心肌梗死病理病理生理和临床表现.ppt

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1、急性心肌梗死病理、病理生理及临床,【急性心肌梗塞(AMI)】定 义,梗死：血管闭塞引起的组织坏死。 AMI是急性心肌缺血性坏死，大多是在冠状动脉病变的基础上发生冠状动脉血供急剧减少或中断，使相应的心肌严重而持久地急性缺血所致,Coronary Artery,Blood Clot (Thrombus),Unstable Plaque Rupture,Coronary Artery,Infarcted (dead) or injured (dying) tissue,Healthy Heart Muscle (Myocardium),Myocardial Infarction,原因通常是在冠状动脉

2、粥样硬化不稳定斑块病变的基础上继发血栓形成导致冠脉持续、完全阻塞,【急性心肌梗塞(AMI)】定 义,临床诊断要求有病史和应用生化方法、心电图和显像方法的得到心肌坏死间接证据综合评定 病理诊断要求有心肌细胞坏死的证据，坏死是缺血时间过长导致的。细胞坏死的特征性表现包括细胞凝固性坏死和（或）收缩带的坏死，常伴有梗死灶周围的斑片状心肌细胞溶解区。,急性心肌梗死的新定义,（1）典型的心肌坏死生物标志物浓度升高（肌钙蛋白）超过参考值上限（URL）99百分位值并有动态变化，同时伴有以下一项心肌缺血的证据： 缺血性症状 ECG提示新发的缺血性改变（新发的ST段变化或左束支传导阻滞LBBB） 心电图提示病理性

3、Q波形成 影像学证据提示新发的节段性室壁运动异常或存活心肌丢失,新定义,；（2）突发的心源性死亡（包括心脏停搏），通常伴有 心肌缺血的症状 新发ECG缺血性改变或LBBB和（或） 经冠状动脉（冠脉）造影（或尸检）证实的新发血栓证据，但死亡常常发生在获取血标本或发现心肌酶学标志物升高之前；,新定义,（3）基线cTn水平正常者接受经皮冠状动脉介入治疗（PCI）后，如果心脏标志物水平升高超过URL99百分位值，则提示围手术期心肌坏死；如果心脏标志物水平超过URL99百分位值的3倍，则定义为与PCI相关的心肌梗死；,新定义,（4）基线cTn水平正常者接受冠状动脉旁路移植术（CABG）后，如果心脏标志物

4、水平升高超过URL99百分位值，则提示围手术期心肌坏死；如果心脏标志物水平超过URL99百分位值的5倍，同时伴有以下任何一项：新发的病理性Q波、新发的LBBB、冠脉造影证实新发桥血管或自身冠脉闭塞、新出现的存活心肌丢失的影像学证据，则定义为与CABG相关的心肌梗死；（5）病理检查时发现急性心肌梗死。,心肌坏死生化标志物,新定义建议采用cTn，即在症状发生后24小时内，cTn的峰值超过正常对照值的99百分位。因为cTnI或cTnT具有高度的心肌组织特异性和敏感性，即使心肌组织发生微小区域的坏死也能检查到cTn的升高，因此是评价心肌坏死的首选标志物。如果没有条件检测cTn，也可以采用CK-MB m

5、ass作为最佳替换指标，诊断标准与cTn相同。由于CK广泛分布于骨骼肌，缺乏特异性，因此不再推荐用于诊断心肌梗死。,在cTn升高但缺少心肌缺血临床证据时，应寻找其他可能导致心肌坏死的病因，包括急性和慢性充血性心力衰竭、肾功能衰竭、快速性或缓慢性心律失常、急性神经系统疾病、肺栓塞和肺动脉高压、心脏挫伤/消融/起搏/复律、浸润性心脏疾病（如淀粉样变性和硬皮病）、炎性疾病（如心肌炎）、药物毒性、主动脉夹层、肥厚型心肌病、甲状腺功能减退、心尖球型综合征、横纹肌溶解伴心肌损伤、败血症等严重全身性疾病等。,按病因将心肌梗死分为5型,1型：自发性心肌梗死，由于原发的冠状动脉事件如斑块破裂等引起的心肌缺血；

6、2型：心肌梗死继发于心肌的供氧和耗氧不平衡所导致的心肌缺血，如冠状动脉痉挛、贫血、冠状动脉栓塞、心律失常或低血压等； 3型：心源性猝死，有心肌缺血的症状和新出现的ST段抬高或新的LBBB，但未及采集血样之前就死亡； 4型：与因缺血性冠脉事件而进行的PCI相关的心肌梗死；4a 4b 5型：与因缺血性冠脉事件而进行的CABG相关的心肌梗死。,60% Narrowing of Coronary Artery,痉挛Normal Coronary Artery Cross Section,Coronary Artery Thrombus,Source: University of Utah WebPat

7、h,The external anterior view of the heart shows a dark clot formation in this artery,陈旧性心肌梗死的定义标准为：（1）新出现的病理性Q波，伴或不伴症状；（2）影像学证据提示心肌变薄或瘢痕化，失去收缩力或无存活性；（3）病理检查时发现已经或正在愈合的心肌梗死。,【发病机理】,冠状动脉粥样硬化造成管腔狭窄和心肌供血不足，而侧支循环尚未建立时，下列原因加重心肌缺血即可发生心肌梗塞。 一、 冠状动脉完全闭塞 二、心排血量骤降 三、心肌需氧需血量猛增,一、冠状动脉完全闭塞,1、病变血管粥样斑块内或内膜下出血， 2、血小

8、板聚集管腔内血栓形成， 3、动脉持久性痉挛。,二、心排血量骤降,休克、脱水、出血、严重的心律失常或外科手术等引起心排出量骤降,三、心肌需氧需血量猛增,重度体力劳动、情绪激动或血压剧升时，左心室负荷剧增，儿茶酚胺分泌增多，心肌需氧需血量增加。,诱因：,1、 饱餐（尤其是进食大量脂肪） 因餐后血脂增高，血液粘稠度也高，血小板粘附性增强，局部血流缓慢，血小板易于聚集以致血栓形成； 2、睡眠 迷走神经张力增高，易引起冠状动脉痉挛； 3、用力大便 增加心脏负荷。 心肌梗塞后发生的严重心律失常，休克或心力衰竭，均可使冠状动脉灌流量进一步降低，心肌坏死范围扩大。,【病理】,Coronary Artery W

9、ith Plaque and Thrombus Formation,A - Coronary Artery cross-section B - Lumen C - Fissured Plaque w/o Cap D - Acute thrombus,Source: Emergency Cardiovascular Care Library (CD-ROM), American Heart Association, Dallas 1997,Thrombus Causing MI,“Needle-Like” white spots are cholesterol crystals,Thrombus

10、 ocluding artery,Likely site of plaque rupture,高倍镜下可见粥样斑块中有许多泡沫细胞（即吞噬大量脂质的巨噬细胞）和胆固醇结晶。,动脉粥样斑块比右边残存的动脉中膜要厚。可见大量针状的胆固醇结晶（针状空隙），左边有新鲜出血，血栓可在这样的斑块顶部形成。,31,Myocardial Ischemia,Myocardial cell metabolic demands not met Time frame of coronary blockage: 10 seconds following coronary block Decreased strength

11、 of contractions Abnormal hemodynamics See a shift in metabolism, so within minutes: Anaerobic metabolism takes over Get build-up of lactic acid, which is toxic within the cell Electrolyte imbalances Loss of contractibility,32,20 minutes after blockage Myocytes are still viable, so If blood flow is

12、restored, and increased aerobic metabolism, and cell repair, Increased contractility About 30-45 minutes after blockage, if no relief Cardiac infarct 328:981-8.,Acute Right Ventricular Wall MIRight Sided Leads,七、生物标志物浓度的改变：,Shapiro BP, Jaffe AS. Cardiac biomarkers. In: Murphy JG, Lloyd MA, editors.

13、Mayo Clinic Cardiology: Concise Textbook. 3rd ed. Rochester, MN: Mayo Clinic Scientific Press and New York: Informa Healthcare USA, 2007:77380. Anderson JL, et al. J Am Coll Cardiol 2007;50:e1e157, Figure 5.,Non ACS causes of Troponin Elevation,Trauma (including contusion; ablation; pacing; ICD firi

14、ngs, endomyocardial biopsy, cardiac surgery, after-interventional closure of ASDs) Congestive heart failure (acute and chronic) Aortic valve disease and HOCM with significant LVH Hypertension Hypotension, often with arrhythmias Noncardiac surgery Renal failure Critically ill patients, especially wit

15、h diabetes, respiratory failure Drug toxicity (eg, adriamycin, 5 FU, herceptin, snake venoms) Hypothyroidism Coronary vasospasm, including apical ballooning syndrome Inflammatory diseases (eg, myocarditis, Kawasaki disease, smallpox vaccination, Post-PCI Pulmonary embolism, severe pulmonary hyperten

16、sion Sepsis Burns, especially if TBSA greater than 30% Infiltrative diseases: amyloidosis, hemachromatosis, sarcoidosis, and scleroderma Acute neurologic disease, including CVA, subarchnoid bleeds Rhabdomyolysis with cardiac injury Transplant vasculopathy Vital exhaustion,Modified from Apple FS, et

17、al Heart J. 2002;144:981-986.,并发症,Acute Myocardial InfarctionComplications,Death (18% within 1 hour, 36% within 24 hours) Non-fatal arrhythmia Acute left ventricular failure Cardiogenic shock Papillary muscle rupture and mitral regurgitation Myocardial rupture and tamponade Ventricular aneurysm and

18、thrombus,Acute MI: Acute Complications,Postinfarction VSD Free wall rupture Postinfarction ventricular aneurysm associated with ventricular tachyarrhythmias/CHF,Complications of MI,Cardiac Tamponade: Fluid between pericardium/myocardium Pericarditis: Inflammation of the pericardium Emboli: From eith

19、er MI thrombus or atrial clots formed with atrial pooling,Most Common Complications:,Congestive Heart Failure: 75% of MIs experience overt CHF Fluid backs up 25% of MIs experience “compensated” CHF reduced perfusion to “vital organs”? Dysrhythmias: The importance of ECG monitoring post-MI,Cyanosis (

20、blue fingernails 24: 2866.,目的,原则,如果开始PCI治疗的时间要比开始药物纤溶的时间延迟60分钟以上，那么PCI治疗可能并不能降低死亡率 及时采用合适的再灌注治疗比选择治疗方式更重要,Ischemic Coronary Syndromes,“Ischemic and injured tissue have reduced blood flow but may be salvaged. The area of the Penumbra may be viable for several hours after onset of occlusion.” Source:

21、Emergency Cardiovascular Care Library (CD-ROM), American Heart Association, Dallas, 1997,Treatment of Acute MISummary,INFLUENCE OF TIME-TO-TREATMENT ON THE ODDS RATIO (OR) OF MORTALITY,Boersma et al. Lancet 1996; 348: 771775.,ABSOLUTE BENEFIT PER 1,000 TREATED PATIENTS,TREATMENT DELAY IN HOURS,0,3,6

22、,9,12,15,18,21,24,0,20,40,60,80,The “golden hour”: 65 lives are saved for every 1,000 patients treated when the treatment is initiated within the first hour of symptom onset!,IMPACT OF TIME-TO-TREATMENT AND 30-DAY MORTALITY PCI VS. THROMBOLYSIS,30-35-DAY MORTALITY (%),Thrombolysis,PCI,Cannon et al.

23、J Thromb Thrombol 1994; 1: 2734.Cannon et al. JAMA 2000; 283: 29412947. Huber et al. Eur Heart J 2005; 26: 10631074.,TIME FROM ONSET OF PAIN TO THERAPY IN HOURS,0,6,12,2,4,2,4,6,8,10,8,0,1,3,5,7,102,ESC STEMI GUIDELINES 2008: REPERFUSION STRATEGIES,Van de Werf et al. Eur Heart J 2008; 29: 2909-2945.

24、 .,Ambulance,First Medical Contact (FMC),PCI-capable hospital,Non-PCI-capable hospital,primary PCI,rescue PCI,angiography,Pre-, in-hospital fibrinolysis,2h,12h,24h,Time Limits,* Time FMC to first balloon inflation must be shorter than 90 min in patients presenting early ( 2 h after symptom onset), w

25、ith large amount of viable myocardium and low risk of bleeding.,#If PCI is not possible 2 h of FMC, start fibrinolytic therapy as soon as possible.,Not earlier than 3h after start fibrinolysis.,24/7 service,successful,failed,PCI 2h possible* PCI 2h not possible# .,Specifics of Early Hospital Care,An

26、ti-Ischemic Therapy Anti-Platelet Therapy Anticoagulant Therapy,Early Hospital CareAnti-Ischemic Therapy,Class I Bed/Chair rest and Telemetry Oxygen (maintain saturation 90%) Nitrates (SLx3 Oral/topical. IV for ongoing iscemia, heart failure, hypertension) Oral B-blockers in First 24-hours if no con

27、traindications. (IV B-blockers class IIa indication) Non-dihydropyridine Ca-channel blockers for those with contraindication fo B-blockers ACE inhibitors in first 24-hours for heart failure or EF40% (Class IIa for all other pts) (ARBs for those intolerant) Statins,Early Hospital CareAnti-Ischemic Th

28、erapy,Class III Nitrates if BP0.24 sec, 2nd or 3rd degree heart block, active asthma, or reactive airway disease NSAIDS and Cox-2 inhibitors,Early Hospital CareAnti-Platelet Therapy,Class I Aspirin (162-325 mg), non enteric coated Clopidogrel for those with Aspirin allergy/intolerance (300-600 mg lo

29、ad and 75 mg/d) GI prophylaxis if a Hx of GI bleed GP IIb/IIIa inhibitors should be evaluated based on whether an invasive or conservative strategy is used GP IIb/IIIa inhibitors recommended for all diabetics and all patient in early invasive arm,Early Hospital CareAnticoagulant Therapy,Class I Unfr

30、actionated Heparin Enoxaparin Bivalarudin Fondaparinux Relative choice depends on invasive vs conservative strategy and bleeding risk,8,16,32,40,48,56,72,随机后小时,Antman EM, et al. Circulation 1999;100:1593-1601,TIMI - 11B 研究依诺肝素的显著优势在早期（48小时）就显示出来,急性期(48小时) 依诺肝素组事件发生率显著低于普通肝素,10 ,8 ,6 ,4 ,2 ,0,普通肝素,依诺肝素,发生事件病人%,7.3%,5.5%,RRR = 23.8% P=0.029,Cohen M, et al. N Engl J Med. 1997;337:447-52.,ESSENCE 研究依诺肝素与普通肝素相比，显著降低30天终点事件（死亡、MI和复发心绞痛），且14天时就已显现其优势,依诺肝素是唯一被证实优于UFH的LMWH，也是唯一被ACC/AHA UA/NSTEMI治疗指南推荐的LMWH,美国胸科医师学会 (ACCP) 2004指南,2007 ESC NSTE ACS指南推荐,Time is Muscle!,Thank You !,