Coronary Circulation Flashcards

1
Q

Mention the normal coronary blood flow

A

During rest: 250 ml/min (80ml/100gm tissue/min)

During exercise: 1000 ml/min

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2
Q

Mention the charecteristics of coronary blood flow

A

Very rich blood flow
Very low O2 reserve
Blood flow increases to supply extra O2 needs to cardiac tissues
Coronary vessels are functional end arteries
Systole helps blood supply and nutrition for all tissues except LV

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3
Q

Enumerate methods for measurement of coronary blood flow

A
  1. Experimental (cannulation of coronary sinus)
  2. Kety method (based on Fick’s principle)
  3. Coronary angiography
  4. Radionucleotides
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4
Q

The phase in which atria & RV

A

Rapid ejection phase

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5
Q

LV blood flow occurs in …..

Why?

A

Isometric relaxation phase
The wall tension is much reduced and at the same time the aortic diastolic pressure is still high enough to force blood through coronary arteries

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6
Q

Compare blood flow in RCA & LCA

A

R, recives blood maximally during rapid ejection phase

L, early in diastole

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7
Q

Mention bases in which DBP is reduced & LC blood flow is minimal

A

High pulse pressure and tachycardia (diastolic period is reduced)

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8
Q

Autoregulation occurs in the range ……

A

60-140 mmHg mean aortic pressure

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9
Q

Mention the metabolic conditions which cause coronary VD

A

Inc K, lactic acid, H, CO2, adenosine

Lack of O2

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10
Q

The mahor coronary VD agent is ….

A

Adenosine

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11
Q

Describe the role of adrenergic receptors in coronary BV

A

It has alpha (VC) & beta (VD) receptors, the alpha are found more in epicardial vessels while beta are found more in myocardial vessels.

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12
Q

Describe effect of ANS on coronary BV

A

Symp causes direct VC leading to accumulation of metabolites and O2 lack, this continues to certain level till local factors override neural factors and produce VD indirectly.
Vagal stimualation results in diminished activity of heart, which decreases cardiac metabolites and leads to coronary VC.

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