Diagnosis Of Unexplained Syncope Research Articles

Diagnostic yield of head-up tilt table test in hypertrophic cardiomyopathy and unexplained syncope: the knot does not seem to be unraveling.

Conflicting results have been published considering the diagnostic performance of head-up tilt test (HUTT) in patients with hypertrophic cardiomyopathy (HCM). We aimed to conduct a meta-analysis to evaluate the diagnostic value of HUTT in the evaluation of unexplained syncope in patients with HCM. We performed a structured systematic database search using the following keywords: hypertrophic cardiomyopathy, syncope, unexplained syncope, head-up tilt test, tilt table test, tilt testing, orthostatic stress, autonomic function, autonomic response. Studies in which the HUTT was used to define autonomic dysfunction in patients with syncope at baseline or without syncope were included in the final analysis. A total of 252 HCM patients from 6 studies (159 patients without a history of syncope and 93 with a history of syncope, respectively) were evaluated. HUTT was positive in 50 (19.84%) of 252 patients (in 21 of 93 patients (22.58%) with a history of syncope and in 29 of 159 patients (18.24%) without a history of syncope, respectively). The pooled total sensitivity and specificity of the HUTT for detecting syncope were 22.1% (14.8-35.1%) and 83.6% (73.2-91.6%), respectively. The summary receiver operator curve showed that HUTT had an only modest discriminative ability for syncope with an area under the curve value of 0.565 (0.246-0.794). Although HUTT has significant limitations in diagnosis of unexplained syncope in patients with HCM, it may still be used to determine hypotensive susceptibility. Other autonomic tests can be used in diagnostic workflow in this population.

Wearable Ag-NyW textile electrode for continuous ECG monitoring

The diagnosis of unexplained syncope and sustained palpitations remains a challenging task for cardiology community. Continuous monitoring of cardiac activity is essential to know the pumping pattern of the heart for patients with mild and severe symptoms. Although attempts have been made towards developing wearable monitoring system, the demand for new system is still open due to affordability and accessibility to resource constrained settings. This research work proposes a wearable smart jacket with a single lead (Ag-NyW) textile sensor for continuous monitoring of electrocardiogram (ECG) signals. The wearable lead-I textile electrodes are evaluated in terms of visual inspection by the clinician, skin-electrode contact impedance characteristics; fidelity measures such as crest factor, signal band to noise band ratio, mean magnitude squared coherence; and ECG interval characteristics. Experimental study was carried with 212 healthy volunteers after due ethical clearance (age group 18–45 years), and RR variability and heart rate variability were assessed for different age groups and BMI levels. The study revealed that the proposed textile electrodes are comparable to disposable (conventional Ag/AgCl gel) electrodes in terms of fidelity measures, skin-contact impedance, and ECG interval measures. The HRV for different age groups and BMI levels were found to be within the limits as reported in the literature. From the current pilot study with Indian population, this cost-effective wearable ECG monitoring system will be helpful for long-term monitoring in resource constrained settings.

Comparison of trinitroglycerin and adenosine as provocative agents for head-up tilt test in patients with unexplained syncope: a semi-crossover randomized clinical trial with prospective follow-up.

Head-up tilt test (HUTT) is a reasonable diagnostic evaluation for patients with suspected vasovagal syncope; however, its lengthy duration is a remarkable limitation. Although adenosine (AD), as an alternative provocative agent, is a promising option for tackling this shortcoming, it received little appreciation in the literature. We aimed to compare the efficacy and the time to elicit a positive response to HUTT for sublingual trinitroglycerin (TNG) and intravenous AD. Furthermore, we evaluated patients' outcomes in the follow-up. Patients with a chief complaint of transient loss of consciousness (TLOC) were evaluated. We randomized patients with the diagnosis of unexplained syncope after diagnostic evaluations, to undergo TNG-augmented HUTT or AD-augmented HUTT. They were crossed over to receive the other medication in case of negative response to the test. In the follow-up, we evaluated traumatic and non-traumatic TLOCs, hospitalization due to syncope, and death in patients. We randomized 132 patients (41.70 ± 19.37 years, 52.3% female) to receive TNG (n = 66) or AD (n = 66). Respectively, the positivity rate of TNG and AD for the first and the crossover-HUTT was 31.1% and 26.7%, and 20.5% and 26.2% with no statistically significant differences in both tests (P ˃ 0.50). The time to positive response was significantly shorter for AD than TNG (P < 0.001). In the follow-up, re-admission was significantly more prevalent in HUTT-negative patients compared to HUTT-positive patients (P = 0.04). We found that diagnostic yield of TNG and AD in HUTT is comparable, while AD acts 4 times faster than TNG in evoking a vasovagal response.

Atrial fibrillation in elderly patients with implantable loop recorders for unexplained syncope.

An implantable loop recorder (ILR) assists in the diagnosis of unexplained syncope and atrial fibrillation (AF). Both become prevalent with age. Limited data exist describing the incidence of AF as the diagnostic rhythm underlying syncope in the elderly. This study aims to report the incidence of AF in older adults with ILRs for unexplained syncope and identify clinical characteristics associated with AF in this population. Retrospective observational study on patients with unexplained syncope seen in syncope clinics from two Canadian centers. Participants were ≥65years old, without a history of AF, and received an ILR for unexplained syncope. Data were collected from patient's clinic charts. Arrhythmia diagnosis was based on ILR electrocardiogram reading during syncope (symptom-rhythm correlation). Fisher's exact test and the Student's t test were used to compare participants with and without AF. In our cohort of 222 patients, 124 were females and 98 were males. Mean age at implant was 80±8years. Arrhythmia was diagnosed in 98 patients (44.1%). Median time to diagnosis was 18months. AF was diagnosed in 17 (7.7%) participants. There were fewer males in the AF group than the no AF group (11.8%, 46.8%, p=0.01). Age, baseline EKG, and prevalence of hypertension, diabetes, stroke, or ischemic heart disease were not statistically different between patients with AF and without AF. Atrial fibrillation was a common diagnostic rhythm in this cohort of adults, aged 65 and older, with ILRs for unexplained syncope. It was observed more frequently in females.

Implantable Loop Recorder – A Good Opportunity to Diagnose Unexplained Syncope

Summary Implantable loop recorder (ILR) is a method in cardiology, which is used for the diagnosis of unexplained syncope in patients who were not treated successfully using standard methods. Implantable loop recorder is a diagnostic device that is surgically implanted under the skin of the chest area. This device does not have the endovenous implantation of electrodes; instead, electrodes are attached to the machine housing. The device records the heart rhythm continuously, up to 14 months, and stores data outside the activator whenever symptoms appear, or by the automatic activation of the predefined program for bradycardia, asystole, and tachycardia. The aim of this paper was to describe the method for the detection of cardiac syncope with the use of implantable loop recorder.

Evolución a largo plazo de pacientes ancianos con síncope de etiología desconocida: utilidad de los registradores de eventos implantables

BackgroundSyncope in older people remains a diagnostic challenge due to its high prevalence and recurrence rate. Implantable loop recorders (ILR) have been established in recent guidelines as the cornerstone of unexplained syncope diagnosis, but its usefulness in older people, where syncope tends to be multifactorial in origin, remains poorly defined. Herein we review our experience with ILR in identifying the etiology of recurrent unexplained syncope in older patients after conventional management in a Syncope Unit. MethodsConsecutive patients >75years who underwent ILR implantation in our center due to unexplained syncope after complete evaluation were included. Results75 patients (26 male, mean age 79.8±3.2years) with unexplained syncope (3.7±2.3 mean syncope episodes) were included. After mean implant period of 15.5±11.6 months, 32 patients (42.6%) experienced syncope recurrence with diagnostic ILR registry. Arrhythmic causes were identified in 20 cases (AV block 8, sinus pauses/ventricular asystole 10, tachyarrhythmia 2). There were no sudden deaths during monitorization time nor in long term follow up after ILR explantation (median 48.4months, IC rank 17.9-62.5); 2 patients underwent pacemaker implantation due to complete AV block after non-diagnostic ILR. ConclusionOur results confirm usefulness and safety of ILR in diagnosis of unexplained syncope in elderly people. A significant proportion of patients had arrhythmic cause, mostly bradycardias, although neuromediated origin counts for up to 37.5%.

Diagnosis of Unexplained Syncope by Implantable Loop Recorder

Introduction: Implantable loop recorder (ILR) has been reported to provide a symptom-rhythm correlation in patients with recurrent unexplained syncope. Method: ILR was implanted in 11 patients with recurrent unexplained syncope. Results: ILR revealed the mechanism of syncope in 5 patients (45.5%) and the median period after implantation was 52.8±31.9 days, which was a similar rate to those of previous reports. We found 3 patients with intermittent atrioventricular block and 1 patient with sick sinus syndrome whose electrophysiological study was almost normal. Conclusions: Among patients without major structural heart disease, ILR can be useful to detect the mechanism of recurrent unexplained syncope. It is particularly helpful to find intermittent bradycardia which frequently vanishes during an electrophysiology study.

Diagnosis of unexplained syncope in children: a multi-center study

To examine the diagnostic value of head-up tilt test in children with unexplained syncope (UPS). A total of 379 children (171 males, 208 females) aged 3-18 years, mean age (12 +/- 3) years with unexplained syncope from Beijing, Hunan, Hubei and Shanghai and undergoing baseline head-up tilt tests (BHUTT) or head-up tilt tests potentiated with nitroglycerine (SNHUTT) under a quiet circumstance were selected as the syncope group. Ten healthy children (5 males, 5 females) aged 9-15 years with a mean age of (11.4 +/- 2.1) years, were recruited as the control group. SPSS 10.0 software was used for data analysis. In 379 children with unexplained syncope, 67 (17.7%) were of postural orthostatic tachycardia syndrome (POTS), 157 (41.4%) of vasovagal syncope vasoinhibitory pattern, 14 (3.7%) of vasovagal syncope cardioinhibitory pattern, 47 (12.4%) of vasovagal syncope mixed pattern, 1 (0.3%) of orthostatic hypotension (OH) and 93 children (24.5%) of UPS. In syncope group and control group, the positive rate of BHUTT was 55.9% and 0 respectively and it was 75.5% and 20.0% respectively for SNHUTT. During BHUTT, the mean time of positive response occurrence was (16 +/- 12) minutes, and the posture when positive response appeared was at a tilt angle of 60 degrees. For SNHUTT, the mean time of positive response occurrence was (6 +/- 4) minutes and the posture was at a tilt angle of 60 degrees when potentiated with nitroglycerine. HUTT is an objective diagnostic tool of UPS. With a high diagnostic positive rate, SNHUTT can improve the diagnostic positive rate of BHUTT. Meanwhile the time of positive response occurrence during SNHUTT is markedly shorter than BHUTT.

The intravenous adenosine test: a new test for the identification of bradycardia pacing indications? A pilot study in subjects with bradycardia pacing indications, vasovagal syncope and controls

Intravenous adenosine has recently been used in the diagnosis of unexplained syncope, but there is no consensus as to the meaning of a 'positive' test. The objective is to determine the sensitivity and specificity of intravenous adenosine testing in the diagnosis of bradycardia-pacing indications [sinus node dysfunction(SND), atrio-ventricular block (AVB) and cardio-inhibitory carotid sinus syndrome (CSS)]. Pilot cohort study. Patients-(i) Bradycardia-pacing group: Consecutive patients referred for pacing for SND, AVB and CSS; (ii) Consecutive head-up tilt (HUT)-positive VVS patients. Controls-(i) Simple controls (S-Con: normal examination/ECG) and (ii) Electrophysiology controls (EP-Con: consecutive subjects referred for accessory pathway ablation). Pacing referrals and EP-Con had electrophysiology studies to confirm referral diagnosis and exclude others. All subjects had bolus injection of 20 mg intravenous adenosine during continuous ECG and blood pressure monitoring (positive test: >or=6 s asystole, >or=10 s high-degree AVB post-injection). Sensitivity, specificity, safety and tolerability of the test were measured. Of 264 potential participants (4 SND, 8 AVB, 7 CSS, 10 VVS, 10 EP-Con and 11 S-Con) 50 were studied. All (100%) of the bradycardia-pacing group were adenosine test-positive, as were 6 (60%) VVS. None (0%) and 3 (27%) of the EP- and S-Con groups were positive. Adenosine testing was 100% sensitive and 86% specific for bradycardia-pacing indications, and 100% specific using the diagnostically 'clean' EP-Con results. There were no significant adverse or side effects. Adenosine testing reliably identified patients with definitive bradycardia-pacing indications in whom alternative diagnoses were excluded. Further work is needed to evaluate the role of this test in the diagnosis of unexplained syncope.

Utility of implantable loop recorders for diagnosing unexplained syncope in clinical practice.

Establishing a symptom-rhythm correlation in patients with unexplained syncope is complicated because of its sporadic, infrequent, and unpredictable nature. Prolonged monitoring with an implantable loop recorder (ILR) allows the recording of electrocardiogram (ECG) data from a spontaneous syncopal event. The aim of this study was to evaluate the usefulness of the ILR for the diagnosis of syncope of unknown origin after conventional management in clinical practice. We reviewed the results with ILR implantation in patients with syncope of unknown origin after conventional management in the cardiology department at HU Marques de Valdecilla (Santander, Cantabria, Spain). One hundred and forty patients (age 64 +/- 16 y; 86 male [62%]) with syncope of unknown etiology after conventional work-up underwent prolonged monitoring with an ILR from September 1998 to February 2006; 46 patients (33%) had structural heart disease. During a mean follow-up of 346 +/- 160 d, 51 patients (36.5%) had recurrent syncope with diagnostic ECG recording. An arrhythmic cause for syncope was found in 33 of them (64.5%), with bradycardia present in 27 (53%) and tachycardia in 6 (11%). There were no sudden deaths, and 1 patient suffered a complication related to a recurrence of syncope. Long-time experience with the ILR confirmed the utility of this device in the diagnosis of unexplained syncope in clinical practice. Most of these patients had syncope of arrhythmogenic etiology that could be successfully treated. This strategy of prolonged monitoring is safe even in patients with structural heart disease.

Utility of Implantable Loop Recorder in Patients with Syncope—Results of Unexplained Syncope Trial (RUST)

Background: Syncope represents a common problem in cardiology practice. The use of implantable loop recorders (ILR) to provide long-term monitoring may assist in the diagnosis of unexplained syncope.

Adenosine test in the diagnosis of unexplained syncope: marker of conducting tissue disease or neurally mediated syncope?

Adenosine test (supine administration of a 20 mg intravenous bolus with electrocardiographic and blood pressure monitoring) has been endorsed by the European Society of Cardiology guidelines on syncope management as an 'experimental' test in the diagnosis of unexplained syncope. The test is quick and cheap, but there is no consensus as to what condition, if any, the adenosine test is exposing, with conducting tissue disease and neurally mediated syncope proposed by various authors. In this article, we review the possible mechanisms underlying a positive adenosine test, its safety, and a comprehensive examination of the literature supporting each of the putative causal diagnoses.

Utility of implantable loop recorder (Reveal Plus) in the diagnosis of unexplained syncope

In about 30% of patients with syncope, the responsible mechanisms remain unrecognised. Nevertheless, the possibility of an arrhythmic aetiology remains, however, difficult to rule out. We therefore monitored with an implantable loop recorder (ILR, Reveal Plus, Medtronic) 34 subjects (60+/-15 years) with at least two unexplained syncopal episodes and negative neurological and cardiovascular work-up. During a follow-up of 7+/-4 months, syncope occurred in 11 subjects. In nine of them the mechanisms responsible for these events were identified by ILR monitoring: marked bradycardia or asystole (n=6), atrial fibrillation with wide QRS tachycardia (n=1) and sinus rhythm with fine artifacts likely to be due to muscle contractions (n=2). Pre-syncope occurred in seven patients: advanced atrioventricular block (n=3), sinus tachycardia (n=1), and wide QRS tachycardia (n=1) were documented. Thus, when considering all 18 patients with recurrences, a diagnosis was achieved in 53% of subjects. Recognition of the rhythm disorder in seven patients with syncope and four patients with pre-syncope guided patient management. These data indicate that ILR monitoring facilitates the identification of mechanisms responsible for recurrences and therapeutic management in subjects with syncope or pre-syncope and negative traditional neurological and cardiovascular work-up.

Tilt table testing in the diagnosis of unexplained syncope.

While the investigation of the physiological and pathophysiological effects of orthostatic stress induced by head-up tilt table testing in humans began more than 50 years ago,1 it was not until 1986 that the utility of tilt testing in the diagnosis of unexplained syncope was demonstrated.2 In the absence of a `gold-standard' diagnostic test for vasovagal syncope, an appropriate clinical history in association with a positive head-up tilt test currently provides the cornerstone for the diagnosis of vasovagal syncope.3 This article will provide an overview of the rationale for the head-up tilt test in relation to its main diagnostic use, vasovagal syncope, a discussion of the methodological issues surrounding the test and the uses of tilt table testing in the further differential diagnosis of unexplained syncope. More than 60 years after the introduction of the term `vasovagal syncope' by Lewis,4 the exact mechanisms responsible for loss of consciousness associated with profound hypotension and/or bradycardia, and mediated by vagal excess and sympathetic withdrawal, remain uncertain. The main trigger factors for the vasovagal cascade can be divided into central and peripheral provocateurs,5 with the latter providing the substrate for the diagnostic use of the tilt table. Head-up tilt table testing provides a powerful, controlled orthostatic stimulus simulating under laboratory conditions the peripheral provocation of vasovagal syncope. The pathophysiology of the vasovagal response is thus central to an understanding of the role of tilting in its diagnosis. Although central, higher cortical provocation of vasovagal syncope through emotional stress6 and pain7 is a clinical commonplace, the neuronal connections mediating the response are far from certain. Animal models implicate the limbic system as the relay region for stress-related neuronal activity,7,,8 with the ultimate control mechanisms residing in hypothalamic and brain-stem autonomic nuclei.9 Human vasovagal syncope … Professor R.A. Kenny, Cardiovascular Investigation Unit, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne NE1 4LP. e-mail: r.a.kenny{at}ncl.ac.uk

Prueba de inclinación en la evaluación del sincope o presíncope de etiología no precisada en niños y adolescentes

Unexplained syncope or presyncope are rather common problems in children, whose evaluation is not simple. In adults, the t i l t test a'lows to reproduce symptoms and some associated hernodynamic mechanisms in 30 to 75% of the patients with this condition. The purpose of this wox has been to analyze hernodynamic responses during 70 tilt test in 26 consecutive patients younger than 19 years, refered to our center with the diagnosis of unexplained syncope in a period of 2 years. Fifty percent of the tilt test were positive, most of them using isoproterenol (mean dose ± 0.4 micrograms/minute), increasing heart rate by 41%. Systolic arterial pressure decreased significantly in all patients with a positive t i l t test to less than 70 mmHg. Reduction or heart rate was also observed, rarely to marked bradycardia by the end of tne test. Original symptoms were always reproduced during the test. It is concluded that tit test may constitute an imoortant test in the clinical workup of unexpkcined syncope in children and adolescents. This method reproduces clinical symptoms associated 'o syncope or presyncope and precises their hernodynamic mechanisms in aporoxima'e'y 50% of hese patients.

Evaluation of edrophonium as a provocative agent for vasovagal syncope during head-up tilt-table testing

Vasovagal syncope after head-up tilting is thought to be secondary to a complex, neurally-mediated reflex with both vasodepressor and cardioinhibitory efferent components. The efficacy of edrophonium, an acetylcholinesterase inhibitor, as a provocative agent for triggering syncope during head-up tilt testing was evaluated. Forty-five consecutive patients (22 female and 23 male) with history of recurrent unexplained syncope received edrophonium (10 mg intravenous) after 30 minutes of 60 ° head-up tilting atone. Twenty normal control subjects (9 female and 11 male) were tested with head-up tilt testing and edrophonium. Syncope was induced in 19 of 45 patients with the diagnosis of unexplained syncope. In 9 patients who developed syncope with head-up tilting alone, the predominant hemodynamic finding was marked vasodepression. In contrast, in 10 patients who developed syncope only after head-up tilting and edrophonium, the predominant hemodynamic findings were marked vasodepression and bradycardia. Syncope was induced in 1 of 20 normal subjects after head-up tilting and edrophonium. There was no long-term complication from using edrophonium. It is concluded that head-up tilt testing with edrophonium: (1) significantly increases the identification of patients with vasovagal syncope, (2) may be particularly useful when provocation with isoproterenol is undesirable, and (3) may be an effective method to help differentiate patients with a significant reflex cardioinhibitory component from those with a predominantly reflex vasodepressor component.