CURRENT Essentials of Critical Care.pdf

126 Current Essentials of Critical CareMyocardial Infarction (AMI), Acute■ Essentials of Diagnosis• Prolonged substernal chest pressure; lasting 15 minutes• Discomfort radiates to left arm, neck, or jaw; sweating, nausea,vomiting, syncope• Right ventricular MI: suspect with inferior MI or hypotensionwith nitrate administration; confirm with right-sided ECG• ECG with ST segment elevation (tombstones) 1 mm in twocontiguous leads or new bundle branch block• Elevation of CK-MB, troponins, AST, LDH• Echocardiogram: identifies wall motion abnormalities, residualventricular function, valvular abnormalities, MI associated tamponade• Complications: tachy/bradyarrhythmias, heart block, valvularinsufficiencies, pulmonary edema, hypoxemia, cardiogenicshock, pericarditis■ Differential Diagnosis• Cardiovascular: stable or unstable angina, Prinzmetal angina,pericarditis, myocarditis, aortic dissection• Pulmonary: pneumothorax, pulmonary embolism, pneumonia• Gastrointestinal: esophageal reflux or spasm, gastritis, peptic ulcerdisease, cholangitis, hepatitis, pancreatitis• Musculoskeletal pain and costochondritis■ Treatment• Bed rest, monitoring, oxygen, serial cardiac enzymes, ECGs• Immediately chew and swallow aspirin; clopidogrel in those intolerantof aspirin• Pain control with nitrates and/or morphine; anxiolytics• Beta-blockers to reduce myocardial oxygen consumption• ACE inhibitors confer survival benefit when EF 40%,• Thrombolytic reperfusion in ST segment elevation or new leftbundle branch block if no contraindication• Primary angioplasty alternative to thrombolytics if unstable hemodynamicsor chest pain on optimal medical regimen• Right heart catheterization may aid management of hypotension■ PearlWhen an AMI is thought to be associated with cocaine use, the use ofselective beta-blockers may lead to unopposed alpha-adrenergic stimulationand worsening hypertension and cardiac injury.ReferenceCannon CP et al: Critical pathways for management of patients with acutecoronary syndromes: an assessment by the National Heart Attack Alert Program.Am Heart J 2002;143:777. [PMID: 12040337]