Vascular Hemodynamics Flashcards
Radius is (directly proportional/inversley proportional) to vascular resistance by a factor of __.
Inversely proportional; factor of 4
What are factors that influence oxygen supply?
Vascular resistance leading to coronary blood flow and O2 carrying capacity
What are factors that affect oxygen demand?
HR, Wall tension, contractility
__ % is labeled as “significant coronary stenosis.” Coronary arteries are capable of sufficient compensatory dilatation to prevent ischemia up until this percent value.
70%
What is the first line treatment for stable angina?
Medical treatment which includes:
- B-blockers and nitrates to reduce demand
- Aspirin and statins to prevent worsening atherosclerosis and ACS
True or false: PCI for stable angina can improve quality of life and mortality
False, PCI for stable angina does not change mortality
Place these in order of highest to lowest relative resistance: Aorta, arteries, arterioles, capillaries
Arterioles, capillaries, arteries, aorta
Pulmonary circulation is (High/low) resistance and (High/low) pressure
low; low
Cerebral, coronary, skeletal muscle, skin, abdominal organs, kidneys are physiologic resistors that run in __
parralel
Physiologic parallel resistors means that a change in one area will have a (Large/minimal) effect on the total pressure
minimal
Compliance=
change in volume/change in pressure. It is a measure of the distensibility of a vessel wall, which determines the capacitance of the vessel
__ is the tendency of a hollow organ to recoil towards its original dimensions upon removal of a distending force. It is also known as __.
Elastance; reciprocal of compliance
Passive components of compliance is determined by __. While active components are regulated by
extracellular matrix proteins (collagen and elastin); Smooth muscle tone
Veins are (more/less) compliant than arteries. And young arteries are (more/less compliant) than old ones
More; more
Venous compliance is (increased/decreased) when alpha 1 adgrenergic receptors on venous smooth muscle are activated by catecholamines.
Decreased
Decreasing venous compliance will (increase/decrease) venous return to the heart
increase
True or false: Arteriosclerosis can exist in the absence of atherosclerosis
True
Arteriosclerosis is caused by?
Decreasing elasticity of ECM
Which of these factors when increased, will cause vasodilation?: K+, H+, O2, CO2, Pi, adenosine, osmolarity
Increases in: K+, H+, CO2, PI, adenosine, osmolarity will cause vasodilation. Only an increase in O2 will cause vasoconstriction
Functional hyperemia is?
When large changes in metabolic demand lead to larger greater arteriolar dilations leading to greater increase in flow
Which factors provide the most important metabolic control in regulation of coronary vascular resistance?
Adenosine, CO2, H+
Which metabolic factor is often used in nuclear stress tests? How does it work?
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
Wall tension=
Wall tension=(pressure*radius)/(wall thickness)
Rupture occurs if __ exceeds tissue strength
tension
Large abdominal aortic aneursysms are at high risk of rupture due to
Increased pressure and radius
Hypertension (worsens/mitigates) increases in wall tension that occurs due to chronically elevated BP
mitigates
As diameter increases, wall tension __
increases
As pressure increases, wall tension __
increases
As tension __, risk of rupture increases
increases
LaPlace’s law
T=(P*R)/h. Arterial wall tension is proportional to the pressure times the radius of the arterial conduit
What are rupture risks %/year for the following diameters: <5, 5, 5.5, 6, 7, 8
0, 1, 5, 10, 20, 40
Small AAA (<5.5 cm) require which treatment?
Serial CT scans
Large AAA (>5.5 cm) require which treatment?
Surgical repair
Rapid expansion of >0.5cm/year for AAA require which treatment
Surgical repair?
Symptomatic AAA requires which treatment?
Surgical repair
Wall stress if a major determinant of __.
Myocardial oxygen demand
Citrate/acetate cause which metabolic effect?
vasodilation
hypoxia causes which metabolic effect?
vasodilation
acidosis causes which metabolic effect?
vasodilation
