急性心肌梗死心电图.ppt

急性心肌梗死的心电图诊断急性心肌梗死的心电图诊断 心电图是最常单独应用，价格-效益比最好的心脏病学诊断工具，但是它常被错误的分析。Henry Marriot急性心肌梗死的心电图诊断1、正常的解剖学参照 前壁LAD 下壁RCA 侧壁Lcx 后壁与左室相对的后胸壁急性心肌梗死的心电图诊断2、ST段抬高的意义 最初ST段的变化总和是影响开始溶栓时间（door-to-thrombolysis time)的主要变量。下壁（、aVF）或侧壁（V5、V6、aVL）至少1个导联ST段抬高1mm。前壁至少1个导联ST段抬高2mm。此标准的准确性83%，敏感性56%，特异性94%。急性心肌梗死的心电图诊断3、心电图与冠脉造影的关系 梗死相关血管最常发生于LAD（44-56%），其次为RCA（27-39%），再次为Lcx（17%）。急性心肌梗死的心电图诊断前壁/前间壁/前侧壁梗死（LAD闭塞）前壁/高侧壁梗死（D1闭塞）下壁梗死（RCA或Lcx闭塞）侧壁和后壁梗死（Lcx闭塞）急性心肌梗死的心电图诊断前壁/前间壁/前侧壁梗死（LAD闭塞）LAD闭塞后，ST段抬高最常出现在V2（敏感性91-95%），依次为V3、V4、V5、aVL、V1和V6。ST段抬高在V2、V3最明显。LAD近段闭塞的强有力的预测因素为aVL导联ST段抬高，下壁导联ST段压低。ST段抬高波及到、aVL常合并存在下壁导联的ST段压低。急性心肌梗死的心电图诊断前壁/前间壁/前侧壁梗死（LAD闭塞）LAD于第一间隔支水平闭塞：aVR导联ST段抬高（敏感性43%，特异性95%）侧壁导联原有的间隔性Q波消失（敏感性30%，特异性84%）V5导联ST段压低（敏感性17%，特异性98%）RBBB（敏感性14%，特异性100%）V1导联ST段抬高2.5mm（敏感性12%，特异性100%）急性心肌梗死的心电图诊断前壁/前间壁/前侧壁梗死（LAD闭塞）LAD远段闭塞 V2导联ST段抬高3.2mm V4V6出现新的Q波 V2导联R波增高急性心肌梗死的心电图诊断前壁/前间壁/前侧壁梗死（LAD闭塞）V1导联ST段抬高：V1导联记录的电变化来自右侧室间隔区域，它是由LAD的间隔支供血或RCA的圆锥支提供额外的血供。这有助于解释为什么2/3的前壁AMI患者无V1ST段抬高。V1导联ST段的抬高提示某些少见的解剖学情况，即RCA圆锥支短而未达到心室间隔部位。V1-V4导联ST段抬高的病人有7%继发于RCA闭塞，其心电图特点为ST段高度由V1-V4递减。Use of the Electrocardiogram in Acute Myocardial InfarctionUse of the Electrocardiogram in Acute Myocardial InfarctionFigure:Acute anterior wall infarction in proximal LAD occlusion Anterior wall infarction is present,as indicated by ST-segment elevation in leads V2 and V3.In addition,the precordial leads show marked ST-segment elevation in lead V1 and ST-segment depression in leads V5 and V6.The extremity leads show Stsegment elevation in lead aVR and ST-segment depression in inferior leads II,III,and aVF.Use of the Electrocardiogram in Acute Myocardial InfarctionUse of the Electrocardiogram in Acute Myocardial Infarction Figure:Acute anterior wall infarction in distal LAD occlusion.Signs of acute anterior wall infarction are seen,but ST-segment elevation is present in the inferior leads.Note also ST-segment depression in lead aVR.Use of the Electrocardiogram in Acute Myocardial InfarctionUse of the Electrocardiogram in Acute Myocardial Infarction Figure:Acute anterior wall infarction due to LAD occlusion distal to the first diagonal but proximal to the first septal branch.The precordial leads show evidence of acute anterior wall infarction,but lead aVL shows ST-segment depression.Use of the Electrocardiogram in Acute Myocardial InfarctionUse of the Electrocardiogram in Acute Myocardial Infarction急性心肌梗死的心电图诊断前壁/高侧壁梗死（D1闭塞）左室前侧壁的血供是由D1和M1提供。M1为罪犯血管的心电图表现：、aVL导联ST段抬高合并V2导联ST段压低。D1为罪犯血管的心电图表现：敏感性指标为、aVL导联ST段抬高；特异性指标为胸前导联ST段抬高合并aVL导联ST段抬高。急性心肌梗死的心电图诊断前壁/高侧壁梗死（D1闭塞）前壁中央（mid-anterior)梗死：D1闭塞造成的独特心电图改变，即非连续性aVL和V2ST段抬高，加上、aVF或V4导联ST段压低。它表现为除室间隔和左室心尖部外的左室壁运动消失。急性心肌梗死的心电图诊断下壁梗死（RCA或Lcx闭塞）典型的下壁心梗心电图表现为、aVF的ST段抬高。其中80-90%为RCA闭塞，其余为Lcx病变。导联ST段的抬高大于导联，强烈提示病变位于RCA。aVL导联ST段压低，往往提示RCA闭塞（敏感性94%，特异性71%），且不支持同时合并有后壁和右室梗死。无aVL导联ST段压低提示Lcx近段闭塞。急性心肌梗死的心电图诊断下壁梗死（RCA或Lcx闭塞）V5、V6导联ST段抬高：80年代-单纯Lcx病变。多动脉受累-V5、V6导联ST段抬高2mm，提示大面积的缺血负荷，往往有RCA和Lcx同时受累。这是由于左室后侧壁的血供有Lcx的OM，后侧支和LAD的分支提供。急性心肌梗死的心电图诊断下壁梗死（RCA或Lcx闭塞）合并胸前导联ST段压低：合并胸前导联ST段压低-提示Lcx病变而非RCA病变。V3/：1.2提示Lcx病变 0.5提示RCA近段病变 0.51.2提示RCA中段闭塞 V1、V2不出现ST段压低可除外Lcx闭塞。急性心肌梗死的心电图诊断下壁梗死（RCA或Lcx闭塞）较少应用的导联：V7-9ST段抬高，V4RST段压低-Lcx闭塞。aVR ST段压低常合并、aVL或V5、V6 ST段抬高，它提示大面积的梗死。急性心肌梗死的心电图诊断侧壁和后壁梗死（Lcx闭塞）Lcx的解剖变异大，供应左室的面积小。常规12导联心电图仅能显示不到一半病例的ST段抬高。ST段抬高最常出现在、aVF，其次为V5、V6、aVL V7-V9导联ST段抬高与后壁运动异常有关，诊断特异性高。Use of the Electrocardiogram in Acute Myocardial InfarctionThe added finding of ST-segment elevation in lead V 1 suggests proximal occlusion of the right coronary artery with associated right ventricular infarction.V3/III ratio:1.2 in the LCX lead II,a V3/III ratio approximately 0.3 mm,plus ST depression in aVL all suggest proximal RCA occlusion.急性心肌梗死的心电图诊断4、特殊的心电图的损伤表现 前壁+下壁损伤 间隔梗死 左主干病变 右室梗死 心房梗死急性心肌梗死的心电图诊断前壁+下壁损伤 前壁和下壁联合的心电图ST段抬高给人以大面积心肌损伤的印象。然而它常是由于长的LAD远段闭塞，且LAD绕过心尖，其室壁运动异常仅限于心尖部。当、aVF的损伤合并V1ST段抬高，而V2ST段压低时，提示右室梗死。急性心肌梗死的心电图诊断间隔梗死 在多数LAD闭塞的病人中V1-V3ST段抬高常假设存在室间隔梗死。其实不然，它是合并明显的心尖部运动异常。实际上，与超声室间隔运动减弱相一致的心电图表现为V3-V4的ST段抬高。急性心肌梗死的心电图诊断左主干病变 左主干完全或次全闭塞的病人静息心绞痛的心电图表现为aVR导联ST段抬高，、V4-V6ST段压低。ST段变化的总和18mm。急性心肌梗死的心电图诊断右室梗死 透壁性右室梗死为右胸导联ST段抬高1mm；V1导联ST段抬高对RCA近段闭塞有很高的特异性；右室梗死常与下壁梗死同时发生，单纯右室梗死少见，且主要出现在右室肥厚的病人，常出现RBBB；右胸导联ST段抬高存在时间很短，10小时内有50%的病人的ST段抬高会消失，故陈旧性右室梗死不能通过心电图诊断。Use of the Electrocardiogram in Acute Myocardial InfarctionRIGHT VENTRICULAR MYOCARDIAL INFARCTIONRight ventricular myocardial infarction is always associated with occlusion of the proximal segment of the right coronary artery.ST-segment elevation of more than 1 mm in lead V4R with an upright T wave in that lead.This sign is rarely present more than 12 hours after the infarction.急性心肌梗死的心电图诊断心房梗死 心房梗死很难在心电图上做出相应的诊断，目前没有明确的心房梗死的诊断标准；PQ间期的变化在识别心房梗死中是最有用的，PQ段抬高提示心房损伤；单纯PQ段下移的意义不大；心室梗死合并某一种房性心律失常提示心房梗死。急性心肌梗死的心电图诊断5、ST段压低 可能的机制：镜影现象区域性心内膜下缺血或梗死急性心肌梗死的心电图诊断ST段压低与ST段抬高同时存在 前壁梗死中出现下壁ST段压低，常为镜影现象，而非下壁心内膜下缺血所致；下壁梗死合并以V1-V3或、aVL ST段压低为主，提示Lcx闭塞，可以做为同时合并LAD病变的“除外现象”；下壁梗死合并V4-V6 ST段压低为主，提示LMA、LAD或3支病变。急性心肌梗死的心电图诊断单纯ST段压低 单纯ST段压低的导联6个，AMI的特异性为96.5%；V2-V3导联ST段压低最大，提示Lcx闭塞，它可以得益于溶栓治疗；V4-V6导联ST段压低最明显，可能是由于LAD的次全闭塞所致的心内膜下缺血，其特点是ST段压低合并T波直立而不演变为T波倒置；V4-V6导联ST段压低，T波倒置，表现为由于Lcx闭塞所致亚急性 后壁损伤或左室氧耗量的增加。急性心肌梗死的心电图诊断Q波的意义 ST段抬高的心梗并不总是出现病理性Q波，亦并非为透壁性心梗；反之亦然；Q波可能提示冠状动脉的高闭塞率；心电图的Q波心梗提示局部室壁运动不协调。急性心肌梗死的心电图诊断RBBB与AMI RBBB合并AMI很少会被传导障碍所隐匿，前壁和下壁的ST段抬高均能被记录到；V1-V3/V4导联T波的假性正常化提示前壁损伤。急性心肌梗死的心电图诊断LBBB与AMI 心电图评分：5ST段抬高1mm且QRS波向上；3V1-V3ST段压低1mm；2 ST段抬高5mm在QRS波向下的导联；分数3诊断AMI的特异性为90%。Use of the Electrocardiogram in Acute Myocardial InfarctionLEFT BUNDLE-BRANCH BLOCKQ waves cannot be used to diagnose infarctionST elevation 1 mm in leads with a positive QRSST depression 1 mm in leads V1 through V3ST deviation 5 mm is also suggestive of myocardial infarction in the presence of left bundle-branch block.急性心肌梗死的心电图诊断起搏器与AMI 出现QRS波向下的导联ST段抬高0.5mv提示AMI，特异性88%，敏感性53%。急性心肌梗死的心电图诊断假性梗死图形 正常变异急性心包炎其它急性心肌梗死的心电图诊断正常变异 复极过早综合征V1-V3导联ST段可抬高4mm，这一图形是由于左室复极的不一致性造成的。在正常人群中为1-2%，在急诊室胸痛患者中多达48%，这些人处于接受不适当的AMI治疗的危险之中！急性心肌梗死的心电图诊断急性心包炎 急性心包炎可持续3-4周，早期心电图表现为广泛ST段抬高，T波直立。待ST段恢复正常后，会有明显的T波改变。心梗后一过性ST段与T波同时恢复是证实心包炎的关键。急性心肌梗死的心电图诊断其它 严重的高钾血症 原发或继发的心脏肿瘤 急性肺栓塞 室壁瘤 左室肥厚 运动诱发的ST段抬高急性心肌梗死的心电图诊断不能确诊的心电图 15-18%的AMI不出现早期的ECG改变，25%为非特异性改变。连续的ECG观察可以增加这类AMI诊断的可能性。15导联或18导联ECG能增加发现AMI的可能性，且不减少特异性。Use of the Electrocardiogram in Acute Myocardial InfarctionELECTROCARDIOGRAPHIC PREDICTORS OF REPERFUSIONUse of the Electrocardiogram in Acute Myocardial InfarctionResolution of ST-segment elevation is believed to be an excellent marker of tissue perfusion,and the degree of resolution has proved to be a powerful indicator of short-term(30-day)and long-term(1-year)prognosis.Assessment of ST-segment resolution is also useful for guiding reperfusion therapy:the absence of ST-segment resolution during the first 90 minutes after the administration of fibrinolytic medications should prompt consideration of rescue angioplasty.A reduction in ST-segment elevation by more than 70 percent in the leads with maximal elevation is associated with the most favorable outcomes.Use of the Electrocardiogram in Acute Myocardial InfarctionT-wave inversion that occurs during the first few hours of reperfusion therapy is a highly specific sign of reperfusion.T-wave inversion that develops more than four hours after the start of reperfusion therapy is consistent with the normal electrocardiographic evolution of myocardial infarction and does not indicate that reperfusion has occurred.An accelerated idioventricular rhythm(defined as a heart rate of 60 to 120 beats per minute initiated by a late,coupled,ventricular premature depolarization)is a highly specific marker of reperfusion.Polymorphic ventricular tachycardia and ventricular fibrillation may be seen with reperfusion but are rare and should raise the suspicion of ongoing arterial occlusion.Use of the Electrocardiogram in Acute Myocardial InfarctionARRHYTHMIAS AND CONDUCTIONDISEASE IN ACUTE MYOCARDIALINFARCTIONUse of the Electrocardiogram in Acute Myocardial InfarctionConduction abnormalities,including bundle-branch block or varying forms of heart block during acute myocardial infarction,may be associated with a poor prognosis.The incidence of conduction abnormalities associated with acute myocardial infarction has diminished in the era of early revascularization therapy,but the mortality and morbidity associated with these abnormalities remain unchanged.Use of the Electrocardiogram in Acute Myocardial InfarctionThe sinus node is supplied by the right coronary artery in 60 percent of people and by the left circumflex artery in 40 percent.The atrioventricular node is supplied by the right coronary artery in 90 percent of people and by the left circumflex artery in 10 percent.The bundle of His is supplied by the atrioventricular nodal branch of the right coronary artery,with a small contribution from the septal perforators of the left anterior descending artery.Use of the Electrocardiogram in Acute Myocardial InfarctionThe right bundle branch receives most of its blood from septal perforators of the left anterior descending artery.There may also be collateral blood supply from the right coronary artery or left circumflex artery.The left anterior fascicle is supplied by septal perforators from the left anterior descending artery and is particularly susceptible to ischemia or infarction.The proximal portion of the left posterior fascicle is supplied by the atrioventricular nodal artery(i.e.,the right coronary artery)and by septal perforators of the left anterior descending artery.The distal portion of the posterior fascicle has a dual blood supply from the anterior and posterior septal perforating arteries.Use of the Electrocardiogram in Acute Myocardial InfarctionInferior myocardial infarctionSinus bradycardia or varying degrees of atrioventricular block(including complete heart block)can occur within the first two hours after an acute inferior myocardial infarction as a result of heightened vagal tone.Such conditions often resolve within 24 hours,and they are very responsive to atropine.Later in the course of inferior myocardial infarction,progressive conduction delay and block may occur.This phase of atrioventricular conduction problems appears to be related to edema and local accumulation of adenosine.It is less responsive to atropine than the acute phase and may respond to aminophylline.Use of the Electrocardiogram in Acute Myocardial InfarctionThe atrioventricular node is the site of conduction disturbances in inferior myocardial infarction;therefore,complete atrioventricular block is generally associated with a narrow complex escaperhythm of between 40 and 60 beats per minuteA ventricular escape rhythm with a widened QRS complex may signify the presence of block below the atrioventricular node and impaired collateral circulation to an occluded left anterior descending artery.Use of the Electrocardiogram in Acute Myocardial InfarctionBradyarrhythmias during the first few hours after an acute inferior myocardial infarction are responsive to atropine;conduction disease that begins or persists after the first 24 hours of myocardial infarction is not responsive to atropine.In most instances,conduction abnormalities associated with acute inferior myocardial infarction resolve within two weeks,and permanent pacing is not required.Use of the Electrocardiogram in Acute Myocardial InfarctionANTERIOR MYOCARDIAL INFARCTIONAs opposed to inferior myocardial infarction,conduction disease associated with anterior myocardial infarction is not related to heightened vagal tone but instead to necrosis of the intramyocardial conduction system.More commonly,necrosis of the septum is associated with slight PR prolongation(usually 0.12 second)with a right bundle-branch block pattern.Second-degree atrioventricular block with anterior myocardial infarction is usually Mobitz type II block secondary to block in the HisPurkinje system.Use of the Electrocardiogram in Acute Myocardial InfarctionANTERIOR MYOCARDIAL INFARCTIONThe mortality associated with complete heart block in anterior myocardial infarction,with or without preceding right bundle-branch block and left fascicular block,may be as high as 80percent.A temporary pacemaker should be placed in patients with anterior infarction and new right bundle-branch block(QR in lead V1)with left anterior or left posterior fascicular block if there is associated PR prolongation.Another indication for temporary pacing during anterior myocardial infarction is alternating right and left bundle-branch block.Use of the Electrocardiogram in Acute Myocardial InfarctionTACHYARRHYTHMIASUse of the Electrocardiogram in Acute Myocardial InfarctionAtrial fibrillation is associated with a worsened prognosis,regardless of the site of infarction.Ventricular premature depolarizations are common during acute myocardial infarction but do not predict the subsequent development of sustained ventricular arrhythmias and should not be suppressed.Initially,ventricular fibrillation may be seen as an acute manifestation of ischemia;later(at two or three weeks),it may be seen as a consequence of progressive pump dysfunction.Use of the Electrocardiogram in Acute Myocardial InfarctionThe presence of anterior myocardial infarction with right bundle-branch block and an ejection fraction of 35 percent or less is associated with recurrent ventricular tachycardia or fibrillation in the second and third weeks after myocardial infarction.In most instances,ventricular fibrillation in acute myocardial infarction is associated with lack of reperfusion of the infarct-related artery and should prompt evaluation for cardiac catheterization.Use of the Electrocardiogram in Acute Myocardial InfarctionCONCLUSIONSIn patients with acute myocardial infarction and ST-segment elevation,the earlier reperfusion therapy is provided,the greater the benefit.Since“time is myocardium,”it is important to make the diagnosis as quickly as possible.It is equally important,however,not to confuse other causes of ST-segment elevation with acute myocardial infarction.Use of the Electrocardiogram in Acute Myocardial InfarctionCONCLUSIONSImportant information to guide management and determine prognosis can be derived from the electrocardiogram in patients with acute myocardial infarction.Electrocardiographic markers of proximal coronary-artery occlusion identify relatively large myocardial infarctions that benefit most from early and complete revascularization strategies.Use of the Electrocardiogram in Acute Myocardial InfarctionCONCLUSIONSThe degree of ST-segment resolution is a simple and powerful predictor of ventricular function and prognosis after myocardial infarction.The recognition of abnormalities of conduction that result from different types of myocardial infarction is essential to the proper management of these conditions.