-IBIS-1.5.0-
tx
cardiovascular system
myocardial infarction sequelae
diagnoses

definition and etiology

myocardial infarction is a medical emergency requiring immediate hospitalization

definition:
permanent myocardial damage due to myocardial infarction

etiology:
The most common cause is coronary artery disease, following the many attendant risk factors for atherosclerosis. Occlusion may be gradual or thrombotic, and involve coronary spasm or emboli. Lesions may be transmural or subendocardial.
Curiously, Traditional Chinese Medicine considers excessive joy as a potential contributing factor. This contrasts sharply with the emerging Western understanding of suppression of anger and other emotions, or the more familiar implication of 'type A' behavior as etiologic factors.

signs and symptoms

complications:
• pericarditis
• mural thrombi (subject to rupture)
• peripheral artery embolism
• frank rupture
• cardiac tamponade (intrapericardial hemorrhage)
• ventricular aneurysm

signs and symptoms:
classic symptoms of an MI include:
• deep, severe substernal pain referred to the left arm, jaw, or back; the pain is refractory to nitroglycerin; it may be preceded by one of the angina variants
• fear, sweating, great anxiety
• shortness of breath
other associated symptoms are:
• hypotension, poor peripheral blood flow, pulmonary edema, arrhythmias, fever, leukocytosis

lab findings:
• elevated levels of CPK, LDH, and AST, depending on timing
• elevated levels of alkaline phosphatase
• CPK-MB isoenzyme returns to normal after 3 days
• LDH increases 10-12 hours after MI, peaks @ 48-72 hours; LDH isoenzymes flip so LDH1/LDH2 ratio >1
• AST level increases @ 6-8 hours, peaks @ 24 hours, normal in 4-6 days
• leukocytosis invariable by day two
• ESR increased 2nd-3rd day
• glycosuria in 50% of patients

course and prognosis

Damage to the heart muscle results in coagulative necrosis of the muscle fibers and loss of normal contractile and conductive responses of the myocardium. In the post infarction phase, scar tissue is the primary consideration. There can be many complications (listed under signs and symptoms) but the depth, extent, and health of the scar tissue determines the length and quality of life after an MI. Early intervention with tissue plasminogen activator (TPA) has been shown to reduce mortality by causing early dissolution of vessel obstruction.

differential diagnosis

• indigestion, peptic ulcer, hiatal hernia, gall bladder disease
• angina pectoris
• abdominal emergency
• aortic aneurysm
• pneumonia, pleuritis, pneumothorax, pulmonary embolism
• costochondritis
• anxiety


footnotes