CV 9

Question 1

3 general treatments for angina

Answer 1

Organic nitrates (ex: nitroglycerin)
Beta blockers
Calcium channel blockers

Question 2

How do organic nitrates work to treat angina?

Answer 2

Cause venodilation

Decreases wall stress and oxygen demand

Question 3

How do beta blockers work to treat angina?

Answer 3

Beta 1 is on the heart
They affect oxygen demand
Decreasing HR lengthens diastolic time so coronary blood can flow
Reduce contractility of the heart - decrease oxygen demand of the heart muscle

Question 4

How do calcium channel blockers work to treat angina?

Answer 4

L-type calcium channels
They affect oxygen demand and supply - decrease it
Decreases HR lengthens diastolic time so coronary blood can flow
Cause vessel dilation
Reduce the force of contraction

Question 5

As ischemic myocardial cells lose K+, what changes?

Answer 5

[K+]out increases

Question 6

5 major differences between a normal AP and an ischemic AP

Answer 6

Change in resting potential (less negative in ischemic)
Slope of depolarization is more to the right in ischemic
Peak isnt as high
Plateau is lower
Repolarization happens faster

Question 7

Subendocardial ischemia

Answer 7

When some of the subendocardial cells are ischemic

Question 8

Resting current in subendocardial ischemia

Answer 8

Current flows from ischemic to healthy cells towards the electrode
Results in a positive deflection during PR interval
PR segment used as baseline so looks as though ST segment is depressed

Question 9

Depolarized current in subendocardial ischemia

Answer 9

Current flow from healthy to ischemic flow is away from the electrode
Seen as an ST depression

Question 10

Repolarization current in subendocardial ischemia

Answer 10

May see T wave inversion

Because the subendocardial cells have decreases AP duration, so they repolarize before the subepicardial cells

Question 11

When would you see

1. ST depression
2. ST elevation

Answer 11

1. Subendocardial ischemia (baseline is actually elevated)

2. Transmural ischemia (baseline is actually depressed)

Question 12

Transmural ischemia (and what is the current doing)

Answer 12

The entire cardiac wall is ischemic
At rest the current flows away from the electrode so you have depression of PR segment
Looks as if ST segment is elevated

Question 13

2 causes of atherosclerosis

Answer 13

Fixed vessel narrowing

Endothelial cell dysfunction

Question 14

What is fixed vessel narrowing

Answer 14

Atherosclerotic plaque narrows vessels and therefore increases resistance to flow
To compensate, there is downstream dilation due to local metabolic need

Question 15

What is endothelial cell dysfunction

Answer 15

Occurs early in atherosclerosis
Impaired release of vasodilators
Attenuated effect of local metabolites
Relative vasoconstriction occurs

Question 16

5 changes in activated endothelial cells

Answer 16

Increased permeability
Increased inflammatory cytokines
Increased leukocyte adhesion molecules
Decreased vasodilatory molecules
Decreased anti-thrombotic molecules

Question 17

2 things that cause endothelial dysfunction

Answer 17

Physical stress

Chemical irritants

Question 18

3 changes in activated smooth muscle cells

Answer 18

Increased inflammatory cytokines
Increased extracellular matrix synthesis
Increased migration and proliferation into subintima

Question 19

How is a fatty streak formed?

Answer 19

LDL enters intima and is modified
Stimulates leukocyte recruitment
Foam cells are formed from monocytes entering intima and differentiating into macrophages which eat lipoproteins

Question 20

How is a fibrous atheromatous plaque formed?

Answer 20

Smooth muscle cell migration to intima and proliferation in intima
Smooth muscle increase secretion of ECM
Fibrous cap formed over lipid core
Protrusion into lumen altering diameter