Myocardial Infarction Flashcards
What are the gross manifestations of MI w/in 0-4 hrs
None
What are the LM findings of MI w/in 0-4 hrs?
None
What complications of MI may arise w/ in first 0-4 hrs?
Arrythmia, HF, cardiogenic shock
What are the gross manifestations of MI w/in 4-24hrs
Dark mottling, pale w/ tetrazolium stain.
What are the light microscope findings of MI w/in 4-24 hrs?
Early coagulative necrosis (no nuclei)
Release of necrotic contents into blood: Edema, hemorrhage, wavy fibers
Neutrophils begin to appear
What is reperfusion injury?
1) Reactive oxygen species
2) Huge Ca2+ influx in irreversibly damaged cells leads to hypercontraction of myofibrils
What is the light microscope finding associated with reperfusion injury?
Contraction bands due to free radical damage and hypercontraction
What are the gross manifestations of MI w/in 1-3 days?
Hyperemia - yellowish pallor due to WBC infiltration of myocardium
What are the light microscope findings of MI w/in 1-3days?
Extensive coagulative necrosis.
Tissue surrounding infarct shows acute inflammation with neutrophils
What complications may arise w/in 1-3 days following MI?
Post-infarction fibrinous pericarditis
What are the gross manifestations of MI w/in 3-14 days?
Hyperemic border - central yellow-borwn softening, maximally yellow and soft by 10 days. Red border will emerge as granulation tissue appears.
What are the light microscope findings of MI w/in 3-14days?
Macrophages, then granulation tissue at margins (plump fibroblasts, collagen, blood vessels).
What complications may arise w/in 3-14 days following MI?
This is the weakest time of myocardium, as macs are at work.
- Free wall rupture can lead to cardiac tamponade
- Papillary muscle rupture and lead to MR
- Interventricular septal rupture can lead to shunt
Venticular pseudoaneursym formation - contained free wall rupture.
What are the gross manifestations of MI w/in 2 weeks to several months?
Gray-white scar
What are the light microscope findings of MI w/in 2 weeks to several months?
Contracted scar complete: fibrosis.
What complications may arise w/in 2 weeks to several monthsdays following MI?
- Dressler syndrome: transmural infarct exposes pericardial antigens to immune system.
- Ventricular aneurysm (risk of mural thrombus)
When is the heart at greatest risk of a subsequent structure rupture?
3-14 days due to macs.
What does ventricular free wall rupture cause?
Cardiac tamponade
What does papillary muscle rupture cause?
MR
What does interventricular septum rupture cause
VSD –> shunt
When does ventricular true aneurysm form? When is it most prominent?
2weeks-months afterwards. Outward bulge during contraction - dyskinesia.
