Myocardial Infarction (MI) Flashcards
MI
“heart attack”
another type of acute coronary syndrome that occurs when ischemia progresses to irreversible damage and necrosis of myocardium occurs
result of prolonged ischemia
total obstruction of a coronary artery
MI differs from unstable angina how?
necrosis in MI => release of serum cardiac markers
in MI, pain persists after rest or vasodilators, lasts >20mins, and is more severe (“crushing”) and more sudden
MI manifestations
- chest pain
- ↓CO
- sweating and nausea
- dyspnea, orthopnea and syncope/presyncope
- detection of cardiac serum markers
- fever
- hyperkalemia and acidosis
- anxiety
chest pain manifestation in MI
similar to anginal pain
may be more severe or “silent”
↓CO manifestation in MI
from loss of contractile and conductive fixation of necrotic/fibrous area
ventricular dysfunction
sweating and nausea manifestation in MI
SNS activation
detection of cardiac serum markers manifestation in MI
enzymes specific to myocardial tissue released from necrotic cells
eg. CK-MB, LDH-1
fever manifestation in MI
release of pyrogens from inflammatory cells
hyperkalemia and acidosis manifestation in MI
necrosis
what does ischemia trigger in MI
triggers switch from aerobic to anaerobic metabolism w/ inadequate energy production to maintain normal myocardial function
necrotic death and MI
necrotic death of cardiac muscle results from prolonged ischemia (>60mins) => irreversible dysfunction
cardiac muscle death and MI
begins at about 1hr and usually takes up to 12hrs before completion
most cell death has occured within first 6hrs
where does necrosis begin in MI
begins on endocardial (inside) surface of heart and progresses to pericardial (outside) surface
following MI, three zones of tissue damage
- necrotic zone
- injured area (some cells recover)
- ischemic zone (cells recover if perfusion is restored)
