Shortened head-up tilt testing potentiated with sublingual nitroglycerin in patients with unexplained syncope

Prevalence of asystole during tilt test-induced vasovagal syncope may depend on test methodology

This review addresses tilt-testing methodology by searching the literature which reports timing of asystole and loss of consciousness (LOC). Despite the Italian protocol being the most widely adopted, its stipulations are not always followed to the letter of the European Society of Cardiology guidelines. The discrepancies permit reassessment of the incidence of asystole when tilt-down is early, impending syncope, compared with late, established LOC. Asystole is uncommon with early tilt down and diminishes with increasing age. However, if LOC is established as test-end, asystole is more common, and it is age-independent. Thus, the implications are that asystole is commonly under-diagnosed by early tilt-down. The prevalence of asystolic responses observed using the Italian protocol with a rigorous tilt down time is numerically close to that observed during spontaneous attacks by electrocardiogram loop recorder. Recently, tilt-testing has been questioned as to its validity but, in selection of pacemaker therapy in older highly symptomatic vasovagal syncope patients, the occurrence of asystole has been shown to be an effective guide for treatment. The use of head-up tilt test as an indication for cardiac pacing therapy requires pursuing the test until complete LOC. This review offers explanations for the findings and their applicability to practice. A novel interpretation is offered to explain why pacing induced earlier may combat vasodepression by raising the heart rate when sufficient blood remains in the heart.

Cardioinhibitory syncope with asystole during nitroglycerin potentiated head up tilt test: prevalence and clinical predictors

Aims

The aim of our study was to evaluate the prevalence and clinical predictors of cardioinhibitory (CI) responses with asystole at the nitroglycerin (NTG)-potentiated head-up tilt test (HUTT) in patients with a history of syncope admitted to a tertiary referral syncope unit.

Methods

We retrospectively evaluated all consecutive patients who underwent NTG-potentiated HUTT for suspected reflex syncope at our institution from March 1 2017 to May 1 2020. The prevalence of HUTT-induced CI syncope was assessed. Univariate and multivariate analyses were performed to test the association of asystolic response to HUTT with a set of clinical covariates.

Results

We enrolled 1285 patients (45 ± 19.1 years; 49.6% male); 368 (28.6%) showed HUTT-induced CI response with asystole. A multivariate analysis revealed that the following factors were independently associated with HUTT-induced CI syncope: male sex (OR 1.48; ConInt 1.14–1.92; P = 0.003), smoking (OR 2.22; ConInt 1.56–3.115; P < 0.001), traumatic syncope (OR: 2.81; ConInt 1.79–4.42; P < 0.001), situational syncope (OR 0.45; ConInt 0.27–0.73; P = 0.002), and the use of diuretics (OR 9.94; ConInt 3.83–25.76; P < 0.001).

Conclusions

The cardioinhibitory syncope with asystole induced by NTG-potentiated HUTT is more frequent than previously reported. The male gender, smoking habit, history of traumatic syncope, and use of diuretics were independent predictors of HUTT-induced CI responses. Conversely, the history of situational syncope seems to reduce this probability.

What is the optimal duration of the TILT after administration of 0.4 mg nitroglycerin spray?

Performing a head-up tilt test can be of great value for the diagnosis of vasovagal syncope. The European Society of Cardiology recommends a drug challenge phase duration of 15 to 20 minutes, with either Isoprenaline or Nitroglycerin administration.We sought to investigate the outcome of a ten-minute active phase with Nitroglycerin in patients suspected of vasovagal syncope and determine the percentage of loss in the positivity rate, using this short duration approach.We consecutively enrolled patients presenting with syncope undergoing the head-up tilt test (HUTT), with a clinical suspicion of vasovagal syncope between the years 2009 to 2019. The HUTT consisted of 2 successive phases: passive and active. During the passive phase, the patients were tilted at 70° for 20 minutes. If negative, the test was continued after administration of 0.4 mg sublingual Nitroglycerin. Applying the (VASIS) Vasovagal Syncope International Study classification of the vasovagal syncope international study and comparing for age and gender, positive responses were categorized into 3 types.A number of 306 patients (age = 43.5 +/-20.3; male = 140 [45.7%]) with suspected vasovagal syncope, undergoing HUTT, were enrolled in the years of 2009 to 2019. Of those, 245 (80.2%) presented a positive test, with 200 patients (82.0%) during the being positive during the active phase of the test. The results were as follows: 116 subjects (47.2%) presented with a mixed response (VASIS I), 52 (21.3%) showed a cardio inhibitory response (VASIS II), and 77 (31.5%) displayed a vasodepressor response (VASIS III). We found no relationship between the type of syncope with neither gender, nor age of the patient. Three minutes represented the median time to positivity, after Nitroglycerine administration. The time distribution showed a peak incidence appearing between minutes 3 and 5, ranging from 1 to 20 minutes. Only 3 patients tested positive after minute 10.Shortening the active phase to 10 minutes would result in a positivity rate loss of 1.5%.

Neurally Mediated Syncope During Cesarean Delivery: A Case Report

A 28-year-old woman with preeclampsia at 32 weeks of gestation underwent a cesarean delivery under spinal anesthesia. Administration of nitroglycerin at 200 μg to relax uterine smooth muscles and the application of fundal pressure led to severe bradycardia and loss of consciousness, followed by cardiac arrest. Delivery was completed immediately and recovery was achieved 10 seconds later following cardiopulmonary resuscitation. Neurally mediated syncope was considered the cause of cardiac arrest. Anesthetists should be aware of the potential risk during cesarean delivery following the administration of nitroglycerin, fundal pressure, regional anesthesia, and hypovolemia because of preeclampsia.

Safety and tolerability of Tilt Testing and Carotid Sinus Massage in the octogenarians

OBJECTIVE

to evaluate the safety and tolerability of Tilt Testing (TT) and Carotid Sinus Massage (CSM) in octogenarians with unexplained syncope.

METHODS

patients consecutively referred for transient loss of consciousness to the 'Syncope Units' of three hospitals were enrolled. TT and CSM were performed according to the European Society of Cardiology guidelines on syncope. Complications were evaluated in each group. An early interruption of TT was defined as 'intolerance' and considered as a non-diagnostic response.

RESULTS

one thousand four hundred and one patients were enrolled (mean age 72 ± 16 years, male 40.8%). Six hundred and ninety-four patients (49.5%) were 80 years old or older (mean age 83 ± 3 years) and 707 (50.5%) were younger (mean age 60 ± 17 years). Complications after TT occurred in 4.5% of older patients and in 2.1% of the younger ones (P = 0.01). All complications were 'minor/moderate', as prolonged hypotension, observed in ∼3% of patients ≥80 years. Major complications such as sustained ventricular tachycardia, ventricular fibrillation, asystole requiring cardiac massage, transient ischaemic attack, stroke and death were not observed in any patient. The presence of orthostatic hypotension and the mean number of syncopal episodes were predictors of TT complications. Intolerance was reported in 2.4% of older patients and 1% of the younger ones (P = 0.08), mainly due to orthostatic intolerance. No complications occurred after CSM.

CONCLUSIONS

TT and CSM appear to be safe and well tolerated in octogenarians, who should not be excluded by age from the diagnostic work-up of syncope.

The Role of the Syncope Management Unit

Syncope is a common symptom, experienced by 15% of persons less than 18 years old and up to 23% of elderly nursing home residents, so it is important to consider optimizing strategies for the management of these patients. The strategy selected will inevitably differ from place to place. However, an organized structure offers more cost-effective care. This article discusses possible health care delivery models for syncope management and reviews the current status of the organization of syncope care, to show the value of a multidisciplinary approach to the organized management of patients with syncope.

Arg389Gly β1-adrenergic receptor polymorphism and susceptibility to syncope during tilt test

INTRODUCTION

Numerous hormones, neurotransmitters, and other stimuli exert their biological effect on cellular functioning through heptahelical receptors coupled to G proteins (GPCR - G protein-coupled receptors). Adrenergic receptors that belong to this superfamily of receptors are components of the sympathetic nervous system. They play a pivotal role in blood pressure regulation and myocardial contractility. Alterations of the adrenergic receptor pathway have been suggested to be involved in the pathophysiology of vasovagal syncope (VVS). The aim of the present study was to evaluate the distribution of Arg389Gly polymorphism within the ADRB1 gene among patients with recurrent syncope.

MATERIAL AND METHODS

Arg389Gly single nucleotide polymorphism was analyzed in 205 patients with recurrent syncope. Ninety-five patients (46%) had a positive head-up tilt test (HUT) result. The control group comprised 143 non-fainting subjects. Genotyping was performed by restriction fragment length polymorphism (RFLP) with BstNI enzyme.

RESULTS

Both analyzed groups had similar distribution of the 389Gly allele. Sixty percent of polymorphic 389Gly carriers belong to the group of syncopal patients, while 40% belong to the control group of healthy subjects.

CONCLUSIONS

An association between syncopal incidence and Arg389Gly polymorphism within the ADRB1 gene was not found. The analyzed polymorphism affecting sympathetic activity does not influence vasovagal syncope in Polish patients.

Poor diagnostic performance of tilt testing in hypertensive patients with unexplained syncope

Syncope is a common condition. Tilt testing with sublingual nitroglycerin (TT-TNT) provides a test with good specificity and positivity rate in young and old patients. Its use in hypertensive patients with unexplained syncope has not been validated. The aims of this study were to evaluate the positivity rate, specificity and tolerability of TT-TNT in hypertensive patients with unexplained syncope. Five hundred and ten subjects (mean age 55 years) were enrolled, 388 patients with unexplained syncope (73 hypertensive and 315 normotensive) and 122 controls (59 hypertensive and 63 normotensive). All subjects underwent TT-TNT. The responses were classified as positive, negative or exaggerated (aspecific). In hypertensive patients, the usual hypotensive therapy was taken on the day of the test. In hypertensive controls, the positive responses were higher than in normotensives (19% vs 6%, P<0.001). The overall specificity was 81% in hypertensives and 94% in normotensives. The positivity rate was significantly lower in hypertensives (55% vs 72%, P<0.03). There was no significant difference between young patients and patients >65 years. TT was well tolerated, and no serious side effects occurred. TT potentiated with TNT has a lower positivity rate and specificity in hypertensive than in normotensive patients with syncope.

Tilt testing with combined lower body negative pressure: a "gold standard" for measuring orthostatic tolerance

Orthostatic tolerance (OT) refers to the ability to maintain cardiovascular stability when upright, against the hydrostatic effects of gravity, and hence to maintain cerebral perfusion and prevent syncope (fainting). Various techniques are available to assess OT and the effects of gravitational stress upon the circulation, typically by reproducing a presyncopal event (near-fainting episode) in a controlled laboratory environment. The time and/or degree of stress required to provoke this response provides the measure of OT. Any technique used to determine OT should: enable distinction between patients with orthostatic intolerance (of various causes) and asymptomatic control subjects; be highly reproducible, enabling evaluation of therapeutic interventions; avoid invasive procedures, which are known to impair OT(1). In the late 1980s head-upright tilt testing was first utilized for diagnosing syncope(2). Since then it has been used to assess OT in patients with syncope of unknown cause, as well as in healthy subjects to study postural cardiovascular reflexes(2-6). Tilting protocols comprise three categories: passive tilt; passive tilt accompanied by pharmacological provocation; and passive tilt with combined lower body negative pressure (LBNP). However, the effects of tilt testing (and other orthostatic stress testing modalities) are often poorly reproducible, with low sensitivity and specificity to diagnose orthostatic intolerance(7). Typically, a passive tilt includes 20-60 min of orthostatic stress continued until the onset of presyncope in patients(2-6). However, the main drawback of this procedure is its inability to invoke presyncope in all individuals undergoing the test, and corresponding low sensitivity(8,9). Thus, different methods were explored to increase the orthostatic stress and improve sensitivity. Pharmacological provocation has been used to increase the orthostatic challenge, for example using isoprenaline(4,7,10,11) or sublingual nitrate(12,13). However, the main drawback of these approaches are increases in sensitivity at the cost of unacceptable decreases in specificity(10,14), with a high positive response rate immediately after administration(15). Furthermore, invasive procedures associated with some pharmacological provocations greatly increase the false positive rate(1). Another approach is to combine passive tilt testing with LBNP, providing a stronger orthostatic stress without invasive procedures or drug side-effects, using the technique pioneered by Professor Roger Hainsworth in the 1990s(16-18). This approach provokes presyncope in almost all subjects (allowing for symptom recognition in patients with syncope), while discriminating between patients with syncope and healthy controls, with a specificity of 92%, sensitivity of 85%, and repeatability of 1.1±0.6 min(16,17). This allows not only diagnosis and pathophysiological assessment(19-22), but also the evaluation of treatments for orthostatic intolerance due to its high repeatability(23-30). For these reasons, we argue this should be the "gold standard" for orthostatic stress testing, and accordingly this will be the method described in this paper.

Head-up tilt testing for diagnosing vasovagal syncope: a meta-analysis

BACKGROUND

A systematic evaluation focused on sensitivity and specificity of head-up tilt testing (HUT) for diagnosing vasovagal syncope has not been previously performed. We conducted a meta-analysis of studies comparing HUT outcome between patients with syncope of unknown origin and control subjects without previous syncope.

METHODS

We searched Pubmed and Embase databases for all English-only articles concerning case-control studies estimating the diagnostic yield of HUT, and selected 55 articles, published before March 2012, including 4361 patients and 1791 controls. The influence of age, test duration, tilt angle, and nitroglycerine or isoproterenol stimulation on tilt testing outcome was analyzed.

RESULTS

Head-up tilt testing demonstrated to have a good overall ability to discriminate between symptomatic patients and asymptomatic controls with an area under the summary receiver-operating characteristics curve of 0.84 and an adjusted diagnostic odds ratio of 12.15 (p<0.001). A significant inverse relationship between sensitivity and specificity of tilt testing for each study was observed (p<0.001). At multivariate analysis, advancing age and a 60° tilt angle showed a significant effect in reducing sensitivity and increasing specificity of the test. Nitroglycerine significantly raised tilt testing sensitivity by maintaining a similar specificity in comparison to isoproterenol.

CONCLUSIONS

The results from this meta-analysis show the high overall performance of HUT for diagnosing vasovagal syncope. Our findings provide useful information for evaluating clinical and instrumental parameters together with pharmacological stressors influencing HUT accuracy. This could allow the drawing of tilt testing protocols tailored on the diagnostic needs of each patient with unexplained syncope.

Head Up Tilt Testing: An Appraisal of Its Current Role in the Management of Patients with Syncope

Head up tilt testing (HTT) is now commonly used to investigate otherwise unexplained syncope and presyncope. This test has been used for over 20 years primarily to diagnose neurally mediated syncope, but HTT's exact role in the diagnostic process remains uncertain. Recognized limitations include poor reproducibility, lack of prognostic role, and insufficient randomized studies to guide therapeutic choice. In this review, we describe the indications and methods recommended by present guidelines on utilizing HTT. In addition, present criticisms and limitations of this test, along with future perspectives, are outlined.

Reduced systemic vascular resistance in healthy volunteers with presyncopal symptoms during a nitrate-stimulated tilt-table test

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Nitrates may facilitate syncope through various pathways, but the precise mechanism of nitrate-induced syncope is still under debate. The purpose of the present study was to compare the underlying haemodynamic mechanisms in subjects without and with presyncopal symptoms during a nitroglycerin-stimulated tilt-table test.

WHAT THIS STUDY ADDS

A major decrease in systemic vascular resistance was documented in subjects with presyncope during 0.25 mg nitroglycerin-stimulated tilt-table test, in the absence of changes in cardiac output. These findings indicated that even a small dose of nitroglycerin significantly decreased arterial resistance and cardiac afterload. AIMS The mechanism of nitrate-induced syncope remains controversial. We examined the haemodynamic changes in healthy volunteers during nitroglycerin-stimulated tilt-table test.

METHODS

Continuous radial pulse wave analysis, whole-body impedance cardiography and plethysmographic finger blood pressure were recorded in a supine position and during head-up tilt in 21 subjects with presyncopal symptoms (6 male/15 female, age 43 ± 3 years) after 0.25 mg sublingual nitroglycerin and 21 control subjects (6 male/15 female, age 43 ± 2 years). The drug was administered in the supine position and a passive head-up tilt followed 5 min later. Additionally, nitroglycerin was only administered during head-up tilt in 19 subjects and the haemodynamics were recorded.

RESULTS

Supine and upright haemodynamics were similar before nitroglycerin administration in the two groups. During the nitroglycerin-stimulated tilt test, aortic and radial mean blood pressure decreased significantly more in the presyncope group when compared with the controls (P= 0.0006 and P= 0.0004, respectively). The decreases in systemic vascular resistance (P= 0.0008) and heart rate (P= 0.002), and increase in aortic reflection time (P= 0.0002) were greater in the presyncope group, while the change in cardiac index was not different between the groups (P= 0.14). If nitroglycerin was administered during the upright tilt and not in supine position, the haemodynamic changes were quite corresponding.

CONCLUSIONS

Presyncopal symptoms during nitrate-stimulated tilt test were explained by decreased systemic vascular resistance and increased aortic reflection time, while cardiac output remained unchanged. These findings indicated reduced arterial resistance in nitroglycerin-induced presyncope.

Genetic insight into syncopal tilted population with severe clinical presentation

An impairment of cardiovascular reflexes may be the result of functional alterations in the G proteins intracellular signaling produced by functional genes' polymorphisms. The aim was to evaluate the relationships between single nucleotide polymorphisms in genes encoding G-proteins signaling pathways and syncopal patients with severe clinical manifestation.

METHODS AND RESULTS

From 307 syncopal patients free from any other diseases 83 (27%) had at least one malignant episode of syncope with a significant injury as fractures. There was 1.9 malignant spells per patient. All patients were tilted and genotyped by polymerase chain reaction followed by restriction fragment length polymorphism method. 74 healthy volunteers with negative history of syncope constituted the control group were also genotyped. Following polymorphisms were detected: C393T in gene encoding the alfa-subunit of Gs-protein (GNAS1), C825T of gene for G-protein beta 3 subunit (GNB3) and C1114G for the gene of cardiac regulator of G-protein signaling (RGS2). We found an association with lower risk of malignant syncope in positive tilting patients during passive phase of the test compared to NTG-enhanced (OR 0.38; 95% CI 0.15-0.95; P=0.04). No difference between healthy controls and patients in the alleles frequency was found (P>0.05). Neither the 393T allele of GNAS1 and 825T allele of GNB3 nor 1114G allele of RGS2 was associated with enhanced risk of severe clinical manifestation (P>0.05).

CONCLUSIONS

The studied single nucleotide polymorphisms of genes encoding G-proteins signaling pathways seem to be not connected with the severe clinical manifestation of syncope.

Polymorphism C1114G of gene encoding the cardiac regulator of G-protein signaling 2 may be associated with number of episodes of neurally mediated syncope

BACKGROUND AND AIMS

The cardiac regulator of G-protein signaling 2 (RGS2) negatively regulates G-protein-coupled receptor signaling. The C1114G polymorphism reduces RGS2 gene expression. This molecular disorder may be one of the important factors influencing progress of neurally mediated syncope. The aim of the study was to evaluate the association between C1114G RGS2 polymorphism and tilting results and number of syncope episodes in patients with no other diseases.

METHODS

Of 214 tilted patients (39% males, 39.7 +/- 17.1 years of age), genomic DNA was extracted from cellular blood components. C1114G RGS2 polymorphism was diagnosed by designed primers. Clinical variables and genetic traits were introduced into multivariate stepwise regression. Analysis was performed as follows: positive tilting n = 145 vs. negative n = 69, positive passive n = 49 vs. nitroglycerin (NTG)-positive n = 96, dominant vasodepressive n = 111 vs. cardioinhibition n = 34; and in number of syncope groups with cut-off >or=10 vs. <10.

RESULTS

No relationship was found between the studied polymorphism and outcome of tilting (p >0.05). In multivariate regression model, homozygosity G/G 1114 RGS2 was the only variable associated with a reduced number of episodes of syncope (95% CI 2.3-10.9; p = 0.04).

CONCLUSIONS

Our preliminary results suggest the association of G/G 1114 RGS2 genotype with the number of episodes of neurally mediated syncope. Detailed molecular mechanism of the influence of the studied polymorphism on syncopal number is probably associated with the reduced expression of RGS2 gene.

A novel approach to syncopal patients: association analysis of polymorphisms in G-protein genes and tilt outcome

AIMS

G-proteins signal transduction pathways play a basic role in cardiovascular reflexes. We hypothesized that the predisposition to reflex-mediated syncope may be associated with genetic variations in G-protein genes. The aim of this study was to evaluate the effect of three single-nucleotide polymorphisms in G-protein genes on tilting outcome in syncopal patients.

METHODS AND RESULTS

A total of 217 syncopal patients free from any other disease were genotyped and examined related to tilting results. Genotyping was performed by polymerase chain reaction followed by restriction fragment length polymorphism in gene encoding the Gs-protein alpha-subunit (polymorphism C393T), the G-protein beta 3 subunit--GNB3 (polymorphism C825T)--and for the cardiac regulator of G-protein signalling RGS2 (polymorphism C1114G). In multivariate logistic regression analysis, the homozygotes 825TT GNB3 (OR 0.37; 95% CI 0.14-0.97; P < 0.05) and body mass index (OR 0.87; 95% CI 0.78-0.97; P = 0.005) were independently associated with a lower chance of positive tilting results. No relationship was found between Vasovagal Syncope International Study type of syncope and the studied genotypes or the carriage of the polymorphic alleles.

CONCLUSIONS

An association between tilting results and C825T GNB3 polymorphism in syncopal patients was found. The syncopal homozygotes 825TT GNB3 had a significantly lower chance of syncope during tilt testing.

Head-up tilt testing with different nitroglycerin dosages: experience in elderly patients with unexplained syncope

AIMS

Protocols using sublingual nitrates have been increasingly used to improve diagnostic accuracy of head-up tilt testing (HUT). Nevertheless, exaggerated responses to nitrates have been frequently described, particularly in elderly patients. The aim of this article is to evaluate, in an elderly population with unexplained syncope, whether the impact of sublingual nitroglycerin (NTG) used as a provocative agent is dose-dependent.

METHODS AND RESULTS

One hundred and twenty consecutive elderly patients submitted to HUT using NTG after an asymptomatic drug-free phase were studied. Patients were divided into three groups according to the NTG dosage: 500, 375 and 250 microg. The test was considered positive when there was reproduction of symptoms with bradycardia and/or arterial hypotension. A gradual decrease in the blood pressure after NTG was considered an exaggerated response to nitrates. There were no differences in the clinical characteristics of the different subgroups. A positive test was obtained in 50% of the patients in each group. The rate of exaggerated responses was identical in all groups and ranged between 15 and 17%.

CONCLUSION

In an elderly population with syncope of unknown origin submitted to HUT, the response to NTG is not dose-dependent, and no difference was found in the rate of exaggerated responses to nitrates with different NTG dosages.

Mutation T/C,Ile 131 of the gene encoding the alfa subunit of the human Gs protein and predisposition to vasovagal syncope

BACKGROUND

Mutation T/C inside codon 131 of the gene encoding the alpha subunit of Gs protein (GNAS1) causes the increased activation of adenyl cyclase, which plays an important role in cardiovascular regulation. The aim of the present study was to evaluate GNAS1 T/C,Ile 131 mutation's manifestation in syncopal patients regarding head-up tilt test (HUTT) results.

METHODS AND RESULTS

In 137 syncopal patients (without any other diseases) the silent T/C,Ile 131 mutation within the GNAS1 codon on chromosome 20 q was identified. This mutation consists of the presence (+) or absence (-) of a target site for endonuclease FokI (Promega). Ninety-six patients (70%) with positive HUTT had a higher FokI+ allele frequency compared with those with negative tilting results (49% vs 27%, X(2)=12.05; p<0.001). In positive tilted patients, the studied mutation had significant influence on blood pressure (p<0.05). When comparing positive HUTT with vasodepressore component, cardioinhibition results and negative HUTT, the frequencies of the FokI+ allele were decreased among these groups: 53%, 36% and 27%, respectively.

CONCLUSIONS

An association between positive tilting and mutation C/T,Ile 131 within the GNAS1 codon was found. The predisposition to vasovagal syncope seems to be associated with the GNAS1 FokI+ allele.

'Front-loaded' head-up tilt table testing: validation of a rapid first line nitrate-provoked tilt protocol for the diagnosis of vasovagal syncope

Head-up tilt testing is the investigation of choice in the diagnosis of vasovagal syncope. The test is time consuming and labour intensive, with conventional tilt testing taking up to 45 min. We compared a shortened 'front-loaded' 20-min glyceryl trinitrate-provoked head-up tilt (FLGTN-HUT) with the standard 40-min passive tilt (HUT) as first line investigations in patients with unexplained syncope and asymptomatic controls. In the study, 149 consecutive patients with unexplained syncope and 83 asymptomatic controls were enrolled. Subjects were randomly assigned to FLGTN-HUT (800 mcg, metred spray) or HUT, then the opposite tilt-test 1 week later. Seventeen (11.4%) patients had diagnostic haemodynamic changes and symptom reproduction during HUT and 54 (36.2%) during FLGTN-HUT. A total of 24.8% more patients had a positive test with FLGTN-HUT than with passive HUT (95% CI: 16.3%, 33.4%). Nine (10.8%) controls had significant haemodynamic changes during HUT and 23 (27.7%) during GTN provocation. Seven controls had haemodynamic changes on both HUT and FLGTN-HUT testing. The controls group had 16.8% more significant haemodynamic changes with FLGTN-HUT than with HUT (95% CI: 0.06, 27.4). The front-loaded GTN protocol provided a higher diagnostic rate than passive tilt testing, and provides a rapid alternative to conventional methods, though false positivity rates are higher.

A new alcohol provocation head up tilt protocol in the patients with alcohol-related syncope

AIMS

Drinking alcohol is known to be one of the triggering factors of neurally-mediated syncope. Little is known about the diagnostic utility of the conventional and alcohol provocation head up tilt-test (HUT) in patients with alcohol-related syncope. We investigated the effect of the alcohol provocation HUT.

METHODS AND RESULTS

We studied 12 patients (8 males, age 51 +/- 19 years) who had a history of unexplained post-alcohol ingestion syncope. An alcohol provocation protocol HUT (alcohol HUT), in which the protocol required 350 mL of 5% alcohol beer to be drunk over 5 min followed by positioning with the table tilted up for up to 30 min, was performed after the control and isoproterenol (ISP) HUT. None of the subjects (0/12) exhibited a positive response in the control HUT, and only one subject had a positive response (1/12; 8.3%) in the ISP HUT. In the alcohol HUT a positive response (9/12; 75%) increased in the patient group, whereas there were no positive responses in the normal control group.

CONCLUSION

In the conventional HUT protocols, including ISP provocation, it was difficult to produce a positive response in the patients with alcohol-related syncope. Alcohol ingestion was a useful diagnostic provocation method in such patients.

Increased Postural Sway in Control Subjects With Poor Orthostatic Tolerance

OBJECTIVES

This study sought to evaluate postural sway in control subjects with good and poor orthostatic tolerance (OT).

BACKGROUND

Some asymptomatic volunteers, when subjected to a progressive orthostatic stress test, show early presyncope. We hypothesized that normal subjects with poor OT do not usually faint because they adopt a strategy of increased lower limb movement, which helps maintain venous return.

METHODS

In 12 asymptomatic subjects with good OT and 11 with poor OT, assessed by the combined orthostatic stress of head-up tilting and lower body suction, we determined postural sway using a force platform after 1, 5, and 10 min of motionless standing.

RESULTS

The subjects with poor tolerance had greater distances and velocities of sway in the anteroposterior direction but not the mediolateral direction. There was a significant negative correlation between postural sway and orthostatic tolerance.

CONCLUSIONS

We have shown that in normal subjects with poor OT during a passive orthostatic stress test, their leg movements tend to be greater when standing. These movements are likely to enhance venous return and may at least partly explain why, despite their poor test results, they do not normally faint.

[Syncope and epileptic seizures]

Syncope is one of the most common symptoms leading to hospital admission. Thereby syncope can be induced by several diseases. It is crucial to detect underlying structural heart disease or high grade arrhythmias, as these are associated with an increased mortality. The careful history and physical examination can often give sufficient evidence to evaluate the origin of syncope. Additional examinations should only be applied selectively. In patients with structural heart disease the specific treatment should be initiated, in patients with cardiac arrhythmias the implantation of a pacemaker or ICD might be indicated. The most common neurally-mediated and orthostatic syncopes can often be treated successfully by physical training. Beside syncope epilepsy might be responsible for a transient loss of consciousness. Again careful history taking helps to differentiate between these two entities.

Late Hemodynamic Changes During a Negative Passive Head-up Tilt Predict the Symptomatic Outcome to a Nitroglycerin Sensitized Tilt

BACKGROUND

Sublingual nitroglycerin is advocated to sensitize the passive 70 degrees head-upright tilt test (HUTT) of patients with unexplained syncope. We hypothesized that a detailed analysis of hemodynamic responses recorded during a negative HUTT could predict the outcome to a subsequent nitroglycerin sensitized HUTT (NTG-HUTT).

METHODS

Thirty-two patients (46 +/- 3 years, 17 males) with recurrent unexplained syncope but a negative HUTT were included. Heart rate, arterial blood pressure, and central hemodynamics assessed by transthoracic impedance (preejection and rapid left ventricular ejection time, slow ejection time, peak amplitude of first derivative, and cardiac index) were recorded during supine rest and 45 minutes HUTT. Changes from supine rest of the variables were retrospectively compared between patients with a negative (n = 15, NTG-HUTT(-)) and positive (n = 17, NTG-HUTT(+)) outcome to 10 minutes subsequent NTG-HUTT.

RESULT

Significant differences between groups were observed during the 15th-20th minutes (Italian protocol) and during the last 5 minutes of passive HUTT (Westminster protocol). The combination of cutoff values, determined by receiver operating curves, on hemodynamic variables changes during the last 5 minutes predicted the outcome to a NTG-HUTT with a sensitivity of 76% and a specificity of 87%. The cutoff values determined during 15th-20th minutes gave an attractive sensitivity (85%) but a too weak specificity (53%) to shorten the 45 minutes passive HUTT at 20 minutes.

CONCLUSION

Outcome to a NTG-HUTT can be reliably predicted by selected criteria determined from multiple hemodynamic variables recorded during a passive 70 degrees HUTT.

Unprovoked and glyceryl trinitrate-provoked head-up tilt table test is safe in older people: a review of 10 years' experience

OBJECTIVES

To test the safety of the head-up tilt test (HUT) in older adults.

DESIGN

Direct observation and measurements.

SETTING

Tests performed in a quiet room with dim lighting in a laboratory setting.

PARTICIPANTS

One thousand ninety-six subjects aged 60 to 74; 873 aged 75 and older.

MEASUREMENTS

Blood pressure and pulse at baseline for 10 minutes and 70 degrees tilt for maximum of 45 minutes. Subjects with unprovoked HUT had test repeated on a separate day after 800 mg glyceryl trinitrate (GTN).

RESULTS

One thousand four hundred ninety-five drug-free and 474 GTN-provoked HUTs were studied. In those aged 60 to 74, the proportion of hypotensive unprovoked HUT was 16% (27% in those aged > or =75); this was higher with GTN provocation (43% in those aged 60-74, 44% in those aged > or =75; P<.01). Systolic blood pressure decreased during provoked HUT (lowest mean+/-standard deviation=67+/-20 in those aged 60-74, 63+/-24 in those aged > or =75; P<.01). There was one cardiovascular and no neurological complications.

CONCLUSION

This study included 10 times as many people as previous studies and demonstrates the safety of HUT in older people.

Single-stage adenosine tilt testing in patients with unexplained syncope

INTRODUCTION

We previously have shown that a 3-minute single-stage adenosine tilt test has a diagnostic yield comparable to a two-stage protocol consisting of a 30-minute drug-free tilt followed by a 15-minute isoproterenol tilt. In this study, we sought to further define the clinical utility of adenosine tilt testing in patients with unexplained syncope by prospectively evaluating test specificity and determining predictors of a positive test response.

METHODS AND RESULTS

The specificity of single-stage adenosine tilt testing was determined using 30 control subjects. To determine the diagnostic yield of this protocol, adenosine tilts were performed in 129 patients with unexplained syncope. The adenosine tilt test protocol had high specificity (100%) but a low overall diagnostic yield (18%). However, the yield was affected significantly by age. In patients </=40 years of age, the tilt test was positive in 15 (41%) of 37 patients, which was significantly greater than the yield in patients between the ages of 41 and 64 years (6/41 patients [15%], P = 0.012) and those >/=65 years of age (2/41 patients [5%], P < 0.0001).

CONCLUSION

These data support single-stage adenosine tilt testing in patients </=40 years of age because the diagnostic yield of the test is maximal in this group and the test can be completed in </=3 minutes. Conversely, the diagnostic yield of adenosine tilt testing in patients >40 years of age is low, suggesting that the clinical utility of this protocol is limited in these patients.

Short Head-Up Tilt Test Potentiated with Oral Nitroglycerine:. Comparison with a Conventional Test Using Isoproterenol

Conventional tilt test protocols are time consuming and there is no consensus regarding the optimal duration of the test and the provocative drug to be used. This study evaluated the diagnostic power of a short nitroglycerine test against a conventional isoproterenol protocol. A cohort of 128 patients with unexplained syncope was studied. A group of 64 consecutive patients were tilted with a short nitroglycerine test consisting of a passive phase of 15 minutes and if this proved negative, 400 microg of sublingual nitroglycerin spray for a further 15 minutes. The control group consisted of 64 patients tilted with a conventional isoproterenol protocol with a passive phase of 30 minutes and a drug-challenge phase of 20 minutes. In the nitroglycerine protocol 39 (60.9%) patients showed a positive response versus 27(42.2%) in the isoproterenol group (P = 0.034). The duration of the protocol was 23.2 +/- 7.2 minutes in the nitroglycerine group versus 41.1 +/- 15.5 minutes with isoproterenol (P = 0.001). The time until syncope was 18.87 +/- 6.1 versus 29 +/- 18, respectively (P = 0.002). For evaluating unexplained syncope the short tilt test protocol with nitroglycerine is less time consuming, easier to perform, and has a higher rate of positive response than a conventional isoproterenol protocol.

[Effect of time elapsed from spontaneous syncope on the diagnostic performance of the head-up tilt table test]

OBJECTIVES

The propensity for spontaneous and tilt-induced neurocardiogenic syncope may exhibit temporal variations. Therefore the diagnostic performance of the head-up tilt test could be improved if it were performed soon after the occurrence of spontaneous syncope. The objective of this study was to assess whether the time interval between the last syncopal episode and tilt table testing influenced the outcome of the test.

PATIENTS AND METHOD

Three hundred and fifteen patients undergoing diagnostic tilt table testing potentiated with nitroglycerin for suspected neurocardiogenic syncope were included in the study. The time between the last spontaneous syncope and the tilt table test was recorded and its relationship with the results of the test was analyzed.

RESULTS

The tilt table test was positive in 211 patients (67.0%). The time from syncope to test was similar for patients with positive and negative tilt table test results: 28 (1-500) vs 32 (2-700) days (NS). No significant relation was observed between the results of the test and the occurrence of spontaneous syncope during the week, the month or the three months previous to the procedure. However, in men and in patients older than 50 years a higher rate of positive tests was observed if the tilt test was performed within the first month after the last spontaneous syncope.

CONCLUSIONS

The time from the last previous spontaneous syncope to the head-up tilt test does not have a significant impact on test outcome in the overall population with suspected neurocardiogenic syncope. However, the rate of positivity might decrease in men and patients older than 50 years if the test is performed later than one month after the spontaneous syncopal episode.

Usefulness and safety of shortened head-up tilt testing potentiated with sublingual glyceryl trinitrate in older patients with recurrent unexplained syncope

OBJECTIVES

To evaluate the sensitivity and tolerability of shortened, glyceryl trinitrate (GTN)-potentiated, head-up tilt test (HUT) in patients older and younger than 65 with unexplained syncope and to compare the specificity of GTN-potentiated HUT (GTN-HUT) in older and younger controls.

DESIGN

Methodological study.

SETTING

Syncope units in secondary and tertiary hospitals.

PARTICIPANTS

Three hundred twenty-four consecutive patients with unexplained syncope (100 aged > or =65 (mean age +/- standard deviation 73 +/- 6; 35 men) and 224 aged <65 (41 +/- 15; 111 men)) and 64 controls (29 aged > or =65 (73 +/- 6; 13 men) and 35 aged <65 (42 +/- 13; 16 men)).

INTERVENTION

Patients and controls were tilted upright to 60 degrees for 20 minutes. If syncope did not occur, sublingual GTN (400 microg) was administered and 60 degrees HUT was continued for 15 minutes. Responses were classified as positive, negative, or exaggerated (slow decrease in blood pressure with a slight decrease in heart rate after GTN).

MEASUREMENTS

Electrocardiogram and arterial pressure were monitored continuously.

RESULTS

GTN-HUT was positive in 60% and 66% (NS), negative in 29% and 33% (NS), and exaggerated in 11% and 1% (P <.001) of older and younger patients, respectively. In older and younger controls, the GTN-HUT was negative in 70% and 86% and exaggerated in 28% and 9% of cases, respectively, (P <.05). The overall specificity (considering as negative also the exaggerated responses) was 97% in older and 94% in younger subjects. No patient or control experienced serious side effects.

CONCLUSION

The shortened GTN-HUT provides satisfactory positivity rate and specificity in older patients. This test may be considered as a diagnostic tool in assessing recurrent unexplained syncope in older patients.

[Head-up tilt test potentiated with nitroglycerin. What is the optimal duration of the test after administration of the drug?]

INTRODUCTION AND OBJECTIVES

Numerous variations of the head-up tilt-table test potentiated with nitrates have been reported. After the administration of nitroglycerin, between 10 and 25 min of continued tilting have been recommended. The aim of this study was to assess the optimal duration of the pharmacological phase of the head-up tilt-table test potentiated with sublingual administration of nitroglycerin spray (NTG-TT).

METHOD

The records of 498 consecutive NTG-TT were reviewed. Our protocol consisted of a 20-min drug-free phase at a 60o angle. If syncope does not develop, 400 microgram of sublingual nitroglycerin spray is administered and the patient continues to be tilted for a further 25 min. The test results and time to a positive response were analyzed.

RESULTS

The result of NTG-TT was positive in 288 procedures, most of them after nitroglycerin administration (255, 88.5%). The mean time to a positive response was 10.7 6.7 and 5.0 2.4 min during the control and pharmacological phases respectively. Most positive responses were concentrated in the 3 to 5 min after drug administration. The time to syncope after nitroglycerin administration was over 10 min in 9 patients and 15 min in only 2 patients.

CONCLUSIONS

The duration of the pharmacological phase of NTG-TT using the described protocol can be reduced to 15 min without loss of sensitivity. A further reduction to 10 min would decrease the rate of positive responses by a small amount and might be considered clinically acceptable.

Specificity and total positive rate of head-up tilt testing potentiated with sublingual nitroglycerin in older patients with unexplained syncope

The aim of this study was to assess the specificity and total positive rate of head-up tilt testing (HUTT) potentiated with sublingual nitroglycerin in detecting the vasovagal origin of unexplained syncope in the elderly, since the diagnostic value of this non-invasive test has not yet been proven in this age group. In a period of 3 years, 128 elderly patients (mean age 71.6+/-5.1 years, 50% males) with syncope of unknown origin, and 101 control subjects matched for age and gender were tilted upright to 60 degrees for 45 minutes. If syncope did not occur, sublingual nitroglycerin (0.4 mg) was administered, and observation was continued for 20 minutes. The positive response was defined as the reproduction of syncope or pre-syncope according to VASIS definition. During the unmedicated phase, syncope occurred in 26 patients (20.3%) and in no members of the control group. After nitroglycerin, 53 patients (41.4%) and 2 control subjects (2%) displayed syncope. The total positive rate of the test was 61.8% with a specificity of 98.0%. In conclusion, HUTT potentiated with sublingual nitroglycerin provides an adequate specificity and total positive rate in old patients with unexplained syncope; therefore it can be proposed as a useful diagnostic tool to detect the vasovagal origin of syncope not only in middle but also in advanced age.

[Diagnostic accuracy of a protocol in the evaluation of unexplained syncope]

INTRODUCTION AND OBJECTIVES

To assess the diagnostic capacity of a protocol to study syncope of unknown cause in which electrophysiological studies and tilting table tests are selectively used.

PATIENTS AND METHODS

The study was performed in 137 consecutive patients (94 men and 43 women, with a mean age of 57.6+/-18.3 years) with syncope of unknown cause after the initial clinical evaluation, who were divided into two groups. Group A consisted of 77 patients meeting any of the following criteria: a) presence of structural heart disease; b) abnormal ECG; c) presence of significant non-symptomatic arrhythmia in the Holter recording, and d) presence of paroxysmal palpitations. These patients initially underwent an electrophysiological study. Group B consisted of 60 patients not meeting any of the above criteria, who were initially submitted to tilting table tests.Results. In group A, the electrophysiological study was positive in 43 patients (55%). In group B, the tilting test was positive in 41 patients (68%). Among patients in group A with a negative study, 20 (59%) were submitted to the tilting table test, with positive results in 7 cases (35%). Five patients from group B with a negative tilting test underwent the electrophysiological study, which was negative in all of them. Overall, a positive diagnosis was achieved in 91 of 137 patients (66%).

CONCLUSIONS

In patients with syncope of a non-apparent cause in the initial assessment, selective use of electrophysiological studies or tilting table tests, guided by clinical criteria, allows for a positive diagnosis in over 60% of the cases. Our results suggest that the tilting table test should be performed in cases of group A with a negative electrophysiological study.

Comparison of diagnostic accuracy of sublingual nitroglycerin test and low-dose isoproterenol test in patients with unexplained syncope

Despite the widespread use of head-up tilt testing as a means for diagnosing vasovagal syncope, standardization of test methodology remains a controversial issue. The aim of this study was to compare the diagnostic value of head-up tilt testing potentiated with sublingual nitroglycerin with that of head-up tilt testing potentiated with low-dose isoproterenol. For this purpose, 71 patients with unexplained syncope (mean age 43 years) and 30 asymptomatic controls were studied. All underwent the sublingual nitroglycerin and low-dose isoproterenol tests on separate days in a randomized fashion. The protocol of the 2 tests was similar and consisted of 2 phases. Initially, subjects were tilted at 60 degrees for 20 minutes without medication; then, if syncope did not occur, patients and controls received sublingual nitroglycerin (300 microg) or low-dose intravenous isoproterenol (mean infusion rate 1.3 +/- 0.5 microg/min) and continued to be tilted at 60 degrees for a further 20 minutes. During the sublingual nitroglycerin test, a positive response (syncope associated with sudden hypotension and bradycardia) occurred in 35 patients (49%), a negative response in 36 (51%), and drug intolerance in none (0%). During the low-dose isoproterenol test, these percentages were 41%, 59%, and 6%, respectively. A concordant response was observed in 53 cases (75%). Among controls, 3 subjects (10%) had a positive response to the sublingual nitroglycerin test and 4 (13%) to the low-dose isoproterenol test. It is concluded that sublingual nitroglycerin and low-dose isoproterenol are equivalent tests for evaluating patients with unexplained syncope. The sublingual nitroglycerin test, however, is simpler, better tolerated, and safer than the low-dose isoproterenol test and, thus, more suitable for routine clinical use.

Methodology of head-up tilt testing potentiated with sublingual nitroglycerin in unexplained syncope

Shortened head-up tilt testing (HUT) potentiated with sublingual nitroglycerin (60 degrees passive standing for 20 minutes followed, if negative, by 400 microg of sublingual nitroglycerin spray with the test continuing for another 20 minutes) differs from conventional nitroglycerin HUT for a shorter drug-free phase (20 vs 45 minutes). To compare the positivity rate of the 2 protocols, both tests were performed in a randomized sequence in 10 patients with unexplained syncope (study 1), and another 42 patients were randomly assigned either to conventional or to shortened nitroglycerin HUT (study 2). To evaluate the reproducibility of the shortened nitroglycerin HUT, another 38 patients with unexplained syncope underwent 2 consecutive tests within a 7+/-8 day interval (study 3). Finally, to evaluate the specificity of the test, 47 control subjects underwent shortened nitroglycerin HUT (study 4). Seven positive responses were observed during shortened nitroglycerin HUT, and there were 8 positive responses during conventional nitroglycerin HUT (p = NS) in the study 1 group. Fifteen positive (71%) responses, 5 negative responses, and 1 exaggerated response were observed during shortened nitroglycerin HUT; 16 positive (76%, p = NS vs. shortened nitroglycerin HUT), 3 negative, and 2 exaggerated responses were observed during conventional nitroglycerin HUT in the study 2 group. During the first test, 21 patients (55%) had a positive, 15 patients had a negative, and 2 patients had an exaggerated response in study group 3. During the second test, 15 positive (39%), 19 negative, and 4 exaggerated responses were observed. Thus, the reproducibility was 67% for a positive and 94% for a negative test. In control subjects, 2 positive (4%) responses, 38 negative, and 7 exaggerated responses were observed with a specificity of 96% in study group 4. In patients with unexplained syncope, shortened nitroglycerin HUT allowed a positivity rate similar to that of the conventional test. Moreover, the shortened test provided a high specificity and adequate reproducibility for both the positive and the negative responses.

Reproducibility of head-up tilt testing potentiated with sublingual nitroglycerin in patients with unexplained syncope

Head-up tilt testing (HUTT) potentiated with sublingual nitroglycerin has gained acceptance as means of diagnosing neurally mediated syncope. To evaluate the reproducibility of HUTT potentiated with sublingual nitroglycerin, 48 patients with unexplained syncope prospectively underwent 2 consecutive tests 1 to 28 days apart. The initial test ended in syncope in 34 patients (71%). In 9 patients (19%) the test was positive during the drug-free phase, whereas 25 patients (52%) had syncope after nitroglycerin administration. Of these 34 patients with an initial positive test result, 27 (79%) had a reproducible outcome on repeat testing. Of 12 patients (25%) with an initial negative test result, 10 (83%) had a reproducible outcome on repeat testing. Of 2 patients (4%) with a first test ending in exaggerated response, both had a negative repeat test response. The overall reproducibility of sublingual nitroglycerin tilt-table testing was 77%. In a group of 23 patients with both positive tests, 19 (83%) had the same response modality (2 vasodepressor, 4 cardioinhibitory, 13 mixed response). In the same group of patients, individual trough heart rates correlated well with each other between tests. Finally, in the 27 patients with both positive tests, intrapatient time of onset of symptoms did not significantly correlate between tests. Thus, in patients with syncope of unknown origin, HUTT potentiated with sublingual nitroglycerin provides an adequate reproducibility when repeated on different days.