CV 8 Flashcards

1
Q

How much oxygen does the heart usually extract

A

70-80% extraction

Cannot increase oxygen supply by increasing extraction

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2
Q

Right coronary artery

A

Travels in right AV groove
Acute marginal branches that feed RA and RV
Posterior descending artery feeds posterior wall

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3
Q

Left coronary artery

A

Feeds most of septum, LV and LA

Splits into left anterior descending artery and left circumflex artery in AV groove

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4
Q

Left anterior descending artery

A

Branch of LCA

Extends down anterior ventricular septum towards apex

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5
Q

Coronary perfusion pressure

A

BP within coronary pressure

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6
Q

When is there maximal flow and perfusion to the LV?

A

During diastole

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7
Q

What happens to the vasculature during systole?

A

Heart contracts
Muscle tension compresses the coronary vasculature and obstructs blood flow
Least flow near endocardium

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8
Q

What happens to the vasculature during diastole?

A

Heart relaxed

No compression so blood can flow freely

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9
Q

Coronary perfusion pressure approximated by…

A

Aortic diastolic pressure

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10
Q

3 things that effect myocardial metabolic rate

A

Heart rate
Contractility
Wall stress

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11
Q

What changes to the ST segment do you see during subendocardial ischemia?

A
ST depression
(horizontal depression, downsloping, or T wave inversion)
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12
Q

What changes to the ST segment do you see during transmural ischemia?

A

ST elevation

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13
Q

Adenosine

A

Potent vasodilator of VSM
Binds to receptor, decreases Ca entry
Most important metabolic regulator of coronary flow
No oxygen, not enough ATP = more ADP, breaks down into adenosine, can leave muscles and bind causes dilation

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14
Q

3 vasodilators

A

NO
Prostacyclin (PGI2)
Endothelium-derived hyperpolarizing factor (EDHF)

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15
Q

1 examples of a vasoconstrictor

A

Endothelin 1

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16
Q

Fixed vessel narrowing

A

Atherosclerotic plaque narrow vessels and therefore increase resistance to flow
Compensation occurs by downstream dilation due to local metabolic need
Occurs in large arteries where there is a higher chance of turbulence

17
Q

Endothelial cell dysfunction

A

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

18
Q

What happens to
1. Normal resting flow
2. Maximal flow
at 70% occlusion?

A
  1. Normal

2. Low

19
Q

What happens to
1. Normal resting flow
2. Maximal flow
at 90% occlusion?

A
  1. Low

2. Low

20
Q

Myocardial O2 supply depends on (2)

A

Arterial O2 content

Coronary blood flow

21
Q

Myocardial demand depends on (1)

A

Myocardial metabolic rate