Head-up tilt test: A highly sensitive,specific test for children with unexplained syncope

Unexplained syncope may cause diagnostic and therapeutic problems in children. The head-up tilt test has been shown to be a useful tool for investigating unexplained syncope, especially for diagnosis of neurally mediated syncope. In this study 20 patients aged 9–18 years (12.0±2.5 years) with syncope of unknown origin and 10 healthy age-matched children were evaluated by head-up tilt to 60° for 25 minutes. The test was considered positive if syncope or presyncope developed in association with hypotension, bradycardia, or both. If tilting alone did not induce symptoms (syncope or presyncope), isoproterenol infusion was administered with increasing doses (0.02–0.08 μg/kg per minute). During the tilt test, symptoms were elicited in 15 (75%) of the patients with unexplained syncope but in only one (10%) of the control group (p<0.001). The sensitivity of the test was 75% and its specificity 90%. Three patterns of response to upright tilt were observed in symptomatic patients: vasodepressor pattern with an abrupt fall in blood pressure in 67%; cardioinhibitory pattern with profound bradycardia in 6%; and mixed pattern in 27%. In patients with positive head-up tilt, there were sudden decreases in systolic blood pressure (from 130±15 to 61±33 mmHg) and in mean heart rate (from 147±26 to 90±38 beats per minute) (p<0.001) during symptoms. Treatments with atenolol 25 mg/day has shown complete suppression of syncope in positive responders during a mean follow-up period of 18±6 months. The head-up tilt test is a noninvasive, sensitive, specific diagnostic tool for evaluating children with unexplained syncope.     

舌下含化硝酸甘油直立倾斜试验对儿童不明原因晕厥的诊断研究

目的 探讨舌下含化硝酸甘油直立倾斜试验对不明原因晕厥患儿的诊断价值。方法 对25例不明原因晕厥的患儿(晕厥组)及10例无晕厥史的正常健康儿童(对照组)先行基础直立倾斜试验,阴性者再行舌下含化硝酸甘油直立倾斜试验(4～6μg／kg,最大量不超过300μg)。结果 基础直立倾斜试验在晕厥组的阳性率为48％(12／25),对照组为0;舌下含化硝酸甘油直立倾斜试验在晕厥组阳性率为80％(20／25),对照组为20％(2／10);舌下含化硝酸甘油直立倾斜试验诊断的敏感度、特异度及诊断价值均为80％。两组患儿中仅有1例在试验中出现头痛,但能坚持试验完成。结论 舌下含化硝酸甘油直立倾斜试验对诊断儿童血管迷走性晕厥具有良好的敏感性和特异性,且具有操作简便、不良反应小的特点。值得推广应用。     

The value of the head-up tilt table test for with unexplained syncope in children and young adolescents

Syncope occurs in about 15% of children and young adolescents. The diagnosis of syncope of unknown origin is frequently difficult. In 1986, Kenny et al. introduced the Head-up Tilt Table Test (HUT), which enables to reproduce syncope. The aim of the study was to evaluate HUT in diagnosis of syncope in children and young adolescents. Ninety five children and young adolescents (57 females, 38 males, age range 7-18 years) with recurrent syncope of unexplained etiology were referred for HUT. The study group was divided into two subgroups: A--with history consistent with vasovagal syncope (VVS) and B--with non-characteristic symptoms for VVS. HUT was performed according to the Westminster protocol. The patient was tilted at 60 degree for 45 min. or until syncope occurred. Positive response to HUT was 36%. Negative outcome occurred in 59%. Non-diagnostic HUT was observed in 5%. The vasodepressive type of VVS was recognised in 35%, cardioinhibitory in 12% and mixed in 53%. In group A positive response of HUT occurred in 65% of pts., negative in 31%. In group B positive HUT was observed in 4% of pts. and negative in 89%. CONCLUSIONS: 1. In children and young adolescents head-up tilt test is a very useful diagnostic method. 2. In patients referred for the head-up tilt test the history of syncope should be taken into consideration.     

Usefulness of the Head-Up Tilt Test in Distinguishing Neurally Mediated Syncope and Epilepsy in Children Aged 5–20 Years Old

Many nonepileptic disorders may mimic epilepsy by history or clinical presentation. Neurally mediated syncope is one of the most important conditions that might be difficult to differentiate from epilepsy on clinical grounds. We investigated the value of the head-up tilt test (HUT) to diagnose syncope in epileptic children. We studied 40 patients (18 girls and 22 boys) between 5 and 20 years old (mean, 11.5 ± 3.5) who had a previous diagnosis of epilepsy. All patients underwent a HUT test. The HUT test was positive in 26 patients (65%). No statistical difference was observed between the tilt positive and negative groups in sex, age, provocating factors, associated symptoms, family history of syncope and heart disease, findings in physical examination, and electroencephalogram result. There was a history in favor of true syncope in 58% of tilt positive patients compared to 14% of tilt negative patients (p < 0.05). Also, family history of seizure was more frequent in tilt positive patients (p < 0.05). After 18 ± 6 months of follow-up, 18 of 26 patients with a positive tilt test were completely asymptomatic. Inadequate history taking and overemphasis on positive family history for seizures were important causes of misdiagnosis of epilepsy in our study. The HUT test is a simple, noninvasive diagnostic tool for distinguishing syncope and epilepsy in children and should be considered early in the diagnostic plan and for determining management of selected patients with a history of drop attack and loss of consciousness.     

Reproducibility of Head-Up Tilt-Table Testing in Pediatric Patients with Neurocardiogenic Syncope

The aim of this study is to assess the reproducibility of a head-up tilt-table test protocol so it may be used to more accurately evaluate the effectiveness of a treatment protocol. Children between the ages of 10 and 18 years presenting to the cardiology department at Children’s Hospital of Wisconsin with a diagnosis of neurocardiogenic syncope were eligible for the study. The patients were tilted to 70° for 30 minutes or until a positive test occurred. Patients with a positive test were retilted using the same protocol. Parameters measured included heart rate, blood pressure, and the presence or absence of syncope or presyncope. Twenty-two patients were enrolled in the study. Seventeen patients had a positive test on first tilt. Fifteen had a positive tilt test on the second tilt. There were no significant differences between the two tilts with regard to mean differences of baseline heart rate, systolic blood pressure, or mean arterial pressure. There were no significant differences between the two tilts with regard to mean differences in time until symptoms, heart rate, systolic blood pressure, or mean arterial blood pressure at time of symptoms. This study shows that the head-up tilt-table test protocol used is reproducible in adolescents with the diagnosis of neurocardiogenic syncope. D.A. Lewis Deceased     

6岁以下儿童直立倾斜试验探讨

目的：探讨6岁以下儿童直立倾斜试验（HUTT）的临床价值和安全性。方法：对2000年9月至2011年8月对144例因不明原因晕厥、头晕等症状就诊的儿童（年龄2～6岁,男81例,女63例）的HUTT结果进行回顾性分析。结果：（1）HUTT依从性：144例受试儿童中8例仅完成了基础直立倾斜试验,136例完成了舌下含服硝酸甘油倾斜试验。（2）HUTT安全性：受试儿童完成HUTT后均未出现严重副反应。（3）HUTT阳性率：HUTT阳性率为22.2%（32/144）,男童（18例）与女童（14例）阳性率差异无统计学意义（P>0.05）。（4）HUTT阳性反应的处理：HUTT达到阳性诊断标准后,将诊断床放至平卧位,保持呼吸道通畅、鼻导管给氧、口服牛奶等,5 min 内心电图和血压均恢复正常。结论：6岁以下儿童行HUTT在临床上有一定实用价值,具有较好的安全性和依从性。     

Sublingual Isosorbide Dinitrate-Stimulated Tilt Test for Diagnosis of Vasovagal Syncope in Children and Adolescents

Vasovagal syncope is the most likely cause of syncope in the young. Head-up tilt-table test (HUT) provides the ability to provoke vasovagal syncope under controlled laboratory settings. In adult populations, pharmacologic stimulation with intravenous/sublingual isosorbide dinitrate (ISDN) has been shown to be an alternative to isoproterenol for increasing the diagnostic yield of HUT. In this study, 40 patients aged 9-18 years with unexplained syncope and 12 healthy age-matched children were evaluated by HUT to 70 degrees for 45 minutes. If tilting alone did not induce symptoms (syncope and presyncope), 0.1 mg/kg ISDN was given while the patient lay supine. After 5 min, the table was tilted to 70 degrees for 15 min or until the symptoms occurred. The control group consisted of 12 healthy age-matched children studied in a similar manner. Six patients (15%) had a positive basal tilt test. Twenty-five patients (62.5%) lost consciousness following ISDN administration. In the control group, nobody had a syncopal episode during the basal tilt test. However, ISDN administration resulted in 1 positive response (8.3%). The sensitivity of the test was 77.5% and its specificity was 91.6%. It is concluded that sublingual nitroglycerin HUT is suitable for routine clinical practice in children and adolescents with unexplained syncope.     

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目的探讨鉴别血管迷走性晕厥(VVS)及体位性心动过速综合征(POTS)的临床依据。方法 2009年4月至2011年4月于北京大学第一医院儿科门诊就诊并确诊为VVS的儿童40例,年龄6～18岁,平均(11.8±2.9)岁;POTS儿童165例,年龄5～19岁,平均(11.4±2.7)岁。评价与检查手段包括临床表现、家族史、生活习惯、直立试验以及直立倾斜试验。结果 VVS和POTS在儿童时期的共同特征包括学龄期及青春期多发、女孩稍多于男孩、发作季节以夏秋季多见、多数患儿有诱因和发作先兆、发作后仍有不适、平卧后症状可缓解。在VVS儿童中以晕厥为主要表现者明显多于POTS(P<0.001),在POTS儿童中,以头晕为表现的患儿明显多于VVS(P<0.001)。VVS患儿中父方有直立不耐受家族史者明显多于POTS患儿(P<0.05)。结论直立倾斜试验是鉴别VVS与POTS的重要客观检查手段。晕厥及头晕的发生频率对于临床鉴别诊断VVS与POTS具有参考价值。     

儿童体位性心动过速综合征合并血管迷走性晕厥的诊断探讨

目的：探讨儿童体位性心动过速综合征（POTS）合并血管迷走性晕厥（VVS）的诊断。方法：回顾性地复习2007年1月至2010年12月经直立倾斜试验（HUT）诊断为POTS的57例儿童的临床资料,其中男29例,女28例,年龄5～16(12.2±1.9)岁。结果：57例POTS儿童中,在可以耐受倾斜体位的前提下,通过延长HUT时间,24例(42%)经HUT诊断合并VVS,其中血管抑制型20例,混合型3例,心脏抑制型1例。合并VVS儿童平均年龄（13.0±1.4岁）大于未合并VVS的POTS儿童（11.5±2.1岁）,差异有统计学意义（P0.05）。结论：部分POTS儿童合并VVS,在可以耐受倾斜体位的前提下,延长HUT时间有利于防止VVS漏诊。与未合并VVS的POTS儿童比较,合并VVS儿童年龄较大,但性别、临床症状无明显差异。     

The head-up tilt test and the differential diagnosis between epileptic attacks and syncope. Case report

Often patients who have undergone a false diagnosis of epileptic attack have actually been affected by syncope. One of the most common causes of such misdiagnosis is an abnormal interictal electroencephalographic (EEG) trace. The purpose of this paper is to suggest the usefulness of the head-up tilt test as a differential diagnosis between epileptic attack and syncope. Patients underwent the head-up tilt test, which was considered positive only if the syncopal symptomatology was reproduced. The subjects were patients in a neuropsychiatric clinic. Four patients with a positive anamnesis due to brief episodes of unconsciousness and to falls were assessed. All 4 patients showed an abnormal EEG with focal spikes and sharp-waves. The head-up tilt test produced a syncope in all 4 cases. In the symptomatology evoked by the test the patients and their parents recognized the exact same characteristics of those episodes for which they had sought consultation, so a diagnosis of a vasovagal syncope of 3 different types was made. The head-up tilt test proved appropriate to differentiate syncope from epileptic attacks in patients with symptoms of unconsciousness, falls and interictal EEG spikes or sharp-waves.     

Autonomic Changes and Heart Rate Variability in Children with Neurocardiac Syncope

This study evaluated resting autonomic function and autonomic responses to head-up tilt-table testing in children who experienced neurocardiac syncope to determine whether predictable differences existed between these patients and normal volunteers. Neurocardiac syncope is a common cause of syncope in children. The mechanism, though related to abnormalities in autonomic function, has not been fully elucidated, particularly in pediatric patients. This study evaluated resting autonomic tone using noninvasive autonomic function tests (i.e., Valsalva, handgrip, and deep breathing) and 24-hour heart rate variability (HRV). In addition, heart rate and blood pressure were evaluated during head-up tilt examination. Values from patients who experienced neurocardiac syncope were compared to those from age-matched normal volunteers. No significant differences were noted during noninvasive testing. Some time domain HRV variables demonstrated a trend toward significant difference (p < 0.10). Tilt testing data were significantly different in sinus beat to sinus beat (RR) intervals between controls and syncope patients at 2, 5, and 10 minutes after tilting. In addition, significant differences were noted in RR interval and the standard deviation of RR interval 1 or 2 minutes prior to syncope when compared to controls at 5 and 10 minutes after tilting. Children with syncope exhibited abnormalities during tilt testing indicating an increased sympathetic or decreased parasympathetic tone, particularly prior to syncope. Some measures of HRV might constitute noninvasive parameters that correlate with the positive tilt table test.     

直立倾斜试验对不明原因晕厥患儿的诊断价值

目的：讨基础直立倾斜试验对不明原因晕厥(UPS)患儿的诊断价值。方法：UPS患儿30例,年龄6～18岁,平均(11.74±2.82)岁,采用电动倾斜床取头高脚低位直立倾斜70° 后每 5 min自动测量血压和心电变化,评价倾斜试验结果。结果：30例UPS中倾斜试验阳性10例(占 33.3%),反应类型为心脏抑制型及血管抑制型各5例,晕厥发作在倾斜站立10～40 min,平均(24.0±12.2) min。结论：倾斜试验是诊断儿童血管迷走性晕厥(VVS)的有效方法,对临床UPS患儿具有很好地诊断价值。     

Orthostatic intolerance in adolescent chronic fatigue syndrome

OBJECTIVES: To demonstrate the association between orthostatic intolerance and the chronic fatigue syndrome (CFS) in adolescents and to delineate the form that orthostatic intolerance takes in these children. STUDY DESIGN: We investigated the heart rate and blood pressure (BP) responses to head-up tilt (HUT) in 26 adolescents aged 11 to 19 years with CFS compared with responses in adolescents referred for the evaluation of simple faint and to responses in 13 normal healthy control children of similar age. RESULTS: A total of 4/13 of the controls and 18/26 simple faint patients experienced typical faints with an abrupt decrease in BP and heart rate associated with loss of consciousness. One CFS patient had a normal HUT. A total of 25/26 CFS patients experienced severe orthostatic symptoms associated with syncope in 7/25, orthostatic tachycardia with hypotension in 15/25, and orthostatic tachycardia without significant hypotension in 3/25. Acrocyanosis, cool extremities, and edema indicated venous pooling in 18/25. None of the control or simple faint patients experienced comparable acral or tachycardic findings. CONCLUSIONS: We conclude that chronic fatigue syndrome is highly related to orthostatic intolerance in adolescents. The orthostatic intolerance of CFS often has heart rate and BP responses similar to responses in the syndrome of orthostatic tachycardia suggesting that a partial autonomic defect may contribute to symptomatology in these patients.     

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目的探讨儿童体位性心动过速综合征(POTS)的临床特点。方法2008年5月至2009年10月于北京大学第一医院儿科门诊就诊,经直立试验或直立倾斜试验确诊POTS的患儿109例(POTS组),平均年龄(11.79±2.55)岁;20名健康儿童为对照组,平均年龄(11.55±3.65)岁。对每例POTS患儿详细询问病史并进行体格检查,对比分析两组儿童在生活习惯、家族史及体质特征方面特点,总结POTS组患儿发病的临床特征。结果与对照组相比,POTS组患儿在性别比例、年龄、身高、体重、平卧心率、平均动脉压方面差异无统计学意义。POTS患儿主要症状以晕厥多见(52.3%),42.2%症状发作频繁(就诊时>10次),主要症状发生季节以夏秋季多见(42.1%),发作持续时间多在1min以内(29%)。83.5%患儿发作前有诱因,发作诱因以持久站立为多见(50.5%),发作前多伴有先兆症状(78.0%),其中以头晕、黑矇、大汗、面色苍白最为常见。18例(16.5%)患儿有伴随症状,32例(29.4%)发作后仍有不适,以乏力最常见(24例)。90例(82.6%)患儿无既往疾病史,30例(27.6%)有直立不耐受家族史,46例(...     

儿童不明原因晕厥诱因分析

目的：分析儿童不明原因晕厥的常见诱因。方法：详细询问2006年1月至2011年10月就诊的434例不明原因晕厥儿童（3.0～17.9岁,男192例,女242例）的晕厥病史及诱因,分析诱因在不同年龄、性别、晕厥频次、直立倾斜试验（HUTT）结果之间的差异。结果：（1）偶发晕厥常见诱因依次为持久站立（30%）、运动（13%）、体位改变（9%）、坐位（7%）、玩耍（6%）等。①性别比较：持久站立引起的偶发晕厥女性较男性多见(P<0.01）;排尿晕厥主要见于男性;闷热环境主要诱发女性晕厥。②年龄比较：体位改变诱发偶发晕厥在≥12岁组较<12岁组常见（P<0.05）,其余诱因在不同年龄间差异未见统计学意义。③不同HUTT结果比较：体位改变诱发偶发晕厥多见于HUTT阴性组（P<0.05）。（2）所有偶发晕厥诱因均可诱发反复晕厥,56.2%的反复晕厥为同一诱因所致。结论：儿童不明原因晕厥常见诱因为持久站立、运动、体位改变等,临床上避免诱因有助于预防晕厥发作。     

Dysrhythmia as a cause of syncope in children without neurological or cardiac morphological abnormalities

BACKGROUND: Arrhythmias are among the malignant causes of syncope. This study has been undertaken to determine the relative incidence and significance of dysrhythmia in the pathogenesis of syncope among patients referred to a pediatric cardiology unit. METHODS: Between March 1997 and March 1999, 105 consecutive patients (59 female, 46 male) aged 11.5 +/- 3.6 years without neurologic or cardiac morphologic causes were evaluated for at least one episode of syncope. A pediatric cardiologist and a pediatric neurologist evaluated all the patients. Routine chest X-ray, 12-lead electrocardiogram (ECG), electroencephalography (EEG), 24-h Holter monitoring and echocardiography were carried out. When deemed necessary, further tests were undertaken for the cases of syncope which were unexplained by routine tests. RESULT: The cause of syncope was identified as vasovagal in 25.7% (n = 27) and related to dysrhythmia in 30.5% (n = 32). The cause was migraine-associated syncope in two children, psychogenic syncope in three children and orthostatic hypotension in one patient. The cause was unknown in 36.2% (n = 38). CONCLUSION: We conclude that dysrhythmia is a significant and frequent cause in children referred to pediatric cardiology units. The combination of ECG, Holter monitoring, electrophysiologic study, transtelephonic ECG and head-up tilt test can identify the underlying cause of syncope in as many as 58% of these patients that present with syncope.     

Cerebral blood flow during vasovagal syncope induced by active standing or head up tilt.

BACKGROUND: Vasovagal syncope is usually associated with a sudden drop of blood pressure and/or heart rate. However, occasionally the symptoms of syncope induced by orthostatic stress testing are not associated with obvious haemodynamic changes. The mechanisms of syncope in these patients are not clear. AIM: To evaluate changes in cerebral blood flow velocities during orthostatic stress testing in children and adolescents with vasovagal syncope. METHODS: Electrocardiogram, instantaneous arterial blood pressure, and right middle cerebral artery blood flow velocity were recorded at rest, during active standing, and 80 degrees head up tilt. 32 children and adolescents aged between 7 and 18 years with a history of repeated vasovagal syncope and 23 healthy control subjects were studied. RESULTS: Presyncope occurred in 10 patients during standing, and 13 patients during head up tilt. None of the controls had symptoms during the test. The transcranial Doppler study showed that the symptoms were associated with significant decreases of diastolic cerebral blood flow velocity and an increase of pulsatility. There was no significant change of the systolic cerebral blood flow velocity. The changes of cerebral blood flow velocities occurred in all episodes of presyncope, including those not associated with severe drop of blood pressure or heart rate. CONCLUSIONS: Diastolic cerebral blood flow velocity decreased significantly during episodes of presyncope induced by orthostatic stress. Impairment of autoregulation of cerebral blood flow might play an important role in the pathophysiology of syncope.     

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目的应用多普勒超声显像法探讨血管迷走性晕厥(VVS)儿童的血管内皮功能。方法研究对象共20例,均为2002年1月至2003年12月在北京大学第一医院儿科就诊儿童,分为VVS组(n=10)及非VVS对照组(n=10),对10例经直立倾斜试验确诊的血管迷走性晕厥儿童,应用多普勒超声测定肱动脉的血流介导的血管舒张反应,并与10例经直立倾斜试验除外VVS的对照组儿童进行比较。结果两组患儿的年龄、性别、身高、体重、基础血压及基础肱动脉血管内径均无显著性差异,但血管迷走性晕厥儿童的血管内皮依赖性舒张功能较对照组显著增强[(11.93±4.46)%vs(8.46±2.18)%,P<0.05]。结论血管内皮依赖性舒张功能增强可能是儿童血管迷走性晕厥发生机制之一。     

Autonomic nervous system dysfunction in adolescents with postural orthostatic tachycardia syndrome and chronic fatigue syndrome is characterized by attenuated vagal baroreflex and potentiated sympathetic vasomotion

The objective was to determine the nature of autonomic and vasomotor changes in adolescent patients with orthostatic tachycardia associated with the chronic fatigue syndrome (CFS) and the postural orthostatic tachycardia syndrome (POTS). Continuous electrocardiography and arterial tonometry was used to investigate the heart rate and blood pressure responses before and 3-5 min after head-up tilt in 22 adolescents with POTS and 14 adolescents with CFS, compared with control subjects comprising 10 healthy adolescents and 20 patients with simple faint. Heart rate and blood pressure variability, determined baroreceptor function using transfer function analysis, and measured cardiac vagal and adrenergic autonomic responses were calculated using timed breathing and the quantitative Valsalva maneuver. Two of 10 healthy controls and 14 of 20 simple faint patients experienced vasovagal syncope during head-up tilt. By design, all CFS and POTS patients experienced orthostatic tachycardia, often associated with hypotension. R-R interval and heart rate variability were decreased in CFS and POTS patients compared with control subjects and remained decreased with head-up tilt. Low-frequency (0.05-0.15 Hz) blood pressure variability reflecting vasomotion was increased in CFS and POTS patients compared with control subjects and increased further with head-up tilt. This was associated with depressed baroreflex transfer indicating baroreceptor attenuation through defective vagal efferent response. Only the sympathetic response remained. Heart rate variability declined progressively from normal healthy control subjects through syncope to POTS to CFS patients. Timed breathing and Valsalva maneuver were most often normal in CFS and POTS patients, although abnormalities in select individuals were found. Heart rate and blood pressure regulation in POTS and CFS patients are similar and indicate attenuated efferent vagal baroreflex associated with increased vasomotor tone. Loss of beat-to-beat heart rate control may contribute to a destabilized blood pressure resulting in orthostatic intolerance. The dysautonomia of orthostatic intolerance in POTS and in chronic fatigue are similar.     

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??Objective To analyze the cerebral blood flow dynamics of vasovagal syncope??VVS?? by transcranial cerebral Doppler??TCD?? and explore the clinical value of TCD to VVS. Methods A total of 38 children with vasovagal syncope and 20 healthy children received head-up tilt test??HUTT??. In the process of test??they were monitored by TCD. Results Under basic condition??there were no obvious differences between patients and healthy children on the result of TCD. In the process of HUTT for healthy children??there were no obvious differences on the result of TCD. In the process of HUTT for vasovagal syncope children??compared with data of TCD under basic condition??the cerebral blood flow velocity??Vs??Vd??Vm?? and pulse index??PI?? had great improvement when syncope was induced by HUTT. Conclusion Patients with vasovagal syncope have obstacles in terms of cerebral blood flow regulation. TCD can become a routine examination method in those children with vasovagal syncope.