Clinical Features of MI

1) Severe, crushing substernal chest pain 2) radiate to the neck, jaw, epigastrium, or left arm. 3- rapid and weak pulse 4- nausea (posterior MI). 5- cardiogenic shock (massive MIs >40% of the left ventricle) 6- dyspnea (pulmonary congestion and edema) } 10% to 15% of MIs are asymptomatic (silent infarcts)è particularly in patients with: 1- DM (peripheral neuropathies) 2- the elderly MI = heart attack § necrosis of heart muscle due to ischemia. § A very significant cause of death worldwide. § 33% -50% die before hospitalè lethal arrhythmia è Sudden Cardiac Death § Arrhythmias are caused by electrical abnormalities of the ischemic myocardium and conduction system. § } Acute occlusion of the proximal left anterior descending (LAD) artery is the cause of 40% to 50% of all Mis § frequency of MIs rises with increasing age and presence of risk factors such as hypertension, smoking, and diabetes } } } Clinical signs and symptoms Electrocardiographic(ECG) abnormalities Laboratory evaluation: blood levels of intracellular macromolecules that leak out of injured myocardial cells through damaged cell membranes. 1-myoglobin. 2-cardiac troponins T and I (TnT, TnI) 3-creatine kinase (CK, and more specifically the myocardialspecific isoform, CK-MB) 4- lactate dehydrogenase § § Cardiac troponins T and I (TnT, TnI), are the best markers for acute MI. creatine kinase CK-MB is the second best marker after the cardiac-specific troponins. (<24 hr)è coagulative necrosis and wavy fibers. Necrotic cells are separated by edema fluid. 2- to 3-day old - infarctè Dense neutrophil infiltrate (7 to 10 days)è complete removal of necrotic myocytes by phagocytic macrophages up to 14 daysè Granulation tissue characterized by loose connective tissue and abundant capillaries. several weeksè Healed myocardial infarct consisting of a dense collagenous scar. Microscopic features of myocardial infarction and its repair. (<24 hr)è coagulative necrosis and wavy fibers Necrotic cells are separated by edema fluid Microscopic features of myocardial infarction and its repair. 2- to 3-day old infarctè Dense neutrophil infiltrate • in case of reperfusionà contraction bands Microscopic features of myocardial infarction and its repair. 7 to 10 days)è complete removal of necrotic myocytes by macrophages Microscopic features of myocardial infarction and its repair. up to 14 daysè Granulation tissue =loose connective tissue (blue) and abundant capillaries (red) Microscopic features of myocardial infarction and its repair. several weeksè Healed infarct consisting of a dense collagenous scar (blue) § § 1- Death: Unfortunately, 50% of the deaths associated with acute MI occur in individuals who never reach the hospital (within 1 hour of symptom onset-usually as a result of arrhythmias) Extraordinary progress has been made in patient outcomes subsequent to acute MI (thein-hospital) death rate has declined from approximately 30% to an overall rate of between 10% and 13%). 2- cardiogenic shock. - (10% to 15%) of patients after acute MI - with a large infarct ( >40% of the Left ventricle). - 70% mortality rate; 2/3 of in-hospital deaths. § 3-Myocardial rupture § 4-Pericarditis. § 5-Infarct expansion § 6-Ventricular aneurysm § 7-Progressive late heart failure § (1) rupture of the ventricular free wallà hemopericardium and cardiac tamponade (usually fatal) (2) rupture of the ventricular septumà VSD and left-to-right shunt (3) papillary muscle ruptureà severe mitral regurgitation § § 4-Pericarditis. - fibrinous or hemorrhagic pericarditis - usually 2 to 3 days of a transmural MI - typically spontaneously resolves with time (immunologic mechanism). 5-Infarct expansion. Because of the weakening of necrotic muscle, there may be disproportionate stretching, thinning, and dilation of the infarct region (especially with anteroseptal infarcts) § § 6-Mural thrombus. -the combination of a local loss of contractility (causing stasis) + endocardial damage (causing a thrombogenic surface) à thromboembolism 7-Ventricular aneurysm. - A late complication - most commonly result from a large transmural anteroseptal infarct that heals with the formation of thin scar tissue Ventricular aneurysmComplications of ventricular aneurysms include: 1-mural thrombus 2-arrhythmias 3-heart failure 8-Papillary muscle dysfunction (post-infarct mitral regurgitation ) § dysfunction of a papillary muscle after MI occurs due to: 1- rupture. 2- ischemic dysfunction 3- fibrosis and shortening 4- ventricular dilation. § 9-Progressive late heart failure § - } depends on many factors, the most important of which are left ventricular function and the severity of atherosclerotic narrowing of vessels perfusing the remaining viable myocardium. Mortality rate within the first year =30% Thereafter, the annual mortality rate is 3% to 4%. } } } Chronic IHD usually results from post-infarction cardiac decompensation that follows exhaustion of the hypertrophic viable myocardium. progressive heart failure as a consequence of ischemic myocardial damage; sometimes punctuated by episodes of angina or MI. Arrhythmias are common along with CHF } } } } } Affecting some 300,000 to 400,000 individuals annually in the United States SCD is most commonly defined as unexpected death from cardiac causes either without symptoms or within 1 to 24 hours of symptom onset Coronary artery disease is the most common underlying cause In many adults SCD is the first clinical manifestation of IHD. With younger victims, other non-atherosclerotic causes are more common: Congenital coronary arterial abnormalities } Aortic valve stenosis } Mitral valve prolapse } Myocarditis } Dilated or hypertrophic cardiomyopathy } Pulmonary hypertension } Hereditary or acquired abnormalities of the cardiac conduction system. } Isolated myocardial hypertrophy. } unknown causes. }