Coronary Blood Flow Flashcards Preview

Cardio 2 > Coronary Blood Flow > Flashcards

Flashcards in Coronary Blood Flow Deck (14)
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1
Q

Metabolic cost of a HB

A

Will inc in HTN because of the decreased afterload

Will inc in exercise bc of tachycardia

2
Q

Special aspects of coronary circulation

A

Never has an opportunity to repay metabolic debt…must supply O2 as rapidly as consumed

Vessels are surrounded by contracting muscle…coronary flow to LV will peak during diastole

Extraction ratio is very high - myocardium cannot obtain more O2 by inc extraction

3
Q

Healthy coronary circulation

A

Blood flow adjusted to match metabolic demand

4
Q

Metabolic factors

A

Match between CBF and MVo@ is achieved becyase they change in proportion to demand

Po2, H, and K

5
Q

Systolic compression

A

Flow is lower during systole due to throttle effect from myocardial contraction

Concept of trnasmural pressure…external pressure will exceed internal pressure during systole due to muscle

6
Q

Thorttle effect accentuated by

A

Tachycardia

Inc extra-luminal pressure (compressive form muscle contraction)

Positive inotropism

7
Q

Coronary artery dz

HR inc

BP inc

High symp

A

Diastole is smaller % of cycle

Thorttle effect accentuated

Myocardial metabolic demand elevated

More likely to expereince myocardial ischemia

8
Q

Why is sub-ednocardium more susceptible to ischemia

A

Systolic compression/throttle effect inc as one descends deepter

Elevated preload constitituee another mechanical compression

9
Q

Intrinsic and autoreg factors

A

Coronary flow does NOT change linearly with arterial perfusion pressure

Myogenic mech - inc strethc means inc contraction

Direct particpation of endothelium in controlling flow

10
Q

Severe hypoxia/anoxia

A

Adenosine will contribute to coronary vasdoailtio

11
Q

Inc cardiac symp

A

Will directly vasoconstrict but net effect vasodilation due to increase in metabolites from inc contractility

12
Q

Advanced coronary artery dz and inc sympthatietc activity

A

Symp activity may limited blood flow in those who have exhausted their metabolibc reserve

13
Q

Contractile forces in ischmic

A

Above occlusion - force will inc due to inc symp

Below occlusion - force will dec due to lack of O2

14
Q

PVC characteristics

A

Not preceded by a P wave

Premature

Bizarre QRS

Systolic pressure lower for the beat and may not even open aortic valve

Compensatory pause prior to next beat