利用LQT2兔心脏模型研究吡那地尔对心室复极的影响

目的 本研究通过制作一种模拟LQT2的动物模型--Langendorff离体灌流兔心脏LQT2的动物模型,然后用钾通道开放剂吡那地尔(pinacidil)干预,研究吡那地尔对离体LQT2兔心脏模型心室复极的影响,并探讨其作用机制.方法 将30只体重为2.5-3.5kg的健康新西兰兔随机分为A、B、C三组,A组(对照组),B组(吡那地尔组),C组(吡那地尔 优降糖组).取出心脏,立即行逆行主动脉灌注,然后用有齿镊钳夹房室结造成Ⅲ度房室传导阻滞,在Langendorff离体灌流兔心脏上同步记录左室心内膜及心外膜单相动作电位和容积传导心电图.分别用1000ms刺激周长(CLs)起搏至少100个心动周期,体表心电图提示无sT-T明显压低或抬高.然后用加有右旋索他洛尔(d-Sotalol)100μmol/L浓度的台氏液逆行Langendorff灌流30min后再分别用上述刺激周期进行刺激,观察:①90%动作电位时程(APD90);②90%复极时间(RT90);③跨室壁复极离散度(TDR);④早期后去极化(EAD)及尖端扭转型室性心动过速的发生率;⑤平均QT问期等的变化.并对A、B、C三组进行不同的药物制剂干预.结果 右旋索他洛尔明显延长离体兔心脏心内膜及心外膜单相动作电位时程(P＜0.001);TDR延长(P＜0.001);同步记录容积传导心电图的QT间期延长(P＜0.001);EAD发生率从0%到86.67%(P＜0.01);TdP发生率从0%-43.33%(P＜0.05).吡那地尔缩短由d-Sotalol所引起的动作电位时程延长,使左室心内膜、心外膜的APD90缩短,缩短容积传导心电图QT间期,减少跨壁复极离散度TDR(P＜0.001);消除早期后去极化EAD(P＜0.01),并抑制触发性心律失常TdP(P＜0.05).吡那地尔 优降糖组的结果显示:APD90、TDR、EAD、TdP等指标在处理后与对照组相比,P＞0.05,无统计学意义.结论 吡那地尔能抑制LQT2兔心律失常的发生.     

复极时程和跨室壁复极离散在尖端扭转型室性心动过速中的作用

目的:探讨复极时程和跨室壁复极离散(TDR)在尖端扭转型室性心动过速(TdP)发生的作用. 方法:32只兔随机等分为4组,低浓度索他洛尔组(10 μmol/L),高浓度索他洛尔组(100 μmol/L),低浓度奎尼丁组(1 μmol/L),高浓度奎尼丁组(10 μmol/L). 采用Langendorff技术离体兔心脏灌流,同步记录用药后三层心肌的单相动作电位(MAP)和TDR,观察早期后除极(EAD)、TdP的发生情况. 结果:索他洛尔浓度依赖性地延长三层心肌MAP时程(MAPD)和TDR,高浓度索他洛尔组诱发EAD,TdP分别为8只和6只,而低浓度组诱发EAD,TdP分别为4只和0只. 奎尼丁浓度依赖性地延长三层心肌MAPD,但逆浓度依赖性地延长TDR,高浓度奎尼丁组诱发EAD,TdP分别为7只和1只,而低浓度组诱发EAD,TdP分别为6只和4只. 结论:与TdP的发生密切相关的主要是TDR,而不是复极时程.     

不同血钾水平时索他洛尔对在体跨室壁心肌复极不均一性的影响

为了观察正常血钾和低血钾时索他洛尔对在体跨室壁心肌复极不均一性的影响,探讨索他洛尔致室性心律失常的机制。24只兔随机分为两组,正常血钾组（12只）和低血钾组（12只）,分别静注索他洛尔1.0mg/kg,3.0mg/kg;同步记录兔左室心外膜心肌(Epi)、中层心肌(Mid)和心内膜心肌(Endo)的单相动作电位（MAP）,研究发现低钾时与血钾正常时相比,索他洛尔增加跨室壁心肌复极离散度（TDR）的作用更明显;更易引起Mid发生早期后除极（EAD）;低血钾组尖端扭转性室速（TdP）的发生率亦更高。     

性激素在尖端扭转型室性心动过速发生机制中的作用

目的 通过研究雌雄激素替代法对大鼠离体心室肌细胞单相动作电位(MAP)的影响及奎尼丁诱导下致心律失常作用性别差异性的机制，阐明性激素在尖端扭转型室性心动过速(TdP)发生中的作用。方法 制造苯甲酸雌二醇、丙酸睾酮替代的大鼠模型，Langendorff法灌流离体大鼠心脏，采用MAP技术记录6组大鼠(①去势雌性大鼠；②去势雌性大鼠 雌激素；③去势雌性大鼠 雄激素；④去势雄性大鼠；⑤去势雄性大鼠 雌激素；⑥去势雄性大鼠 雄激素)的MAP，比较组间的性别差异，并观察奎尼丁诱发各组早期后除极(EAD)、TdP发生率的差异。结果 去势雌性大鼠 雌激素组的单向动作电位时程(MAPD)显著长于去势雌性大鼠 雄激素组，去势雄性大鼠 雌激素组MAPD显著长于去势雄性大鼠 雄激素组；雌激素替代组与单纯去势组相比MAPD也延长，雄激素组则相反；而去势雌性大鼠组和去势雄性大鼠组无差别。各组在应用奎尼丁后MAPD都有显著延长，EAD发生率均较高；而雌激素替代组的EAD、TdP发生率都高于雄激素组。结论 雌雄大鼠发生TdP的性别差异性与性别本身无关，关键在于性激素的差异，雌激素可通过使心肌细胞在复极延长的基础上EAD发生增加，导致触发活动，从而发生TdP；雄激素的作用则相反。     

灯盏花素对家兔肥厚心肌室性心律失常的影响

目的观察口服灯盏花素对家兔肥厚心肌室性心律失常的影响,探讨灯盏花素抗心律失常的作用机制。方法 30只家兔随机分为假手术组、心肌肥厚组和灯盏花素组,每组10只。假手术组开腹但不行腹主动脉缩窄术;心肌肥厚组和灯盏花素组采用腹主动脉缩窄术制备家兔心肌肥厚模型;灯盏花素组自手术后第2天开始喂服灯盏花素,每只每日1片,喂养8周。制备兔左心室楔形心肌块,利用浮置玻璃微电极法同步记录楔形心肌块内、外膜心肌细胞跨膜动作电位和跨壁心电图;测心脏质量(HW)、体质量(BW)和左心室游离壁厚度(LVT)。观察各组QT间期和内、外膜心肌细胞跨膜动作电位以及跨室壁复极离散度(TDR),程序电刺激诱发室性心律失常,记录跨膜动作电位复极90%的时程(APD90),早期后除极(EAD)和尖端扭转性室性心动过速(Tdp)的发生率。结果心肌肥厚组与灯盏花素组HW、HW/BW及LVT值与假手术组相比均明显升高(P<0.05);灯盏花素组HW、HW/BW及LVT值与心肌肥厚组相比均明显减小(P<0.05)。心肌肥厚组与灯盏花素组QT间期及内、外膜心肌APD90较假手术组明显延长(P<0.05);灯盏花素组QT间期及内、外膜心肌APD90与心肌肥厚组相比明显缩短(P<0.05)。假手术组、心肌肥厚组和灯盏花素组TDR分别为(55±17)、(99±12)和(68±11)ms,3组间比较差别有统计学意义(P<0.05)。灯盏花素组EAD和Tdp的发生率明显低于心肌肥厚组(P<0.05)。结论肥厚心肌TDR增大,心律失常的发生率显著升高。灯盏花素可减少TDR,明显降低EAD和Tdp的发生率。     

低钾对扩张型心肌病跨室壁复极不均一性的影响

目的　研究低钾是否为扩张型心肌病 (DCM )发生室性心律失常的重要促发因素及其电生理机制。方法　将家兔随机分成DCM实验组及正常对照组 ,建立DCM家兔模型并进行离体心脏灌流 ,观察低钾时两组之间 3层心肌APD及跨室壁复极离散度 (TDR)的改变。结果　低K+ 灌流时DCM实验组和正常对照组中层心肌细胞单相动作电位复极 90 %时程 (APD90 )、TDR均长于正常K+ 灌流 (P <0 0 0 1) ,但以DCM实验组延长更为明显 (P <0 0 0 1)。结论　低K+ 延长中层心肌细胞APD ,增加跨室壁复极不均一性 ,可能是DCM易发室性心律失常的重要促发因素。     

药物致尖端扭转型室性心动过速的发生机制

目的探讨药物致尖端扭转型室性心动过速(Tdp)的发生机制。方法建立冠状动脉灌注的犬左室心肌楔形组织块模型,同步记录左心室内膜、中层、外膜心肌细胞的动作电位及跨壁心电图,观察不同浓度D-Sotalol对动作电位时间(APD)、QT间期、跨壁复极离散度(TDR)、早期后除极(EAD)及Tdp发生的影响。结果浓度为0～100μmol/L的D-Sotalol呈剂量依赖性地延长各层细胞APD,尤以中层细胞最为显著(P<0.05),因而增加TDR;D-Sotalol在中层细胞可诱发EAD,触发室性早博并形成跨壁折返导致Tdp。结论 D-Sotalol在中层细胞诱发EAD、R on T室性早博是其致Tdp的始动因子,在TDR增加的基础上形成跨室壁折返是Tdp得以维持的关键。     

人类果蝇相关基因(HERG)通道与药物相关性长QT综合征的关系研究

人类果蝇相关基因一HERG(human ether-go-gorelated gene)基因编码心脏快速延迟整流钾通道(IKr)的α亚基[1],快速延迟整流钾电流在心肌复极化过程中起着重要作用,当HERG钾离子通道被药物阻断时,将会延长动作电位时程(APD)及QT间期,导致长QT综合症(LQTS)并诱发尖端扭转型室性心动过速(TdP)等快速型室性心律失常的发生.     

单相动作电位测定槐定，硫酸镁对兔心脏触发性心律失常的抑制作用

在氯化铯引起的兔触发性心律失常模型上，通过单相动作电位（Monophasic action potential,MAP)测定，观察了槐定和硫酸镁对触发性心律失常的抑制作用。结果显示：（1）静脉注射氯化铯后QT间期延长，心律减慢，单相动作电位90％复极间期（MAPD90）延长，出现早期后除极（Early afterdepolarization,EAD),由EAD诱发心律失常，发生率100％，其中室性心动过速为50％。（2）静脉注射槐定和硫酸镁后，EAD振幅（EADA）均减小，心律失常发生率分别为30％和25％（与对照组比两者均P＜0．05），无一例发生室性心动过速。     

长期血浆内皮素-1水平升高对兔心室电生理特性及心律失常的影响

目的:探讨长期血浆内皮素-1(ET-1)水平升高对兔心室电生理特性及室性心律失常(VA)的影响。方法:雄性新西兰大耳兔30只,随机分为对照组(CTL组)和血浆ET-1升高组(ET-1组),每组15只。所有动物连续14d经耳缘静脉注射药物,其中ET-1组按10μg/(kg·d)剂量注射ET-1,而CTL组则给予注射0.9%生理盐水[1ml/(kg·d)]。所有动物完成药物注射7d后,在整体心脏Langendorff灌流条件下行离体电生理研究。同步记录起搏周长(PCL)为300ms时左室前游离壁心内膜(LAF-Endo)及心外膜(LAF-Epi)单相动作电位(MAP),并计算动作电位复极跨壁离散度(TDR);测量LAF-Epi的有效不应期(ERP),并构建标准动作电位恢复性质(AP-DR)曲线,计算标准APDR曲线最大斜率(Smax);于LAF-Epi行程控增频刺激,进行动作电位电交替(ALT)及室性心律失常(VA)诱发,记录诱发ALT及VA的最大PCL(PCLmax)。结果:与CTL组相比,ET-1组LAF-Epi及LAF-Endo的90%单相动作电位时程(MAPD90)、APDR曲线Smax、诱发ALT及VA的PCLmax中位数均增大(P均<0.05),而LAF-Epi的ERP/MAPD90(P<0.01)却明显减小;CTL组动物LAF-Epi的MAPD90短于LAF-Endo,而ET组动物LAF-Epi的MAPD90却较LAF-Endo延长(P均<0.05);TDR及LAF-Epi的ERP在两组间无明显差异(P均>0.05)。结论:长期血浆ET-1水平升高可引起心室正常复极顺序发生逆向改变、增大标准APDR曲线最大Smax及减小心室发生ALT的频率阈值,进而促进VA的发生。     

12导Holter、3导Holter和ECG对冠心病检测的对比分析

目的 评价12导联动态心电图(12导Holter)、3导动态心电图(3导Holter)和常规心电图(ECG)对冠心病(CHD)的诊断价值。方法 选择30例经冠状动脉造影(CAG)证实的冠心病(CHD)思考，同期内(间隔小于1周)接受12导Holter、3导Holter及ECG检查，将检查结果进行对比分析。结果 12导Holter、3导Holter和ECG对CHD的检出率分别是86．7％、76．7％和46．7％，两两比较，差异有显著性(P＜0．05，P＜0．0l)。结论 在冠心病的检出方面，12导Holter优于3导Holter和ECG。     

12导联动态心电图对冠心病的诊断价值

目的:评价12导联动态心电图(12导Holter)对冠心病(CHD)的诊断价值.方法:选择47例拟诊为冠心病的心内科住院患者.同期内(间隔≤1周)分别接受冠状动脉造影(CAG)﹑12导Holter及二维多谱勒心脏超声心动图(2DE)检查,以CAG作为对照,以心超结果作为参考对12导HolterST段进行分析.结果:(1)三种方法检出率分别为90.6%,64.7%,47.3% .(2) 12导Holter诊断冠心病的敏感性﹑特异性分别为71.43%,60%.对单支病变组﹑多支病变组检出率分别为68.96%,76.92%.单支组与多支组检出率比较差异无显著性(p>0.05);心超诊断冠心病的敏感性﹑特异性分别为52.38%,100%;对单支病变组﹑多支病变组检出率分别为31.03%,100% ,单支组与多支组检出率比较有统计学意义(p<0.05).(3)12导Holter检测结果还表明冠脉狭窄程度越重ST段下移程度越大,持续时间越长,心律失常检出率越高,且心律失常频度及复杂性越明显. 结论:12导Holter对冠心病的诊断具较高的敏感性,且无创、费用低,可作为冠心病诊断的基本方法.     

心电能量谱对慢性肾衰竭患者心肌缺血诊断价值探讨

目的探讨12导联心电能量谱(ECG 12-lead frequency domain cardiogram,FCG)对慢性肾衰竭(chronic renal failure,CRF)患者是否并发心肌缺血的诊断价值。方法对105例慢性肾衰竭的患者,分别进行FCG和12导联心电图(12-lead electrocardiogram,12-lead ECG)检查,对检查结果进行比较分析。结果 FCG检查显示为阳性的56例,阳性率53.33%;ECG检查显示为阳性的21例,阳性率20.00%;二者阳性率比较,有统计学意义(P<0.01)。结论 FCG对CRF并发心肌缺血的诊断价值高于ECG,是当前CRF患者是否并发心肌缺血的一项重要的,有价值的,早期诊断参考指标。     

分析12导联心电图对冠心病心肌缺血的监测价值

目的分析12导联心电图对冠心病心肌缺血的监测价值。方法选取2017年5月至2019年4月我院接诊的老年冠心病患者90例为研究对象,均行12导联心电图与常规心电图检查,比较两种检查方法对冠心病检出率、检出部位及对心肌缺血检出率,分析两种方法对冠心病心肌缺血的监测价值。结果12导联心电图对冠心病检出率高于常规心电图(P<0.05),12导联心电图对下壁、侧壁的检出率高于常规心电图,且12导联心电图对ST段抬高、ST段压低的检出率也高于常规心电图(P<0.05);12导联心电图诊断冠心病心肌缺血的灵敏度明显高于常规心电图(P<0.05),两者诊断特异度、准确度比较差异无统计学意义(P>0.05)。结论12导联心电图用于冠心病心肌缺血的诊断中有较高价值,可较好检出心肌缺血及缺血部位,值得广泛应用。     

Electrocardiogram and rhythm strip interpretation by final year medical students.

The pre-registration house officers (PRHO) is often called upon to interpret electrocardiograms ECG. We invited final-year medical students who had successfully completed their written final examinations, to interpret three rhythm-strip tracings, and three 12-lead ECG tracings. The rhythm-strips were of ventricular fibrillation (VF), ventricular tachycardia (VT), and complete heart block. Of the three 12-lead ECG tracings, one was an inferior myocardial infarction (MI), one was atrial fibrillation (AF), and one showed no abnormality. Forty-six medical students attended. Of these, 50% had received no formal training in ECG interpretation, although 89% had tried to learn ECG interpretation from books. Only 9% felt confident in their interpretation of ECG tracings. Of the rhythm-strips, 100% correctly identified VF, 96% recognised VT, and 67% identified complete heart block. Of the 12-lead ECG tracings, 61 % recognised the MI, 54% recognised AF, and only 46% successfully identified the normal ECG as such. The group were significantly worse at 12-lead ECG interpretation compared to rhythm-strips (p<0.01). The members of the group who had received formal training in ECG interpretation were significantly better at interpreting both rhythm-strips and 12-lead ECG tracings (p<0.05). It would appear that formal ECG training as an undergraduate improves PRHO interpretation of ECG tracings, and the PRHO should not interpret 12-lead ECG tracings without consulting more senior medical staff.     

12导联同步心电图中国成年人R波振幅正常值的研究

目的:由于12导联同步心电图R波振幅无正常值标准,本组研究12导联同步心电图与单导联心电图R波振幅差异,将12导联同步心电图R波振幅转换为单导联心电图R波振幅,从而换算出12导联同步心电图各导联R波振幅的正常值。方法:选择健康人心电图408例,以单导联R波振幅在正常范围作为对照组,12导联同步心电图 作观察组,进行12导联同步心电图与单导联心电图同一导联R波振幅测定对比。结果:12导联同步心电图与单导联心电图R波振幅测定值对比,统计学处理,P<0.01～P<0.001,两组Ⅰ导联至V_6导联总回归系数为0.781,相关系数为0.967,呈密切相关。结论:12导联同步心电图与单导联心电图R波振幅有明显差异,12导联同步心电图R波振幅转换为单导联心电图R波振幅的公式:单导联心电图R波振幅=0.781×12导联同步心电图R波振幅。根据公式可换算成12导联同步心电图各导联R波振幅正常值。     

T波复杂性比率对急性非ST段抬高型心肌梗死的诊断价值

目的 探讨T波复杂性比率在急性非ST段抬高型心肌梗死(NSTEMI)患者中的诊断价值.方法 回顾性分析436例急性冠脉综合征患者的临床资料,所有患者入院后立即行12导联Holter检查,通过对12导联心电图做主成分分析并计算T波复杂性比率.临床结果通过病历记录获得.采用多因素回归分析对NSTEMI和住院期间主要不良心血管事件(MACE)的影响因素进行分析.结果 T波复杂性比率升高是NSTEMI(OR=2.248,95％CI 1.549～3.263,P＜0.001)和住院期间MACE(OR =3.037,95％CI 1.886～4.890,P＜0.001)的预测因子,进行ROC分析,AUC分别为0.715和0.770.结论 测量体表12导联心电图的总体T波复杂性比率可以发现和定量NSTEMI患者非局限性的心肌损伤,并给早期冠心病胸痛患者的评估带来了潜在获益.     

Effect of ambulance 12-lead ECG recording on times to hospital reperfusion in acute myocardial infarction

OBJECTIVE: To review the evidence that recording a prehospital 12-lead electrocardiogram (ECG) reduces time from hospital arrival to initiation of reperfusion therapy for acute myocardial infarction (AMI). DATA SOURCES: Medline search from 1966 to the present (articles in all languages) and examination of bibliographies. STUDY SELECTION: Published studies of prehospital 12-lead ECG recording that included control groups and reported time intervals from hospital arrival to start of reperfusion therapy. DATA EXTRACTION: Eight articles satisfied selection criteria (two randomised controlled trials, four non-randomised interventional studies and two prospective observational studies). DATA SYNTHESIS: Widely varying study methodologies precluded meta-analysis. All studies had methodological problems, but hospital delays were consistently reduced. Such improvements appear to be small in hospitals where delays are already minimal. CONCLUSIONS: Little evidence is available to support routine prehospital 12-lead ECG recording if the median hospital time to reperfusion is already less than 30 minutes. Improvement of in-hospital treatment times may be a better initial strategy than prehospital 12-lead ECG recording, as this will benefit more patients and allow ambulance services to better allocate their available resources.     

Monitoring for myocardial ischemia during noncardiac surgery. A technology assessment of transesophageal echocardiography and 12-lead electrocardiography. The Study of Perioperative Ischemia Research Group.

OBJECTIVE--Transesophageal echocardiography (TEE) and 12-lead electrocardiography (ECG) are sophisticated techniques that are increasingly being used to monitor for myocardial ischemia during noncardiac surgery. We examined whether the routine use of these techniques has incremental clinical value in identifying patients at high risk for perioperative ischemic outcomes when compared with preoperative clinical data and intraoperative monitoring using continuous two-lead bipolar ECG. DESIGN--Cohort study. SETTING--Veterans Affairs medical center. PATIENTS--A total of 332 men undergoing noncardiac surgery who had or were at high risk for coronary artery disease. INTERVENTIONS--TEE, 12-lead ECG, and two-lead ECG were performed continuously during noncardiac surgery (47% vascular, 53% nonvascular). Monitoring results were not available to anesthesiologists or surgeons, and data were blindly analyzed after surgery. MAIN OUTCOME MEASURE--Perioperative ischemic outcomes (cardiac death, nonfatal myocardial infarction, unstable angina). RESULTS--In a subset of 285 patients who were adequately studied by all three techniques, 111 patients (39%) were identified as having intraoperative myocardial ischemia (by one or more monitoring techniques). By univariate analysis, intraoperative ischemia was associated with all perioperative cardiac outcomes, including ischemic outcomes, congestive heart failure, and ventricular tachycardia (P less than or equal to .02 for each of the three monitoring techniques). However, when monitoring results for TEE and 12-lead ECG were added to a multivariate model that included preoperative clinical data and continuous two-lead ECG results, the incremental value of TEE was small (odds ratio, 2.6; 95% confidence interval [CI], 1.2 to 5.7; P = .02) and that of 12-lead ECG was not significant (odds ratio, 1.5; 95% CI, 0.6 to 3.8). Furthermore, when the multivariate analysis was repeated with only ischemic outcomes, neither TEE nor 12-lead ECG retained significant associations (odds ratio, 2.2; 95% CI, 0.5 to 9.4, and odds ratio, 1.1; 95% CI, 0.2 to 6.1, respectively). CONCLUSION--When compared with preoperative clinical data and intraoperative monitoring using two-lead ECG, routine monitoring for myocardial ischemia with TEE or 12-lead ECG during noncardiac surgery has little incremental clinical value in identifying patients at high risk for perioperative ischemic outcomes.     

推衍12导联心电图用于全麻下骨科手术围术期心肌缺血的检测

目的 应用推衍12导联心电图ST段连续监测得出全身麻醉(全麻)下骨科术中心肌缺血的发生规律.方法 对73例全麻下骨科患者术中连续监测推衍(EASI)心电图12导联ST段.结果 被调查病例术中心肌缺血的发生率为34.2%(25/73);苏醒拔管期发生的缺血事件占30.4%(18/59);术中发生的心肌缺血事件有81.4%(48/59),持续时间≤5 min,有66.1%(39/59)ST段压低,≤0.15 mV.结论 推衍12导联·心电图可用于全麻下骨科术中心肌缺血的检测,近1/3的缺血事件发生在苏醒拔管期,术中发生的心肌缺血绝大多数持续时间短、ST段压低程度轻.