Vascular Hemodynamics

Question 1

Radius is (directly proportional/inversley proportional) to vascular resistance by a factor of __.

Answer 1

Inversely proportional; factor of 4

Question 2

What are factors that influence oxygen supply?

Answer 2

Vascular resistance leading to coronary blood flow and O2 carrying capacity

Question 3

What are factors that affect oxygen demand?

Answer 3

HR, Wall tension, contractility

Question 4

__ % is labeled as “significant coronary stenosis.” Coronary arteries are capable of sufficient compensatory dilatation to prevent ischemia up until this percent value.

Answer 4

70%

Question 5

What is the first line treatment for stable angina?

Answer 5

Medical treatment which includes:

• B-blockers and nitrates to reduce demand
• Aspirin and statins to prevent worsening atherosclerosis and ACS

Question 6

True or false: PCI for stable angina can improve quality of life and mortality

Answer 6

False, PCI for stable angina does not change mortality

Question 7

Place these in order of highest to lowest relative resistance: Aorta, arteries, arterioles, capillaries

Answer 7

Arterioles, capillaries, arteries, aorta

Question 8

Pulmonary circulation is (High/low) resistance and (High/low) pressure

Answer 8

low; low

Question 9

Cerebral, coronary, skeletal muscle, skin, abdominal organs, kidneys are physiologic resistors that run in __

Answer 9

parralel

Question 10

Physiologic parallel resistors means that a change in one area will have a (Large/minimal) effect on the total pressure

Answer 10

minimal

Question 11

Compliance=

Answer 11

change in volume/change in pressure. It is a measure of the distensibility of a vessel wall, which determines the capacitance of the vessel

Question 12

__ is the tendency of a hollow organ to recoil towards its original dimensions upon removal of a distending force. It is also known as __.

Answer 12

Elastance; reciprocal of compliance

Question 13

Passive components of compliance is determined by __. While active components are regulated by

Answer 13

extracellular matrix proteins (collagen and elastin); Smooth muscle tone

Question 14

Veins are (more/less) compliant than arteries. And young arteries are (more/less compliant) than old ones

Answer 14

More; more

Question 15

Venous compliance is (increased/decreased) when alpha 1 adgrenergic receptors on venous smooth muscle are activated by catecholamines.

Answer 15

Decreased

Question 16

Decreasing venous compliance will (increase/decrease) venous return to the heart

Answer 16

increase

Question 17

True or false: Arteriosclerosis can exist in the absence of atherosclerosis

Answer 17

True

Question 18

Arteriosclerosis is caused by?

Answer 18

Decreasing elasticity of ECM

Question 19

Which of these factors when increased, will cause vasodilation?: K+, H+, O2, CO2, Pi, adenosine, osmolarity

Answer 19

Increases in: K+, H+, CO2, PI, adenosine, osmolarity will cause vasodilation. Only an increase in O2 will cause vasoconstriction

Question 20

Functional hyperemia is?

Answer 20

When large changes in metabolic demand lead to larger greater arteriolar dilations leading to greater increase in flow

Question 21

Which factors provide the most important metabolic control in regulation of coronary vascular resistance?

Answer 21

Adenosine, CO2, H+

Question 22

Which metabolic factor is often used in nuclear stress tests? How does it work?

Answer 22

Adenosine; When given as a “stressor” adenosine will dilate normal coronary arteries (increasing flow of blood and tracer). While in atherosclerotic arteries, coronary arteries will not dilate. This works because adenosine requires normally functioning endothelium to cause coronary vasodilation

Question 23

Wall tension=

Answer 23

Wall tension=(pressure*radius)/(wall thickness)

Question 24

Rupture occurs if __ exceeds tissue strength

Answer 24

tension

Question 25

Large abdominal aortic aneursysms are at high risk of rupture due to

Answer 25

Increased pressure and radius

Question 26

Hypertension (worsens/mitigates) increases in wall tension that occurs due to chronically elevated BP

Answer 26

mitigates

Question 27

As diameter increases, wall tension __

Answer 27

increases

Question 28

As pressure increases, wall tension __

Answer 28

increases

Question 29

As tension __, risk of rupture increases

Answer 29

increases

Question 30

LaPlace’s law

Answer 30

T=(P*R)/h. Arterial wall tension is proportional to the pressure times the radius of the arterial conduit

Question 31

What are rupture risks %/year for the following diameters: <5, 5, 5.5, 6, 7, 8

Answer 31

0, 1, 5, 10, 20, 40

Question 32

Small AAA (<5.5 cm) require which treatment?

Answer 32

Serial CT scans

Question 33

Large AAA (>5.5 cm) require which treatment?

Answer 33

Surgical repair

Question 34

Rapid expansion of >0.5cm/year for AAA require which treatment

Answer 34

Surgical repair?

Question 35

Symptomatic AAA requires which treatment?

Answer 35

Surgical repair

Question 36

Wall stress if a major determinant of __.

Answer 36

Myocardial oxygen demand

Question 37

Citrate/acetate cause which metabolic effect?

Answer 37

vasodilation

Question 38

hypoxia causes which metabolic effect?

Answer 38

vasodilation

Question 39

acidosis causes which metabolic effect?

Answer 39

vasodilation