 1.9%; P = .026) were lower in group 1 than in group 2. The carotid elastic modulus (0.88 ± 0.33 versus 0.74 ± 0.25 cm(2) × dyne(-1) × 10(-6); P = .002) and stiffness index (6.7 ± 0.4 versus 6.2 ± 0.5; P = .038) were higher in group 1.

CONCLUSIONS

In this study, we concluded that elastic properties of the carotid artery are impaired in patients with neurally mediated syncope. This finding suggests that impaired carotid arterial elasticity may be a factor in the pathophysiologic mechanisms of neurally mediated syncope.

Dissociation Following Traumatic Stress

We postulate that the cascade “Freeze-Flight-Fight-Fright-Flag-Faint” is a coherent sequence of six fear responses that escalate as a function of defense possibilities and proximity to danger during life-threat. The actual sequence of trauma-related response dispositions acted out in an extremely dangerous situation therefore depends on the appraisal of the threat by the organism in relation to her/his own power to act (e.g., age and gender) as well as the perceived characteristics of threat and perpetrator. These reaction patterns provide optimal adaption for particular stages of imminence. Subsequent to the traumatic threats, portions of the experience may be replayed. The actual individual cascade of defense stages a survivor has gone through during the traumatic event will repeat itself every time the fear network, which has evolved peritraumatically, is activated again (i.e., through internal or external triggers or, e.g., during exposure therapy).When a parasympathetically dominated ‘‘shut-down’’ was the prominent peri-traumatic response during the traumatic incident, comparable dissociative responses may dominate responding to subsequently experienced threat and may also reappear when the traumatic memory is reactivated. Repeated experience of traumatic stress forms a fear network that can become pathologically detached from contextual cues such as time and location of the danger, a condition which manifests itself as posttraumatic stress disorder (PTSD). Intrusions, for example, can therefore be understood as repetitive displays of fragments of the event, which would then, depending on the dominant physiological response during the threat, elicit a corresponding combination of hyperarousal and dissociation. We suggest that trauma treatment must therefore differentiate between patients on two dimensions: those with peritraumatic sympathetic activation versus those who went down the whole defense cascade, which leads to parasympathetic dominance during the trauma and a corresponding replay of physiological and dissociative responding, when reminded. The differential management of dissociative stages (“fright” and “faint”) has important treatment implications.

A guide to disorders causing transient loss of consciousness: focus on syncope

Episodes of transient loss of consciousness (TLOC) events pose diagnostic difficulties, as the causes are diverse, carry vastly different risks, and span various specialties. An inconsistent terminology contributes to the confusion. Here, we present a classification scheme for TLOC, based on ongoing multidisciplinary efforts including those of the Task Force on Syncope of the European Society of Cardiology. We also discuss the pathophysiology of TLOC and the key clinical features that aid diagnosis. TLOC is defined as an apparent loss of consciousness with an abrupt onset, a short duration, and a spontaneous and complete recovery. Syncope is defined as TLOC due to cerebral hypoperfusion, and is divided into reflex syncope (synonymous with neurally mediated syncope), syncope due to orthostatic hypotension, and cardiac syncope (arrhythmic or associated with structural cardiac disease). The other major groups of TLOC are generalized epileptic seizures, functional TLOC (psychogenic TLOC mimicking either epilepsy or syncope), and a further group of miscellaneous disorders. The management of patients who experience TLOC requires the recognition of the defining features of each of the major groups, and cooperation between different clinical specialties.