INTRODUCTION

Survival to hospital discharge for out-of-hospital cardiac arrest (OHCA) victims found to be in bradycardia or asystole is low (2%). The wearable cardioverter-defibrillator (WCD) has been increasingly utilized to detect and treat potentially fatal ventricular arrhythmias in high-risk patients with cardiomyopathy and low left ventricular ejection fraction (LVEF). Most life-threatening arrhythmias recorded by the WCD are ventricular arrhythmias (VA) such as ventricular tachycardia (VT) and ventricular fibrillation (VF). The WCD can deliver treatment shocks to terminate these tachyarrhythmias. However, a significant percentage of recorded episodes with WCD have been asystole or severe bradycardia episodes; 24.5% of SCAs in the study by Chung et al[1]. The WCD does not have antibradycardia pacing capabilities, but does alarm and instruct bystanders to call for help and perform CPR.

据统计，截至2017年底，全国创投机构累计投资项目数达到20 674项，累计投资金额4 110.2亿元。其中，2017年当年披露投资项目2 687项，投资金额845.3亿元，平均投资额为3 145万元/项，较2016年大幅增加。

Patients with OHCA due to bradycardia or asystole are less likely than those with VT or VF to arrive to the hospital alive and survive to discharge[2,3]. Shorter time intervals between collapse to initiation of bystander cardiopulmonary resuscitation (CPR) and notification of emergency medical services (EMS) are associated with improved overall survival as well as neurologically favorable survival[4-9]. Since the WCD alerts for asystole, it may contribute to improved outcomes in patients who suffer from severe bradycardia or asystolic cardiac arrest by alerting bystanders to perform CPR and contact EMS. We examined the incidence of WCD alerts related to outcomes in patients with asystole and/or severe bradycardia.

MATERIALS AND METHODS

Patient population and definitions

All patients prescribed a WCD between January 1,2013 and December 31, 2013 were analyzed using a corporate database (ZOLL LifeVest). This database includes indications for WCD prescription, baseline demographics (age and gender), complaints, and all device-recorded events. All patients signed consent to use their data and all data were de-identified.

An “asystole episode” was defined as bradycardia with heart rate ＜ 10 beats/min, or having a pause lasting ≥ 5 s. To identify patients with asystole episodes, the database was retrospectively screened to identify all episodes of primary asystole ECG recordings. Episodes of post-shock asystole or asystole following untreated VT episodes were excluded from the study. All episodes were manually adjudicated to ensure that a true asystole event had occurred.For the purposes of this study, a “serious asystole episode” was defined as any life-threatening asystole episode which either required hospitalization or led to unconsciousness or death. “Acute survival” was defined as recovery at the scene or arrival to a medical facility alive, or not requiring immediate medical attention. For the purposes of this study, asystole episodes occurring in a “health care setting” were defined as any events in a hospital, nursing home, or ambulance. Survival was determined by customer call reports at the end of WCD use, or by a mortality search of the Social Security death index if the customer call report at the end of WCD use did not indicate death (data available to 2/28/2014).

可桃花一开，啥活儿都来了。父亲忙着在生产队犁田打坝，母亲不但要操心着菜园子点豆种瓜，还要忙着侍候一窝刚下的仔猪。只有我和小姐姐最高兴，因为猪草好打了，田间地头的鹅儿长、细米蒿、野萝卜缨子和黄花苗赛着劲儿地长，我们再不用背着背笼爬几条沟千辛万苦地去捡干枯的葛藤叶子。

Statistical analysis

Descriptive statistics wereutilized to describe this population based on data collected at the time of referral for WCD prescription or during use. All continuous values were reported as mean ± SD, or median and range for skewed distributions. Categorical values were expressed as absolute numbers and percentages. To test for differences in the proportionsof clinical variables between serious and non-serious asystole episodes, Fisher’s exact test was used.Univariate logistical regression analysis was used to identify potential variables associated with survival of serious asystole episodes, where a P value of 0.05 was considered statistically significant.

RESULTS

Of the total 51933 patients having worn the WCD in 2013, there were 257 patients (0.5%) who had isolated asystole episodes and comprised the study cohort (Supplemental Figure). The cohort wore the WCD for 40.8 total patient-years during which a total of 264 asystole episodes occurred (one asystole episode in 251 patients, 2 asystole episodes in 5 patients, 3 asystole episodes in 1 patient). The cohort was 74% male and had a median age of 69 years.Over three-fourths of WCD prescriptions were for recent myocardial infarction (MI) or non-ischemic cardiomyopathy (NICM). Table 1 summarizes the baseline characteristics. A greater proportion of patients having a serious event had a history of diabetes mellitus (P ＜ 0.001), while more patients with non-serious asystole episodes had a history of a bundle branch block (P ＜ 0.05).

7 Maeda T, Yamashita A, Myojo Y, Wato Y, Inaba H. Augmented survival of out-of-hospital cardiac arrest victims with the use of mobile phones for emergency communication under the DACPR protocol getting information from callers beside the victim.Resuscitation 2016; 107: 80-87 [PMID: 27562948 DOI: 10.1016/j.resuscitation.2016.08.010]

1)首先随机从样本点中取3个点，然后进行空间圆拟合。参考上述的方法，得到平面方程系数A、B、C和D，空间圆的圆心坐标及半径。

For the 108 patients that survived the acute event,twenty-two (20%) of them later died (median 4 d post-asystole episode), while 86 (80%) survived post-WCD use. Information regarding reason for WCD discontinuation is shown in Table 2. Overall, 44% of patients were implanted with an ICD or pacemaker a median of four days after the asystole episode.

DISCUSSION

This study examines the outcomes of asystole and severe bradycardia during WCD use among patients who were prescribed the device to prevent sudden death due to ventricular arrhythmias. In this population, asystole episodes were infrequent,occurring in 0.5% of patients treated with WCD during the time period. Over three quarters of these asystole episodes were serious enough to result in unconsciousness, hospitalization, or death. Survival rates after asystole episodes and serious asystole episodes were 44% and 26% respectively. These rates are significantly higher than those reported in the literature for non-shockable cardiac arrest.

Due to the increased incidence of life-threatening ventricular arrhythmias in patients with cardiomyopathy and low ejection fraction, a WCD is often recommended for patients who are not immediate candidates for ICD therapy[10]. These patients may possess a history of palpitations or syncope which may cause concern for sustained VAs. However, it is important to recognize that in such patients with structural heart disease there is also a high incidence of conduction disease;furthermore, conduction disease may be exacerbated by the concomitant use of medications such as betablockers, digoxin, or antiarrhythmic drugs (i.e.,amiodarone, sotalol, dofetilide, etc.).

The WCD appears to serve as an effective monitoring device for severe bradycardic events. While the WCD has been shown to prevent sudden cardiac death due to VAs in certain patients[1,11-16], our study suggests that it may also provide an additional benefit in improving outcomes in patients who suffer from bradycardic conditions both in the acute setting as well as long-term by helping to determine which patients qualify for permanent pacemaker devices. Of the 86 patients surviving to WCD discontinuation, 48 (56%)of them were implanted with an ICD or pacemaker,a median of four days after the asystole episode.Although the device does not provide antibradycardia treatment, it does aid patients by alerting bystanders with an audible tone, thus potentially decreasing time to CPR and EMS notification. Shorter time to CPR and EMS arrival have been repeatedly shown to correlate with improved survival and neurologic outcome after cardiac arrests[8]. Just as pacemakers or rhythm monitors may detect sustained ventricular arrhythmias which would meet indications for ICD implantation or upgrade, the WCD may detect symptomatic bradycardic rhythms which would lead to permanent pacemaker or ICD implantation.

2)运行状态控制。上机位软件具有对现场设备的远程控制能力，可进行空压机的启停操作，但为保证工作状态稳定，一般运行自动控制系统，仅在维修作业、调试等环节，对其进行手动控制。另外，在获得操作权限后，还可对设备工作时间、供气压力、冷却循环能力等参数进行远程设置。

Limitations

This was an observational retrospective study and data was derived from the manufacturer’s database. While rhythm strips for each recorded event was adjudicated to assure that a bradycardic/asystolic event meeting criteria for device detection had occurred, the clinical details surrounding the asystole episodes for each patient were limited. The WCD database included a limited amount of patient information, and information regarding patient comorbidities, medical therapy,and outcomes. For example, the fact that the overall survival rates among patients with serious episodes was lower in patients whose event occurred in a location under medical care (i.e., hospital, emergency room, dialysis center, rehabilitation center, or longterm care nursing facility) could be due to the fact that patients already under medical care may have had more comorbidities than those whose serious asystole episode occurred outside of a medical facility. Thus our findings, while interesting, should be considered hypothesis-generating.

In conclusion, while the current indication for WCDs in high-risk patients is to detect and treat VAs, patients with reduced LVEF are also at increased risk of having severe bradycardic events. The WCD may improve survival in patients with severe bradycardic/asystolic episodes by alerting bystanders to notify EMS and to perform early CPR, as well as to detect episodes leading to appropriate permanent device implantation.

ARTICLE HIGHLIGHTS

Research background

Outcomes in patients with asystole and severe bradycardic events is poor.The wearable cardioverter defibrillator (WCD) can deliver shocks to terminate ventricular tachycardia and fibrillation, and also alarms for asystole and severe bradycardia events which can alert bystanders to help.

这是前所未有的沧桑巨变，是毕节人民艰苦奋斗的精神写照，是乌蒙山集中连片贫困地区脱贫攻坚的一面旗帜，为贫困地区全面建成小康社会闯出了一条新路子。

Research motivation

Minimal data exists on whether WCD improves outcomes and survival in patients with asystole and severe bradycardia events.

9 Vukmir RB. Survival from prehospital cardiac arrest is critically dependent upon response time. Resuscitation 2006; 69: 229-234[PMID: 16500015 DOI: 10.1016/j.resuscitation.2005.08.014]

Research objectives

This study aimed to examine whether WCD alarms for asystole improve patient outcomes and survival.

Research methods

[6]For all is not well in Xinjiang,traditional home to the Muslim Uighur people,where discontent with China’s iron rule runs high and a new terrorist threat has emerged in recent months,apparently inspired by a dangerous blend of separatism and radical Islam.

Research results

There were 264 asystole episodes in 257 patients and 76% of these events were considered “serious”. Overall patient survival after asystole or severe bradycardia events was 42%, and survival after “serious” asystole events was 26%. Among acute survivors, 20% later died during WCD use. Of the 86 living patients at the end of WCD use period, 48 (56%) received ICD/pacemaker and 17 (20%) improved their condition.

缩略法是指将一个较长的单词取其首部或主干构成与原词同义的短单词，或将一个组成词汇短语的各个单词的首字母拼接为一个大写字母的字符串，该字符串没有单词读音，只按字母拼读。如：

Research conclusions

While the current indication for WCDs in high-risk patients is to detect and treat ventricular arrhythmias, patients with reduced LVEF are also at increased risk of having severe bradycardic events. The WCD may improve survival in patients with severe bradycardic/asystolic episodes by alerting bystanders to notify emergency medical services and to perform early cardiopulmonary resuscitation, as well as to detect episodes leading to appropriate permanent device implantation.

Research perspectives

Future large prospective studies examining outcomes of WCD for asystole and severe bradycardia events are necessary to confirm a survival benefit with the device.

3 Rea TD, Eisenberg MS, Sinibaldi G, White RD. Incidence of EMS-treated out-of-hospital cardiac arrest in the United States.Resuscitation 2004; 63: 17-24 [PMID: 15451582 DOI: 10.1016/j.resuscitation.2004.03.025]

1 Chung MK, Szymkiewicz SJ, Shao M, Zishiri E, Niebauer MJ,Lindsay BD, Tchou PJ. Aggregate national experience with the wearable cardioverter-defibrillator: event rates, compliance, and survival. J Am Coll Cardiol 2010; 56: 194-203 [PMID: 20620738 DOI: 10.1016/j.jacc.2010.04.016]

11 Epstein AE, Abraham WT, Bianco NR, Kern KB, Mirro M, Rao SV,Rhee EK, Solomon SD, Szymkiewicz SJ. Wearable cardioverterdefibrillator use in patients perceived to be at high risk early postmyocardial infarction. J Am Coll Cardiol 2013; 62: 2000-2007[PMID: 23916930 DOI: 10.1016/j.jacc.2013.05.086]

REFERENCES

Retrospective analysis all asystole episodes documented in the WCD registry during the year of 2013 and examination of outcomes and survival.

4 Engdahl J, Bång A, Lindqvist J, Herlitz J. Factors affecting shortand long-term prognosis among 1069 patients with out-of-hospital cardiac arrest and pulseless electrical activity. Resuscitation 2001;51: 17-25 [PMID: 11719169]

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6 Hostler D, Thomas EG, Emerson SS, Christenson J, Stiell IG,Rittenberger JC, Gorman KR, Bigham BL, Callaway CW, Vilke GM,Beaudoin T, Cheskes S, Craig A, Davis DP, Reed A, Idris A, Nichol G; Resuscitation Outcomes Consortium Investigators. Increased survival after EMS witnessed cardiac arrest. Observations from the Resuscitation Outcomes Consortium (ROC) Epistry-Cardiac arrest.Resuscitation 2010; 81: 826-830 [PMID: 20403656 DOI: 10.1016/j.resuscitation.2010.02.005]

将手术病理检查结果作为金标准,计算出感兴趣区域小于病灶大小两倍以及感兴趣区域大于等于病灶大小两倍时,乳腺恶性病变的检查准确性、误诊率。

Overall survival for patients with asystole episodes was 42%. The majority of patients had asystole episodes that were considered serious (201; 78%).The rate of acute survival in patients with serious asystole episodes was 26%, while all 56 patients with non-serious asystole episodes survived. Further analysis for patients with serious asystole episodes suggested that survival was worse when the location was in a healthcare setting (Supplemental Table).

8 Rajan S, Wissenberg M, Folke F, Hansen SM, Gerds TA, Kragholm K, Hansen CM, Karlsson L, Lippert FK, Køber L, Gislason GH, Torp-Pedersen C. Association of Bystander Cardiopulmonary Resuscitation and Survival According to Ambulance Response Times After Out-of-Hospital Cardiac Arrest. Circulation 2016; 134: 2095-2104 [PMID:27881566 DOI: 10.1161/CIRCULATIONAHA.116.024400]

和过来人聊天，她总会嘱咐孕产妇们在孕期要多活动活动，否则顺产比较费劲。可是以往人们总觉得怀孕后就不适宜再做运动了，应该在家静养，以免动了所谓的“胎气”。其实不然，孕期适当地锻炼有利于分娩的顺利进行，是安全有益的。

“用不着了，我准备明天去自首。”范坚强淡淡地说，“后事已经安排好了，公司的财产已转到你名下，明天开始，你就是一风公司的总经理。我这样做，不是要你原谅我什么，这只是我对你们母子的一点补偿。”

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2 Atwood C, Eisenberg MS, Herlitz J, Rea TD. Incidence of EMS-treated out-of-hospital cardiac arrest in Europe. Resuscitation 2005; 67: 75-80 [PMID: 16199289 DOI: 10.1016/j.resuscitation.20 05.03.021]

12 Kutyifa V, Moss AJ, Klein H, Biton Y, McNitt S, MacKecknie B, Zareba W, Goldenberg I. Use of the wearable cardioverter defibrillator in high-risk cardiac patients: data from the Prospective Registry of Patients Using the Wearable Cardioverter Defibrillator(WEARIT-II Registry). Circulation 2015; 132: 1613-1619 [PMID:26316618 DOI: 10.1161/CIRCULATIONAHA.115.015677]

13 Opreanu M, Wan C, Singh V, Salehi N, Ahmad J, Szymkiewicz SJ, Thakur RK. Wearable cardioverter-defibrillator as a bridge to cardiac transplantation: A national database analysis. J Heart Lung Transplant 2015; 34: 1305-1309 [PMID: 26094085 DOI: 10.1016/j.healun.2015.04.004]

“上帝”为啥创造这些搬弄是非的人呢？长此下去，这些好事之徒、长舌之君难免有意无意地宣传丑化她，想待下去，可不容易啊！

14 Rao M, Goldenberg I, Moss AJ, Klein H, Huang DT, Bianco NR,Szymkiewicz SJ, Zareba W, Brenyo A, Buber J, Barsheshet A.Wearable defibrillator in congenital structural heart disease and inherited arrhythmias. Am J Cardiol 2011; 108: 1632-1638 [PMID:21890075 DOI: 10.1016/j.amjcard.2011.07.021]

15 Salehi N, Nasiri M, Bianco NR, Opreanu M, Singh V, Satija V, Jhand AS, Karapetyan L, Safadi AR, Surapaneni P, Thakur RK. The Wearable Cardioverter Defibrillator in Nonischemic Cardiomyopathy: A US National Database Analysis. Can J Cardiol 2016; 32: 1247.e1-1247.e6 [PMID: 26975224 DOI: 10.1016/j.cjca.2015.12.035]

流通部是图书馆的重要对外窗口，直接面对广大读者，代表着整个图书馆的形象，因此流通部馆员必须改变传统思想观念，加强思想修养，提高思想觉悟，增强服务意识，强化“读者第一，以人为本”的服务理念，把封闭式服务改变为开放式，变被动服务为主动服务，始终把“读者第一，服务至上”放在第一位，牢固树立全心全意为读者服务的思想理念。

16 Wäßnig NK, Günther M, Quick S, Pfluecke C, Rottstädt F,Szymkiewicz SJ, Ringquist S, Strasser RH, Speiser U. Experience With the Wearable Cardioverter-Defibrillator in Patients at High Risk for Sudden Cardiac Death. Circulation 2016; 134: 635-643 [PMID:27458236 DOI: 10.1161/CIRCULATIONAHA.115.019124]