浅析血管迷走性晕厥患者的临床诊治

血管迷走性晕厥是不伴有器质性病变,以心脏神经调节功能异常为主的一种疾病。其临床表现差异大,可见胸痛、胸闷、心悸、头晕、出汗、恶心及晕厥等多种症状,伴心率时快时慢,血压偏低等体征,故疾病指征特异性差,易导致临床误诊及漏诊。其主要发病机制为各种原因引起交感神经兴奋,迷走神经反射性张力增高抑制交感神经过度,而出现的"矫枉过正"现象。随着医疗技术迅速发展,对血管迷走性晕厥的检查技术也越来越多,其中以直立倾斜试验最为常用。治疗上有药物治疗和神经消融,以药物治疗为主。     

临床护理路径在倾斜试验中对不明原因晕厥老年人的应用

晕厥(syncope)是临床常见症状,可由许多原因引起。临床护理路径(Clinical Nursing Pathway,CNP)是近年发展起来的一种标准化护理方法。我院2011年6月～2012年5月对33例不明原因引起晕厥的老年患者进行倾斜试验,试验前采用临床护理路径模式,制定针对老年人合理的整体护理计划,加强了健康宣教,有效地指导了护士正确掌握操作     

血浆内皮素配合描记动态脑电图在儿童晕厥诊断中应用的临床意义

摘要 目的：探究血浆内皮素配合描记动态脑电图在儿童晕厥诊断中的应用意义。方法：选择2017年1月至2020年1月于我院接受治疗的83例存在晕厥风险儿童,采集其静脉血样进行血浆内皮素水平测定,并实施动态脑电图检测,而后以倾斜试验结果为金标准,分别分析单纯血浆内皮素、单纯动态脑电图以及血浆内皮素+动态脑电图对晕厥的诊断应用意义。结果：（1）83例入组儿童中阳性为68例,阴性为15例,血浆内皮素检测阳性51例,阴性32例,一致性为77.11 %,灵敏度为73.53 %,特异度为93.33 %,阳性预测值为98.04 %, 阴性预测值为43.75 %;（2）动态脑电图诊断一致性为78.31 %,灵敏度为80.88 %,特异度为66.67 %,阳性预测值为91.67 %,阴性预测值为43.48 %;（3）联合检测诊断一致性为93.98 %,灵敏度为94.12 %,特异度为93.33 %,阳性预测值为98.46 %,阴性预测值为77.78 %;（4）检测方式差异性比较发现,联合检测在一致性、灵敏度、阴性预测值方面明显优于血浆内皮素和动态脑电图检测,在特异度方面优于动态脑电图检测（P<0.05）。结论：血浆内皮素联合描记动态脑电图对儿童晕厥具有较好的诊断辅助价值,能够显著提高诊断的一致性、灵敏度和特异度。     

体位性心动过速综合征儿童P波离散度

目的:比较体位性心动过速综合征(POTS)晕厥患儿与非体位性心动过速综合征晕厥患儿体表12导联心电图P波离散度。探讨P波离散度作为心电学标志在体位性心动过速综合征患儿中的意义。方法:2016年7月至2018年1月对我院门诊晕厥患儿186例行基础直立倾斜试验(HUTT)。取单纯体位性心动过速阳性反应作为HUTT-POTS组,共45例,HUTT阴性反应作为HUTT-(-)组,共39例。体位性心动过速阳性反应标准:平卧时心率在正常范围,直立倾斜试验的10分钟内心率较平卧位增加大于等于40次/分和(或)心率最大值达到标准(6～12岁大于等于130次/分,13～18岁大于等于125次/分);同时收缩压下降幅度小于20 mm Hg,舒张压下降幅度小于10 mm Hg。测量两组患儿平卧位12导联心电图P波离散度(PWD,PWD=Pmax-Pmin)并比较。结果:HUTT-POTS组男性比例为51%。两组患儿年龄、性别、体重指数间差异无统计学意义。两组患儿平卧位收缩压、舒张压、心率间差异无统计学意义。PWD在HUTT-POTS组(35.22±9.53 ms)较HUTT-(-)组(15.5±6.47 ms)增高,P0.01,两组患儿PWD差异有显著统计学意义。结论:PWD可以作为体位性心动过速综合征患儿自主神经功能紊乱的心电学标志。     

MSCTA对基底动脉变异的初步研究及其临床意义

目的:研究MSCT血管成像对基底动脉变异的诊断价值,并探讨其临床意义.方法:回顾性分析MSCT血管成像诊断基底动脉变异120例.所有患者均采用GELightSpeed64层螺旋CT对其头颈部动脉进行CT血管成像扫描,将获得的原始数据传入AW4.2P后处理工作站,血管重建技术包括容积再现(VR)、最大密度投影(MIP)、多平面重建(MPR)及曲面重建(CPR),影像分析采用智能血管分析与目测法相结合.结果:基底动脉走行弯曲50例(42%),包括左侧凸30例(25%)、右侧凸例15例(占12.5%)、S型凸5例(3.5%);基底动脉起止点变异47例(39.3%),其中起点变异35例(29.3%)、终点变异12例(10%);基底动脉形态变异14例(11.7%),其中开窗型lO例(8.3%)、管径粗大2例(占1.7%)、管径细小2例(1.7%);基底动脉主要分支变异9例(7.5%).结论:MSCT血管成像是一种无创性诊断基底动脉变异的有效方法,能够解释临床上部分不明原因的基底动脉供血不足,具有重要的临床意义.     

心脏磁共振在不明原因脑卒中病因筛查中的应用

目的探讨心脏磁共振成像技术在不明原因缺血性脑卒中患者病因筛查中的应用价值。方法选取2014年9月~2015年2月在我院诊治的不明原因缺血性脑卒中患者53例为研究对象,均行心脏MRI和经胸超声心动图检查,并对检查出卵圆孔未闭(PFO)的患者进行分析。结果 53例不明原因缺血性脑卒中患者中,心脏MRI检查诊断合并PFO为27例(50.94%),经胸超声动图(TTE)检查诊断合并PFO为7例(13.21%),差异有统计学意义(P0.001)。结论心脏MRI对PFO的检出率较高,可作为不明原因缺血性脑卒中患者病因筛查的有效手段。     

胃食管反流性咳嗽的临床诊断分析

目的:探讨胃食管反流(GER)性咳嗽的临床特征、诊断和治疗.方法:对33例X线胸片、组胺激发试验、鼻部检查正常的慢性咳嗽患者进行24 h食管pH监测,并利用症状相关性概率(SAP)来分析咳嗽与反流的相关性.对Demeester总积分≥14.72,和(或)咳嗽与反流SAP≥75%者进行为期12周的抗反流治疗.结果:33例患者中,有23例诊断为GER性咳嗽,并给予抗反流治疗,完成疗程后,有12例患者咳嗽完全消失,咳嗽与反流的SAP(上电极为0.80±0.18,下电极为0.87±0.11)显著高于另11例对抗反流治疗反应较差或无效的患者(上电极为0.39±0.27,下电极为0.48±0.31;P＜0.05).结论:GER是不明原因慢性咳嗽的一个重要的独立原因.24 h食管pH监测结合症状相关性分析有助于GER性咳嗽的诊断,抗反流治疗对其有较好的近期疗效.     

全血γ干扰素释放试验在儿童和成人中的结核病诊断价值

为研究全血γ干扰素释放试验试剂盒QuantiFERON-TB Gold In-Tube(QFT-GIT)在中国(属结核病高发、卡介苗高接种地区)成人和儿童中的结核病诊断价值,入组临床怀疑结核病的儿童和成人患者各60例,进行QFT-GIT检测,并收集临床资料进行诊断分类。结果显示,在儿童中QFT-GIT诊断灵敏度为83.87%、特异度为92.00%、阳性预测值(PPV)为92.86%、阴性预测值(NPV)为82.14%;在成人中诊断灵敏度为78.57%、特异度为84.62%、PPV为84.62%、NPV为78.57%。结果证实QFT-GIT具有良好的结核病诊断价值,尤其在儿童中的诊断价值高于成人。     

家长健康教育及护理干预在减少儿童百白破疫苗接种不良反应中的作用

目的:通过对接种百白破疫苗后儿童不良反应发生情况进行比对工作,以探讨家长健康教育以及护理干预实际应用价值。方法:选取某院预防保健科2012年6月至2014年6月400例接种百白破疫苗的儿童作为研究对象,按照接种时间分为对照组与研究组各200例,对照组采用常规护理干预;研究组在采用常规护理干预基础上进行家长健康教育,比较两组儿童不良反应发生情况。结果:研究组通过采用家长健康教育及护理干预,儿童弱反应4例(2%)、中反应1例(0.5%)、强反应0例、总体不良反应5例(2.5%),明显低于对照组12例(6%)、5例(2.5%)、2例(1%)、19例(9.5),取得了比较理想的预防效果,两组儿童比对数据经过统计学处理具有统计学意义(P0.05)。结论:对接种百白破疫苗的儿童进行护理干预并对家长进行健康教育,能够有效降低儿童不良反应发生率,具有较高的使用价值,值得临床推广使用。     

血清CRP与PCT在儿童血液细菌感染诊断中的临床应用

目的:研究血清C-反应蛋白(CRP)与降钙素原(PCT)在儿童血液细菌感染诊断中的价值,为临床诊疗提供依据。方法:选取2012年1月到2016年1月我院收治的血液细菌感染患儿84例为研究组,另选取同期健康体检儿童106例为对照组。检测两组儿童血清CRP和PCT水平,并观察血清CRP和PCT的阳性预测值、阴性预测值、灵敏度和特异度。结果:研究组血清CRP、PCT水平和阳性率均显著高于对照组,比较差异具有统计学意义(P0.05);血清PCT诊断的特异度、灵敏度、阴性预测值和阳性预测值分别为84.91%、92.86%、93.75%、82.98%,均分别显著高于血清CRP的67.92%、50.00%、63.16%、55.26%,比较差异均具有统计学意义(P0.05)。结论:血清CRP和PCT对儿童血液细菌感染均具有一定诊断价值,但是血清PCT的诊断效能更高。     

Usefulness of tilt testing in children with syncope: a survey of pediatric electrophysiologists

The role of tilt table testing as a diagnostic modality in children with unexplained syncope is unclear. We sent a questionnaire to members of the Pediatric and Congenital Electrophysiology Society to assess the current practice pattern. Of the 186 members, 97 (52%) replied. Twenty four percent of the pediatric electrophysiologists have completely stopped doing tilt table tests and of those performing the tests, a majority (76%) did < 10 tests/yr (median=3 tilts/yr, range 0-100/yr). Of those performing the test, 95% rarely or never accepted direct referrals from the general practioners and 62% felt that the frequency of tilt table tests being performed had decreased since they had started practicing. The median usefulness of the test was rated at 3 (range 1-9) on a scale of 1 to 10 with 10 being very useful. A majority (68%) felt they rarely or never altered treatment based on the results of the tilt test. Wide variability was noted in the test protocol including the tilt angle, tilt duration, use of pharmacologic agents and the duration of fasting prior to the test. We therefore conclude that there is significant lack of standardization in tilt table tests performed in children. Tilt table testing, as perceived by pediatric electrophysiologists, is of limited utility and progressively less used in children with syncope.     

Response of plasma renin activity to postural change in vasovagal syncope in children, with observations on syncope

37 children aged 7-14 years with a history of repetitive fainting (vasovagal syncope) were studied. Plasma renin activity (PRA), blood pressure and heart rate were measured before and after standing for 15 min. Standing PRA was significantly higher in cases of fainting (n = 14) than in cases of nonfainting (n = 23). A significant positive correlation was observed between PRA and fall in systolic blood pressure on standing in cases of fainting, but not in cases of nonfainting. These findings suggest that the renin-angiotensin system may respond to the fall in blood pressure in children subject to fainting, unlike their adult counterparts previously reported.     

Randomized Prospective Comparison of Two Protocols for Head-up Tilt Testing in Patients with Normal Heart and Recurrent Unexplained Syncope

BackgroundThis randomized study was aimed to compare the diagnostic value of two head-up tilt testing protocols using sublingual nitroglycerin for provocation in patients with recurrent unexplained syncope and normal heart.MethodsThe patients with normal findings in physical examination, electrocardiography and echocardiography were randomly submitted to one of upright tilt test protocols. The only difference between two protocols was that nitroglycerin was administered after a five minute resting phase in supine position during protocol B. We also considered eighty normal persons as the control group.ResultsOut of 290 patients that underwent tilt testing, 132 patients were in group A versus 158 patients in group B. Both groups had an identical distribution of clinical characteristics. Tilt test was positive in 79 patients in group A (25 in passive phase, 54 in active phase) versus 96 patients in group B (43 in passive phase, 53 in active phase). There was no significant difference between results in two groups (P value = 0.127). Forty cases were tested with protocol A and forty underwent tilt testing with protocol B. Tilt test was positive in 4 cases with protocol A versus 3 cases in protocol B. The positive rates of tilt testing with protocol A was 60% while it was 61% in protocol B. The specificity of testing with protocol A was 90% and it was 92.5% in protocol B.ConclusionsAccording to our data, adding a period of rest and returning to supine position before nitroglycerin administration had no additional diagnostic yield.     

Syncope, cerebral perfusion, and oxygenation.

During standing, both the position of the cerebral circulation and the reductions in mean arterial pressure (MAP) and cardiac output challenge cerebral autoregulatory (CA) mechanisms. Syncope is most often associated with the upright position and can be provoked by any condition that jeopardizes cerebral blood flow (CBF) and regional cerebral tissue oxygenation (cO(2)Hb). Reflex (vasovagal) responses, cardiac arrhythmias, and autonomic failure are common causes. An important defense against a critical reduction in the central blood volume is that of muscle activity ("the muscle pump"), and if it is not applied even normal humans faint. Continuous tracking of CBF by transcranial Doppler-determined cerebral blood velocity (V(mean)) and near-infrared spectroscopy-determined cO(2)Hb contribute to understanding the cerebrovascular adjustments to postural stress; e.g., MAP does not necessarily reflect the cerebrovascular phenomena associated with (pre)syncope. CA may be interpreted as a frequency-dependent phenomenon with attenuated transfer of oscillations in MAP to V(mean) at low frequencies. The clinical implication is that CA does not respond to rapid changes in MAP; e.g., there is a transient fall in V(mean) on standing up and therefore a feeling of lightheadedness that even healthy humans sometimes experience. In subjects with recurrent vasovagal syncope, dynamic CA seems not different from that of healthy controls even during the last minutes before the syncope. Redistribution of cardiac output may affect cerebral perfusion by increased cerebral vascular resistance, supporting the view that cerebral perfusion depends on arterial inflow pressure provided that there is a sufficient cardiac output.     

Permanent cardiac pacing for neurocardiogenic syncope

Vasovagal syncope is not a benign condition in the elderly population. In patients not responsive to conservative therapy and whose abrupt faints are associated with serious injuries and seriously affected quality of life, pacemaker therapy was suggested. However, the usefulness of cardiac pacing for the prevention of recurrences of vasovagal syncope remains controversial because of the dominant role of the vasodepressor component during the episode. In the Medical Center Alkmaar, the Head-Up Tilt Test (HUTT) has been used since 1996 during the work-up of patients who present with vasovagal syncope. The HUTT showed a dominant cardioinhibitory response in 4.5% of our patients; in elderly patients with vasovagal syncope without prodromal symptoms and refractory on conservative therapy, pacemaker therapy was very effective in preventing syncope during long-term follow-up. (Neth Heart J 2008;16(suppl 1):S15-S19.)     

Physiological phenomenology of neurally-mediated syncope with management implications

Background

Due to lack of efficacy in recent trials, current guidelines for the treatment of neurally-mediated (vasovagal) syncope do not promote cardiac pacemaker implantation. However, the finding of asystole during head-up tilt –induced (pre)syncope may lead to excessive cardioinhibitory syncope diagnosis and treatment with cardiac pacemakers as blood pressure is often discontinuously measured. Furthermore, physicians may be more inclined to implant cardiac pacemakers in older patients. We hypothesized that true cardioinhibitory syncope in which the decrease in heart rate precedes the fall in blood pressure is a very rare finding which might explain the lack of efficacy of pacemakers in neurally-mediated syncope.

Methods

We studied 173 consecutive patients referred for unexplained syncope (114 women, 59 men, 42±1 years, 17±2 syncopal episodes). All had experienced (pre)syncope during head-up tilt testing followed by additional lower body negative suction. We classified hemodynamic responses according to the modified Vasovagal Syncope International Study (VASIS) classification as mixed response (VASIS I), cardioinhibitory without (VASIS IIa) or with asystole (VASIS IIb), and vasodepressor (VASIS III). Then, we defined the exact temporal relationship between hypotension and bradycardia to identify patients with true cardioinhibitory syncope.

Results

Of the (pre)syncopal events during tilt testing, 63% were classified as VASIS I, 6% as VASIS IIb, 2% as VASIS IIa, and 29% as VASIS III. Cardioinhibitory responses (VASIS class II) progressively decreased from the youngest to the oldest age quartile. With more detailed temporal analysis, blood pressure reduction preceded the heart-rate decrease in all but six individuals (97%) overall and in 10 out of 11 patients with asystole (VASIS IIb).

Conclusions

Hypotension precedes bradycardia onset during head-up tilt-induced (pre)syncope in the vast majority of patients, even in those classified as cardioinhibitory syncope according to the modified VASIS classification. Furthermore, cardioinhibitory syncope becomes less frequent with increasing age.     

Decrease in cardiac output and muscle sympathetic activity during vasovagal syncope

The importance of cardiac output (CO) to blood pressure level during vasovagal syncope is unknown. We measured thermodilution CO, mean blood pressure (MBP), and leg muscle mean sympathetic nerve activity (MSNA) each minute during 60 degrees head-up tilt in 26 patients with recurrent syncope. Eight patients tolerated tilt (TT) for 45 min (mean age 60 +/- 5 yr) and 15 patients developed syncope during tilt (TS) (mean age 58 +/- 4 yr, mean tilt time 15.4 +/- 2 min). In TT patients, CO decreased during the first minute of tilt (from 3.2 +/- 0.2 to 2.5 +/- 0.3 l x min(-1) x m(-2), P = 0.001) and thereafter remained stable between 2.5 +/- 0.3 (P = 0.001) and 2.4 +/- 0.2 l x min(-1) x m(-2) (P = 0.004) at 5 and 45 min, respectively. In TS patients, CO decreased during the first minute (from 3.3 +/- 0.2 to 2.7 +/- 0.1 l x min(-1) x m(-2), P = 0.02) and was stable until 7 min before syncope, falling to 2.0 +/- 0.2 at syncope (P = 0.001). Regression slopes for CO versus time during tilt were -0.01 min(-1) in TT versus -0.1 l x min(-1) x m(-2) x min(-1) in TS (P = 0.001). However, MBP was more closely correlated to total peripheral resistance (R = 0.56, P = 0.001) and MSNA (R = 0.58, P = 0.001) than CO (R = 0.32, P = 0.001). In vasovagal reactions, a progressive decline in CO may contribute to hypotension some minutes before syncope occurs.     

Respiration drives phase synchronization between blood pressure and RR interval following loss of cardiovagal baroreflex during vasovagal syncope

Loss of the cardiovagal baroreflex (CVB), thoracic hypovolemia, and hyperpnea contribute to the nonlinear time-dependent hemodynamic instability of vasovagal syncope. We used a nonlinear phase synchronization index (PhSI) to describe the extent of coupling between cardiorespiratory parameters, systolic blood pressure (SBP) or arterial pressure (AP), RR interval (RR), and ventilation, and a directional index (DI) measuring the direction of coupling. We also examined phase differences directly. We hypothesized that AP-RR interval PhSI would be normal during early upright tilt, indicating intact CVB, but would progressively decrease as faint approached and CVB failed. Continuous measurements of AP, RR interval, respiratory plethysomography, and end-tidal CO2 were recorded supine and during 70-degree head-up tilt in 15 control subjects and 15 fainters. Data were evaluated during five distinct times: baseline, early tilt, late tilt, faint, and recovery. During late tilt to faint, fainters exhibited a biphasic change in SBP-RR interval PhSI. Initially in fainters during late tilt, SBP-RR interval PhSI decreased (fainters, from 0.65±0.04 to 0.24±0.03 vs. control subjects, from 0.51±0.03 to 0.48±0.03; P<0.01) but then increased at the time of faint (fainters=0.80±0.03 vs. control subjects=0.42±0.04; P<0.001) coinciding with a change in phase difference from positive to negative. Starting in late tilt and continuing through faint, fainters exhibited increasing phase coupling between respiration and AP PhSI (fainters=0.54±0.06 vs. control subjects=0.27±0.03; P<0.001) and between respiration and RR interval (fainters=0.54±0.05 vs. control subjects=0.37±0.04; P<0.01). DI indicated respiratory driven AP (fainters=0.84±0.04 vs. control subjects=0.39±0.09; P<0.01) and RR interval (fainters=0.73±0.10 vs. control subjects=0.23±0.11; P<0.001) in fainters. The initial drop in the SBP-RR interval PhSI and directional change of phase difference at late tilt indicates loss of cardiovagal baroreflex. The subsequent increase in SBP-RR interval PhSI is due to a respiratory synchronization and drive on both AP and RR interval. Cardiovagal baroreflex is lost before syncope and supplanted by respiratory reflexes, producing hypotension and bradycardia.     

Arterial hemodynamics during head-up tilt in conscious dogs

The purpose of this study was to measure the major arterial hemodynamic responses to head-up tilt in the conscious dog. After recovery from surgery for instrumentation, and after habituation to tilt, the dogs were tilted from horizontal to 75 degrees for 5 min. The arterial hemodynamic response after the initial cardiovascular adjustments to the tilt consisted of no change in heart rate and significantly increased arterial blood pressure, with significantly reduced stroke volume and cardiac output. Both renal blood flow and terminal aorta blood flow declined significantly, even more than cardiac output. Muscular exertion was not part of the tilt response because upright standing on the hindlimbs elicited a sustained increase in heart rate and a significantly smaller increase in estimated total peripheral resistance. When compared with the orthostatic response in humans, the increase in arterial pressure was exaggerated in the dogs.