Peripheral and Coronary Circulation

Question 1

Coronary arteries and branches

Answer 1

• Right coronary artery (supplies RA, RV, SA and AV nodes)
  
  • Right posterior descending artery
  • Acute marginal artery
• Left coronary artery (supplies LA and LV)
  
  • Left anterior descending artery
  • Left circumflex artery

Question 2

Veins that supply the Coronary sinus

Answer 2

• Small cardiac vein (tracks with superior part of right descending artery)
• Middle cardiac vein (tracks with inferior part of right descending artery)
• Posterior cardiac vein (tracks withinferior part of left circumflex artery)
• Great cardiac vein (tracks with the left anterior descending artery and goes along with circumflex its back superior branches)

Question 3

Anterior vein

Answer 3

Does not join with coronary sinus, but rather drains directly into right atrium.

Tracks with the anterior, superior branches of the right coronary artery

Question 4

All heart blood vessels diagram (ant and post view)

Answer 4

Question 5

Peripheral arterial disease

Answer 5

Atherosclerosis of the lower extremeties. Intermittent claudication (pain, aching, cramping). Most commonly felt in calf during exercise. May present as exercise-inducible ischemia.

Question 6

Ankle-brachial index

Answer 6

Measure the BP in the ankle and brachium and take a ratio of the systolic blood pressures. If 0.9 > P_{ankle systole} / P_{brachium systole}, then this result is diatnostic for PAD.

Question 7

Major determinants of myocardium oxygen supply and demand

Answer 7

Question 8

The predominance of coronary flow takes place during ___.

Answer 8

The predominance of coronary flow takes place during diastole.

Coronary flow is unimpaired in diastole because the relaxed myocardium does not compress the coronary vasculature. Thus, in the case of the coronaries, perfusion pressure can be approximated by the aortic diastolic pressure.

Question 9

Moreover, when the myocardium contracts ___ is subjected to greater force than are the outer muscle layers.

Answer 9

Moreover, when the myocardium contracts the subendocardium is subjected to greater force than are the outer muscle layers.

It is also the poorest perfused, and, like the rest of the heart, uses a high level of the available oxygen from hemoglobin at baseline. All of these make it especially vulnerable to ischemia.

Question 10

Factors that participate in the regulation of coronary vascular resistance

Answer 10

1. Accumulation of metabolites (ADP and AMP build up. Released as adenosine, which is a potent vasodilator)
2. Endothelium-derived substances (ACh / eNOS / NO axis, prostacyclin, endothelin-1, etc)
3. Neuronal innervation (α and β2 receptors)

Question 11

endothelium-derived relaxing factor (EDRF)

Answer 11

Normally, acetylcholine results in smooth muscle contraction. However, when endothelium covers the smooth muscle, it results in vasodilation. This is due to the activity of EDRF, which is released from endothelial cells in response to acetylcholine.

EDRF is really a nitric oxide radical, generated by eNOS from L-arginine.

Question 12

Blood - Endothelium - Smooth muscle axis

Answer 12

Question 13

Adrenergic receptors on coronary endothelium

Answer 13

Coronary vessels contain both α-adrenergic and β2-adrenergic receptors

Stimulation of α-adrenergic receptors results in vasoconstriction, whereas β2-receptors promote vasodilatation.

Question 14

The hemodynamic significance of a coronary artery narrowing depends on. . .

Answer 14

1. degree of stenosis
2. compensatory vasodilatation the distal resistance vessels are able to achieve

Question 15

When a stenosis narrows the diameter by more than approximately 70% . . .

Answer 15

When a stenosis narrows the diameter by more than approximately 70%, resting blood flow is normal, but maximal blood flow is reduced even with full dilatation of the resistance vessels.

Question 16

Resting and max coronary flow

Answer 16

Question 17

Endothelial dysfunction in coronary artery disease

Answer 17

Abnormal endothelial cell function can contribute to the pathophysiology of ischemia in two ways:

(1) by inappropriate vasoconstriction of coronary arteries and
(2) through loss of normal antithrombotic properties.

Question 18

It is postulated that in typical people, the relaxation effect of NO outweighs . . .

Answer 18

It is postulated that in typical people, the relaxation effect of NO outweighs the direct α-adrenergic constrictor effect of catecholamines on arterial smooth muscle, such that vasodilatation results.

Question 19

endothelial dysfunction occurs ___ in the atherosclerotic process.

Answer 19

endothelial dysfunction occurs very early in the atherosclerotic process.

Question 20

Platelet/endothelium interactions in vascular tone

Answer 20

Question 21

ther common causes of decreased myocardial oxygen supply

Answer 21

• decreased perfusion pressure due to hypotension (e.g., in a patient with hypovolemia or septic shock)
• a severely decreased blood oxygen content (e.g., marked anemia, or impaired oxygenation of blood by the lungs)
• profound increase in myocardial oxygen demand can cause ischemia even in the absence of coronary atherosclerosis (rapid tachycardias, acute hypertension, or severe aortic stenosis)

Question 22

Stable vs Unstable angina diagram

Answer 22

Question 23

Levine sign

Answer 23

While describing angina, the patient may place a clenched fist over his or her sternum, referred to as the Levine sign, as if defining the constricting discomfort by that tight grip.

Question 24

Things that influence oxygen demand in order of magnitude

Answer 24

1. Contractility
2. Heart rate
3. Wall stress

Question 25

Systolic vs diastolic heart failure on PV diagram

Answer 25