CV Pathology 2 Flashcards
troponin - overview
*biomarker of myocardial damage
*normally regulate calcium-mediated contraction of cardiac muscle
*serum elevation = cardiac myocyte death (infarction, myocarditis, trauma)
-serum levels rise in 2-4 hours and peak 24-48 hours after an acute infarct
-levels may be higher and peak earlier with reperfusion = washout from necrotic tissue
ischemic heart disease - overview
*group of related entities resulting from myocardial ischemia
*imbalance between myocardial perfusion and cardiac O2 demand
*chief cause of mortality in US
ischemic heart disease - pathogenesis
*coronary artery disease: decreased blood flow caused by atherosclerosis
ischemic heart disease - clinical variants
- chronic coronary syndromes:
a. stable angina = fixed stenosis
b. prinzmetal = coronary spasm - acute coronary syndromes:
a. unstable angina = fixed stenosis with thrombosis
b. myocardial infarction = obstruction with NECROSIS
myocardial infarction (MI) - overview
*necrosis of heart muscle resulting from ischemia
*increased incidence with age and atherosclerosis risk factors
myocardial infarction (MI) - pathogenesis
*acute thrombotic obstruction of coronary artery due to rupture of atherosclerotic plaque
*disruption typically sudden
*hemorrhage into plaque or additional thrombosis
* > 30 min = irreversible myocyte coagulative necrosis
myocardial infarction (MI) - transmural vs. endocardial
- transmural infarct:
-FULL THICKNESS MYOCARDIAL NECROSIS
-caused by COMPLETE OBSTRUCTION of coronary vessel
-causes STEMI - endocardial infarct:
-only inner portion myocardial necrosis
-obstruction of distal coronary vessels or severe/incomplete obstructions
-causes NSTEMI
normal appearance of myocardium
*viable nuclei
*cross-striations
*intercalated discs
myocardial infarction (MI) - morphology 4-8 hours post-MI
*microscopic coagulative necrosis detectable:
-loss of nuclei (karyolysis)
-beginning loss of cross-striations
wavy CONTRACTION BANDS () extending across the fibers
myocardial infarction (MI) - morphology 12-24 hours post-MI
*gross and microscopically identified hemorrhage
*prominent contraction bands
myocardial infarction (MI) - morphology 1-3 days post-MI
*necrosis elicits NEUTROPHILIC INFILTRATE
myocardial infarction (MI) - morphology 3-7 days post-MI
*influx of MACROPHAGES
*removing necrotic myocytes and neutrophil fragments
myocardial infarction (MI) - morphology 10-14 days post-MI
*granulation tissue
*healing requires ingrowth of new vessels from the infarct margins
*large infarcts take longer to heal than smaller ones
myocardial infarction (MI) - morphology 2-8 weeks post-MI
*healing well underway
*EXTENSIVE COLLAGEN DEPOSITION (scar)
*MI size determines clinical sequelae
myocardial infarction - complication: arrhythmia
*90% develop some rhythm disturbance
*ex: ventricular fibrillation (causes the majority of deaths occurring prior to hospitalizations)
myocardial infarction - complication: contractile dysfunction
*impaired function proportional to size of damage
*ex. transmural infarct causes severe pump failure (cardiogenic shock)
myocardial infarction - complication: mural thrombus
*stasis due to diminished myocardial contractility
*endocardial damage fosters mural thrombosis with risk for left-sided thromboembolism
myocardial infarction - complication: papillary muscle dysfunction/rupture
*leads to post-infarct regurgitation
*mechanical complications most prevalent 3-14 days after MI
myocardial infarction - complication: ventricular dilation/aneurysm
*weakened necrotic muscle → stretching, thinning, and dilation of infarcted region
*large transmural infarctions → ventricular aneurysms
*prone to mural thrombosis
*mechanical complications most prevalent 3-14 days after MI
myocardial infarction - complication: myocardial rupture
*usually occurs < 5 days
*left ventricular rupture → rapidly fatal cardiac tamponade
*ventricular septal rupture → left-to-right shunt
*mechanical complications most prevalent 3-14 days after MI
myocardial infarction - complication: pericarditis
*transmural infarction → painful fibrinohemorrhagic pericarditis
*typically appears 2-3 days after infarction
*resolves after a few days
valvular heart disease - overview
*cardiac dysfunction caused by valvular disease
*usually acquired; more common on left side of heart
*abnormal flow = murmurs (auscultated), thrills (palpated)