Positive Head-up Tilt Table Test Research Articles

Syncope without prodromes is associated with excessive plasma release of adenosine at the time of syncope during head-up tilt table test

BackgroundIn syncopal patients without underlying structural disease, we sought to investigate the association of Adenosine Plasma Levels (ADP) with the clinical presentation of neurally mediated syncope (NMS) and the outcomes of Head-Up Tilt Table Test (HUTT) and Adenosine test (ADT). MethodsWe studied 124 patients with different clinical types of NMS, i.e., Vasovagal (VVS, n=58), non-prodromes (NPS, n=18), or situational syncope (SS, n=48), using a standard protocol including HUTT and ADT. During HUTT, ADP was measured in the supine position, at table tilting and in syncope. ResultsBaseline ADP did not differ among groups. ADP at syncope were higher in NPS (n=5) compared to VVS (n=20): 0.23 vs. 0.12 μΜ, p=0.03, and SS (n=22): 0.04 μΜ, p=0.02. In NPS, ADP increased from supine to syncope (n=5): 0.15 vs. 0.23 μΜ, p=0.04. In VVS, ADP increased only from supine to tilt position: 0.11 vs. 0.14 μΜ, p=0.02. In SS, ADP did not change during HUTT. In positive vasodepressor HUTT, ADP increased from supine to tilt position (p=0.002) and at syncope (p=0.01). In SS, 20.0% exhibited cardioinhibitory HUTT vs. 6.8% in other forms of syncope (p=0.04). In SS, 22.9% manifested positive ADT vs 6.6% in other types of syncope (p=0.012). ConclusionThe subset of NPS patients with positive HUTT, show excessive ADP release at the time of syncope. This may explain the lack of prodromes in this form of syncope. Such observations contribute to the understanding of distinct profiles of clinical forms of syncope and may differentiate the management approach accordingly.

Adenosine plasma levels and adenosine receptor levels determine the outcome of adenosine test and head-up tilt test in syncopal patients with a normal heart

Abstract Background/Introduction The neurohumoral profile underlying the manifestation of reflex syncope remains incompletely understood. Adenosine plasma (ADP) and adenosine receptor (ADR) levels may differentiate the outcomes of head-up tilt table test (HUTT) and adenosine test (ADT) but their role in the diagnostic evaluation of patients with syncope has yet to be determined. Purpose We sought to assess the ADP and ADR levels in patients without structural heart disease who underwent HUTT and ADT tests as part of the diagnostic workup of syncope. We specifically investigated differences in the outcomes of the HUTT and ADT tests as well as to the ADP levels during HUTT. Methods HUTT and ADT were performed as per the standard protocols. ADT was considered positive in the event of asystole >6 seconds or heart block for >10 seconds after intravenous Adenosine 0.15 mg/kg administration in the supine position. ADP levels were assessed at three timepoints during the HUTT: at baseline (supine), immediately after bed tilt and, in cases of a positive HUTT, at the time of syncope. Patients were categorized in quintiles of very low, low, intermediate, high and very high baseline ADP levels. We also assessed the A2A ADR levels of monocytes. Results We prospectively analyzed 124 patients (71 women, age 46.78±21.01 years). ADT was positive in 12.9% of patients and HUTT in 44.4% of patients. Patients with very low baseline ADP levels (lowest quintile) more frequently presented with a positive ADT (odds ratio [OR] 4.08, 95% Confidence Interval [CI] 1.40 to 13.13, p<0.05). Baseline ADP did not differ between patients with positive and negative HUTT. However, patients with vasodepressor response to HUTT exhibited increase in ADP from baseline to bed tilt (0.33±1.03 vs. 0.42±1.14 ppm/Um/L, p<0.05) and in syncope (0.70±1.89, P<0.05), while no difference was noted in patients with cardioinhibitory or mixed response. Patients with positive ADT and negative HUTT had higher ADR levels (221.5±88.56 MFI) as compared to patients with negative ADT and positive HUTT (59.78±83.65 MFI, p<0.05) and to patients with positive ADT and HUTT (33.29±35.77 MFI, p<0.05). Within patients with positive HUTT, those with onset of syncope in the Isoprenaline provocation phase (>20 min) had lower ADR levels (80.88±238.98 vs 89.43±96.08 MFI, p<0.05). Conclusion(s) Baseline ADP levels are related to the outcome of ADT while an ADP increase immediately after bed tilt and in syncope is evident in vasodepressor response to HUTT. Higher ADR levels are related to positive ADT and negative HUTT. Lower ADR levels are associated with more delayed onset of syncope during HUTT. ADP and ADR levels warrant further investigation as they may characterize a subset of patients with specific responses to ADT and HUTT and may be implicated in the pathophysiology of reflex syncope. Funding Acknowledgement Type of funding sources: None.

Repolarization disparity as a predictor of response to Head up Tilt-table Test in pediatric syncope.

Head up Tilt-table Test (HUTT) is a practical examination of the most common type of pediatrics syncope. The electrocardiographic (ECG) changes during this test, show the autonomic defects that cause neuraly-mediated syncope in response to tilting process. All pediatric syncope patients referred to our center in a 1-year period, were included in the study. HUTT was performed and patients were classified into two groups of Negative and Positive HUTT results, and the latter group was subclassified as three subgroups of "vasodepressor", "cardioinhibitory" and "mixed type" responses to HUTT. QT and corrected QT (QTc) dispersion was measured by the baseline standard 12-lead ECG obtained before HUTT. Eighty-six patients with a mean age of 12.19 ± 5.34 were included. Patients with positive HUTT were significantly younger and male gender was more prevalent in this group. Mean QT dispersion was significantly higher in patients with positive HUTT result and also in patients with mixed response to HUTT compared to isolated vasodepressor response. Duration of QTc interval did not change between different study groups. Reciever-Operating-Characteristic (ROC) analysis showed that QT dispersion higher than 32ms is a significant predictor of positive HUTT result (with 92% sensitivity and 98% specificity) and values higher than 40ms can predict the mixed type of response to HUTT (with 84% sensitivity and 63% specificity). Baseline myocardial repolarization disparity significantly correlates with susceptibility to symptomatic vasovagal syncope. This pathology seems to play its role mainly via excessive vagotonic response to sympathetic activation during HUTT process (known as cardioinhibitory response).

Early-onset and recurrent reflex syncope is associated with left ventricular diastolic filling and left atrial function properties

Abstract Background/Introduction The effects of the left atrial and ventricular function in the pathophysiology of reflex syncope remain elusive. Head-up tilt table test (HUTT) is frequently used in the diagnostic workup of patients with syncope, but the outcomes of HUTT have not been attributed to any anatomical or functional cardiac characteristics. Purpose We sought to assess the effects of anatomical and functional echocardiographic features of the left atrium and the left ventricle at rest in the clinical presentation of syncope and the outcomes of HUTT. Methods We investigated patients with a history of syncope and symptoms suggestive of reflex syncope who underwent HUTT. Specific echocardiographic indices of left cardiac morphology and function were assessed at rest. The patients were divided into two groups, those who presented with syncopal episodes at age <35 years (group A) and those who presented with syncopal episodes at age >35 years (group B). Results In 119 patients (age 46.75±21.17 years, 69 women), patients in group A exhibited a higher chance for numerous (>3) syncopal episodes (odds ratio [OR] 3.4, 95% Confidence Interval [CI] 1.41 to 7.93, p<0.05). Group A showed also a trend for positive HUTT (OR 1.99, 95% CI 0.97 to 4.23, p=0.08). In patients with positive HUTT, Group A had higher E-wave velocity (0.83 vs 0.65 m/sec, p<0.05), lower A-wave velocity (0.60 vs 0.75 m/sec, p<0.05), higher E/A ratio (1.54 vs 1.00, p<0.05), higher e' wave velocity (0.16 vs 0.10 m/sec, p<0.05) and lower E/e' (5.64 vs 7.85, p<0.05). Also, patients in group A exhibited lower left atrial volumes (min 9.88 vs 16.21 ml, p<0.05, max 30.42 vs 44.89 ml, p<0.05), higher left atrial strain reservoir (40.56 vs 32.42%, p<0.05) and higher left atrial strain booster (25.94 vs 18.06%, p<0.05). Conclusion(s) Patients with a younger age of onset and recurrent syncopal episodes manifest smaller dimensions of the left atrium with distinct patterns of diastolic performance and better reservoir and booster function. These findings may indicate a more pronounced susceptibility of this group of patients to preload reduction, thereby triggering the mechanism of reflex syncope. Funding Acknowledgement Type of funding source: None

POLYMORPHISMS IN β-ADRENERGIC RECEPTORS ARE ASSOCIATED WITH INCREASED RISK TO HAVE A POSITIVE HEAD-UP TILT TABLE TEST IN PATIENTS WITH VASOVAGAL SYNCOPE.

Vasovagal syncope (VVS) is a frequent clinical condition in which a genetic background seems to be implicated. Considering that the adrenergic receptors (ARs) may play a role in VVS, the present study has as principal aim to determine if the α- and β-AR (ADRA and ADRB) gene polymorphisms are associated with an increased risk to have a positive head-up tilt table (HUTT) test in patients with VVS. Methods: Nine polymorphisms in the ADRA1A (rs1048101, rs1383914, rs574584, and rs573542), ADRB1 (rs1801252 and rs1801253), ADRB2 (rs1042713 and rs1042714), and ADRB3 (rs4994) genes were analyzed using the 5' exonuclease TaqMan genotyping assay in a group of 134 patients with VVS. Under different models, the rs1801252 (OR = 8.63, 95% CI: 0.95-78.72, Precessive = 0.02), rs1042713 (OR = 1.94, 95% CI: 1.02-3.66, Padditive = 0.04), and rs4994 (OR = 2.46, 95% CI: 1.01-6.01, Pdominant = 0.042 and OR = 2.62, 95% CI: 1.04-6.63, Pover-dominant = 0.03) polymorphisms were associated with increased risk for a positive HUTT. All models were adjusted for statistically significant covariates. These results suggest that some polymorphisms of the β-AR genes could contribute to a positive tilt test in patients with VVS.

Cerebral Perfusion Monitoring Using Near-Infrared Spectroscopy During Head-Up Tilt Table Test in Patients With Orthostatic Intolerance.

The head-up tilt table test (HUT) is one of the primary clinical examinations for evaluating orthostatic intolerance (OI). HUT can be divided into three phases: dynamic tilt phase (supine to tilt up), static tilt phase (remain tilted at 70°), and post tilt phase (tilt down back to supine position). Commonly, blood pressure (BP) and heart rate (HR) are monitored to observe for OI symptoms, but are indirect measurements of cerebral perfusion and can lead to inaccurate HUT evaluation. In this study, we implemented a 108-channel near-infrared spectroscopy (NIRS) probe to characterize HUT performance by monitoring cerebral hemodynamic changes for healthy controls (HCs), OI patients with normal HUT results, and OI patients with positive HUT results: vasovagal syncope (VS), postural orthostatic tachycardia syndrome (POTS), orthostatic hypotension (OH), and orthostatic hypertension (OHT). By the end of the static tilt phase, OI patients typically did not show a complete recovery back to baseline cerebral oxygenation and total blood volume compared to HCs. We characterized the return to cerebral homeostasis by polynomial fitting total blood volume changes and determining the inflection point. The OI patients with normal HUT results, VS, OH, or OHT showed a delay in the return to cerebral homeostasis compared to the HC group during HUT.

A single-center randomized controlled trial observing the safety and efficacy of modified step-up graded Valsalva manoeuver in patients with vasovagal syncope.

Non-pharmacological therapies, especially the physical maneuvers, are viewed as important and promising strategies for reducing syncope recurrences in vasovagal syncope (VVS) patients. We observed the efficacy of a modified Valsalva maneuver (MVM) in VVS patients. 72 VVS patients with syncope history and positive head-up tilt table testing (HUTT) results were randomly divided into conventional treatment group (NVM group, n = 36) and conventional treatment plus standard MVM for 30 days group (MVM group, n = 36). Incidence of recurrent syncope after 12 months (6.5% vs. 41.2%, P<0.01) and rate of positive HUTT after 30 days (9.7% vs.79.4%, P<0.01) were significantly lower in MVM group than in NVM group. HRV results showed that low frequency (LF), LF/ high frequency (HF), standard deviation of NN intervals (SDNN) and standard deviation of all 5-min average NN intervals (SDANN) values were significantly lower in the NVM and MVM groups than in the control group at baseline. After 30 days treatment, LF, LF/HF, SDNN, SDANN values were significantly higher compared to baseline in MVM group. Results of Cox proportional hazard model showed that higher SDNN and SDANN values at 30 days after intervention were protective factors, while positive HUTT at 30 days after intervention was risk factor for recurrent syncope. Our results indicate that 30 days MVM intervention could effectively reduce the incidence of recurrent syncope up to 12 months in VVS patients, possibly through improving sympathetic function of VVS patients.

Correlation of head‐up tilt table test time interval with future risk of recurrent syncope

Head-up tilt table test (HUTT) is widely used for the investigation of syncope and presyncope. Time required for positive response has a probable relationship to the sensitivity of neural reflex mechanism underlying syncope. We evaluated patients with history of syncope. Group A included patients with recurrent syncope defined as two or more episodes of syncope and group B included those with one episode of syncope. Time required for the test to become positive in both the groups was analyzed. Patients with positive HUTT were followed for 1 year. Of 80 patients, 68 eligible study patients were divided into group A (32.35%) and group B (67.65%). HUTT was positive in 41 patients (positivity rate=60.29%). Positivity rate was 100% in group A and 41.3% in group B. Median time interval for positive response in groups A and B were 12.5 and 30.0 minutes, respectively. An inverse association was found between recurrent syncope and time interval for positive response (R=-0.282, P=0.002). Time interval of less than 19.5 minutes for positive response had 94.5% sensitivity and 97.89% specificity for recurrent syncope. On follow-up, positive association was found between time interval for positive response less than 19.5 minutes and future recurrence of syncope (odds ratio=22.75, 95% confidence interval=4.37-118.34, P=0.000). HUTT time interval of less than 19.5 minutes for positive response predicted future recurrence of syncope. Hence, it may serve as an important predictor of future recurrence of syncope.

Genome-Wide Association Study of Copy Number Variations in Patients with Familial Neurocardiogenic Syncope.

Neurocardiogenic syncope (NCS) is the most frequent type of syncope characterized by a self-limited episode of systemic hypotension. In this study, we conducted the first genome-wide association study testing copy number variations for association with NCS. Study population consisted of 107 consecutive patients with recurrent syncope and positive head-up tilt table testing. Four families with NCS were selected for CNV analysis. Affymetrix GeneChip(®) SNP 6.0 array was used for CNV analysis. Data and statistical analysis were performed with Affymetrix genotyping console 4.0 and GraphPad Prism v6. Positive family history of NCS was present in 19.6% (n=21) in our study population (n=107). Twenty-six CNV regions were found to be significantly altered in families with NCS (P<0.05). Several CNVs were identified in families with NCS. Further studies comprising wider study population are required to determine the effect of these variations on NCS development.

Early Hemodynamic Changes during Head-Up Tilt Table Testing Can Predict a Neurocardiogenic Response in an African-American Patient Population

Background: Head-up tilt table testing (HUTT) is time-consuming and associated with increased patient morbidity. Hemodynamic changes that occur during the early phase of HUTT may be predictive of neurocardiogenic syncope. Methods: A retrospective chart review was performed in 119 consecutive African Americans ( 57 ± 19) who underwent HUTT for evaluation of syncope of unknown etiology. Positive responses were defined as the development of symptoms linked with a systolic blood pressure (BP) <90 mm Hg, heart rate <50 b.p.m. or sinus arrest >3 s. Hemodynamic variables during the passive phase of HUTT were analyzed and results were then classified as a function of various predictors. Results: Sixty-two subjects (52%) had positive HUTT, and 57 (48%) had negative HUTT. Early changes in BP variables from baseline significantly predicted HUTT responses (p < 0.05). There was also a significant interaction between age and BP. An algorithm based on age and BP was developed which had positive and negative predictive values of 67.7 and 93%, respectively, with an accuracy of 79.8%. Conclusion: A novel algorithm utilizing the patients' age and changes in both systolic and diastolic BP during the early phase of HUTT enables the prediction of HUTT results without the use of vasoactive stimulation, allowing for rapid diagnosis, decreased patient morbidity and reduction in costs.

Prevalence and Clinical Factors of Anxiety and Depression in Neurally Mediated and Unexplained Syncope

PurposeSeveral studies have demonstrated that psychiatric disorders such as anxiety, depression and panic attack are associated with syncope, especially vasovagal and unexplained syncope (US). The aim of this study was to compare the prevalence of anxiety and depression between patients with neurally mediated syncope (NMS) and US and to investigate the clinical factors associated with anxiety and depression.Materials and MethodsBetween January 2009 and March 2010, 383 patients with syncopal episodes completed a Hospital Anxiety and Depression Scale questionnaire to assess symptoms of anxiety and depression. Inclusion criteria were NMS and US. Exclusion criteria were cardiac syncope, orthostatic hypotension and other disorders mimicking syncope. After exclusion, 199 patients were included.ResultsThere were 176 (88.4%) NMS patients and 23 (11.6%) US patients. The prevalence of abnormal anxiety and depression were not significantly different between the NMS and US groups (10.2% vs. 8.7%, p=0.99; 8.5% vs. 17.4%, p=0.24). Clinical factors associated with anxiety were female gender (p=0.01) and six or more recurrent syncopal episodes (p=0.01) by univariate analysis. The only factor associated with abnormal anxiety score (OR=20.26, 95% CI: 1.4-291.6, p=0.01) was more than six recurrent syncopal episodes, while a positive head-up tilt table testing response was inversely associated with abnormal depression score (OR=0.28, CI: 0.08-0.97, p=0.04) in the multiple logistic regression analysis.ConclusionAnxiety was associated with frequent syncopal episodes. Thus, anxiety might be considered in the management of syncope patients.

Usability of QTc dispersion for the prediction of orthostatic intolerance syndromes

BackgroundSyncope is defined as transient loss of consciousness and muscle tone, usually of short duration. Noncardiac causes of syncope are classified as orthostatic intolerance syndromes (OIS). QT and QTc (corrected QT) dispersions are the measurements of myocardial instability and show predisposition to arrhythmias. In this study; clinical findings, QT and QTc dispersions of the patients who were diagnosed as OIS were evaluated retrospectively. Also, the aim of the study is to clarify the association of clinical characteristics of unexplained syncope with the outcome of the QT and QTc dispersions in children. MethodsWe designed a retrospective study including 152 children and adolescents who had repeated unexplained syncope or presyncope between June 2002 and August 2010. Head-up Tilt table test (HUTT) were performed for all patients. Control group consisted of 67 healthy children. The QT and QTc dispersions were measured from the 12 ECG leads. ResultsEighty-four (55.2%) patients had positive and 68 (44.8%) had negative response to HUTT. QT and QTc dispersions were significantly higher in HUTT-positive group than in negative (p < 0.01, p < 0.001 respectively). Also, QTc dispersion was significantly higher in both vasovagal syncope and postural orthostatic tachycardia syndrome groups than in HUTT-negative group (p < 0.001, p < 0.05 respectively). Specifity and sensitivity of QTc dispersion for predicting positive HUTT are 76.5% and 59.5% respectively. The positive predictive value of the test calculated as 75.8%. ConclusionsThese results revealed that we can use QTc dispersion measurement as a noninvasive electrocardiographic test to evaluate OIS for predicting positive result before performing HUTT.

Syncope in Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is a debilitating pain syndrome characterized clinically by severe pain along with signs and symptoms of autonomic dysfunction. Presyncope and syncope are common in these patients. The purpose of this study was to investigate the cause of these symptoms in these patients. Patients with CRPS are more prone to presyncope and syncope as evidenced by head-up tilt table testing (HUTT). Patients with CRPS underwent a complete cardiac evaluation that included a 12-lead electrocardiogram, 2-dimensional echocardiography, 24-hour Holter monitoring, and HUTT. Seventy-four patients with CRPS were evaluated. Eight CRPS patients (10%) could not complete a HUTT due to pain. Of the 66 CRPS patients who completed a HUTT, 15 (37.9%) reported pretest symptoms of presyncope or syncope. Twenty-eight CRPS patients (42.4%) had a positive HUTT. CRPS patients with lower limb involvement were more likely to have vasovagal syncope or orthostasis on HUTT than those with upper extremity or total body involvement (12 of 18 [67%] vs 16 of 48 [33%]; P = 0.015). Syncope is common in patients with CRPS, especially with lower limb involvement. Autonomic dysregulation of the lower extremities leads to impaired sympathetic vasoconstriction and venous pooling, which can predispose these patients to syncope. Physician awareness of this syndrome will lead to improved recognition and treatment of their symptoms of presyncope or syncope.

Application of Head-up Tilt Table Testing in Children

We investigated the application of head-up tilt table testing (HUT) and management of neurocardiogenic syncope (NCS) in children, as pediatric studies are limited. Seventy-nine patients (ages 6-18 years) underwent HUT for evaluation of syncope. Patient triggers and premonitory symptoms allowed the clinical diagnosis of NCS or non-NCS. Results were divided into four hemodynamic types (1, 2A, 2B, and 3) according to patient response to HUT. NCS occurred in 65 patients and non-NCS in 14 patients. Isoproterenol infusion significantly increased the sensitivity of the test (from 28% to 45%) and was associated with a slight decrease in the specificity (from 93% to 86%). Subjects in the type 1 group accounted for the majority of responses to the test (69%). There were no complications associated with the test. At follow-up (16.6 ± 9.3 months), the overall recurrence rate was 30.8% but NCS was less severe in most patients. The recurrence rate was similar for patients with a positive or negative HUT and for both pharmacologically and non-pharmacologically treated patients. HUT can be safely performed with a high specificity in children, with the sensitivity of HUT improved by isoproterenol. Therefore, a positive response to treatment is reassuring to the physician and family. NCS is generally a self-limited condition despite a high recurrence rate.

Home orthostatic training in vasovagal syncope modifies autonomic tone: results of a randomized, placebo-controlled pilot study

To detect possible autonomic changes due to home orthostatic training (HOT) and to assess the feasibility of a larger, placebo-controlled study of HOT in vasovagal syncope (VVS). Twenty-two consecutive patients, aged 18-85, diagnosed with VVS following a positive head-up tilt-table test were randomized to 40 min of HOT (n = 12) or 10 min of sham training (n = 10) daily for 6 months. Baroreflex sensitivity (BRS) and heart rate variability (HRV) were measured at weeks 0, 1, 4, and 24. Symptom response was assessed by event diaries. Home orthostatic training resulted in increases in up and down slope BRS at week 4 (e(log difference) = 1.59, 95% CI = 0.84-3.03 and 1.79, 95% CI = 1.00-3.22) and week 24 (e(log difference) = 1.75, 95% CI = 1.01-3.06 and 1.53, 95% CI = 0.66-2.68) compared with placebo. Relative improvements in low- and high-frequency HRV were also observed in the HOT group compared with placebo at week 4 (e(log difference) = 3.22, 95% CI = 1.06-9.86 and 3.19, 95% CI = 1.03-10.59) and week 24 (e(log difference) = 2.11, 95% CI = 0.72-6.17 and 2.13, 95% CI = 0.52-8.79). Fifty percentage of HOT subjects and 20% of control subjects were syncope-free at 6 months. This was the first placebo-controlled study in orthostatic training which has demonstrated that such a study is indeed feasible. An enhancement in overall autonomic tone is observed with HOT in tandem with a non-significant trend in symptom improvement. A larger, adequately powered, randomized controlled trial of tilt-training is now needed.

The relationship between carotid sinus hypersensitivity, orthostatic hypotension, and vasovagal syncope: a case-control study

Previous uncontrolled studies reported an overlap between carotid sinus hypersensitivity (CSH), vasovagal syncope (VVS), and orthostatic hypotension (OH). We conducted a case-control study evaluating this relationship in a large patient cohort. The electronically stored continuous electrocardiograph and blood pressure (BP) measurements for active stand and head-up tilt-table (HUT) tests of 302 consecutive patients investigated with carotid sinus massage (CSM) were analysed. Carotid sinus hypersensitivity was defined as >or=3 s asystole and/or systolic BP (SBP) drop of >or=50 mmHg during CSM. Orthostatic hypotension was defined as BP reductions of >or=20 mmHg systolic or of >or=10 mmHg diastolic, whereas VVS was diagnosed with a positive HUT test. There was no significant difference in the number of subjects with OH (57 vs. 55%; P = 0.778) or HUT-positive VVS (45 vs. 47%; P = 0.828) between cases with CSH and controls without CSH. Carotid sinus hypersensitivity subjects had significantly larger SBP reduction (P = 0.039) and longer time to nadir (P = 0.007) during active stand, and trends to vasodepressor (P = 0.071) and dysautonomic responses to HUT (P = 0.151). Carotid sinus hypersensitivity, OH, and VVS are common conditions affecting patients with syncope and falls which are likely to co-exist in such individuals. The differences in haemodynamic response patterns to active stand and HUT in CSH subjects could be the result of an age-associated delay in sympathetic responses.

Abstract 4121: Clomipramine Infusion During Tilt Test To Imply The Neurocardiogenic Origin Of Syncopes And Presyncopes Of Unknown Aetiology

The aim of this study was to prospectively evaluate the diagnostic accuracy for neurocardiogenic syncopes (NCS) of two Head-Up Tilt table test (HUT) strategies in 991 patients with syncopes/presyncopes of unknown aetiology after negative clinical and non invasive investigations. HUT is a widely accepted tool in the evaluation of patients with evidence of VVS but questions remain about the sensitivity and the use of provocative agents.Clomipramine (CP), a serotonin re-uptake inhibitor, was recently proposed as a new drug challenge test for the diagnosis of neurocardiogenic syncope (NCS). Group A : the first 341 pts (207 male ; mean age = 49,9 ± 23 years) were passively tilted at 60° for 30 minutes (min), then for 15 min with 2 μg/min isoproterenol infusion rate. Group B : the following 650 pts (383 male ; mean age = 48,3 ± 21 years) were tilted at 60° for 20 min with 5 mg CP infused during the first 5 min of tilt. A positive HUT was defined as reproducting the patient’s syncope or presyncope, associated with an abrupt fall in blood pressure (systolic blood pressure &lt;80 mmHg) and/or concomitant bradycardia (&lt;50 beats/min). Positives responses were classified in 3 types according to the Brignole’s modification of the VASIS classification. There was no significant difference between group A/B in sex or age. Group A : Positive HUT* : 103 (Sensitivity : 30,2%) Group B : Positive HUT* : 382 (Sensitivity : 58,8 %) (*) type 1 : 36 vs 157 ; type 2A : 8 vs 13 ; Type 2B: 9 vs 57 (14,9%) ; Type 3 : 50 vs 155. No adverse effect was noticed. CP during HUT increase significantly the accuracy of the test for NCS diagnosis, especially for type 2B answers, and patients &lt;30 yo. The duration of the test is notably shortened, and the tolerance is remarkable. If previously reported specificity (87 to 94%) was confirmed, CP-HUT might be the most valuable tool in the evaluation of pts with syncopes/presyncopes of unknown aetiology.

Abstract 5963: Prevention of Tilt-Table Induced Vasovagal Response by Angiotensin-Converting Enzyme Inhibition

The use of various pharmacologic agents has been proposed for the preventive treatment of vasovagal syncopal episodes, with conflicting efficacy results from various studies. Angiotensin-converting enzyme inhibitors (ACEIs), although reported in small studies to have a beneficial effect in patients with vasovagal syncope, have not been generally accepted as part of conventional treatment in such patients. Our population consisted of 125 consecutive patients (60 male, mean age 40±15 years), with a positive head-up tilt-table testing (HUTTT) (cardioinhibitory or vasodepressive or mixed response), who were randomized to receive either the ACEI fosinopril (N=63), at a dose of 10 mg qd, or placebo (N=62), for 30 days. They were then submitted to a new HUTTT (80 degrees, before and after infusion of isoproterenol, at a max. rate of 5 mcg/min). Before randomization, the patients were stratified according to the use of other vasoactive agents. Physicians performing the HUTTT were blinded as to each patient’s randomization group. Twenty-eight (44%) of fosinopril-treated patients were positive in the second HUTTT versus 52 (84%) in the placebo group (p=0.015). In a multivariate analysis, entering, apart from the treatment group, patient age, gender, smoking habit, hypertension, the use of beta-blocking agents and various demographic factors, with a negative result in the second HUTTT as the dependent variable, female gender, younger age and the use of fosinopril were independently associated with a negative repeat HUTTT. The present study reports a potential preventive effect of ACEIs in vasovagal syncope and indicates that younger, female patients, taking fosinopril were more likely to have a negative repeat HUTTT. The observed effect may be related to the ability of ACEIs to reduce cardiac wall tension, thus decreasing the activation of C-mechanoreceptors, as well as to their potential to inhibit angiotensin-related catecholamine release.

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

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. 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. 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. 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.

Long QT syndrome patients may faint due to neurocardiogenic syncope.

Syncope in long QT syndrome (LQTS) is expected to be due to Torsades de Pointes ventricular tachycardia (TdP). Often these patients faint in situations with emotional stress. The aim of the present study was to evaluate whether neurocardiogenic syncope occurs in LQTS. Ten untreated consecutive LQTS patients (age 11-72 years, median 37.5 years, five males and five females from five different families (one KvLQT1 mutation, two HERG mutations in three families and one without established genetic background)) were examined by a head-up tilt-table test (HUT). If syncope did not occur within 25 min, the patient received 0.25 mg nitroglycerine sublingually and the HUT was continued for 20 min. Nine out of 10 patients had a positive HUT. The syncope resulted from a combined vasodepressor and bradycardiac response. There were no cases of TdP. No syncope occurred in a 42-year-old asymptomatic male LQTS patient with a borderline prolonged QTc of 0.45 s and a HERG mutation. In 11 of 21 patients referred for syncope without LQTS a positive HUT was found (P < 0.10). Syncope in LQTS can be of neurocardiogenic origin and is not necessarily due to TdP. The reason for neurocardiogenic syncope in LQTS is unknown, but involvement of the autonomic nervous system outside the heart is possible.