Lecture 9 Theme B

Question 1

What are some other words for ischemic heart disease?

Answer 1

coronary artery disease

coronary heart disease

heart disease

Question 2

What are the symptoms of ischemic heart disease?

Answer 2

None until eventually angina develops.

Question 3

How is angina pectoris felt?

Answer 3

lactate and adenosine activate pain nerve endings in the heart

Question 4

What is cardiac ischaemia?

Answer 4

Coronary flow is inadequate to maintain steady state metabolism.

Question 5

What are the factors that contribute to an increased oxygen demand?

Answer 5

ventricular wall stress:
increase in intraventricular pressure means more strength needed from contraction. Wall thickness increase decreases oxygen per gram but increases overall oxygen demand.

Heart rate increase

increase contractility meas more energy is expended to exhibit inotropic effect.

Question 6

What are the factors that influence oxygen supply?

Answer 6

Diastolic pressure because coronary flow is highest in this period.

Coronary resistance is modulated by vascular tone of that artery. Vessel obstruction

Oxygen carrying capacity depends on Hb level and oxygen saturation and

Question 7

What are the kinds of factors that influence coronary vascular tone?

Answer 7

Metabolic factors: Constrictors include oxygen, dilators include adenosine, lactate, H+, and CO2.

Endothelial factors:
Constrictors include endothelin - 1, dilators include nitric oxide and prostacyclin.

Neural/hormonal factors:

alpha-1 receptor is a constrictor and beta-2 is a dilator.

Question 8

How does atherosclerosis occur?

Answer 8

Streaks of fatty tissue form on the outer edges of the coronary blood vessel,

Fatty tissue gets penetrated by muscle cells.

Fibrous scar tissue forms above the plaque, this starts to occlude the vessel. This also reduces coronary artery elasticity.

When a plaque is stable the lipid core within it expands and smc’s proliferate. As a result the bulge grows.

Vulnerable plaque results from rupture of the plaque cap and so as a result collagen is exposed for thrombosis.

Question 9

How does plaque obstruction affect the flow?

Answer 9

90% : Basal ischemia

100% : Total occlusion

Question 10

What are the heart responses to myocardial infarction?

Answer 10

Partially hibernation occurs in some heart cells and this is maintained.

Some cells end up being stunned for a while before dying.

Question 11

What is an infarct?

Answer 11

irreversible necrosis of myocardium due to prolonged intense ischemia.

Question 12

What is cardiac stunning?

Answer 12

prolonged contractile depression

Question 13

What is cardiac hybernation?

Answer 13

Heart suppresses itself metabolically until it gets its blood flow again.

Question 14

What is the main cause of a myocardial infarction?

Answer 14

90% of MI’s are due to plaque rupture which leads to thrombus formation.

Question 15

What does MI pain feel like?

Answer 15

MI pain feels like angina in 75% of cases but causes no pain in 25% of cases.

Question 16

How is an MI diagnosed?

Answer 16

Heart releases intracellular macromolecules into the serum which can be used to diagnose a myocardial infarction.

Question 17

What happens to myocytes in heart cells during an MI?

Answer 17

ischaemia results in a decrease in activate of ATP pumps and exchangers causing sodium to build up in the cell as well as calcium (due to Na/Ca exchanger)

Question 18

What happens to the heart 1 - 2 minutes after MI?

Answer 18

ATP drops and heart stops contracting

Question 19

What happens to the heart 10 minutes after MI?

Answer 19

@50% ATP, cell swells due to osmotic gradient, RMP drops, arrhythmias result.

Question 20

What happens to the heart 20 - 24 minutes after MI?

Answer 20

Irreversible cell injury

Question 21

What happens to the heart 1 - 3 hours after MI?

Answer 21

Interstitial oedema and disruption.

Question 22

What happens to the heart 4 - 12 hours after MI?

Answer 22

Neutrophil infiltration

Question 23

What happens to the heart 4-12 hours after MI?

Answer 23

neutrophil infiltration which results in necrosis after a few hours

Question 24

What happens to the heart after a few days of experiencing an MI?

Answer 24

Extensive phagocytosis of myocytes, fibroblasts, and connective tissue.

dead tissue is resorped and fibrosis/scarring is complete.

Question 25

What is the way to fix/prevent ischemia?

Answer 25

reperfusion (reopening blood vessel)

Question 26

What are the negative effects that reperfusion can cause?

Answer 26

H+ is flushed away by reinstated blood flow.

H+ flushed rapidly out of the cell and exchanged with Na+.

Na+ buildup within cell causing opposite direction flow of Ca/Na exchanged.

Ca buildup in the cell followed by overload.

Question 27

Why is calcium overload caused by early reperfusion a bad thing?

Answer 27

Contraction can be so immense that it can cause cell death.

Fatal arrhythmias

Cardiomyocyte death

Question 28

How can Ca triggered problems be reduced (in ischemia/reperfusion)?

Answer 28

CAMK2 is upregulated to produce proteins that handle Ca++ and Na+.

CaMK2 inhibition reduces reperfusion pathologies in the heart.

Question 29

What is the normal physiological stimulus that results in activation of CAMK2?

Answer 29

Sudden increase in calcium concentration.