M1 Lecture: Hemodynamics and Vascular Principles Flashcards
What is the main function of blood
transports oxygen to tissues
What is the main force responsible for blood flow
pressure
What is required for blood to flow
pressure difference
How does blood flow
from areas of high to low pressure
What is the primary propelling force for blood flow
the heart
What is vasoconstriction
smaller vessels, results in high resistant flow
What is vasodilation
larger vessels, results in lower resistant flow
What is the best vasodilator
excersize
What does low resistant flow mean
flow to organs that always need blood, flow always occurs when heart is pumping and at rest
ex. liver, kidneys, brain
What does high resistant flow mean
when flow only occurs when the heart is pumping
ex. skeletal muscles, arteries in arms/legs
What is the resistive index
an indicator of resistance to perfusion, determined by diastolic flow
What is diastolic flow
flow when the heart is refilling
What is systolic flow
flow when the heart is pumping
What is the formula for resistive index
(PSV-EDV) / PSV
What is PSV
peak systolic velocity
What is EDV
end diastolic velocity
What is triphasic flow
normal flow to organs that don’t require constant flow, 3 phases (foward, back, foward)
What is biphasic flow
flow to organs that require moderate flow, 2 phases (upstroke, flow reversal)
What is monophasic flow
1 phase (continued foward flow), does not go below baseline, low resistant flow, flows to organs that require constant flow
What happens during inhalation in the lower extremeties
pressure in thorax decreases and pressure in abdomen increases
What happens during exhalation in the lower extremeties
pressure in thorax increases, and pressure in abdomen decreases
What happens during inhalation in the upper extremities
decreases thoracic pressure and increase in abdominal presssure
What happens during exhalation in upper extremeties
increase in thoracic pressure and decrease in abdominal pressure
what is plug flow
flow that travels at the same velocity and direction
what is laminar flow
flow that is foward and parallel to vessel wall, flow along vessel wall is slightly slower
what is disturbed flow
flow is foward but not parallel, occurs at bifurcation or stenosis
what is turbulent flow
flow is random and chaotic, moves in different directions, swirling, still maintains foward direction
what is poiseuille’s law
the relationship between pressure, volume flow, and resistance
Increase in resistance= increase in viscosity, increase in length of vessel, decrease in diameter (most significant)
what is bernoulli’s principle
pressure and velocity are inversely proportional
increase in velocity equals a decrease in pressure and vice versa
what is the continuity rule
volume flow rate must remain constant
body must adjust to maintain same amount of oxygen flow
what is a hemodynamic significant stenosis
occurs when there is a 50% diameter reduction
what is the diameter reduction equation
<1-(d-D)> x100
what is D in the diameter reduction equation
original/true lumen
What is d in the diameter reduction equation
residual lumen
what is area reduction
2D measurement
measure vessel then lumen area
machine usually auto calculates this
what is the doppler effect
the change in frequency of an echo relative to motion between sound source and reciever
what is doppler shift
the actual changed frequency
motion toward probe= positive shift
motion away from probe= negative shift
what is ideal doppler shift
when the sound beam is paralell with flow (impossible)
45-60 degree angle is used
what is the continuous wave doppler
a probe that produces continuous sound wave
this is always on
2 crystals
detects any movement along sound beam
what is the pulsed wave doppler
this produces soun waves in pulses
1 crystal
sends out pulse then listens for pulse to return
what is sample volume
it is from a specific location
has no info about flow in other parts of vessel
placement is very important (45-60 degree angle)
what is spectral analysis
when flow direction is displayed relative to transducer
what is antegrade
when flow is above baseline and toward transducer
whats is retrograde
flow is below baseline and away from transducer
what is color doppler
it is a variation of PW doppler
angle dependent
Red=towards us
Blue=away
what is power doppler
uses color to represent differences in amplitude and energy
does not indicate direction, detects any flow
not angle dependent
can detect slow flow
