Nichols- Myocardial Ischemia & Infarction

Question 1

Is myocardial ischemia reversible or irreversible?

Answer 1

Reversible

Question 2

List 5 causes of myocardial ischemia

Answer 2

Cici’s!

1. Coronary stenosis
2. Increased myocardial demand
3. Coronary vasospasm
4. Interplaque hemorrhage
5. Superimposed thrombosis

Question 3

How do acutely ischemic myocytes look under LM?

Answer 3

Normal! They look fine, but they dont work

Question 4

What do myocytes look like under LM for chronic ischemia?

Answer 4

Myocytolysis takes place where the myocytes “hunker down” metabolically to preserve energy.. Abundant cytoplasm

Question 5

Sometimes during periods of brief ischemia, protective proteins are made so that, next time, the heart will better respond to ischemia. This phenomenon is known as?

Answer 5

Ischemic preconditioning

Question 6

This is an irreversible necrosis of heart muscle

Answer 6

MI

Question 7

What are most MI’s caused by?

Answer 7

Thrombosis superimposed on atherosclerosis

Question 8

Describe the gross appearance of a classic unreperfused acute phase of 0-12 hours. What about LM?

Answer 8

Gross: Looks normal
LM: maybe thin wavy myocytes (1-3 hrs); coagulation necrosis- loss of striations & hypereosinophilia (4-12 hrs)
Also, neutrophils start to show at 6-12 hours, peak at day 3

Question 9

Gross appearance of classic MI at 12-24 hr?

Answer 9

Progressive pallor

Question 10

Gross appearance of classic MI at 2-3 days? LM?

Answer 10

Gross: Yellow & softened
LM: neutrophil infiltration- peaks at DAY 3!; also some CONTRACTION BAND NECROSIS

Question 11

Describe the gross appearance of a classic MI in the subacute phase of 4-7 days. LM?

Answer 11

Gross: Red granulation tissue is present
LM: macrophages and fibroblasts

Question 12

Gross MI in subacute phase of 1-6 weeks?

Answer 12

Gradual replacement of yellow infarct by red granulation tissue

Question 13

Gross MI in subacute phase of 6-12 weeks?

Answer 13

Gradual white scarring

Question 14

Acute phase (days 1-3) LM?

Answer 14

Thin wavy myocytes –> coagulation necrosis –> neutrophil infiltration BEGINS –> contraction band necrosis

Question 15

Early subacute phase (days 4-10) LM?

Answer 15

Day 2: lymphocytes
Day 3: macrophages
Day 4: fibroblasts

Question 16

Late subacute phase (day 11-week 12) LM?

Answer 16

Angiogenesis + fibroblast proliferation = GRANULATION TISSUE

Question 17

There are 9 reperfusion effects. What are they?

Answer 17

1. Smaller
2. Patchier
3. Hemorrhage
4. More contraction band necrosis
5. Accelerated repair
6. Diffusion of inflammation/repair
7. Fewer neutrophils
8. More macrophages
9. More interstitial fibrosis

Question 18

Gross reperfused MI acute phase (days 1-3)?

Answer 18

Dark mottling and hemorrhage

Question 19

Due to what, healing of a large infarct can be accelerated from 12 to 7 weeks?

Answer 19

Reperfusion

Question 20

With reperfusion, you get patches of preserved myocardium interspersed with scar. What problem can this lead to?

Answer 20

Re-entrant ventricular arrhythmias