The efficacy of non-pharmacological and non-pacing therapies in preventing vasovagal syncope: Tilt training, physical counter pressure maneuvers, and yoga - A systematic review and meta-analysis

BACKGROUND

Vasovagal syncope (VVS) is a prevalent condition characterized by a sudden drop in blood pressure and heart rate, leading to a brief loss of consciousness and postural control. Recurrent episodes of VVS significantly impact the quality of life and are a common reason for emergency department visits. Non-pharmacological interventions, such as tilt training, physical counter pressure maneuvers, and yoga, have been proposed as potential treatments for VVS. However, their efficacy in preventing VVS remains uncertain.

METHODS

A systematic review and meta-analysis were conducted following PRISMA guidelines. PubMed, Web of Science, and Embase were searched up to March 2023 for randomized controlled trials comparing non-pharmacological interventions with control in preventing VVS recurrence. The primary outcome was the recurrence rate of VVS episodes.

RESULTS

A total of 1130 participants from 18 studies were included in the meta-analysis. The overall mean effect size for non-pharmacological interventions versus control was 0.245 (95 % CI: 0.128-0.471, p-value <0.001). Subgroup analysis showed that yoga had the largest effect size (odds ratio 0.068, 95 % CI: 0.018-0.250), while tilt training had the lowest effect size (odds ratio 0.402, 95 % CI: 0.171-0.946) compared to control. Physical counter pressure maneuvers demonstrated an odds ratio of 0.294 (95 % CI: 0.165-0.524) compared to control.

CONCLUSION

Non-pharmacological interventions show promise in preventing recurrent VVS episodes. Yoga, physical counter pressure maneuvers, and tilt training can be considered as viable treatment options. Further research, including randomized studies comparing pharmacological and non-pharmacological approaches, is needed to evaluate the safety and efficacy of these interventions for VVS treatment.

Temporal relationship between haemodynamic changes and activation of closed-loop stimulation during a tilt-induced vasovagal syncope

AIMS

A dual-chamber pacemaker with closed-loop stimulation (CLS) mode is effective in reducing syncopal recurrences in patients with asystolic vasovagal syncope (VVS). In this study, we explored the haemodynamic and temporal relationship of CLS during a tilt-induced vasovagal reflex.

METHODS AND RESULTS

Twenty patients underwent a tilt test under video recording 3.9 years after CLS pacemaker implantation. Three patients were excluded from the analysis because of no VVS induced by the tilt test (n = 1) and protocol violation (n = 2). In 14 of the remaining 17 patients, CLS pacing emerged during the pre-syncopal phase of circulatory instability when the mean intrinsic heart rate (HR) was 88 ± 12 b.p.m. and systolic blood pressure (SBP) was 108 ± 19 mmHg. The CLS pacing rate thereafter rapidly increased to 105 ± 14 b.p.m. within a median of 0.1 min [inter-quartile range (IQR), 0.1-0.7 min] when the SBP was 99 ± 21 mmHg. At the time of maximum vasovagal effect (syncope or pre-syncope), SBP was 63 ± 17 mmHg and the CLS rate was 95 ± 13 b.p.m. The onset of CLS pacing was 1.7 min (IQR, 1.5-3.4) before syncope or lowest SBP. The total duration of CLS pacing was 5.0 min (IQR, 3.3-8.3). Closed-loop stimulation pacing was not observed in three patients who had a similar SBP decrease from 142 ± 22 mmHg at baseline to 69 ± 4 mmHg at the time of maximum vasovagal effect, but there was no significant increase in HR (59 ± 1 b.p.m.).

CONCLUSION

The reproducibility of a vasovagal reflex was high. High-rate CLS pacing was observed early during the pre-syncopal phase in most patients and persisted, although attenuated, at the time of maximum vasovagal effect.

REGISTRATION

ClinicalTrials.gov identifier: NCT06038708.

Interventions aimed to increase average 24-h systolic blood pressure reduce blood pressure drops in patients with reflex syncope and orthostatic intolerance

AIMS

Systolic blood pressure (SBP) drops recorded by 24-h ambulatory blood pressure (BP) monitoring (ABPM) identify patients with susceptibility to reflex syncope and orthostatic intolerance. We tested the hypothesis that treatments aimed to increase BP (reassurance, education, and lifestyle measures plus pharmacological strategies) can reduce SBP drops.

METHODS AND RESULTS

This was a multicentre, observational proof-of-concept study performed in patients with reflex syncope and/or orthostatic intolerance and with SBP drops on a screening ABPM. Among 144 eligible patients, 111 underwent a second ABPM on average 2.5 months after start of treatment. Overall, mean 24-h SBP increased from 114.1 ± 12.1 to 121.4 ± 14.5 mmHg (P < 0.0001). The number of SBP drops <90 and <100 mmHg decreased by 61%, 46% during daytime, and by 48% and 37% during 24-h period, respectively (P < 0.0001 for all). The dose-response relationship between difference in 24-h average SBP increase and reduction in number of SBP drops reached a plateau around ∼15 mmHg increase of 24-h SBP. The reduction in SBP drop rate was consistent and significant in patients who underwent deprescription of hypotensive medications (n = 44) and in patients who received BP-rising drugs (n = 67).

CONCLUSION

In patients with reflex syncope and/or orthostatic intolerance, an increase in average 24-h SBP, regardless of the implemented strategy, significantly reduced the number of SBP drops and symptom burden. A 13 mmHg increase in 24-h SBP appears to represent the optimal goal for aborting the maximal number of SBP drops, representing a possible target for future interventions. ClincalTrials.gov identifier: NCT05729724.

Prevention strategies for vasovagal reaction in whole blood donors: A quadri-armed randomised control trial

INTRODUCTION

Vasovagal reaction (VVR) is a frequently encountered generalised donor adverse reaction, associated with donor deterrence towards future donation. Several mitigation strategies for prevention of VVR were tried but still not standardised. This quadri-armed randomised study evaluated the utility of water ingestion, applied muscle tension (AMT) and combination of both in preventing the VVR among blood donors.

METHODS

A quadri-armed randomised controlled trial was performed on 4320 whole blood donors. Blood donors of 18-65 years of age were randomised into four groups based on the interventions performed i.e., control with no intervention (Group 1, n = 1081), water ingestion (Group 2, n = 1082), AMT (Group 3, n = 1070) and combined intervention (Group 4, n = 1087). VVR during and immediately after blood donation were observed along with assessment of risk factors in blood donors and the effectiveness of interventions were analysed.

RESULTS

The incidence of VVR observed 1.6% in our study, with the highest occurrence in the control group (2.5%) and the lowest in the combined intervention group (0.9%). Multivariable logistic regression revealed that the control group donors faced a 1.38-fold greater risk of VVR compared to those receiving interventions (OR: 1.38, 95% CI: 1.10-1.75). Other risk factors included younger age (OR: 1.5, 95% CI: 1.05-2.17), first-time donation (OR: 5.7, 95% CI: 1.66-5.74), prior history of VVR (OR: 2.5, 95% CI: 10.4-101.52).

DISCUSSION/CONCLUSION

The combined approach of water ingestion and AMT proved significantly more effective in VVR prevention compared to individual interventions.

Serotonin reuptake inhibition for the prevention of vasovagal syncope: a systematic review and meta-analysis

PURPOSE

Vasovagal syncope is a common clinical condition that lacks effective medical therapies despite being associated with significant morbidity. Current guidelines suggest that serotonin-specific reuptake inhibitors might suppress vasovagal syncope but supporting studies have been small and heterogenous. The purpose of this study was to evaluate the efficacy of serotonin-specific reuptake inhibitors to prevent syncope in patients with recurrent vasovagal syncope by conducting a systematic review and meta-analysis of published studies.

METHODS

Relevant randomized controlled trials were identified from the MEDLINE and Embase databases without language restriction from inception to August 2022, and ClinicalTrials.gov. All studies were conducted in clinical syncope populations and compared the benefit of serotonin versus placebo. Weighted relative risks were estimated using random effects meta-analysis techniques.

RESULTS

Three studies (n = 204) met inclusion criteria. Patients were 42 ± 13 years of age and 51% female. Serotonin-specific reuptake inhibitors were found to substantially reduce the likelihood of a patient having at least one recurrence of vasovagal syncope [relative risk (RR) 0.34 (0.20-0.60), p < 0.01] with minimal between-study heterogeneity (I2 = 0%, p = 0.67). Serotonin-specific reuptake inhibitors in two reports provided significant protection against clinical presyncope [RR 0.43 (0.24-0.77), p < 0.01], with minimal between-study heterogeneity (I2 = 0%, p = 0.80).

CONCLUSIONS

Serotonin-specific reuptake inhibitors may be effective in preventing syncope induced by head-up tilt testing and in syncope in the community in randomized, double-blinded clinical trials.

A new risk predictive scoring system of vasovagal reactions in patients with preoperative autologous blood donation

BACKGROUND AND OBJECTIVES

Vasovagal response (VVR) is the most common adverse reaction during blood donation and it is the main element for the safety of the patients with preoperative autologous blood donation (PABD). Accurate identification high-risk group is of great significance for PABD. Our study aimed to establish a scoring system based on the nomogram to screen the high-risk population and provide evidence for preventing the occurrence of VVRs.

MATERIALS AND METHODS

A number of 4829 patients underwent PABD between July 2017 and June 2020 in the first medical center of Chinese PLA Hospital were recruited, 3387 of whom were included in the training group (70 %; 108 VVRs patients vs 3279 Non-VVRs patients), 1442 were included in the validation group (30 %; 46 VVRs patients vs 1396 Non-VVRs patients). The data were analyzed by univariate and multivariate logistic regression. The nomogram of the scoring system was created by using the RMS tool in R software.

RESULTS

Seven variables including BMI, hematocrit, pre-phlebotomy heart rate and systolic blood pressure, history of blood donation, age group and primary disease were selected to build the nomogram, which was shown as prediction model. And the score was 0-1 for BMI, 0-2 for hematocrit, systolic blood pressure, heart rate and no blood donation history, 0-10 for age, 0-3 for primary disease. When the total cutoff score was 11, the predictive system for identifying VVRs displayed higher diagnostic accuracy. The area under the curve, specificity, and sensitivity of the training group were 0.942, 82.41 % and 97.17 %, respectively, whereas those of the validation group were 0.836, 78.26 % and 78.15 %, respectively.

CONCLUSION

A risk predictive scoring system was successfully developed to identify high-risk VVRs group form PABD patients that performed well.

Pain associated with intravascular instrumentation reduces orthostatic tolerance and predisposes to vasovagal reactions in healthy young adults without needle phobia: a randomised controlled study

PURPOSE

Vasovagal syncope (VVS), or fainting, is frequently triggered by pain, fear, or emotional distress, especially with blood-injection-injury stimuli. We aimed to examine the impact of intravenous (IV) instrumentation on orthostatic tolerance (OT; fainting susceptibility) in healthy young adults. We hypothesized that pain associated with IV procedures would reduce OT.

METHODS

In this randomised, double-blind, placebo-controlled, cross-over study, participants (N = 23; 14 women; age 24.2 ± 4.4 years) underwent head-up tilt with combined lower body negative pressure to presyncope on three separate days: (1) IV cannulation with local anaesthetic cream (EMLA) (IV + EMLA); (2) IV cannulation with placebo cream (IV + Placebo); (3) sham IV cannulation with local anaesthetic cream (Sham + EMLA). Participants rated pain associated with IV procedures on a 1-5 scale. Cardiovascular (finger plethysmography and electrocardiogram; Finometer Pro), and forearm vascular resistance (FVR; brachial Doppler) responses were recorded continuously and non-invasively.

RESULTS

Compared to Sham + EMLA (27.8 ± 2.4 min), OT was reduced in IV + Placebo (23.0 ± 2.8 min; p = 0.026), but not in IV + EMLA (26.2 ± 2.2 min; p = 0.185). Pain was increased in IV + Placebo (2.8 ± 0.2) compared to IV + EMLA (2.0 ± 2.2; p = 0.002) and Sham + EMLA (1.1 ± 0.1; p < 0.001). Orthostatic heart rate responses were lower in IV + Placebo (84.4 ± 3.1 bpm) than IV + EMLA (87.3 ± 3.1 bpm; p = 0.007) and Sham + EMLA (87.7 ± 3.1 bpm; p = 0.001). Maximal FVR responses were reduced in IV + Placebo (+ 140.7 ± 19.0%) compared to IV + EMLA (+ 221.2 ± 25.9%; p < 0.001) and Sham + EMLA (+ 190.6 ± 17.0%; p = 0.017).

CONCLUSIONS

Pain plays a key role in predisposing to VVS following venipuncture, and our data suggest this effect is mediated through reduced capacity to achieve maximal sympathetic activation during orthostatic stress. Topical anaesthetics, such as EMLA, may reduce the frequency and severity of VVS during procedures requiring needles and intravascular instrumentation.

Evaluation of interventions to prevent vasovagal reactions among whole blood donors: rationale and design of a large cluster randomised trial

BACKGROUND

Vasovagal reactions (VVRs) are the most common acute complications of blood donation. Responsible for substantial morbidity, they also reduce the likelihood of repeated donations and are disruptive and costly for blood services. Although blood establishments worldwide have adopted different strategies to prevent VVRs (including water loading and applied muscle tension [AMT]), robust evidence is limited. The Strategies to Improve Donor Experiences (STRIDES) trial aims to reliably assess the impact of four different interventions to prevent VVRs among blood donors.

METHODS

STRIDES is a cluster-randomised cross-over/stepped-wedge factorial trial of four interventions to reduce VVRs involving about 1.4 million whole blood donors enrolled from all 73 blood donation sites (mobile teams and donor centres) of National Health Service Blood and Transplant (NHSBT) in England. Each site ("cluster") has been randomly allocated to receive one or more interventions during a 36-month period, using principles of cross-over, stepped-wedge and factorial trial design to assign the sequence of interventions. Each of the four interventions is compared to NHSBT's current practices: (i) 500-ml isotonic drink before donation (vs current 500-ml plain water); (ii) 3-min rest on donation chair after donation (vs current 2 min); (iii) new modified AMT (vs current practice of AMT); and (iv) psychosocial intervention using preparatory materials (vs current practice of nothing). The primary outcome is the number of in-session VVRs with loss of consciousness (i.e. episodes involving loss of consciousness of any duration, with or without additional complications). Secondary outcomes include all in-session VVRs (i.e. with and without loss of consciousness), all delayed VVRs (i.e. those occurring after leaving the venue) and any in-session non-VVR adverse events or reactions.

DISCUSSION

The STRIDES trial should yield novel information about interventions, singly and in combination, for the prevention of VVRs, with the aim of generating policy-shaping evidence to help inform blood services to improve donor health, donor experience, and service efficiency.

TRIAL REGISTRATION

ISRCTN: 10412338. Registration date: October 24, 2019.

Lidocaine Tape Application for 3 Hours Prevents Vasovagal Syncope During Venipuncture: A Case Series

Vasovagal syncope (VVS) or reflex is usually caused by physical and mental stress-related factors, like pain, anxiety, and fear, and it is one of the most frequent complications during dental treatment. Two patients, both with histories of dental phobia and of VVS during vaccination, venipuncture, and dental treatment with local anesthetics, were scheduled for dental treatment under intravenous (IV) sedation. However, both experienced episodes of VVS that occurred during venipuncture using a 24-gauge indwelling needle. We determined that pain was the main trigger of VVS for these patients and attempted to reduce venipuncture-associated pain using 60% lidocaine tape applied 3 hours before venipuncture at their next dental visits, respectively. Use of the lidocaine tape was successful and permitted comfortable placement of the IV catheter without any onset of VVS.

Vasovagal Reactions during Interventional Pain Management Procedures—A Review of Pathophysiology, Incidence, Risk Factors, Prevention, and Management

Vasovagal reactions are a benign but common outcome of interventional pain management procedures that can negatively impact patient care, including aborted procedures and fear of future procedures that would otherwise help the patient. Research has been done on the incidence, risk factors, and management of vasovagal reactions resulting from such procedures, but less is known about how to prevent these reactions from occurring. In this paper, we present a literature review of the pathophysiology, incidence, risk factors, prevention, and management of vasovagal reactions during interventional pain management procedures, with an emphasis on the relative lack of research and conflicting advice on preventive measures. We found that moderate sedation and anxiolytics have been used prophylactically to prevent vasovagal reactions, but their side-effect profiles prevent them from being used commonly. Less studied is the prophylactic administration of antimuscarinics and IV fluids, despite the potential benefit of these measures and relatively low side-effect profile. We explore these topics here and offer advice for future research to fill the gaps in our knowledge.

A Device to Reduce Vasovagal Syncope in Blood Donors

Vasovagal Syncope (VVS), or the transient loss of consciousness is the most widely recognized reason for syncope. (VVS), is a typical dysfunction of the autonomic nervous system. There are various factors which can influence the syncope. The major classification of the syncope are reflex(neurally mediated) syncope, syncope due to orthostatic hypertension, Cardiac syncope(cardiovascular). The vasovagal syncope is the part of reflex (neurally mediated)syncope, there are various cause of vasovagal reactions but in blood donation it is mediated due to the pooling of blood at calf muscles. Such near syncope incidence while donating the blood or after donation hampers the future motivation for blood donation of the donors. In this paper, we developed an electronic massager for calf muscles that can reduce the risk of VVS. It has a programmable circuit which can control the vacuum pump so that it can inflate and deflate the cuffs synergistically. The massager can relax the blood donor thereby reducing apprehension prior to blood donation and thus diverting from the trigger of Phlebotomy and improve peripheral blood circulation thereby improving venous return to the heart. This is expected to reduce the risk of VVS.

Effects of Performing Applied Muscle Tension during Recovery after Phlebotomy in Young, First-Time Donors: A Pilot Study

Vasovagal reaction (VVR) compromises donor safety and reduces the subsequent return rates. Performing applied muscle tension (AMT) during phlebotomy may reduce the incidence of VVR. However, the effectiveness of performing AMT after phlebotomy to reduce delayed VVR remains unclear. With ethics approval, 12 young, first-time donors (YFTD) were recruited to study the effects on stroke volume (SV), cardiac output (CO) and systemic vascular resistance (SVR) while performing AMT from needle insertion to end of recovery. Measurements from 12 matched control YFTD were used for comparison. Pre-donation anxiety and VVR severity were assessed. Compared to controls, donors who performed AMT had higher SV (Control: 57 mL vs. AMT: 69 mL, p = 0.045), higher CO (Control: 3.7 L·min⁻¹ vs. AMT: 5.2 L·min⁻¹, p = 0.006) and lower SVR (Control: 1962 dyn·s·cm⁻⁵ vs. AMT: 1569 dyn·s·cm⁻⁵, p = 0.032) during mid-phlebotomy. During recovery, the AMT group retained higher SV, higher CO and lower SVR than the control, but not reaching statistical significance. Practicing AMT during recovery resulted in sustained haemodynamic improvements beyond the donation period, despite the reduction in delayed VVR was insignificant compared to the control group. A larger sample size is needed to validate the effectiveness of performing AMT after donation to mitigate delayed VVR.

Physical manoeuvers as a preventive intervention to manage vasovagal syncope: A systematic review

AIMS

To summarize the best available evidence on the effectiveness of physical counterpressure manoeuvers (PCM) for vasovagal syncope management compared to a control intervention. Control interventions included either a PCM, no intervention, or other interventions feasible in a lay setting.

METHODS

A systematic literature search (March 21st 2018) was performed in the Cochrane Central Register of Controlled Trials, MEDLINE, and Embase. PCM were subdivided into 1) PCM decreasing orthostatic load (PCMOL), 2) PCM shortening the hydrostatic column between heart and brain (PCMHC), 3) PCM using mechanical compression of the veins (PCMMC). The primary outcome was syncope, secondary outcomes included systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR). When possible, a random effects meta-analysis was performed. Odds ratios (OR) with 95% confidence intervals (CI) were calculated for dichotomous outcomes, and mean differences (MD) or standardized mean differences (SMD) were calculated for continuous outcomes. Heterogeneity was assessed by means of the I2 statistic. The total body of evidence was evaluated by means of the GRADE methodology.

RESULTS

Eleven trials involving 688 people with vasovagal syncope were included. Risk of bias was high in all included studies. The total body of evidence (GRADE) was considered to be low or very low. PCM were found to improve syncope as compared to control (OR: 0.52, 95% CI [0.33;0.81], p = 0.004). Similarly, before-and-after studies without a control group showed a significant reduction in syncope following PCM (OR: 0.01, 95%CI [0.00;0.01], p<0.001). No studies investigated PCMOL. PCMHC increased SBP, DBP, MAP, SV, and CO, and decreased HR. PCMMC increased SBP, DBP, and MAP.

CONCLUSION

PCM may reduce syncope and increase SBP, DBP, and MAP. The effects on other outcomes are less clear. Additional high-quality studies are needed.

Remote Limb Ischemic Preconditioning Attenuates Cerebrovascular Depression During Sinusoidal Galvanic Vestibular Stimulation via α1-Adrenoceptor-Protein Kinase Cε-Endothelial NO Synthase Pathway in Rats

BACKGROUND

Vasovagal syncope (VVS) is characterized by hypotension and bradycardia followed by lowering of cerebral blood flow. Remote limb ischemic preconditioning (RIPC) is well documented to provide cardio- and neuroprotection as well as to improve cerebral blood flow. We hypothesized that RIPC will provide protection against VVS-induced hypotension, bradycardia, and cerebral hypoperfusion. Second, because endothelial nitric oxide synthase has been reported as a mediator of cerebral blood flow control, we hypothesized that the mechanism by which RIPC primes the vasculature against VVS is via the α1-adrenoceptor-protein kinase Cε-endothelial nitric oxide synthase pathway.

METHODS AND RESULTS

We utilized sinusoidal galvanic vestibular stimulation in rats as a model of VVS. RIPC attenuated the lowerings of mean arterial pressure, heart rate, and cerebral blood flow caused by sinusoidal galvanic vestibular stimulation, as well as improving behavior during, and recovery after, stimulation. RIPC induced elevated serum norepinephrine, increased expression of brain α1-adrenoceptors, and reduced brain expression of norepinephrine transporter 1. Antagonizing adrenoceptors and norepinephrine transporter 1 prevented RIPC protection of cerebral perfusion during sinusoidal galvanic vestibular stimulation.

CONCLUSIONS

Taken together, this study indicates that RIPC may be a potential therapy that can prevent VVS pathophysiology, decrease syncopal episodes, and reduce the injuries associated with syncopal falls. Furthermore, the α1-adrenoceptor-protein kinase Cε-endothelial nitric oxide synthase pathway may be a therapeutic target for regulating changes in cerebral blood flow.

Predictive Tools in the Care of Blood Donors: Prevention of Vasovagal Syndrome

Prediction in healthcare is essential in order to promote safe and quality care. Taking adequate care of blood donors, who perform an altruistic act towards society, is paramount. Therefore, the use of tools which allow to predict the risk of Vasovagal Syndrome during the act of blood donation is necessary. The objective of this study is to design a predictive engine of an expert system to determine the risk of Vasovagal Syndrome through the use of deductive methodology. Five clusters of predictors of this syndrome were obtained by applying grouping tables of the variables established by logical formulation in such a way that after combinatorial variables, 5 values were obtained for the determination of risk using a Lickert scale. With these results we could design the predictive engine that will allow the development of a computational tool to improve the quality of care of blood donors.

Rationale for the Assessment of Metoprolol in the Prevention of Vasovagal Syncope in Aging Subjects Trial (POST5)

BACKGROUND

Vasovagal syncope (VVS) is a common problem associated with a poor quality of life, which improves when syncope frequency is reduced. Effective pharmacological therapies for VVS are lacking. Metoprolol is a β-adrenergic receptor antagonist that is ineffective in younger patients, but may benefit older (≥40 years) VVS patients. Given the limited therapeutic options, a placebo-controlled clinical trial of metoprolol for the prevention of VVS in older patients is needed.

STRUCTURE OF STUDY

The POST5 is a multicenter, international, randomized, placebo-controlled study of metoprolol in the prevention of VVS in patients ≥40 years old. The primary endpoint is the time to first recurrence of syncope. Patients will be randomized 1:1 to receive metoprolol 25 to 100 mg BID or matching placebo, and followed up for 1 year. Secondary end points include syncope frequency, presyncope, quality of life, and cost analysis. Primary analysis will be intention to treat, with a secondary on-treatment analysis.

POWER CALCULATIONS

A sample size of 222, split equally between the groups achieves 85% power to detect a hazard rate of 0.3561 when the event rates are 50% and 30% in the placebo and metoprolol arms. Allowing for 10% dropout, we propose to enroll 248 patients.

IMPLICATIONS

This study will be the first adequately powered trial to determine whether metoprolol is effective in preventing VVS in patients ≥40 years. If effective, metoprolol may become the first line pharmacological therapy for these patients.

Diclofenac suppository pretreatment in prevention of vasovagal reflex-associated complications for infertile women undergoing local endometrial injury

PURPOSE OF INVESTIGATION

To assess the effects of the diclofenac suppository pretreatment in prevention of vasovagal reflex-associated complications for infertile women undergoing local endometrial injury (LEI).

MATERIALS AND METHODS

Eighty-six infertile outpatients with repeated implantation failure following transfer of morphologically good embryos and/or blastocysts underwent single curettage LEI to improve the pregnancy outcome in the subsequent embryo/blastocyst transfer cycle. Of them, 35 patients chose diclofenac suppository administration prior to LEI, whereas 51 patients did not. The occurrence of palpitations, bradycardia, hypotension, presyncope, and requirement of bed rest was compared between the two groups.

RESULTS

There were no significant differences in the demographics between the two groups. The prevalence of presyncope and requirement of bed rest was significantly lower in the diclofenac suppository group than in the control group. The pregnancy outcome was similar between the two groups.

CONCLUSION

The diclofenac suppository administration is a low-cost effective method to reduce the risk of the vasovagal reflex-associated complications in infertile women undergoing LEI.

[Pacing in vasovagal syncope]

This article presents a critical review of the literature about the potential benefit of cardiac pacing in patients suffering from vasovagal or neurocardiogenic syncope. The manifestation of vasovagal syncope comprises some reflex bradycardia and vasoplegia resulting in cerebral hypoperfusion that ultimately leads to a loss of consciousness. The literature reports conflicting results of the potential benefit of cardiac pacing on the prevention of recurrence of vasovagal events. A detailed analysis of the inclusion criteria of these studies permits to clarify the discrepancy. Only patients older than 50 years with prolonged sinus pause at time of syncope benefit of the implantation of a cardiac pacemaker.

G-suited for prevention of syncope in patients with vasovagal syncope: a pilot study

BACKGROUND

Vasovagal syncope (VVS) represents by far the most common cause of syncope as it is diagnosed in around 50% of all patients that come to an emergency department. Although VVS is not fatal, it can cause an injury. Even serious injuries are not common, but there are reports of serious injuries of up to 5%. There are no current studies that demonstrate the effectiveness of any treatment. Past studies found that an Anti-Gravity suit (G-suit) can increase blood pressure and has been reported to prevent orthostatic hypotension effectively in patients with diabetes. It is possible that the G-suit can prevent VVS.

OBJECTIVE

In the present study, the authors assessed the efficacy of G-suit for vasovagal syncope prevention.

MATERIAL AND METHOD

In this open-label, randomized controlled study, we used the Italian tilt protocol, namely 60 degree passive tilting followed by 0.4 mg nitroglycerin challenge when the passive phase fails to induce syncope. If test was positive, then patient was enrolled. Tilt table test was repeated to compare G-suited and no G-suited to assess efficacy of G-suit for vasovagal syncope prevention.

RESULTS

10 patients were enrolled. There is no difference between the control group and an experimental group. In this study there is no cardio-inhibition vasovagal syncope. Positive tilt table test occurred in 50% of the patients receiving G-suited and 100% in control group (p 0.133).

CONCLUSION

G-suit is unable to prevent syncope in patients with positive tilt table test but the result is not statistically significant. However, the number of patients may be too small.

Utilization of collagen-based vascular closure devices in patients with severe peripheral artery disease

BACKGROUND

Collagen-based vascular closure devices (VCD) are commonly used after catheterization with femoral access. However, data about complication rates due to the utilization of VCDs in patients with known peripheral artery disease (PAD) of the lower limbs are inconsistent and patients with significant PAD are excluded in most VCD trials. In this study, we aimed to assess complication rates of collagen-based VCDs in patients with significant PAD.

METHODS

Patients with significant PAD treated with a VCD (Angio-Seal; St Jude Medical, Inc) after percutaneous therapeutic interventions of lower extremities were included in this study. Significant PAD was defined as Fontaine ≥2b. In-hospital complications (bleeding, spurious aneurysm, vessel occlusion, dissection, surgical repair, vasovagal reaction) were recorded.

RESULTS

A total of 121 patients (64.6 ± 11.3 years, 77% male) were included. PAD stage IIb was present in 99 patients (stage III in 8 patients, stage IV in 14 patients). A total of 112 treatments (93.3%) processed without complications (major complication rate, 1.7%; minor complication rate, 5.0%). There was a trend toward higher prevalence of complications with increasing size of closure device and with the stage of PAD; however, this trend was not statistically significant (P>.05 for all).

CONCLUSION

We report moderate complication rates of collagen-based VCDs in patients with significant PAD. Our data suggest that Angio-Seal may be safe in patients with PAD after catheter intervention. Further randomized trials with larger sample size comparing VCD with standard manual compression in patients with significant PAD are required.

Blood donor haemovigilance in Yaoundé, Cameroon

BACKGROUND

Blood availability is an issue of concern in countries of sub-Saharan Africa where both the demand and discard rates of blood are high. Although some degree of attention is paid when transfusion reactions occur in recipients, no information is available on donor reactions in this setting.

OBJECTIVES

This study was carried out in order to obtain some data on adverse reactions (ARs) to blood donations. It would make it possible to monitor and improve the safety of the donation procedure, which constitutes a strategy towards increasing donor supply by encouraging first-time donors to return in the absence of any negative outcomes of donation.

METHODS

A hospital blood bank-based descriptive and prospective study was carried out to document ARs among 1034 blood donors from September 2010 to January 2011. A pre-structured data collection tool was used to record the signs and symptoms observed.

RESULTS

The ARs occurred at a rate of 2.8%. The most frequent reaction was hypotension which constituted 26.62% of all ARs. Haematomas represented 18.42% while weakness and dizziness were each noted in 13.16% of donors. There was no severe vasovagal reaction. Associated factors to vasovagal reactions were first-time donor status (P = 0.004), female sex (P = 0.01) and low body weight (P = 0.02).

CONCLUSION

Our results suggest that blood donation is a relatively safe procedure in our context. The frequency is higher than studies from developed countries. The association of AR with first-time blood donation needs to be verified in a larger study. However, it could suggest another benefit of regular blood donation.

Rationale for the prevention of syncope trial IV: assessment of midodrine

BACKGROUND

Vasovagal syncope is a common problem associated with a poor quality of life, which improves when the frequency of syncope is reduced. Effective pharmacological therapies for vasovagal syncope have been elusive. Midodrine is a pro-drug whose primary metabolite is an alpha-1 adrenoreceptor agonist. A few studies have suggested that it may be beneficial in syncope, but all have had significant methodological limitations. A placebo-controlled clinical trial of midodrine for the prevention of vasovagal syncope is needed.

STRUCTURE OF STUDY

The prevention of syncope trial IV (POST 4) is a multicenter, international, randomized, placebo-controlled study of midodrine in the prevention of vasovagal syncope. The primary end point is the time to first recurrence of syncope. Patients will be randomized 1:1 to receive midodrine 10-30 mg/day or matching placebo, and followed for 1 year. Secondary end points include syncope frequency, presyncope, and quality of life. Primary analysis will be performed with an intention-to-treat approach, with a secondary on-treatment analysis.

POWER CALCULATIONS

A total sample size of 112, split equally between the two groups, achieves 85 % power to detect a 50 % relative risk reduction when the event rates are 55 and 27.5 % in the placebo and midodrine arms. Allowing for 20 % dropout, we propose to enroll 140 patients.

REGISTRATION

POST 4 is registered with http://www.clinicaltrials.gov (NCT01456481).

IMPLICATIONS

This study will be the first adequately powered trial to determine whether midodrine is effective in preventing vasovagal syncope. If it is effective, then midodrine may become the first-line pharmacological therapy for this condition.

[Assessment of vasovagal origin of syncope based on history features]

Study aim was to elaborate questionnaire for diagnostics of vasovagal syncope (VVS) based on data of anamnesis. We examined 182 patients (mean age 37.1+/-14.3 years, 78 men, 104 women). Initial examination included anamnesis, physical examination, electrocardiography at rest, measurement of blood pressure in orthostasis. Each patient was asked 82 questions describing duration of symptoms, characteristics of episodes of loss of consciousness, symptoms of prodromal period before loss on consciousness and in the period of recovery. As a standard method of VVS diagnostics of we used tilt test (TT) according to Westminster or Italian protocols. Using methods of statistical analysis we created questionnaire for diagnostics of VVS. Tilt-positive group comprised 108 patients (age 35.9+/-14.6 years, 45% men), tilt-negative group comprised 74 patients (age 36.1+/-14.3 years, 39% men). Of 82 testing questions 8 had probability ratio (PR) &gt;1 and were significant predictors (&lt;0.05) of positive TT. Seven questions had &lt;1 and were significant predictors (&lt;0.05) of negative TT. These questions were included into logistical regression analysis. The final variant of the questionnaire comprises 15 vasovagal origin questions. Total score necessary for diagnosis of VVS is more or equal 1. Sensitivity of questionnaire for prediction of positive result of TT was 95%, specificity - 57%. This allows to using it as a screening test for selection of further method of investigation in patients with episodes of loss of consciousness.

[Reflex syncope : diagnosis and therapy]

Reflex-mediated syncope is a common cause for syncope. The first step in evaluating the cause of syncope is to assess the risk of a life-threatening cause for syncope, e.g., ventricular arrhythmias. Reflex-mediated syncope has to be differentiated from orthostatic syncope. In orthostatic syncope, there is an insufficient autonomic response. In contrast to a reflex-mediated syncope, in which the autonomic nervous system acts inappropriately, reflex-mediated syncope is classified into the classical vasovagal form, the situational form, or due to carotid sinus hypersensitivity. In the elderly, often a mixed form is present. Treatment is difficult. Most important is educating the patient and avoiding precipitating factors. Physical maneuvers, e.g., counter pressure maneuvers, are more effective than drug treatment. Permanent pacing is rarely needed. However, before indicating a pacemaker, a correlation between bradycardia and syncope should be documented. This is often only possible by implanting a monitoring device at an early stage.

[Case of neurocardiogenic syncope with asystole during insertion of epidural catheter]

A 25-year-old healthy woman was scheduled for enucleatic myomectomy under combined epidural and general anesthesia. During insertion of a lumbar epidural catheter, sudden loss of consciousness associated with asystole developed. This condition was quickly restored by rapid fluid infusion, administration of atropine sulfate (0.5 mg) and oxygen (6l x min(-1)). Diagnosis of neurocardiogenic syncope (NCS) was made by previous episodes of fainting revealed at that point. An epidural catheter was placed under sedation with midazolam 2 mg. Surgery was performed uneventfully under sevoflurane anesthesia. Since NCS occurs recurrently in a susceptible individual, it is important to identify previous syncopal episode preoperatively. If such an event is anticipated, prevention including proper communication to reduce patient's anxiety, careful vigilance on both patient and monitor during procedure, gentle maneuver to reduce pain and use sedative and/or anticholinergic agents must be considered.

The effects of gender and test protocol on the results of head-up tilt test in patients with vasovagal syncope

BACKGROUND

Head-up tilt testing (HUTT) is a well-established method for the diagnosis of reflex syncope. Some controversies exist whether gender and HUTT protocol influence HUTT results.

AIM

To analyse the results of HUTT in patients with syncope in relation to their gender and used protocol of HUTT.

METHODS

We retrospectively analysed data of 537 consecutive patients (313 women and 224 men), aged 13-79 years with history of neurally-mediated syncope referred to HUTT. The cardiogenic and neurological aetiology of syncope was excluded in all patients based on previous examination. In 375 patients standard HUTT (STD HUTT), according to the Westminster protocol, was used. In 257 patients in whom STD HUTT was negative, HUTT was continued with pharmacological provocation using isoproterenol intravenous infusion--114 patients (ISO HUTT) or sublingual nitroglycerin--143 patients (NTG HUTT). In the remaining 162 patients HUTT was performed according to the Italian protocol (ITL HUTT). The HUTT results were classified according to the VASIS scale.

RESULTS

Female gender dominated, however, syncope was induced in a similar proportion of women and men (77.3 vs. 70.5%, NS). There were also no significant differences in the type of vasovagal response (VVR) to HUTT between women and men. Mixed type of VVR was the most frequent after isoproterenol provocation (ISO HUTT), whereas cardioinhibitory type of VVR was the most frequent after nitroglycerin provocation (NTG HUTT).

CONCLUSIONS

There is no significant relationship between gender and the result of HUTT. The type of VVR is related to HUTT protocol--cardioinhibitory response is more frequent following nitroglycerin administration in comparison to standard protocol and HUTT with isoproterenol provocation.

Vasovagal syncope in children and adolescents

Vasovagal syncope is not an uncommon event in children and adolescents; however, this fact is not widely known among the dental community. Although there is little information about the incidence of vasovagal syncope occurring among children and adolescents in the dental setting, dentists should always take care to eliminate factors that can predispose a patient to a vasovagal reaction. The dental team should be familiar with the emergency protocols for a vasovagal syncope episode. For this study, the author conducted a MEDLINE search using the key terms "vasovagal syncope", "syncope in children", "syncope treatments", and "syncope and dentistry" to define the pathophysiology, incidence, treatment options, and dental implications of vasovagal syncope. The articles included those published in English and in peer-reviewed journals, in addition to the most recent medical and dental textbooks as they related to syncope.

Randomized comparison of metoprolol versus conventional treatment in preventing recurrence of vasovagal syncope in children and adolescents

BACKGROUND

Previous studies that have assessed the effects of beta blockers on preventing vasovagal syncope provide conflicting results. We sought to evaluate the effectiveness of metoprolol versus conventional treatment in preventing the recurrence of syncope in children and adolescents.

MATERIAL/METHODS

Twenty-eight children and adolescents (8 boys, 20 girls; mean age, 12+/-3 years; age range, 8-17 years) with vasovagal syncope were randomized to receive either metoprolol (metoprolol group; dosage range, 0.5-1.5 mg/kg/d) or conventional treatment (control group) for 1 year. The main outcome measure was the first recurrence of syncope beginning 2 weeks after the start of treatment. The mean follow-up was 22+/-10 months. Time to first recurrence of syncope was analyzed using Kaplan-Meier curves and compared with a log-rank test.

RESULTS

The 2 groups did not differ in terms of clinical characteristics. The number of syncopal episodes before tilt testing was 8+/-6 in patients in the metoprolol group and 9+/-6 in patients in the control group (P=0.150). Syncope recurred in 6 of 14 children in the metoprolol group and in 4 of 14 children in the control group. No significant between-group differences were found regarding the probability of freedom from a recurrent episode of syncope during follow-up (metoprolol vs controls, 43% vs 29%; P=0.389), as demonstrated by Kaplan-Meier curve analyses.

CONCLUSIONS

Recurrence of vasovagal syncope in children and adolescents treated with metoprolol is similar to that of patients treated with conventional therapy.

Prevention of complications in dermatosurgery

Dermatosurgery has become ever more popular and important in recent years, mostly due to the increasing prevalence of skin malignancies. It also encompasses a wide variety of methods to remove or modify skin tissue for numerous cosmetic reasons. Nowadays, many dermatologists provide complete dermatologic care for their patients, including surgery. Therefore, it is important to be aware of the possible complications and to be able to manage them properly. Complications in cutaneous surgery are not very often, but they can be serious and worrisome including bleeding, infections, allergic reactions, syncope, wound dehiscence, necrosis, and others. In this article special attention is given to bleeding, which is the most common complication in this field. The best way to reduce the number of possible complications is to recognize patients at risk. Thus, complete history and physical examination are required before performing any dermatosurgical operation.

Update in the treatment of neurally-mediated syncope

Syncope is a transient, self-limited loss of consciousness, usually leading to falling. The underlying mechanism is a transient global cerebral hypoperfusion. Since there are many causes of syncope, a specific treatment cannot be administered without knowing of the exact mechanism responsible of loss of consciousness. Drugs are ineffective. The main therapeutic innovations of the most recent years are isometric counter-pressure maneuvres, lower limb compression bandage and therapy guided by implantable loop recorder in patients with recurrent suspected neurally-mediated syncope.

Ictal asystole: a benign condition?

Ictal asystole (IA) has been implicated as a preventable cause of sudden unexplained death in epilepsy presumably provoked by a direct autonomic effect of the electrical stimulus on the heart. An electronic database search of patients with IA was performed comparing heart rate (HR) characteristics to a group of patients with vasovagal asystole. IA was seen in eight patients, all with temporal lobe epilepsy. No statistical difference was found in duration of asystole, bradycardia, and baseline HR characteristics except of a higher HR acceleration postasystole in the controls. None of the six patients with IA who underwent pacemaker implantation had recurrence of asystolic events during mean follow-up of 5 years. This study in a small group of patients suggests that the epileptic activation leading to IA is possibly mediated through a transient increase in vagal tone and not by a direct autonomic effect on the heart.

Worsening of Symptoms Before Presentation with Vasovagal Syncope

INTRODUCTION

Much of the natural history of vasovagal syncope is unknown. We determined whether patients presenting for care have had a recently worsened syncope frequency.

METHODS AND RESULTS

We compared 208 subjects in the referral-based Prevention of Syncope Trial (POST) and 122 subjects who fainted > or =1 in a community survey study. Their mean ages and gender proportions were similar. The POST population had a higher median lifetime syncope frequency (1.16 vs 0.12 spells/year, P < 0.0001) and more subjects began fainting at age > or =35 years (26% vs 6%, P < 0.0001). In POST, the median frequency of syncopal spells in the preceding year was higher than in all previous years (3 vs 0.57, P < 0.0001). POST subjects presented sooner after their first spell (median 11.0 vs 16.8 years, P = 0.0002), and after their last spell (median 0.3 vs 7.4 years, P < 0.0001). POST subjects > or =35 years old had a shorter history than similar community-survey subjects (2.8 vs 14.9 y, P < 0.0001) and presented earlier after their first syncopal spell than POST subjects with a younger onset of syncope (median 2.8 vs 14.7 y, P < 0.0001), despite having fewer faints (median 6 vs 10, P = 0.0002).

CONCLUSIONS

Many syncope patients present for care after a recent worsening of their frequency of syncope.

The effect of a 473-mL (16-oz) water drink on vasovagal donor reaction rates in high-school students

BACKGROUND

Recent clinical studies found that a water drink prevented orthostatic hypotension in healthy subjects subjected to a tilt-table test. A water drink was tested as a method to decrease vasovagal donor reactions in high-school students.

STUDY DESIGN AND METHODS

A total of 8894 high-school donations in Fall 2004 and 2005 were assigned to groups receiving or not receiving a 473-mL water drink after acceptance for whole-blood donation. In addition, 4340 donations in 2004 were reduced to 2895 donations ("balanced 2004 group") with an algorithm that equally balanced the donors between the water and no water arms.

RESULTS

The donor reaction rate was 9.9 percent (349 reactions/3534 donations) in donors given a water drink versus 12.5 percent (668 reactions/5360 donations; p = 0.0002) in donors not given a water drink. Donors given a water drink had a 21 percent reduction in their donor reaction rate. The main benefit of water was in Caucasian, first-time donors. In the balanced 2004 group, the donor reaction rate was 10.6 percent (153 reactions/1438 donations) in donors given a water drink versus 14.8 percent (216 reactions/1457 donations; p = 0.0008) in donors not given a water drink. Donors given a water drink in the balanced 2004 group had a 28 percent reduction in their donor reaction rate. The use of water did not interfere with donor processing and was judged by collection staff as easy to implement.

CONCLUSION

A 473-mL water drink decreased the vasovagal donor reaction rate in high-school donors by 21 percent, but to varying degrees in different subpopulations.

Is home orthostatic self-training effective in preventing neurally mediated syncope?

BACKGROUND

Repeated orthostatic stress may prove to be of benefit in the regulation of neurally mediated syncope. But the role of home orthostatic self-training is not established to prevent symptoms in patients with neurally mediated syncope. We performed a prospective and randomized study to evaluate the effectiveness of repeated home orthostatic self-training in preventing tilt-induced neurally mediated syncope.

METHODS AND RESULTS

Fourty-two consecutive patients (24 males and 18 females, mean age 39 years, 16-68 years) with recurrent neurally mediated syncope were randomized into the tilt training and control groups. The home orthostatic self-training program consisted of daily sessions for 7 days a week for 4 weeks. In order to determine the effects of home orthostatic self-training, we repeated the head-up tilt test in both groups 4 weeks later. Among the tilt-training group, 9 of 16 patients (56%) had a positive response on follow-up head-up tilt test. Among the untreated control group, 9 of 17 patients (53%) had a positive response on follow-up head-up tilt test. In subgroup analyses according to the number of tilt-training sessions or the classified type, we found no differences in the follow-up head-up tilt test responses. Spontaneous syncope or presyncope over mean follow-up of 16.9 months were observed in 42.9% versus 47.1% in the tilt-training and control group, respectively.

CONCLUSIONS

Home orthostatic self-training was ineffective in reducing the positive response rate of head-up tilt test in patients with recurrent neurally mediated syncope.

Coronary spasm: a case of transient ST elevation and syncopal ventricular tachycardia without angina

We report the case of a 60-year-old male with recurrent pre-syncope, referred with a provisional diagnosis of carotid sinus syndrome on the basis of a 4 s asystolic pause following carotid sinus massage. On repeat Holter monitoring there was ST-segment elevation followed by episodes of polymorphic ventricular tachycardia during a mild episode of pre-syncope. Coronary angiography showed mild right coronary artery irregularity without significant stenosis. An automatic cardioverter defibrillator was implanted and high dose combined vasodilator therapy was commenced. At follow-up 18 months after implantation, the device has recorded no episode of tachycardia and the patient reports no recurrence of symptoms.

Trigemino-cardiac reflex during transsphenoidal surgery for pituitary adenomas: Methodological description of a prospective skull base study protocol

A systematic clinical neuroscience protocol is described for the use to examine the trigemino-cardiac reflex (TCR) response in humans. Target neurosurgical conditions are operations that require manipulations around the peripheral and central part of the trigeminal nerve and its branches, e.g. the cerebellopontine angle or the sellar region. To assess the hemodynamic and cardiac responses of patients after TCR initiation, anesthetic monitoring has been applied. The TCR is defined as a drop of more than 20% of the heart rate and the mean arterial blood pressure compared with the baseline values before the stimulus and coinciding with the surgical manipulation at or around any branches of the trigeminal nerve. By help of illustrative cases, we present for the first time preliminary results regarding the differentiation of the TCR in a central and a peripheral induction during transsphenoidal surgery of pituitary adenomas. Based on these results, we can conclude that we have developed a battery of preoperative examination procedures based on event-related diagnostics that was useful to differentiate different subgroups of TCR during transsphenoidal surgery. The presented protocol can be performed directly pre-, intra- and postoperatively and applied for assessment of TCR even in patients with known risk factors.

Preliminary Observations on the Effect of Amitriptyline Treatment in Preventing Syncope Recurrence in Patients with Vasovagel Syncope

PURPOSE

Vasovagal syncope is a common and challenging problem that may result in injury and causes substantial anxiety among patients and their relatives. However, treatment of vasovagal syncope with standard pharmacologic approaches is not satisfactory. The aim of this study is to investigate the effect of amitriptyline, a tricyclic antidepressant drug, by using its anticholinergic effects in preventing syncopal episodes in patients with vasovagal syncope.

METHODS

In this study, 74 patients (mean age 24 +/- 1.9 years, 26 male) with a history of recurrent syncope and baseline positive head-up tilt table test (syncope or presyncope) were included. Oral amitriptyline treatment was given to all patients, with a starting dose of 10 mg once a day. Head-up tilt table test was performed in all patients 4 weeks after the treatment started. Patients were followed up clinically for 6 months.

RESULTS

After 4 weeks, during head-up tilt table test in 69 patients (93%), syncope or presyncope was not seen and test was assumed as negative. At the end of the 6th month, 67 patients (91%) were free of symptoms. Only two patients (0.3%) did not tolerate amitriptyline due to side effects.

CONCLUSIONS

Oral amitriptyline can be used in the prevention of recurrent episodes of vasovagal syncope safely. However, randomized controlled studies are essential to assess the real effectiveness of this therapy.

[Neurally-mediated syncope and occupational accidents: prevention strategies and case report]

A bus driver came to our observation after an occupational traffic accident due to a syncopal event. The positive result of the tilt testing demonstrated the neurally-mediated nature of the syncope. The accident involved approximately 40 people (all the bus passengers), fortunately without severe injuries or deaths. The described episode indicates the need for a procedural algorithm, commonly approved, applicable in the field of prevention, for those occupational categories with severe accident risk. Indeed, the possibility exists to identify at least a part of the subjects predisposed to neurally-mediated syncope. Fundamental steps for such screening are history taking (looking for previous events, familiarity), the physical examination (useful, for example, to exclude orthostatic hypotension or carotid sinus syncope), and, in particular, the tilt testing, a diagnostic investigation recommended for all the workers who have had a previous syncope and are at high occupational accident risk. Moreover, the reported case recalls the need to strengthen the collaboration between the cardiologist and the occupational health physician.

Analysis of rhythm variation during spontaneous cardioinhibitory neurally-mediated syncope. Implications for RDR pacing optimization: an ISSUE 2 substudy

BACKGROUND

Little is known of the variations of the heart rate during spontaneous cardioinhibitory neurally-mediated syncope. Their knowledge has both academic and practical implications for the optimization of rate drop response (RDR) pacing mode.

METHODS AND RESULTS

We describe variations of the rhythm occurring during 48 syncopal episodes documented by implantable loop recorder. The presyncopal phase of 18 s (interquartile range 9-65) was characterized by a fall in heart rate from 83 +/- 20 bpm to maximal bradycardia or (multiple) asystolic pauses which lasted a median of 19 s (10-30). The recovery phase lasted 22 s (7-52). The total duration of the cardioinhibitory reflex was 85 s (47-116). We then calculated the potential increase in benefit that an optimally programmed drop rate detection could provide compared with a reference Lower Rate detection. Compared with Lower Rate detection (defined as two consecutive beats at 40 bpm), drop rate detection (assumed to be drop size = 20 bpm, detection window = 1 min, and drop rate = 50 bpm) would have been able to introduce intervention pacing, a median of 5.7 s (interquartile range -5.1- -10.4) earlier in 28 cases (58%).

CONCLUSION

Cardioinhibitory neurally-mediated reflex varies widely from a few seconds to some minutes. In our data the total duration was <2 min. Optimal RDR programming, being potentially able to anticipate the detection of the cardioinhibitory reflex by a few seconds, could provide an increase in benefit for cardiac pacing therapy in prevention of syncope.

Failure of propranolol to prevent tilt-evoked systemic vasodilatation, adrenaline release and neurocardiogenic syncope

In patients with neurocardiogenic syncope, head-up tilt often evokes acute loss of consciousness accompanied by vasodilatation, increased plasma adrenaline and systemic hypotension. Since hypotension increases adrenaline levels and adrenaline can produce skeletal muscle vasodilatation by activating beta2 receptors, adrenaline might induce a positive feedback loop precipitating circulatory collapse. We hypothesized that propranolol, a non-selective beta-blocker, would prevent adrenaline-induced vasodilatation and thereby prevent syncope. Eight subjects with recurrent neurocardiogenic syncope and previously documented tilt-induced syncope with elevated plasma adrenaline levels participated in the present study. Subjects underwent tilt table testing after receiving oral propranolol or placebo in a double-blind randomized crossover fashion. Haemodynamic and neurochemical variables were measured using intra-arterial monitoring, impedance cardiography, arterial blood sampling and tracer kinetics of simultaneously infused [3H]noradrenaline and [3H]adrenaline. The occurrence of tilt-induced neurally mediated hypotension and syncope, duration of tilt tolerance, extent of the decrease in SVRI (systemic vascular resistance index) and magnitude of plasma adrenaline increases did not differ between the propranolol and placebo treatment phases. SVRI was inversely associated with fractional increase in plasma adrenaline during both phases. One subject did not faint when on propranolol; this subject's response is discussed in the context of central effects of propranolol. In this small, but tightly controlled, study, propranolol did not prevent tilt-induced vasodilatation, syncope or elevated plasma adrenaline.

The efficacy of midodrine hydrochloride in the treatment of children with vasovagal syncope

OBJECTIVE

To determine whether midodrine hydrochloride therapy can prevent vasovagal syncope (VVS) in pediatric patients.

STUDY DESIGN

Children with recurrent syncope (n = 26) were randomly assigned into 2 groups. Group I comprised children given midodrine hydrochloride as first-line therapy in addition to conventional therapy, and group II comprised patients receiving conventional therapy only. Repeat head-up tilt (HUT) testing and follow-up of least 6 months were conducted to evaluate the therapeutic effectiveness and side effects of midodrine in treating VVS in children.

RESULTS

The HUT-based effective rate was significantly higher in group I than in group II (75% vs 20%; P < .05). During the follow-up period, the recurrence of syncope was significantly lower in group I than in group II (P < .05).

CONCLUSIONS

Midodrine hydrochlorate is effective in treating VVS in children, especially in preventing recurrent episodes. Few side effects were observed in the present study.

Leg crossing improves orthostatic tolerance in healthy subjects: a placebo-controlled crossover study

Vasovagal syncope is the most common cause of transient loss of consciousness, and recurrent vasovagal fainting has a profound impact on quality of life. Physical countermaneuvers are applied as a means of tertiary prevention but have so far only proven useful at the onset of a faint. This placebo-controlled crossover study tested the hypothesis that leg crossing increases orthostatic tolerance. Nine naïve healthy subjects [6 females, median age 25 yr (range 20–41 yr), mean body mass index 23 (SD 2)] were subjected to passive head-up tilt combined with a graded lower body negative pressure challenge (20, 40, and 60 mmHg) determining orthostatic tolerance thrice, in randomized order: 1) control, 2) with leg crossing, and 3) with oral placebo. Blood pressure (Finometer), heart rate, and changes in thoracic blood volume (impedance), stroke volume, and cardiac output (Modelflow) were followed during orthostatic stress. Primary outcome was time to presyncope (systolic blood pressure ≤85 mmHg, heart rate ≥140 beats/min). With leg crossing, orthostatic tolerance increased from 26 ± 2 to 34 ± 2 min (placebo 23 ± 3 min, P < 0.001). During leg crossing, mean arterial pressure (81 vs. 81 mmHg) and cardiac output (95 vs. 94% supine) remained unchanged; heart rate increase was lower (13 vs. 18 beats/min, P < 0.05); stroke volume was higher (79 vs. 74% supine, P < 0.05); and there was a trend toward lower thoracic impedance. Leg crossing increases orthostatic tolerance in healthy human subjects. As a measure of prevention, it is a worthwhile addition to the management of vasovagal syncope.

Effectiveness of physical counterpressure maneuvers in preventing vasovagal syncope: the Physical Counterpressure Manoeuvres Trial (PC-Trial)

OBJECTIVES

In this study, we assessed the effectiveness of physical counterpressure maneuvers (PCM) in daily life.

BACKGROUND

There is presently no evidence-based therapy for vasovagal syncope. Current treatment consists of explanation and life-style advice. Physical counterpressure maneuvers have been shown to raise blood pressure and to control or abort vasovagal episodes in laboratory conditions.

METHODS

We performed a multicenter, prospective, randomized clinical trial, which included 223 patients age 38.6 (+/-15.4) years with recurrent vasovagal syncope and recognizable prodromal symptoms. One hundred and seventeen patients were randomized to standardized conventional therapy alone, and 106 patients received conventional therapy plus training in PCM.

RESULTS

The median yearly syncope burden during follow-up was significantly lower in the group trained in PCM than in the control group (p = 0.004). During a mean follow-up period of 14 months, overall 50.9% of the patients with conventional treatment and 31.6% of the patients trained in PCM experienced a syncopal recurrence (p = 0.005). Actuarial recurrence-free survival was better in the treatment group (log-rank p = 0.018), resulting in a relative risk reduction of 39% (95% confidence interval, 11% to 53%). No adverse events were reported.

CONCLUSIONS

Physical counterpressure maneuvers are a risk-free, effective, and low-cost treatment method in patients with vasovagal syncope and recognizable prodromal symptoms, and should be advised as first-line treatment in patients presenting with vasovagal syncope with prodromal symptoms. (The PC-Trial; http://www.controlled-trials.com/isrctn/trial/45146526/0/45146526.html; ISRCTN45146526).