Significance of tilt table testing in patients with suspected arrhythmic syncope and negative electrophysiologic study

BACKGROUND: The diagnostic significance of a tilt table test (TTT) in patients with a suspected arrhythmic etiology for syncope and negative electrophysiologic study (EPS) has not been previously assessed comparing the TTT results with the findings of prolonged monitoring using an implantable loop recorder (ILR). We sought to assess the diagnostic yielding of TTT in patients with suspected arrhythmic syncope and negative EPS. METHODS AND RESULTS: In 81 patients with suspected arrhythmic etiology for syncope and negative EPS, TTT was performed and an ILR implanted regardless the results of TTT. TTT was positive in 38 patients. During follow-up, syncope or presyncope recurred in 32 patients (39.5%). No differences were found in recurrence rates in patients with positive and negative TTT (31.5% vs 46.5%, P = ns). According to rhythm registered during ILR activation, mechanisms of syncopal events were classified as: arrhythmic (atrioventricular [AV] block and ventricular tachycardia; n = 18), neurally mediated (sinus bradycardia and sinus pause; n = 9), and indeterminate (normal sinus rhythm; n = 5). There was no statistical association between the results of TTT and the mechanism of syncope. CONCLUSIONS: In patients with a suspected arrhythmic etiology for syncope and a negative EPS, TTT is of little value to predict the mechanism of syncope and the ILR implantation seems to be a useful and safe diagnostic strategy.     

直立倾斜试验对老年不明原因晕厥患者的诊断价值

目的：探讨直立倾斜试验对老年不明原因晕厥患者的诊断价值。方法：对140例老年不明原因晕厥患者在安静环境下进行直立倾斜试验．持续监测心率和血压变化。结果：140例老年不明原因晕厥患者在直立倾斜试验中,阳性反应80例（男43例．女37例）。其中血管抑制型39例（男21例,女18例）,心脏抑制剂9例（男4例,女5例）,混合刑32例（男18例,女14例）。血管抑制型患者晕厥时与晕厥前相比,血压从（122±14／69±15）mm—Hg下降到（82±15／45±10）mmHg（P〈0．01）;心脏抑制剂患者晕厥前心率为（95±17）次／min．晕厥时下降至（51土8）次／min（P〈0．01）;混合型患者晕厥前心率为（110±21）次／min。晕厥时下降至（63±21）次／min（P〈0．01）,血压从（115±18／65±18）mmHg下降到（83±19／46±10）mmHg（P〈0．01）。结论：直立倾斜试验是诊断老年不明原因晕厥的有效方法,血管抑制型是其最常见的类型．其阳性率和血流动力学模式分布在性别上无显著性差异。     

Reproducibility of head-up tilt test in patients with syncope

As the head-up tilt test (HUT) is employed to verify the efficacy of undertaking a treatment, we prospectively evaluated the reproducibility of positive and negative results, as well as that of the response type in 64 consecutive patients (mean age 34.6 ± 22.9 years) with syncope of unknown cause. Two HUTs (60 min, 75° ), separated by an interval of 9.77 ± 8.21 days, were performed on each patient. Positive responses were reproduced in the second HUT in 54.5% of the patients. A greater reproducibility (84.3%) was observed for negative responses. Of the 31 patients with a negative first test, 5 had a positive response during the second HUT. Using a multivariate analysis, no clinical variable correlated with the reproducibility of positive or negative results. Likewise, neither arterial pressure nor heart rate observed during the test were correlated with reproducibility. Of 18 patients who reproduced positive responses, 12 (66.6%) did so with the same response modality. In three patients with documented monomorphic sustained ventricular tachycardia, which was hemodynamically well tolerated, and in one patient with temporal spike wave activity in the electroencephalogram, HUT was also positive. It was concluded that the low reproducibility of HUT limits its usefulness as a tool for evaluating treatment efficacy. The variability of the type of response suggests a common mechanism leading to cardioinhibitory and vasodepressor reactions. A positive result in only the second study shows the rationale of performing two tests when the first one is negative.     

血管迷走性晕厥直立倾斜试验反应类型研究

目的 观察首次直立倾斜试验阳性．并依据血流动力学特征表现为心脏抑制型和血管减压型晕鳜患者进行直立倾斜试验时血压和心率的反应。方法 对48例心脏抑制型性晕厥和20例血管减压型晕厥患者，间隔1～7d．在相同试验条件下再次行直立倾斜试验，观察血压和心率的再次反应。结果 ①48例心脏抑制型晕厥患者．40例诱发晕厥或晕厥前症状．阳性重复性为83.3％，其中30例仍表现为心脏抑制型晕厥，10例表现为血管减压型和／或混合型晕厥；②20例血管减压型晕厥患者，16例诱发晕厥或先兆晕厥症状，阳性重复性为80％．其中11例仍表现为血管减压型晕厥．5例表现为心脏抑制型和／或混合型晕厥。结论 心脏抑制型和血管减压型晕厥的反应类型可以改变．此类由心脏受体所激发的神经介质反应具有复杂性，有助于我们进一步阐明心脏血管神经源性晕厥的病理生理机制，为临床诊治提供了重要线索。     

Correlation between results of head-up tilt test and clinical features in patients with syncope or presyncope

Background

Head-up tilt test (HUTT) is a well-established diagnostic tool in patients with suspected vasovagal syncope. Identification of factors that predict a positive HUTT result could simplify diagnostic steps. The aim of this study was to assess the correlation between clinical characteristics of patients with suspected neurocardiogenic syncope or presyncope and results of HUTT.

Materials and Methods

The study group consisted of 90 patients (55 men, 35 women; mean age, 43.2 ± 17 years) with a history of syncope or presyncope. Cardiological and neurologic test findings were normal in every patient. The patients were tilted to a 70° position for 45 minutes. If the first phase produced a negative response, the patients received 400 μg of sublingual nitroglycerin for the second phase and continued to be tilted for an additional 15 minutes.

Results

Sixty-four patients had a positive HUTT result, characterized by a vasodepressive response in 26 patients, mixed response in 24 patients, and cardioinhibitory response in 14 patients. In logistic regression analysis, the presence of prodromal symptoms was a predictor of a positive HUTT result (P = .002).

Conclusion

We showed that the prognostic performance of clinical features, including the time interval between the last episode and HUTT, the number of syncope or presyncope episodes, age, and sex, was not ideal. The presence of prodromal symptoms might be more likely to predict a positive response during HUTT.     

倾斜试验中血管迷走性晕厥患者血流动力学和神经激素的变化

目的探讨血管迷走性晕厥患者倾斜试验中血流动力学和神经激素的变化及晕厥触发机制.方法倾斜试验采用平卧10 min和倾斜80°直立30 min.试验阳性标准为晕厥先兆伴收缩期血压<90mm Hg(1 mmHg=0.133 kPa)和/或心率<60次/min.超声心动图于基础平卧,直立2 min和每隔3 min直至试验结束时连续记录左心室收缩末期内径(LVESD),左心室舒张末期内径(LVEDD),短轴缩短分数(SF)和心排出量(CO).同时测量儿茶酚胺血浆浓度.Ⅰ组为正常自愿者且倾斜试验阴性者8例,Ⅱ组为原因不明晕厥伴倾斜试验阴性者8例,Ⅲ组为原因不明晕厥伴倾斜试验阳性者16例.结果3组间年龄、性别以及基础状态下心率、平均动脉压、左心室内径、SF、CO和儿茶酚胺血浆浓度差别不明显.Ⅰ组和Ⅱ组完成了30 min直立试验,Ⅲ组出现阳性反应时间为(10±4)min.直立时各组发生的改变为(1)Ⅰ组和Ⅱ组虽心率明显增加,但血压稳定.Ⅲ组心率增快和血压逐渐下降,终止试验时心率由(110±22)次/min突然降至(82±16)次/min,平均动脉压由(78±14)mmHg降至(50±9)mm Hg,10例为血管抑制性晕厥,6例为混合性晕厥;(2)Ⅰ组和Ⅱ组左心室内径,CO和SF变化不显著;Ⅲ组LVEJDD由基础时(47±5)mm减至(36±6)mm,LVESD由(32±4)mm减至(22±5)mm;SF由(31±2)%增至(39±4)%,与前两组比较差别有显著性;(3)LVEDD和LVESD降低速率Ⅲ组明显大于Ⅰ组和Ⅱ组;(4)肾上腺素浓度在Ⅲ组明显高于前两组,由基础时(18±10)pg/ml达结束时(126±80)pg/ml,去甲肾上腺素在3组均有增高但组间比较无差别.结论血管迷走性晕厥患者倾斜试验中血流动力学和血浆儿茶酚胺浓度发生明显异常改变;左心室容量降低伴肾上腺素异常分泌和SF增强而激发迷走神经反射可能是触发晕厥的主要机制.     

Heart rate variability during head-up tilt test in patients with syncope of unknown origin

BACKGROUND: Analysis of pathophysiological mechanisms responsible for vaso-vagal reaction reveals a close relationship between neurocardiogenic syncope and the preceding abnormalities of autonomic nervous system (ANS). Therefore, the interest in the assessment of heart rate variability (HRV) for detecting and establishing therapy in patients with syncope due to vaso-vagal mechanism is not surprising. AIM: To assess ANS changes during tilt testing in patients with syncope of unknown origin. METHODS: Forty patients (18 males, mean age 34.8+/-15.8 years) with a history of at least two syncopal episodes during the last 6 months and 24 healthy controls underwent tilt testing. Spectral HRV analysis was performed from ECG recorded 5 min before tilting (period A), 5 min after tilting (period B), and 5 min before syncope (or 20-25 min of tilt test when syncope did not occur) (period C). RESULTS: Tilt test was positive in 23 (58%) patients; 12 (30%) had mixed response, 10 (25%) - vasodepressive, and 1 (3%) - cardioinhibitory reaction. The mean time from tilt to syncope was 22.3 minutes. One (4%) control subject developed syncope. In all groups a decrease of LF and HF power, as well as an increase in the LF/HF ratio in response to tilting were observed. The LF/HF values were significantly different between patients with mixed vaso-vagal reaction and controls (1.9 vs 4.2; p=0.04). In the C-B periods the highest decrease in the HF spectra was found in patients with mixed reaction and was significantly greater than in other patients or controls. Also, patients with mixed reaction had the highest increase in LF values which was significantly more pronounced than in patients with vasodepressive reaction (10139.3 vs 466.9; p=0.003). As a result, the change in LF/HF ratio was positive in patients with mixed reaction, controls and patients with negative result of tilt test, and negative - in patients with vaso-depressive syncope, reaching statistical significance between patients with mixed and vaso-depressive response (2.04 vs -0.51; p=0.03). CONCLUSIONS: The pattern of HRV changes during tilt testing depends on the type of vaso-vagal reaction which leads to syncope. The most accurate HRV parameter for identification of patients with reflex syncope is the LF/HF ratio.     

倾斜试验对血管迷走性晕厥的诊断及分型

目的 探讨倾斜试验对血管迷走性晕厥的诊断及分型的意义。方法 ８０例不明原因晕厥患者为病人组,４７例无晕厥病史的健康人作为对照组均采用此试验,包括基础倾斜试验和异丙肾倾斜试验。结果 （１）不明是性主（７６．２５％）明显高于对照组（２９．７９％）,异丙肾滴注后,试验阳性率明显增加,假阳性率相应增加。（２）试验阳性者晕即刻民基础血压比较差异有显著性,而心率比较差异无显著性。（３）在所有试验阳性者中,血管     

不明原因晕厥患者在直立倾斜试验中血流动力学反应模式的研究

目的 探讨不明原因晕厥患者在直立倾斜试验中血流动力学反应模式及构成比例，方法 190例不明原因晕厥患者在安静环境下空腹进行直立倾斜试验。持续监测心电和血压，观察其血压、心率变化，结果 190例不明原因晕厥患者在直立倾斜试验中，经典血管迷走反应者106例（55.8%)，其中混合型12例（6.3%)，心脏抑制型4例（2.1%)，血管减压型90例（47.4%)，正常直立反应者56例（29.4%)，自主神经障碍型10例（5.3%)，体位性心动过速型4例（2.1%)，心脏变时功能障碍型8例（4.2%)，直立性低血压者6例（3.2%)。结论 不明原因晕厥患者在真诚立倾斜试验中以经典血管迷走反应为主，但还存在其他4种异常的血流动力学变化。     

不明原因晕厥患者在直立倾斜试验中的血流动力学研究

目的研究不明原因晕厥患者在直立倾斜试验中的血流动力学改变及其年龄、性别与血流动力学改变的相关性。方法93例不明原因晕厥患者进行基础倾斜试验及硝酸甘油激发试验，持续监测、记录心电、血压变化。分析患者的基本特征及其在倾斜试验早期和倾斜试验过程中的血流动力学反应。结果93例患者均可耐受及完成试验。阳性反应52例（55．9％），其中混合型18例（34．6％）、血管抑制型30例（57．7％）、心脏抑制型4例（7．7％）；阴性反应41例（44．1％），其中正常反应29例（70．7％）、直立体位性心动过速综合征（POTS）4例（9．8％）自主神经反应障碍8例（19．5％），直立位低血压0例。将所有病人按年龄分为3组：A组：≤30岁；B组：31～50岁；C组：≥51岁，随年龄增长，出现变时性不良的可能性增加（OR 0．94095％ CI 0．906-0．975 P=0．001），而随年龄减小，出现心率过度增加的可能性增加（OR 1．10695％ CI 1．034-1．182 P=0．003）。高龄与自主神经反应障碍和混合型血管迷走性晕厥的发生相关，而低龄与血管抑制型血管迷走性晕厥的发生相关（P〈0．01）。性别与倾斜试验的阴性及阳性结果差异元统计学意义（P=0.12）。结论倾斜试验中，年轻人主要表现为心率过度增加，而老年人则多为心率变化不明显。对倾斜试验中血流动力学变化的观察分析、研究年龄性别与血流动力学反应的关系，对明确晕厥原因，选择相应治疗方案具有重要意义。     

Usefulness of head-up tilt test in evaluating patients with syncope of unknown origin and negative electrophysiologic study

The vasovagal nature of syncope, which remained unexplained despite full clinical and electrophysiologic investigation, was evaluated by means of 60 degrees head-up tilt test for 60 minutes. Thirty patients (17 men and 13 women, mean age 65 years, 19 with and 11 without organic heart disease) with 1 to 28 (mean 5) episodes of syncope of unknown origin were studied. Head-up tilt test was considered positive if syncope developed in association with hypotension, bradycardia, or both. During baseline head-up tilt 15 patients (50%) had a positive response. Ten patients had a vasodepressor response (marked hypotension without marked bradycardia) and 5 had a mixed response (marked hypotension with marked bradycardia). None of 8 control subjects became symptomatic during the test. Baseline head-up tilt test was positively reproducible in 10 of 14 patients (71%). Nine of these 10 patients underwent serial head-up tilt tests after drug administration to determine the pathogenesis of vasovagal syncope. Atropine prevented tilt-induced syncope in 3 of 8 patients (37.5%), propranolol in 2 of 8 (25%) and etilephrine in 7 of 7 (100%). Seven patients received long-term drug treatment with drugs selected on the basis of acute drug testing. One responder to atropine received transdermal scopolamine and 6 received etilephrine. None of these 7 patients had syncopal recurrences or death during a mean follow-up of 12 months. Head-up tilt is a very sensitive and highly specific test to unmask susceptibility to vasovagal reaction in patients with syncope of unknown origin. Withdrawal of alpha-sympathetic stimulation is a principal mechanism responsible for vasodilation and syncope during head-up tilt.(ABSTRACT TRUNCATED AT 250 WORDS)     

血管迷走性晕厥患者倾斜试验过程中压力反射敏感性变化及其临床意义

目的：研究血管迷走性晕厥（VS）患发生晕厥时压力反射敏感性（BRS）的变化及其与神经内分泌因素的关系,以探讨BRS的变化在VS发生中的作用。方法：42例不明原因晕厥患,其中基础倾斜试验（HUT）阳性病人22例,阴性20例及20例健康人（HUT呈阴性反应）,进行HUT,在HUT前,HUT结束或阳性反应时,抽取肘静脉血分别测定血浆内皮素（ET）一氧化氮（NO）,去甲肾上腺素（NE）水平,并用新福林法测定（BRS）。结果：HUT（＋）组在晕厥发生时BRS较基础状态明显减弱,在倾斜试验结束时,HUT（＋）组,血浆ET,NO水平较基础水平明显升高,血浆NE水平较基础水平亦有升高趋势。（2）倾斜结束时,HUT（＋）组血浆ET,NO变化与BRS呈负相关,血浆NE浓度变化与BRS无相关。结论：VS患在发生晕厥时BRS减弱;血浆ET,NO水平异常与BRS减弱可能共同参与了VS的发生机制。     

Excessive myocardial contraction in vasovagal syncope demonstrated by echocardiography during head-up tilt test

The purpose of this study was to gain insight into the mechanism of vasovagal syncope and to test the efficacy of theophylline to prevent syncope. Twenty-six patients with vasovagal syncope underwent two-dimensional echocardiography and theophylline test during head-up tilt test. A standard parastemal short-axis view of echocardiography at the level of the papillary muscle was recorded to measure fraction shorting of the left ventricle, and left ventricular end-diastolic and end-systolic dimensions. Heart rate, blood pressure, and symptoms were recorded. There were three groups; Group 1: no syncope with and without isoproterenol (n = 5); Group 2: syncope only after the infusion of isoproterenol (n = 16); Group 3: syncope without isoproterenol (n = 5). Groups 2 and 3 proceeded to theophylline injection (250 mg). The study showed that the 80° tilt induced an increase in heart rate of 6.6 ± 4.0,12.4 ± 6.6, and 25.4 ± 4.5 beats/min in Groups 1,2, and 3, respectively (p < 0.05 in Groups 1 and 2, p < 0.05 in Groups 1 and 3). The addition of isoproterenol during posture change from supine to an 80° tilt made the significant change of fractional shortening from 0.4 ± 5% to 6 ± 13% in Group 2 (p = 0.05), compared with no significant change in Group 1. There were no significant differences in left ventricular end-diastolic dimension and end-systolic dimension in each group between baseline and isoproterenol infusion during posture change. Vasovagal syncope was associated with vigorous myocardial contraction, rather than with contraction against an empty left ventricle. The acute loading of theophylline was not effective in preventing vasovagal syncope.     

Clinical usefulness of head-up tilt test in patients with syncope and intraventricular conduction defect.

Head-up tilt test was performed in 99 patients with syncope of unknown origin and intraventricular conduction defect. Twenty-five per cent had a positive response to tilt with reproduction of spontaneous clinical symptoms. Holter recording revealed paroxysmal atrioventricular (AV) block in three patients. Carotid sinus massage was positive in four patients. An electrophysiological study was performed in 76 patients with abnormal findings in 17 (22%). Thus, vasovagal syncope was the discharge diagnosis in 25 patients (25%). Therefore, tilt test should be considered in patients with intraventricular conduction defect presenting with syncope of unknown origin, especially if clinical findings suggest the possibility of a vasovagal mechanism, or if the results of the electrophysiological study are inconclusive.     

A comparison of non-invasive continuous finger blood pressure measurement (Finapres) with intra-arterial pressure during prolonged head-up tilt

Simultaneous intra-radial and non-invasive (Finapres, Ohmeda)blood pressures were compared during prolonged head-up tilt,in eight patients (mean age 49 years) with malignant vasovagalsyncope. Twelve tilts were performed, of which eight resultedin vasovagal syncope. The mean bias (difference between Finapresand intra-arterial pressures) for systolic pressure was +0.7mmHg (standard deviation 11.3 mmHg) and for diastolic pressurewas +5.4 mmHg (standard deviation 7 mmHg). The within-tilt precision(standard deviation of the bias) of the non-invasive measurementsvaried between 2.9–12.4 mmHg (median 4.5 mmHg) for systoliccomparisons, and 1.6–8.4 mmHg (median 4.4 mmHg) for diastoliccomparisons. In all but one tilt highly significant positiveincreases in both systolic (median 7.1 mmHg) and diastolic bias(median 81 mmHg) occurred on tilt with respect to resting pre-tiltlevels. Independent of the absolute level of agreement, thenon-invasive measurements followed changes in intra-arterialpressure closely, with 89% of beat-to-beat changes in systolicpressure, and 95% of beat-to-beat changes in diastolic pressurefollowed to within ±2 mmHg. This study suggests thatthe Finapres is well suited for use during diagnostic tilt testing,demonstrating an acceptable within-tilt precision and closelyfollowing pressure changes during vasovagal syncope.     

对拟诊血管迷走性晕厥患者进行直立倾斜试验的时程

目的 探讨直立倾斜试验的不同阶段诱导出阳性反应的合适时程.方法 回顾性分析因临床拟诊血管迷走性晕厥而进行直立倾斜试验的773例患者检查资料.直立倾斜试验分为30 min的倾斜位(70°)基础试验阶段和20 min的药物(硝酸甘油0.2 mg舌下含化)激发阶段.结果 直立倾斜试验阳性率为55.2%,其中43例(10.1%)患者阳性反应出现在基础试验阶段,384例(89.9%)出现在药物激发阶段.在基础试验阶段,阳性反应中2例(4.7%)发生在倾斜位7.5 min以后;随着时间延长,阳性反应比例逐渐增加,9例(20.9%)在22.5 min达到最高,之后逐渐下降;93%的阳性反应发生在倾斜位10～25 min内.在硝酸甘油激发阶段,阳性反应发生率在服药后迅速上升,35.7%在10 min达到最高,之后迅速下降;96.1%的阳性患者发生阳性反应在服药后的15 min内.结论 直立倾斜试验的倾斜位时间至少25 min,而药物激发阶段时间至少15 min,继续增加时间并不能明显提高阳性率.

Abstract：

Objective To investigate the time course of positive head-up tilt test (HUTT) for patients with suspected vasovagal syncope.Methods Consecutive patients referred to the syncope unit of our center for recurrent unexplained syncope were included. The HUTT consisted of a 30 minute passive basic phase and a 20 minute sublingual nitroglycerin provocation phase if syncope did not develop during the passive phase.Results Positive HUTT was observed in 427 out of 773 consecutive patients (55.2%) patients including 43 patients (10.1%) during the passive basic phase and 384 patients (89.9%) during the nitroglycerin provocation phase. During the basic phase, the positive Hutt developed at 7.5 minute (n=2) and peaked at 22.5 th minute (20.9%, n=9) and then decreased gradually. Most positive reactions (93.0%, n=40) occurred between the 10 and 25 minutes during the basic phase. During the nitroglycerin provocation phase, the percentage of positive reactions increased rapidly after sublingual nitroglycerin, peaked at the 10th minute (35.7%, n=137) and decreased thereafter. Most positive reactions (96.1%, n=369) occurred within the first 15 minutes of provocation phase.Conclusion The appropriate duration for HUTT test could be modified to a 25 minutes passive basic phase plus 15 minutes nitroglycerin provocation phase.     

The application of a standardized strategy of evaluation in patients with syncope referred to three syncope units.

BACKGROUND: The appropriate diagnostic work-up of patients with syncope is not well defined. We applied the guidelines of Italian 'Associazione Nazionale Medici Cardiologi Ospedalieri' to a group of consecutive patients with syncope referred to three Syncope Units. The aim of the study was to evaluate the applicability of those guidelines in the 'real world' and their impact on the use of the tests. METHODS: We evaluated 308 consecutive patients with syncope (mean age 61 +/- 20 years; median of three syncopal episodes per patient). The hierarchy and appropriateness of diagnostic tests and the definitions of the final diagnosis followed standardized predefined criteria. In brief, all patients underwent initial evaluation consisting of history, physical examination, supine and upright blood pressure measurement and standard electrocardiogram (ECG) (only in patients > 45 years or with history of heart disease). Any subsequent investigations were based on the findings of the initial evaluation. Priority was given to cardiological tests (prolonged ECG monitoring, exercise test, electrophysiological study), or to neurally mediated tests (carotid sinus massage, tilt test, ATP test), or to neuro-psychiatric tests, as appropriate. FINDINGS: The initial evaluation alone was diagnostic in 72 patients (23%). One further test was necessary for diagnosis in 65 patients (21%), > or = 2 tests in 64 (21%) and > or = 3 tests in 50 (16%). The diagnostic yield was 10% for ECG, 3% for echocardiogram, 16% for Holter, 5% for exercise test, 27% for electrophysiological study, 57% for carotid sinus massage, 52% for tilt testing and 15% for ATP test. At the end of the work-up the mechanism of syncope remained unexplained in 57 patients (18%). CONCLUSIONS: When standardized criteria based on the appropriateness of indications are used, few simple tests are usually needed for diagnosis of syncope.     

Cerebrovascular blood flow during the near syncopal phase of head-up tilt test: a comparative study in different types of neurally mediated syncope.

AIMS: This study analyses the changes in cerebral blood flow (CBF) velocity occurring in the near syncopal phase of head-up tilt test (HUT) to determine whether their appearance during the premonitory symptoms permits the differentiation of the different types of haemodynamic response. METHODS AND RESULTS: Six hundred and nineteen patients aged 35.9 +/- 16.4 with a prior history of syncope (55%) or presyncope (45%) were studied. Head-up tilt test was positive in 585 patients. The test was interrupted before syncope, once hypotension was evident and CBF changed. A vasovagal reaction (VVR) was observed in 245 patients. They had a 59% fall in diastolic CBF velocity, whereas systolic CBF velocity decreased by 12%. Postural orthostatic tachycardia syndrome (POTS) was observed in 82, systolic and diastolic CBF velocity decreased 44 and 60%, respectively. A similar response was observed in 258 patients with the orthostatic intolerance (OI) pattern. No significant changes were observed in the negative group. CONCLUSION: Patients with VVR had changes in CBF velocity, which are different from those presented by patients with POTS and OI pattern. Cerebral blood flow monitoring is useful to increase the yield of HUT and may allow early interruption before syncope occurs, reducing patient discomfort.     

Long-term outcome of patients with asystole induced by head-up tilt test.

AIMS: To analyse the long-term outcome of the largest reported cohort of patients presenting asystole during head-up tilt test. METHODS AND RESULTS: Since 1990, 1322 patients with syncope of unknown origin have undergone tilt-table testing. Of those, 330 patients (24 X 9%) presented an abnormal response (syncope or pre-syncope). Furthermore, 58 of those patients (17 X 5%) suffered a period of asystole (> or = 3000 ms) during the test. Asystole (median (interquartile range)) lasted 10 (4, 19 X 2) s (range 3-90). Two different protocols (angles) of tilting (Westminster (60 degrees) n=1124; isoproterenol (80 degrees) n=198)) influenced the time to the syncopal episode (13 (6 X 5, 20 X 5) vs 2 (1, 6 X 5) min, P=0,0005) but not the duration of the asystole. During this period, therapy for asystole featured three different stages: first patients were treated with pacemakers; later drug therapy (metoprolol and/or etilefrine) was recommended; lastly (from 1995), no specific treatment was given. In a cohort age- and gender-matched study, those patients without were compared to those with asystole in a 2:1 basis. During 40 X 7 months of follow-up (17 X 7, 66 X 8), 12 patients (20 X 6%) with asystole had syncopal recurrences. Furthermore, 34 patients (28 X 8%) without asystole presented syncopal episodes during a follow-up of 51 X 6 months (29 X 3, 73 X 1) (P=ns). The Kaplan-Meier analysis in patients with and without asystole showed a mean time free of recurrence of 92 X 6 +/- 6 months vs 82 X 6 +/- 4 X 7 months (P=ns). The previous number of syncopes had a significant relationship with recurrences (P=0 X 002), but not therapy. There were no cardiac related deaths. CONCLUSIONS: (1) Asystole during head-up tilt test does not imply a malignant outcome and syncope recurrence is low; (2) pacemaker or drug therapy do not significantly influence outcome which correlates to the previous number of syncopal episodes but not to gender, age, asystole occurrence, asystole duration and timing to asystole during head-up tilt test; (3) tilting protocol (angle) might influence time to and incidence of asystole during head-up tilt test.     

Swallow syncope associated with complete atrioventricular block and vasovagal syncope

A 21 year old man presented with multiple, recurrent episodes of complete atrioventricular (AV) block associated with swallowing. Electrophysiological study revealed an AV block with swallowing of carbonated beverages and balloon inflation in the lower oesophagus. Evaluation did not demonstrate any underlying oesophageal or cardiac disease, and the AV block was not induced after intravenous atropine administration. The AV block was probably caused by a hypersensitive vagotonic reflex triggered by mechanical receptors in the lower oesophagus, resulting in suppression of the AV node. Head up tilt test revealed an increase in the high frequency spectrum of heart rate variability before the onset of the syncope. These findings suggest that the amplitude of the continual fluctuations in response to a variety of stimuli and derangement from both intrinsic and extrinsic environments was greater in this patient than in normal subjects. Swallow syncope is an unusual but treatable disorder. These reflexes that become exaggerated to the point of causing illness are poorly understood.


Keywords: swallow syncope; AV block; electrophysiological study; head up tilt test