Introduction

Transient ischemic attack (TIA) was fi rst clinically de fi ned in 1964 as any transient neurological de fi cit lasting less than 24 hours caused by focal cerebral or retinal ischemia (Marshall, 1964; 1988). Generally, TIA is considered an unstable condition and is associated with an increased risk of stroke in the following time after fi st event. Previous research has shown that up to 20% of patients with TIA experienced a stroke in the following 3 months, with the most critical time being the first 48 hours after the initial event (Giles and Rothwell, 2007). New revised de fi nitions of TIA, based on the findings of diffusion weighted imaging-magnetic resonance imaging, have been proposed (Albers et al., 2002;Easton et al., 2009). Study has also shown that tissue-based TIA is linked with a high risk of stroke (Al-Khaled and Eggers, 2013). In tissue-based TIA, a higher risk of stroke is associated with evidence of acute infarction than without(Redgrave et al., 2007; Giles et al., 2011; Amarenco et al.,2016). In addition, studies have revealed that an immediate comprehensive evaluation of TIA sources and initiation of treatment of pathological findings, for example, cardioembolic sources such as atrial fibrillation or large-artery arteriosclerosis such symptomatic carotid stenosis, as well as the immediate implementation of secondary prophylaxis,reduced the risk of stroke remarkably (Rothwell and Warlow, 2005; Lavallee et al., 2007; Al-Khaled and Eggers, 2014;Amarenco et al., 2016).

According to the recommendations of the German Stroke Society and the European guidelines of the European Stroke Organization, the evaluation of TIA sources should include cardiac evaluation by transesophageal echocardiography(TEE) to detect cardioembolic sources of TIA to prevent subsequent stroke (European Stroke Organisation Executive and Committee, 2008; Ringleb et al., 2008; Laufs et al., 2010). Data on the frequency and fi ndings of TEE performed in patients with TIA are rare, particularly in patients with TIA who were diagnosed in accordance with the tissue-based definition of TIA. The few studies investigating TEE used data from unselected patients with TIA or stroke (Strandberg et al., 2002;Morris et al., 2009; Jauch et al., 2013; Pallesen et al., 2016).Only one study determined the pathological fi ndings among 59 patients suffering from time-based TIA (Dawn et al.,2006). TEE is the most sensitive ultrasound investigation of the heart’s structure and function and to detect cardioembolic sources causing TIA and stroke. Even the procedure is easy to perform and take short time, it has several limitations, particularly the need of expert knowledge and prior planning, e.g.,fasting patient, sedative or general anesthesia.

Our primary aims were to determine the frequency of TEE and to evaluate the performance of TEE in patients with TIAin accordance with the tissue-based de fi nition of TIA.

Table 1 A comparison of baseline characteristics between patients undergoing TEE vs. those who not

Data are n (%) unless otherwise indicated. TEE: Transoesophageal echocardiography; cCT: cranial computer tomography; cMRI: cranial magnet resonance imaging; TIA: transient ischemic attack; AT:antiplatelet treatment.

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Subjects and Methods

Study design

This prospective cohort study included consecutive patients with TIA who underwent treatment in the Department of Neurology at the University hospital of Schleswig-Holstein,Campus Lübeck between 2011 and 2014.

A TIA diagnosis was de fi ned in this study as any sudden focal neurological deficit lasting less than 24 hours and showed no evidence of infarction on brain imaging (Easton et al., 2009). Patients with TIA were treated by neurologists.The diagnosis of TIA was made by at least one vascular neurologist upon completion of the TIA evaluation and during the patients’ hospital stay. Patients with neurological symptoms who were admitted to hospital were evaluated during their hospital stay. According to the abovementioned guidelines (Laufs et al., 2010); patients with TIA are generally hospitalized so as to undergo an evaluation of TIA causes and monitoring of vital parameters.

随着医保改革的逐渐深入，医院的医保患者比例逐渐增大，医院对医保费用的合理控制直接关系到医院未来的发展，同时也影响广大参保患者的权益。国务院办公厅发布的《城市公立医院综合改革试点的指导意见》中明确指出公立医院要“降低药品和医用耗材费用……严格控制医药费用的不合理增长”。在当前的医改环境下，医院应在提高医疗服务技术和质量的同时，加强精细化管理，提高工作效率，节约运营成本，合理控制药品和耗材费用。

The study was approved by the Ethics Committee of the University of Lübeck (AZ: 4-147). All patients or caregiver provided written informed consent for their inclusion and evaluation in the present study.

电流内环控制器是决定PWM整流器性能优劣的关键[5],用PR替换PI,基本原理是:首先确定比例谐振控制器的基频,当输入信号中包含基频成分时被无限放大,即发生谐振,其他频段增益为零,从而消除静差,实现输入侧正弦电流指令的无静差跟踪[6],其理想传递函数为:

TEE

Of 1071 patients, 288 patients (27%) underwent TEE as part of the TIA evaluations. The median time between hospital admission and TEE investigation was 6 days. The mean time between TEE and discharge from hospital was 1.3 days (SD,1.7), with a median value of 1 day. Patients who underwent TEE stayed in hospital 2 days longer and more frequently received treatment in a stroke unit than those who did not undergo TEE (Table 1). A comparison between patients who underwent TEE and those who did not undergo TEE is shown in Table 1.

Statistical analysis

SPSS 22.0 (IBM SPSS Statistics, Armonk, NY, USA) was used to analyze the data. The data were described with mean and standard deviation (SD) values for continuous variables,median and interquartile range (IQR) values for scores, and absolute numbers and percentages for nominal and categorical variables. We performed a chi-square test or Student’s t-test to determine the difference between categorical or continuous variables, and a Mann-Whitney U test was used for the difference between scores. Adjusted logistic regression was carried out to estimate the odds ratio (OR). All variables with a P-value ＜ 0.1 were entered into the logistic regression model. A P-value ＜ 0.05 was considered signi fi cant.

Con fl icts of interest: The authors reported that they have no any confl icts of interest.

Results

Patients with and without TEE

A total of 1071 patients with TIA were included in the study.The mean age of the patients was 70 years (SD, 13), and the sex distribution was approximately equal (female patients,49.7%). The median time between symptom onset and hospital admission was 6 hours.

黄河特大桥钢栈桥总长为312米，宽度6米，标准跨度为12米。参加栈桥施工的作业人员加班加点施工，争时间抢工期，其间共铺设贝雷片952片、螺旋管296吨、工字钢220吨、钢板387吨。

TEE and associated factors

As part of the TIA evaluations, TEE investigations were performed at the Department of Cardiology of the University Hospital of Schleswig-Holstein, Campus Lübeck by cardiologists who were not involved in the present study. The TEE fi ndings were retrieved from the TEE reports.

Baseline characteristics (Table 1) — age, gender, TIA symptoms, medical history, diagnostic and therapeutic procedures, and secondary prevention strategies — were recorded. Patients who were admitted with TIA symptoms but were diagnosed with an epileptic seizure, migraine, or functional disorders during hospitalization and subsequent diagnostic procedures were not included in the study. In addition, patients who presented with TIA to the Department of Neurology but were rejected hospital admission were not included in the study.

Table 2 Pathological fi ndings detected by transesophageal echocardiography in 288 patients

Itemn (%)Pathological fi ndings detected by the TEE 133(47.8)Thrombogenic arch36(13)Grade 1 2(0.7)Grade 21(0.3)Grade 38(2.7)Grade 48(2.7)Grade 517(6)Patent foramen ovale71(25)Atrial septal aneurysm13(4.6)Aortic insufficiency41(15)Grade 132(11)Grade 25(2)Unknown4(1.7)Aortic valve stenosis5(2)Grade 12(0.7)Grade 22(0.7)Unknown1(0.3)Cardiomyopathy0 Fibroma1(0.3)

Findings of TEE

The TEE investigation showed that of the 288 patients who underwent TEE, 133 patients (48%) had abnormal fi ndings.Based on the TEE findings, 17 patients (6%) received oral anticoagulation. In 1 patient (0.3%), an atrial fibroma was found, which led to heart surgery (Table 2). A change of therapeutic procedures was carried out in 18 patients (6.3%).During hospitalization, 7 patients (2.4 %) experienced a subsequent stroke, and 27 patients (9.4%) had a recurrent TIA(Re-TIA). The rates of stroke, Re-TIA, and death were 2.7%,4.2%, and 1.6%, respectively, at 3 months after patients’ discharge from hospital. The rates of mortality (0.9% vs. 1.8%,P = 0.7), stroke (1.9% vs. 3.0%, P = 0.8), and Re-TIA (5.0%vs. 3.9%, P = 0.8) were similar in patients who underwent TEE and in those who did not.

本文区域经济增长中的GDP总量、城镇和农村人均可支配收入的数据，主要来自于回归式产业转移所在县市2018年的 《政府工作报告》、省级《国民经济和社会发展统计公报》中所回顾的2017年经济发展情况，回归主体的信息来自于2017年各县市的新闻报道、网络搜索等渠道，通过手工收集汇总，着重选取了220多个样本，考虑到样本缺失和有效性，通过筛选和剔除最终确定样本容量为202个。数据的统计性描述如表1：

Discussion

Our study showed that the performance of TEE was associated with age, TIA symptoms, and previous medical history.We also found that the performance of the TEE investigation seemed to lead to a prolonged hospital stay. Approximately half of the cohort that underwent TEE showed pathological findings. A change of therapeutic procedures was carried out in 18 patients (6.3%) and comparable with the fi ndings of other studies investigating the diagnostic impact of TEE on unselected patients with an acute cerebral ischemia (Censori et al., 1998; Pallesen et al., 2016). Previous studies have revealed the presence of a patent foramen ovale (PFO) to be the most common pathological fi nding detected by echocardiography after stroke and TIA (Bogousslavsky et al., 1986;Hausmann et al., 1992; Censori et al., 1998; Pallesen et al.,2016). Whereas the performance of TEE is superior to the transthoracal echocardiography (de Bruijn et al., 2006).

In addition, research has shown that a PFO with an atrial septal aneurysm leads to an exponentially higher risk of stroke (Mas et al., 2001). Recent research has also found that an occlusion of the PFO could be associated with a reduced risk of a subsequent stroke (Carroll et al., 2013). Therefore,the TEE investigation is now considered an important aspect of the evaluation of a cerebral ischemic event. However,the rate of the performance of TEE in our cohort of patients with TIA was low. This finding may be attributable to the fact that our study design only used the tissue-based de fi nition of TIA. Furthermore, following the identi fi cation of the cause of TIA with the use of electrocardiography, long-term electrocardiography, or duplex sonography of the brain-supplying arteries, the diagnostic impact of TEE investigation may be less. In accordance with the tissue-based de fi nition of TIA, we included only patients with negative brain imaging. Previous research has shown embolic causes of cerebral ischemic events in about 23% of patients with TIAs;however, the etiology of TIA remains undetermined in 33%of patients(Al-Khaled and Eggers, 2013). We found that during hospitalization and at 3 months of follow-up, the risk of stroke and the risk of death were lower in patients who underwent TEE than in those who did not, but this fi nding was not statistically signi fi cant, which may be attributable to the small size of the groups who experienced stroke or died.Furthermore, the patient group who experienced a change in medical management after TEE was too small (only 17 patients) for multivariate analysis to detect associated factors. Our fi ndings are comparable with that of other studies detecting the cardioembolic sources by TEE and cardiac MRI in patients suffering from stroke or time-based TIA(Wehrum et al., 2018).

Our study has several limitations. One is that not all TIA patients underwent TEE, older patients may be under represented in the study. The lack of long-term follow-up represents another limitation. The fact that complications of the TEE investigation were not recorded is also a limitation.

回顾分析收集2017年6月—2018年6月在我院进行治疗的子宫内膜癌浸润子宫肌层患者74例，根据诊断方法将患者随机分为试验组和对照组，两组患者均采用两种诊断方法进行诊断，患者的年龄50～70岁，平均年龄为（58.34±5.14）岁，绝经年限为1～15年，平均年限（10.36±3.25）年，前位子宫的患者34例，平位子宫的患者21例，后位子宫的患者19例。本次实验患者均已签署知情书，并经过我院伦理委员会批准。纳入标准：所有患者均经过手术病理结果证实为子宫内膜癌浸润子宫肌层；排除标准：其它类型妇科疾病，严重脏器障碍以及患有严重精神性疾病等。

二期工程范围为江风口分洪闸至蒋史汪橡胶坝，长5 km，面积5 000亩（333.33 hm2），一次性蓄水量 215 万m3。规划建设中央公园、鸟类公园、湿地植物园、湿地探索园、湿地生产园、湿地休闲度假区和沂河休闲度假区各1处，总建筑面积1.5万m2，提升水面面积 1 980 亩（132 hm2），陆生植物面积 2054 亩（136.93hm2）。

In summary, we found that 47.8% of patients with TIA who underwent TEE showed abnormal findings and 6.3%of patients experienced a change of treatment owing to TEE fi ndings in patients with tissue-based TIA. Patients with tissue-based TIA of an undetermined etiology or a suspected cardioembolic cause may bene fi t from the implementation of TEE.

Author contributions: MAK designed the study, conducted the statistics, interpreted the data results and wrote the manuscript. BS collected the data and reviewed the manuscript. TB searched the literature and reviewed the manuscript. All authors approved the final version of the paper.

津保桥所处场地地震动峰值加速度为0.15g，地震动反应谱特征周期为0.55 s，抗震设防烈度为7度，设计地震分组为第二组，按Ⅶ度设防，场地类型为Ⅲ类[5]。根据该桥实际场地特征与抗震设计资料，参考我国相关规范对设计反应谱曲线的相关规定，在Midas/civil中确定的相关参数为：Ch2001：分组=2，烈度=7，场地=Ⅲ，频遇地震，Tg=0.55 s，阻尼=0.05，选取的罕遇地震E1和频遇地震E2反应谱曲线如图3、图4所示。

Financial support: None.

Institutional review board statement: Approval for the study was obtained from the Ethics Committee of the University of Lübeck (AZ: 4-147).

Declaration of patient consent: The authors certify that they have obtained all appropriate patient consent forms. In the form the patients have given their consent for their clinical information to be reported in the journal. The patients understand that their names and initials will not be published.

Reporting statement: This study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement.

Copyright license agreement: The Copyright License Agreement has been signed by all authors before publication.

Data sharing statement: The study was part of the department own bench marking project, the data used in this study can not be shared.

Plagiarism check: Checked twice by iThenticate.

Peer review: Externally peer reviewed.

Open access statement: This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-Non-Commercial-ShareAlike 4.0 License, which allows others to remix,tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.

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