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1、Myocardial Infarction 心肌梗死,Myocardial infarction 心肌梗死,Myocardial infarction (MI or AMI for acute myocardial infarction), also known as a heart attack心脏病发作, occurs when the blood supply to part of the heart is interrupted, resulting ischemia and oxygen shortage, if left untreated for a sufficient per
2、iod, can cause damage and/or myocardium infarction. Angina心绞痛as a result of ischemia causes reversible cellular injury, and infarction is the result of sustained ischemia, causing irreversible cellular death.,Classification 分类,Acute myocardial infarction is a type of acute coronary syndrome急性冠脉综合征.
3、The acute coronary syndromes include: unstable angina (UA)不稳定型心绞痛. ST segment elevation myocardial infarction (STEMI) ST段抬高性心梗 non-ST segment elevation myocardial infarction (NSTEMI) 非ST段抬高性心梗,Myocardial infarction,Infarctions are described by the area of occurrence as anterior前壁, posterior后壁, infer
4、ior下壁 or lateral侧壁 wall infarctions. Inferior MI is also called a diaphragmatic MI (DMI)膈肌心梗 Common combination of areas are the anterolateral前侧壁心肌梗塞 or anteroseptal (房室)隔前的MI.,Pathophysiology病理生理,The most common triggering event is the disruption破损of an atherosclerotic plaque粥样硬化斑块in an epicardial
5、coronary artery. Plaques can become unstable, rupture破裂, and additionally promote a thrombus血栓(blood clot) that occludes阻塞the artery. When a severe enough plaque rupture occurs in the coronary vasculature, it leads to myocardial infarction.,Pathophysiology 病理生理,Depending on the location of the obstr
6、uction in the coronary circulation, different zones of the heart can become injured. An occlusion of the left anterior descending coronary artery(LAD)左冠状动脉前降支will result in an anterior wall myocardial infarct前壁心肌梗死. Infarcts of the lateral wall侧壁心肌梗死are caused by occlusion of the left circumflex cor
7、onary artery(LCx)冠状动脉左回旋支. Both inferior wall and posterior wall infarctions下壁和后壁心梗may be caused by occlusion of either the right coronary artery右冠状动脉or the left circumflex artery左冠状动脉回旋支, depending on which feeds the posterior descending artery. Right ventricular wall infarcts右心室壁梗死are also caused
8、by right coronary artery右冠状动脉occlusion.,Pathophysiology病理生理,The degree of preestablished collateral circulation侧支循环提前建立also determine the severity of infarction. In an individual with a history of heart disease, adequate collateral channels may have been established that provided the area surroundin
9、g the infarction site with a blood supply and oxygen. This is one explanation why the young person who has a severe MI is more likely to have a more serious impairment than an older person with the same degree of occlusion.,Healing process愈合过程,Within 24 hours: The bodys response to cell death is the
10、 inflammation process. Leukocytes白细胞 infiltrate the area. Enzymes 酶are released from the death cardiac cells and are important diagnostic indicators.,Healing process愈合过程,The second or third day: The proteolytic enzymes蛋白水解酶of neutrophils and macrophages巨噬细胞remove all necrotic坏死 tissue and the necrot
11、ic muscle wall is thin. Development of collateral circulation improve the area of poor perfusion and may limit the zones of injury and infarction. Once infarction takes places, catecholamine-mediated儿茶酚胺介导 lipolysis脂解(作用) and glycogenolysis糖原分解 occur. For this reason, serum glucose levels are freque
12、ntly elevated after MI and may be the reason for a pseudodiabetic state假性糖尿病.,Healing process愈合过程,Within 4 to 10 days: The necrotic zone is identifiable by ECG changes, at this point, the phagocytes (neutriphils and monocytes 中性粒细胞和单核细胞) have clear the necrotic debirs坏死的碎片from the injury area and th
13、e collagen matrix 胶原基质that will eventually form the scar瘢痕is laid down. At 10 to 14 day: The beginning of scar tissue 疤痕组织 is weak. The myocardium is considered to be especially vulnerable to increased stress because of the unstable state of the healing heart wall. 6 weeks after MI: Scar tissue has
14、replaced necrotic tissue, at this time, the injured area is said to be healed.,Clinical manifestation 临床表现,Pain Severe, immobilizing chest pain not relieved by rest or nitrate administration is the hallmark of an MI. it is often described as a sensation of tightness, pressure压榨, or squeezing紧缩. Comm
15、on locations are substernal胸骨下and retrosternal胸骨后. Pain radiates most often to the left arm, but may also radiate to the lower jaw下颌， neck, right arm, back, and epigastrium腹上部, where it may mimic heartburn. Pain are commonly occurs in the early morning hours. It usually lasts for 20 minutes or more.
16、,Clinical manifestation,Nausea and vomiting Nausea and vomiting can result from reflex stimulation of the vomiting center by the sever pain and can also result from vasovagal reflex血管迷走性反射from the area of the infarcted myocardium. Sympathetic stimulation Diaphoresis发汗, weakness, light-headedness, an
17、d palpitations心悸. These symptoms are likely induced by a massive surge of catecholamines儿茶酚氨from the sympathetic nervous system which occurs in response to pain and the hemodynamic abnormalities血流动力学的异常that result from cardiac dysfunction心功能不全.,Clinical manifestation,Fever The temperature may increa
18、se within the first 24 hour up to 38 to 39. the temperature elevation may lasts for as long as 1 week. Cardiovascular manifestations The BP and pulse rate may be elevated initially, later BP may drop because of decreased CO. Urine may be decreased. Crackles湿啰音may be noted in the lungs, persisting fo
19、r several hours to days Hepatic engorgement 肝怒张and peripheral edema外周水肿may indicate covert cardiac failure. Jugular veins 颈静脉 may distended and may have obvious pulsations搏动, indicating early right ventricular dysfunction and pulmonary congestion.,Complication,Dysrhythmias 心律失常: are the most common
20、complication, present in 80% of MI patient. The intrinsic rhythm of the heartburn is disrupted, causing either a fast HR (tachycardia心动过速 ), a slow HR (bradycardia心动过缓 ), or an irregular beat. Complete heart block心脏传导阻滞is seen in massive infarction. Ventricular fibrillation室颤, a common cause of sudd
21、en death, is a lethal dysrhythmia that most often occurs within the first 4 hours after the onset of pain. Premature ventricular contractions室性早搏(PVCs) may precede ventricular tachycardia室性心动过速and fibrillation室颤. Ventricular dysrhythmia needs immediate treatment.,Complication,Congestive heart failur
22、e Cardiogenic shock Papillary muscle dysfunction乳头肌功能障碍 Ventricular aneurysm室壁瘤 Pericarditis心包炎 Dressler syndrome德雷斯勒综合征，心肌梗死后综合征 Pulmonary embolism肺栓塞,Diagnostic studies辅助检查,Three noninvasive diagnostic parameters are used to determine whether a person has sustained an acute MI: The patients histor
23、y of pain, risk factors and health history. 12-lead ECG consistent with acute MI (inverted倒置T waves, ST-T waves elevations of greater than 1 mm or more in two contiguous leads, abnormal Q wave) Measurement of serial myocardial serum enzymes Other measures includes: Chest X-ray CBC, thyroid profile N
24、uclear imaging studies Endocardiogram,Diagnostic studies,ECG findings ECG are approximately 80% specific for diagnosing an acute MI and represent a leading diagnostic criterion.,Diagnostic studies辅助检查,Cardiac enzymes: An important diagnostic criterion for acute MI is laboratory assessment of serial
25、cardiac serum enzymes. Creatine kinase肌酸激酶(CK): CK levels begin to rise approximately 6 hours after an acute MI and return to normal within 2 to 3 days. Lactic dehydrogenase乳酸脱氢酶(LDH) Aspartate aminotransferase谷草转氨酶(AST),Therapeutic management治疗方案,IV therapy Initial management of MI is best accompli
26、shed in a cardiac care unit (CCU), where constant monitoring is available. An IV route is established to provide an accessible means for emergency drug therapy. Morphine 吗啡sulfate may be given IV 2-4 mg/hr as needed for relief of pain (or meperidine 度冷丁if patient is allergic to morphine) A continuou
27、s IV infusion of lidocaine 利多卡因may be given, prophylactically to prevent ventricular fibrillation室颤.,Therapeutic management治疗方案,Oxygen therapy Continual ECG monitoring to deter dysrhythmias Vital signs are taken frequently during the first few hours after admission and are monitored 1-4 hr thereafte
28、r. Bed rest and limitation activity are usual initially, with a gradual increase in activity. Recording intake and output A pulmonary artery (PA) catheter肺动脉导管and intraarterial line 动脉内置管may be used to accurately monitor intracardiac, pulmonary artery, and systolic arterial pressures in complicated
29、MI so that the most effective mode of treatment in the acute phase can be determined.,Therapeutic management,Thrombolytic therapy溶栓疗法 It is now known that 80% to 90% of all acute MI are secondary to thrombus formation. Thrombolytic therapy is the standard of practice in the treatment of acute MI. My
30、ocardial cells do no die instantly. It takes approximately 4 to 6 hours for entire thickness of the muscle to become necrosed and this is known as transmural infarction 跨壁梗死. Treatment of acute MI is geared to quickly dissolving thrombus in the coronary artery and reperfusing the myocardium before c
31、ellular death occurs. To be of most benefit, thrombolytics must be given as soon as possible, perferably within the first 6 hours after the onset of pain.,Therapeutic management,Thrombolytic therapy溶栓疗法 Thrombolytic agents used to treat myocardial infarction are: streptokinase (链激酶 ), urokinase (尿激酶
32、 ), tissue plasminogen activator (t-PA) (组织纤维蛋白溶酶原激活剂). Indications of thrombolytic therapy: Chest pain typical of acute MI less than or equal to 6 hr in duration (some centers extend the time limit to 12 hr). 12-lead ECG findings consistent with acute MI.,Thrombolytic therapy溶栓疗法,Contraindications
33、of thrombolytic therapy: Absolute contraindications禁忌: History of hemorrhagic stroke Uncontrolled hypertension (SBP200, DBP120) Recent surgery or trauma (within 2 wk) Active internal bleeding Known bleeding disorder Suspected aortic dissention主动脉剥离 Relative contraindications: History of stroke Acute
34、, poor Uncontrolled hypertension (BP180/110) Malignancy妊娠 Acute pericarditis急性心包炎 Pregnancy妊娠 Active peptic ulcer活动性消化性溃疡 Diabetic hemorrhagic retinopathy 糖尿病性视网膜病变 Artial fibrillation房颤,nursing care for thrombolytic therapy,ECG, vital signs, heart and lung assessments are completed as often as ever
35、y 5 minutes to evaluate the patients response to therapy. When reperfusion occurs, several clinical markers may occurs, nurses should monitor them, those signs of reperfusion includes chest pain resolution, return of ST segment to baseline on the ECG, the presence of reperfusion dysrhythmias再灌注性心律失常
36、 (premature ventricular contractions室性早搏, ventricular tachycardia室性心动过速, ventricular fibrillation心室颤动), rapid rise of the CK enzymes within 3 hrs of therapy, peaking within 12 hrs.,nursing care for thrombolytic therapy,Another major concern with therapy is reocclusion动脉重新堵塞of the artery, because of
37、this possibility, an IV bolus is given, followed by heparin drip to maintain the patients Partial Thromboplasm Time (PPT)部分凝血酶原时间at one to two times normal, this prevent another clot form forming in the coronary artery. The major complication with thrombolytic therapy is bleeding. The nurses must pa
38、y particular attention to signs and symptoms of bleeding such as gingival bleeding牙龈, drop in BP, an increasing in HR, hematuria 血尿, a sudden change in patients level of consciousness and oozing渗出of blood from IV or catheter site.,Therapeutic management 9.Percutaneous Coronary Intervention (PCI)冠状动脉
39、介入治疗,Balloon,Stent,Laser,Rotablator,Percutaneous transluminal coronary angioplasty (PTCA) 经皮腔内冠状动脉成形术,.,Percutaneous transluminal coronary angioplasy (PTCA) 经皮腔内冠状动脉成形术,.,Percutaneous transluminal coronary angioplasy (PTCA) 经皮腔内冠状动脉成形术,.,PCI Complication 冠状动脉介入治疗的并发症,Acute abrupt closure of coronary
40、 vessels serious arrhythmias : VT室速，VF室颤。 Cardiac tamponade心包填塞 Vascular complication Low blood pressure Stroke Hemorrhage Renal failure Heart attack Death,Coronary artery bypass surgery (CABG) 冠状动脉搭桥手术,Coronary artery bypass surgery (CABG) 冠状动脉搭桥手术,Pharmacologic management药物管理,IV nitroglycerin硝酸甘油
41、IV Morphine 吗啡 Morphine can reduce anxiety, decrease cardiac work load, reduce contractility, lower BP and slow the HR. Antidysrhythmic drugs抗心律失常药物 Dystrhythmia are the most common complications after MI. -Blockers Calcium channel blockers Angiotensin-converting enzyme inhibitors Stool softeners,Nu
42、trition management,Diet is restricted in saturated fats饱和脂肪和 and cholesterol胆固醇and is sometimes low in sodium to prevent fluid retention. The patient may have a clear liquid diet the first day when there may still be nausea.,Nursing diagnosis and intervention,Acute pain related to lactic acid produc
43、tion from myocardial ischemia and altered myocardial oxygen supply. Administer oxygen through nasal cannula to increase oxygenation of myocardial tissue and prevent further tissue ischemia. Administer morphine sulfate IV as needed to decrease anxiety, elevated pain and decrease cardiac work load. Mo
44、nitor vital signs q1-2hr to provide on-going assessment of patients response to treatment.,Nursing diagnosis and intervention,Altered cardiac tissue perfusion related to myocardial damage, ineffective CO and potential pulmonary congestion Provide long, uninterrupted rest period to promote cardiac re
45、st and healing. Minimize cardiac workload during healing. Explain necessity of bed rest and decreased activity to promote patient cooperation. Allow rest periods between concentrated nursing care time to reduce fatigue and oxygen requirements of myocardium. Asses urine output to determine adequacy o
46、f renal blood flow.,Nursing diagnosis and intervention,Impaired gas exchange related to ineffective breathing pattern and decreased systemic tissue perfusion secondary to decreased CO. Elevated head of bed to allow gravity to lower the diaghragm and decrease the work of breathing and reduce venous r
47、eturn. Hold morphine and notify physician if respiratory rate less than 10-12/min because morphine is a respiratory depressant. Maintain oxygen therapy as order.,Nursing diagnosis and intervention,Activity intolerance related to fatigue secondary to decreased CO and poor lung and tissue perfusion Me
48、et patients need quickly and efficiently to conserve energy and prevent anxiety. Encourage patient to maintain bed rest. Monitor BP, pulse, respiration and color to monitor patients response to activity and to adjust as necessary. Administer oxygen during activity to increases O2 availability for ca
49、rdiac and other organ perfusion.,Nursing diagnosis and intervention,Constipation related to immobility, change in diet, possible fluid restriction and mediations. Administer stool softeners as ordered. Provide bedside commode. Instruct patients to avoid straining. Provide foods high in fiber. If patient is unsuccessful, obtain laxative order from physician to facilitate easier bowel evacuation. Increased activity and ambulation as tolerated to increase peristalsis and bowel motility.,Nursing diagnosis and intervention,Sleep pattern disturbance related to complex treatment