Timing of Circulatory and Neurological Events in Syncope

Study protocol for the Heads-Up trial: a phase II randomized controlled trial investigating head-up tilt sleeping to alleviate orthostatic intolerance in Parkinson's Disease and parkinsonism

BACKGROUND

In persons with Parkinson's Disease (PD) or certain forms of atypical parkinsonism, orthostatic hypotension is common and disabling, yet often underrecognized and undertreated. About half of affected individuals also exhibit supine hypertension. This common co-occurrence of both orthostatic hypotension and supine hypertension complicates pharmacological treatments as the treatment of the one can aggravate the other. Whole-body head-up tilt sleeping (HUTS) is the only known intervention that may improve both. Evidence on its effectiveness and tolerability is, however, lacking, and little is known about the implementability.

METHODS

In this double-blind multicenter randomized controlled trial (phase II) we will test the efficacy and tolerability of HUTS at different angles in 50 people with PD or parkinsonism who have both symptomatic orthostatic hypotension and supine hypertension. All participants start with one week of horizontal sleeping and subsequently sleep at three different angles, each maintained for two weeks. The exact intervention will vary between the randomly allocated groups. Specifically, the intervention group will consecutively sleep at 6°, 12° and 18°, while the delayed treatment group starts with a placebo angle (1°), followed by 6° and 12°. We will evaluate tolerability using questionnaires and compliance to the study protocol. The primary endpoint is the change in average overnight blood pressure measured by a 24-hour ambulatory blood pressure recording. Secondary outcomes include orthostatic blood pressure, orthostatic tolerance, supine blood pressure, nocturia and various other motor and non-motor tests and questionnaires.

DISCUSSION

We hypothesize that HUTS can simultaneously alleviate orthostatic hypotension and supine hypertension, and that higher angles of HUTS are more effective but less tolerable. The Heads-Up trial will help to clarify the effectiveness, tolerability, and feasibility of this intervention at home and can guide at-home implementation.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05551377; Date of registration: September 22, 2022.

Variability of cardioinhibition in vasovagal syncope: differences between subgroups during cardioinhibition and beyond

PURPOSE

We compared hemodynamic parameters between subjects with marked, intermediate and minimal cardioinhibition during vasovagal syncope.

METHODS

The study included subjects with a decrease in heart rate while experiencing a complete vasovagal syncope during tilt-table testing. The subjects were classified as having marked, intermediate or minimal cardioinhibition, based on tertile values of the decrease in heart rate. Hemodynamic parameters between these groups were compared before tilt in the supine position, shortly after tilt and during cardioinhibition.

RESULTS

A total of 149 subjects with a median age of 43 (interquartile range 24-60) years were included in the study. Among the three groups with different levels of cardioinhibition, the highest heart rate was observed in subjects with marked cardioinhibition both before and shortly after tilt and at the start of cardioinhibition. The heart rate decrease in these subjects was both larger and faster compared to subjects with minimal and intermediate cardioinhibition.

CONCLUSION

Subjects with marked cardioinhibition have both a larger and faster decrease in heart rate compared to subjects with intermediate and minimal cardioinhibition, as early as from the start of cardioinhibition. Marked cardioinhibition is related to differences in hemodynamic profiles already present well before the start of cardioinhibition.

A review of the DTS: Diathermic Syncope® system with a discussion regarding its use for kosher slaughter (shechita)

Over the last several decades an alternative to current methods of stunning cattle has been developed. This system, DTS: Diathermic Syncope®, has been suggested to the Jewish and Muslim communities as a means to achieve pre-cut stunning in conformity with both religious and EU regulations without a need to resort to a derogation that permits an exemption from the EU requirement to pre-stun all animals undergoing slaughter. The developer's contention is that the system induces fainting, and thus should be acceptable to all groups, including the kosher (Jewish) and Halal (Muslim) consumer. A review of the system based on publications and reports from the developer itself suggests that in reality the system selectively heats the brain, leading to an epileptic-type seizure with tonic-clonic phases and unconsciousness lasting several minutes. It does not induce a (benign) faint, and use of the system might cause structural brain damage. Thus, this system is unlikely to be acceptable under Jewish religious law and its animal welfare value can be questioned.

Intracardiac Induced Ventricular Fibrillation for the Euthanasia of Sheep

Euthanasia is the humane termination of an animal's life and an important consideration for scientists, veterinarians, regulators, and others contemplating investigations involving animals. Techniques for euthanasia must induce the most rapid, painless, and distress-free death possible. This study investigated the effectiveness of direct current induction of ventricular fibrillation for the euthanasia of sheep after a primary study in which artifacts or chemical contamination from injectable euthanasia agents were undesirable. Female crossbred adult sheep (Ovis aries; n = 12) under deep isoflurane general anesthesia were instrumented with electrophysiology catheters to induce ventricular fibrillation for euthanasia. Data regarding invasive arterial blood pressure, expired airway gases, limb lead electrocardiograms, and pulse oximetry were collected and assessed just prior to, immediately after, and at 5, 10, 15, and 20min after energy delivery. In all animals, a single 10-s application of 9V of direct current to the right ventricular endocardium via the electrophysiology catheter induced persistent ventricular fibrillation. Arterial blood pressure (mean ± 1 SD) immediately after fibrillation induction was 22.9±4.5mmHg, with negligible difference between systolic and diastolic pressures. The lack of differential pressure continued through the end of the monitoring period. Arterial blood pressure reached an initial nadir at 1??0.5min after fibrillation induction, peaked (40.8±11.1mmHg) due to a vasoconstrictive reflex at 3min after induction, and returned to a static uniform pressure (20.4±17.8mmHg) with mildly increased variability due to reflexive diaphragmatic contractions at 10min after induction. The use of 9V direct current for the induction of ventricular fibrillation via an electrophysiology catheter is a reliable method of euthanasia in sheep.

The Impact of Head-Up Tilt Sleeping on Orthostatic Tolerance: A Scoping Review

To systematically summarize the evidence of head-up tilt sleeping (HUTS) on orthostatic tolerance, we conducted a systematic, predefined search in PubMed, OVID Embase, Cochrane and Web of Science. We included studies assessing the effect of HUTS on orthostatic tolerance and other cardiovascular measures and rated the quality with the American Academy of Neurology risk of bias tool. We included 10 studies (n = 185) in four groups: orthostatic hypotension (OH; 6 studies, n = 103), vasovagal syncope (1 study, n = 12), nocturnal angina pectoris (1 study, n = 10) and healthy subjects (2 studies, n = 58). HUTS duration varied (1 day-4 months) with variable inclinations (5°-15°). In two of six OH studies, HUTS significantly improved standing systolic blood pressure. Orthostatic tolerance was consistently enhanced in OH studies with higher angles (≥12°), in 2 out of 3 with smaller angles (5°) but also in one studying horizontal sleeping. In vasovagal syncope, HUTS significantly augmented resilience to extreme orthostatic stress. One study was rated as a class II risk of bias, one of Class II/III and eight of Class IV. The evidence favouring HUTS to improve orthostatic tolerance is weak due to variable interventions, populations, small samples and a high risk of bias. Despite this, we found some physiological signs suggesting a beneficial effect.

Changes in Blood Pressure Variability in Children with Postural Tachycardia Syndrome

(1) Objective: In this research, we explored the difference in blood pressure variability (BPV) between children with postural tachycardia syndrome (POTS) and healthy children. Furthermore, we tried to investigate the effect of BPV on POTS and its relationship with prognosis of POTS. (2) Methods: 47 children with POTS (11.2 ± 1.8 years, 23 males) were enrolled in the POTS group and 30 healthy children (10.9 ± 1.9 years, 15 males) were matched for the control group. All participants completed 24 h ambulatory blood pressure monitoring (24hABPM). Thirty-three children with POTS were followed up for 52.0 (30.5, 90.5) days and were divided into a response group and a non-response group after evaluation. (3) Results: The 24 h diastolic blood pressure standard deviation (24hDSD), daytime diastolic blood pressure standard deviation (DDSD), nighttime systolic blood pressure standard deviation (NSSD), daytime diastolic blood pressure variation coefficient (DDCV) and nighttime systolic blood pressure variation coefficient (NSCV) in the control group were lower than those in the POTS group (p < 0.05). Percentage of females, age and height were lower in the response group than in the non-response group in children with POTS (p < 0.05). Univariate analysis showed that 24hDSD, DDSD, NSSD, DDCV and NSCV were potential risk factors for POTS, and sex and height were potential risk factors for poor prognosis of POTS. After adjusting for covariates, the risk of POTS increased by 48%, 53% and 49% when DDSD, NSSD and NSCV increased by 1 mmHg, 1 mmHg and 1%, respectively. The risk of poor prognosis in females was 12.99 times higher than that in males. (4) Conclusions: The results suggest that children with POTS may have an abnormal circadian rhythm in blood pressure and increased BPV. DDSD, NSSD and NSCV are independent risk factors for POTS, and being female is an independent risk factor for poor prognosis of POTS.

The future of cardioneuroablation in cardiovascular medicine

INTRODUCTION

Cardioneuroablation is increasingly being utilized to improve outcomes in patients with vagally mediated bradyarrhythmias. However, there are still controversial issues in the field including patient selection, safety and efficacy, and procedural end-points.

AREAS COVERED

In this review, the current role of cardioneuroablation is summarized, and controversial issues related to the modality are discussed.

EXPERT OPINION

According to small open-label cohort studies, overall freedom from syncope recurrence was higher than 90% after cardioneuroablation in patients with vasovagal syncope (VVS). Use of the electrogram-based strategy or high-frequency stimulation demonstrate similar success rate except in procedures limited to the right atrium. Based on a recently published randomized controlled trial and metanalysis, it may be possible now to make a strong recommendation for cardioneuroablation in patients <40 years of age, and those with the cardioinhibitory or mixed type of VVS who continue to experience frequent and/or burdensome syncope recurrences. Considering patients with VVS are prone to significant placebo/expectation effect, sham-controlled trials may help to quantify the placebo effect. In well-selected patients with functional atrioventricular block and sinus bradycardia, may result in encouraging medium-term outcomes. However, functional bradycardia is identified in a minority of patients presenting with high-grade atrioventricular block or sinus node dysfunction.

Orthostatic stress response in pediatric Fontan patients and the effect of ACE inhibition

Background

Many cardiocirculatory mechanisms are involved in the adaptation to orthostatic stress. While these mechanisms may be impaired in Fontan patients. However, it is yet unclear how Fontan patients, who exhibit a critical fluid balance, respond to orthostatic stress. Angiotensin converting enzyme inhibitors are often prescribed to Fontan patients, but they may negatively influence orthostatic tolerance. Therefore, we evaluated the response to orthostatic stress in pediatric Fontan patients before and after treatment with enalapril.

Methods

Thirty-five Fontan patients (aged 14 years) with moderate-good systolic ventricular function without pre-existent enalapril treatment were included. Before and after a three-month enalapril treatment period, the hemodynamic response to head-up tilt test was evaluated by various parameters including cardiac index, blood pressure, cerebral blood flow, aortic stiffness and cardiac autonomous nervous activity. Thirty-four healthy subjects (aged 13 years) served as controls.

Results

Fontan patients had a decreased cerebral blood flow and increased aortic stiffness in the supine position compared to controls, while all other factors did not differ. Patients and controls showed a comparable response to head-up tilt test for most parameters. Twenty-seven patients completed the enalapril study with a mean dosage of 0.3±0.1mg/kg/day. Most parameters were unaffected by enalapril, only the percent decrease in cardiac index to tilt was higher after treatment, but the cardiac index during tilt was not lower (3.0L/min/m2 pre-enalapril versus 2.8L/min/m2 after treatment; P = 0.15).

Conclusion

Pediatric Fontan patients adequately respond to orthostasis with maintenance of blood pressure and cerebral blood flow and sufficient autonomic response. Enalapril treatment did not alter the response.

Clinical trial information

Scientific title: ACE inhibition in Fontan patients: its effect on body fluid regulation (sAFE-study).

The Netherlands National Trial Register: Trail NL6415. Registered 2017-07-20.

Trial information: https://www.trialregister.nl/trial/6415

Diagnosis and treatment of orthostatic hypotension

Orthostatic hypotension is an unusually large decrease in blood pressure on standing that increases the risk of adverse outcomes even when asymptomatic. Improvements in haemodynamic profiling with continuous blood pressure measurements have uncovered four major subtypes: initial orthostatic hypotension, delayed blood pressure recovery, classic orthostatic hypotension, and delayed orthostatic hypotension. Clinical presentations are varied and range from cognitive slowing with hypotensive unawareness or unexplained falls to classic presyncope and syncope. Establishing whether symptoms are due to orthostatic hypotension requires careful history taking, a thorough physical examination, and supine and upright blood pressure measurements. Management and prognosis vary according to the underlying cause, with the main distinction being whether orthostatic hypotension is neurogenic or non-neurogenic. Neurogenic orthostatic hypotension might be the earliest clinical manifestation of Parkinson's disease or related synucleinopathies, and often coincides with supine hypertension. The emerging variety of clinical presentations advocates a stepwise, individualised, and primarily non-pharmacological approach to the management of orthostatic hypotension. Such an approach could include the cessation of blood pressure lowering drugs, adoption of lifestyle measures (eg, counterpressure manoeuvres), and treatment with pharmacological agents in selected cases.

Bedside Assessment of Autonomic Dysfunction in Multiple System Atrophy

Multiple system atrophy (MSA) is a rare, rapidly progressive neurodegenerative disorder of the adulthood, characterized by autonomic failure, parkinsonian and cerebellar features in various combinations. Distinguishing MSA from common clinical look-alikes such as Parkinson's disease, other atypical parkinsonian disorders or alternative causes of sporadic adult-onset cerebellar ataxia may be difficult, especially at early disease stages. Nonetheless, some simple and cost-effective screening tools help detecting important red flags guiding towards a MSA diagnosis. Here we outline which clinical pearls and bedside tests may disclose autonomic dysfunction in multiple domains, enabling an early MSA diagnosis and, even more importantly, personalized treatment.

Autonomic manifestations of epilepsy: emerging pathways to sudden death?

Epileptic networks are intimately connected with the autonomic nervous system, as exemplified by a plethora of ictal (during a seizure) autonomic manifestations, including epigastric sensations, palpitations, goosebumps and syncope (fainting). Ictal autonomic changes might serve as diagnostic clues, provide targets for seizure detection and help us to understand the mechanisms that underlie sudden unexpected death in epilepsy (SUDEP). Autonomic alterations are generally more prominent in focal seizures originating from the temporal lobe, demonstrating the importance of limbic structures to the autonomic nervous system, and are particularly pronounced in focal-to-bilateral and generalized tonic-clonic seizures. The presence, type and severity of autonomic features are determined by the seizure onset zone, propagation pathways, lateralization and timing of the seizures, and the presence of interictal autonomic dysfunction. Evidence is mounting that not all autonomic manifestations are linked to SUDEP. In addition, experimental and clinical data emphasize the heterogeneity of SUDEP and its infrequent overlap with sudden cardiac death. Here, we review the spectrum and diagnostic value of the mostly benign and self-limiting autonomic manifestations of epilepsy. In particular, we focus on presentations that are likely to contribute to SUDEP and discuss how wearable devices might help to prevent SUDEP.

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.

Towards Understanding the Genetic Nature of Vasovagal Syncope

Syncope, defined as a transient loss of consciousness caused by transient global cerebral hypoperfusion, affects 30-40% of humans during their lifetime. Vasovagal syncope (VVS) is the most common cause of syncope, the etiology of which is still unclear. This review summarizes data on the genetics of VVS, describing the inheritance pattern of the disorder, candidate gene association studies and genome-wide studies. According to this evidence, VVS is a complex disorder, which can be caused by the interplay between genetic factors, whose contribution varies from monogenic Mendelian inheritance to polygenic inherited predisposition, and external factors affecting the monogenic (resulting in incomplete penetrance) and polygenic syncope types.

Timing of syncope in ictal asystole as a guide when considering pacemaker implantation

Introduction

In patients with ictal asystole (IA) both cardioinhibition and vasodepression may contribute to syncopal loss of consciousness. We investigated the temporal relationship between onset of asystole and development of syncope in IA, to estimate the frequency with which pacemaker therapy, by preventing severe bradycardia, may diminish syncope risk.

Methods

In this retrospective cohort study, we searched video‐EEG databases for individuals with focal seizures and IA (asystole ≥ 3 s preceded by heart rate deceleration) and assessed the durations of asystole and syncope and their temporal relationship. Syncope was evaluated using both video observations (loss of muscle tone) and EEG (generalized slowing/flattening). We assumed that asystole starting ≤3 s before syncope onset, or after syncope began, could not have been the dominant cause.

Results

We identified 38 seizures with IA from 29 individuals (17 males; median age: 41 years). Syncope occurred in 22/38 seizures with IA and was more frequent in those with longer IA duration (median duration: 20 [range: 5–32] vs. 5 [range: 3–9] s; p < .001) and those with the patient seated vs. supine (79% vs. 46%; p = .049). IA onset always preceded syncope. In 20/22 seizures (91%), IA preceded syncope by >3 s. Thus, in only two instances was vasodepression rather than cardioinhibition the dominant presumptive syncope triggering mechanism.

Conclusions

In IA, cardioinhibition played an important role in most seizure‐induced syncopal events, thereby favoring the potential utility of pacemaker implantation in patients with difficult to suppress IA.

Electrocardiographic Patterns in Patients with Neurally Mediated Syncope

The baseline electrocardiogram (ECG) is less informative in neurally mediated syncope (NMS) than in arrhythmic syncope. However, some of the ECG patterns present in NMS can have diagnostic and prognostic value in such patients. Electrocardiographic documentation of a syncopal spell and thus identification of the ECG changes can be performed during tilt table test (TTT) or during prolonged ECG monitoring. This work reviews the specific ECG patterns in NMS, which are primarily related to the cardioinhibitory reflex. In addition, there are other ECG findings present in patients with NMS that are being analyzed, such as increased heart rate variability as well as specific QRS voltage patterns. In addition to the diagnostic and prognostic value, these ECG patterns in NMS may help improving the selection of patients for pacemaker implant.

Predicting Vasovagal Responses: A Model-Based and Machine Learning Approach

Vasovagal syncope (VVS) or neurogenically induced fainting has resulted in falls, fractures, and death. Methods to deal with VVS are to use implanted pacemakers or beta blockers. These are often ineffective because the underlying changes in the cardiovascular system that lead to the syncope are incompletely understood and diagnosis of frequent occurrences of VVS is still based on history and a tilt test, in which subjects are passively tilted from a supine position to 20° from the spatial vertical (to a 70° position) on the tilt table and maintained in that orientation for 10–15 min. Recently, is has been shown that vasovagal responses (VVRs), which are characterized by transient drops in blood pressure (BP), heart rate (HR), and increased amplitude of low frequency oscillations in BP can be induced by sinusoidal galvanic vestibular stimulation (sGVS) and were similar to the low frequency oscillations that presaged VVS in humans. This transient drop in BP and HR of 25 mmHg and 25 beats per minute (bpm), respectively, were considered to be a VVR. Similar thresholds have been used to identify VVR's in human studies as well. However, this arbitrary threshold of identifying a VVR does not give a clear understanding of the identifying features of a VVR nor what triggers a VVR. In this study, we utilized our model of VVR generation together with a machine learning approach to learn a separating hyperplane between normal and VVR patterns. This methodology is proposed as a technique for more broadly identifying the features that trigger a VVR. If a similar feature identification could be associated with VVRs in humans, it potentially could be utilized to identify onset of a VVS, i.e, fainting, in real time.

["Ictal" Bradyarrhythmias in Patients with Drug-Resistant Epilepsy: Results of Long-Term Heart Rhythm Monitoring]

Aim      To determine the type and incidence of ictal bradyarrhythmias in patients with drug-resistant types of epilepsy by long-term electrocardiogram (ECG) monitoring.Material and methods  Subcutaneous ECG monitors programed for recording pauses &gt;3 sec and episodes of bradycardia ≤45 bpm were implanted in 193 patients with persistent epileptic seizures without organic pathology of the myocardium. Recording was activated by the patient/family at the onset of epileptic seizure. The follow-up period was 36 months with visits to the clinic every three months.Results For 36 months of monitoring, 6494 ECG fragments were recorded. Ictal bradycardia was observed in 6.7 % of patients, including ictal asystole in 2.6 % of patients. Episodes of bradycardia and asystole during epileptic seizures were transient and developed significantly more frequently in men, patients with long duration of the disease, bilateral tonic-clonic or focal seizures with disorder of consciousness, during sleep, on the background of treatment with several antiepileptic agents, mostly from the group of potassium channel blockers.Conclusion      Bradyarrhythmias accompanying epileptic seizures are transient and reproducible from seizure to seizure. They reflect functional changes in the myocardium and do not determine the life prediction for patients with epilepsy without organic pathology of the heart.

Cardiovascular fingolimod effects on rapid baroreceptor unloading are counterbalanced by baroreflex resetting

Background and purpose

Initial cardiovascular fingolimod effects might compromise baroreflex responses to rapid blood pressure (BP) changes during common Valsalva-like maneuvers. This study evaluated cardiovascular responses to Valsalva maneuver (VM)-induced baroreceptor unloading and loading upon fingolimod initiation.

Patients and methods

Twenty-one patients with relapsing-remitting multiple sclerosis performed VMs before and 0.5, 1, 2, 3, 4, 5, and 6 hours after fingolimod initiation. We recorded heart rate (HR) as RR intervals (RRI), systolic and diastolic BP (BPsys, BPdia) during VM phase 1, VM phase 2 early, VM phase 2 late, and VM phase 4. Using linear regression analysis between decreasing BPsys and RRI values during VM phase 2 early, we determined baroreflex gain (BRG) reflecting vagal withdrawal and sympathetic activation upon baroreceptor unloading. To assess cardiovagal activation upon baroreceptor loading, we calculated Valsalva ratios (VR) between maximal and minimal RRIs after strain release. Analysis of variance or Friedman tests with post hoc analysis compared corresponding parameters at the eight time points (significance: p < 0.05).

Results

RRIs at VM phase 1, VM phase 2 early, and VM phase 2 late were higher after than before fingolimod initiation, and maximal after 4 hours. Fingolimod did not affect the longest RRIs upon strain release, but after 3, 5, and 6 hours lowered the highest BPsys values during overshoot and all BPdia values, and thus reduced VRs. BRG was slightly higher after 3 and 5 hours, and significantly higher after 4 hours than before fingolimod initiation.

Conclusions

VR-decreases 3–6 hours after fingolimod initiation are physiologic results of fingolimod-associated attenuations of BP and HR increases at the end of strain and do not suggest impaired cardiovagal activation upon baroreceptor loading. Stable and at the time of HR nadir significantly increased BRGs indicate improved responses to baroreceptor unloading. Thus, cardiovascular fingolimod effects do not impair autonomic responses to sudden baroreceptor loading or unloading but seem to be mitigated by baroreflex resetting.