Flashcards in Vascular Doppler Test 1 Deck (79):
What is duplex imaging?
integrating different forms of Doppler
What are the different modes to combine together?
pulsed doppler - spectral doppler
What is flow analysis?
is there flow?
the presence or absence of flow
how do you determine Portal vein?
traverses across the liver - hepatic veins go up into the liver
What is important about the doppler curser?
called the gate or sample volume
proper placement is important
in the center of the vessel
How do you tell the direction of flow?
above the black line = toward the transducer red
below black line = away from the transducer blue
what does hepatopetal mean?
toward the liver
this is the way you want to the blood to flow
what does hepatofugal mean?
away from the liver
this is the wrong way for the blood to flow
What is spectral display low flow?
Non resistive - low
what is spectral display high flow?
Resistive - high
little diastolic or reversed flow
What is spectral display?
time (on the x axis)
Doppler shift frequency is on the vertical y - axis
gray scale quanitity of blood (z)
What is the computer computing with spectral display?
Doppler frequency shift measured in Hz
the machine changes it to speed
what is the pulsatility index (PI)?
a measure of the variability of blood velocity in a vessel, equal to the difference between the peak systolic and minimum diastolic velocities divided by the mean velocity during the cardiac cycle.
What is plug flow?
pattern of blood flow, typically seen in large arteries, in which most cells are moving at the same velocity across the entire diameter of the vessel
What is turbulent laminar flow?
What are some techniques for using Doppler?
parallel to flow 0 degrees
angle less than 60 degrees
What changes about the SMA after you eat concerning Doppler?
high resistance before
low resistance after
see slides for visual
What is RAS?
renal artery stenosis
what is tardis parvis?
when you lose the point on the doppler wave
Where would you find non resistive low flow confirmed by spectral display?
Where do you find resistive high flow confirmed by spectral doppler?
supply to organs that do not need constant blood supply
How is blood velocity calculated?
by frequency shifts
How do you read a spectral display?
The peak is the systolic and the end is the diastolic
What is the formula for the resistive index?
RI = Peak systolic velocity - lowest diastolic velocity/ peak systolic velocity
RI = S-D/S
What is resistive index?
peak systole is compared with minimum diastole to quantify a vessels impedance
What picture does typical plug flow give you on the spectral doppler?
a "clear window" under systole
What needs to be present for the volume of blood flow to be calculated?
plug flow must be present
What is parabolic flow?
velocity higher in the center of the laminar layers and decreases at the vessel wall
What are the doppler flow patterns for the Aorta?
High systolic peak
varies at different levels
becomes triphasic closer to the legs
What does triphasic mean?
having or occurring in three phases...seen and heard
What is the Doppler flow pattern of the celiac axis?
Some spectral broadening
no change related to meals
what is spectral broadening?
broadening of the spectral lines (makes them thicker)
What are the doppler flow patterns for the hepatic artery?
more spectral broadening is seen during systole and diastole
What are the doppler flow patterns in the splenic artery?
prone to aneurysm
What are the Doppler flow patterns in the SMA?
highly resistive in the fasting state
low resistive in the post prandial state
SMA occulsion is possible
What are the Doppler flow patterns for the Renal arteries?
high diastolic flow
renal artery stenosis possible
What is the doppler flow pattern in renal artery disease?
high velocity jet shown in the right renal artery
spectral waveform shows increased velocity of more than 4 m/sec
How do you improve color images?
increase the PRF or scale
What can cause aliasing of the spectral waveform?
if the frequency shift is too high for the PRF setting
What does aliasing of the spectral waveform mean?
a portion of the waveform is cut off and displayed below the baseline
How do you fix aliasing of the spectral waveform?
by raising the PRF and lowering the baseline
this allows the peak velocity to display correctly and an accurate velocity to be obtained
What does Power Doppler NOT demonstrate?
Direction of flow
What are the doppler flow patterns for a renal transplant?
normal transplants have a diastolic flow that is 30-50% of systole
what does rejection of a transplanted kidney do to the doppler flow patterns?
decreases or reverses the diastolic flow
What does an RI of 0.7 or less indicate in a renal transplant??
indicates good perfusion
What does an RI of 0.7-0.9 indicate in a renal transplant?
What does and RI of 0.9 or greater indicate in a renal transplant?
indicates probable rejection
What is the Doppler flow pattern in the Renal Vein?
tumors make obstructive flow
What pathology could you possibly have if you have a complex waveform in the hepatic veins?
could be reflecting reflux from the right atrium
What kind of flow pattern does the Portal vein have?
continuous flow pattern
hepatopetal (toward the liver)
What might cause HTN in the portal vein?
intrinsic liver disease
what is Budd Chiari?
Thrombosis of the hepatic veins
veins appear reduced in size
may contain echogenic thrombus
What are some things you might find with portal vein hypertension?
Dilated portal, splenic and SMV
patent umbilical vein
What happens to the portal vein's response to respiration when there is portal vein hypertension?
there is a diminished response
What does portal vein hypertension do to the hepatic and splenic arteries?
it dilates them
What is the definition of Portal Hypertension?
acute or chronic hepatocellualr disease can block the flow of blood throughout the liver, causing it to back up into the hepatic portal circulation. This causes the blood pressure in the hepatic circulation to increase
When and why do collateral veins form?
when there is portal hypertension, collateral veins are formed in an effort to relieve the pressure.
they connect to the systemic veins
Where do most collateral (varicose) veins occur?
in the esophagus
What happens if varicose veins in the esophagus, stomach or rectum rupture?
massive bleeding that may result in death
How does pulse repetition frequency (PRF) affect Doppler?
PRF allows one to record lower velocities as the PRF is lowered.
as PRF is increased, the lower velocities are filtered out to record only the higher velocity signal
How is PRF changed on the US machine?
with the scale control on the doppler panel
(look at the color bar on the lt side of the monitor, the PRF will change as the "scale" on the doppler control is changed)
What kind of PRF is needed in order to doppler flow in the hepatic venous system?
a lower PRF is necessary to record the flow pattern because flow in the hepatic venous system is low.
As the flow increases beyond 40cm/sec the PRF should be increased to prevent aliasing
If PRF increases what happens to imaging depth?
it also increases
if imaging depth decreases, PRF also decreases
What helps eliminate "noise" or low level Doppler shifts seen within the vessel?
Doppler angle correction should be less than _______ to display the peak spectral velocity.
What is the doppler flow in the splenic vein?
flow is reversed in the splenic vein...away from the liver
What are the sonographic indications that cavernous transformation of the portal vein has occured?
extrahepatic portal vein is not visualized
high level echoes producedd by fibrosis are present in the porta hepatis
multiple tubular structures are present in the porta hepatis, representing periportal collaterals
When there is portal venous hypertension what does Doppler determine?
whether portal flow is hepatopetal or hepatofugal
What causes portal venous hypertension?
caused by the obstruction of the portal vein, hepatic vein, IVC
prolonged congestive heart failure
How is portal blood diverted when there is portal venous hypertension?
in a hepatofugal direction
through collateral venous pathways
with the formation of multiple portosystemic anastomoses
When portal venous hypertension is present what happens to the velocity of blood flow?
Portal vein shows low velocity
What vein gives the definitive diagnosis of Portal venous hypertension?
Patent paraumbilical vein
Typical portal hypertensive venous flow varies... true or false?
What two pathologies most frequently cause portal venous hypertension?
obstruction of portal venous radicles by fibrosis and regenerating nodules
What do we see happen on US to the portal, splenic and superior mesenteric vein when there is portal venous hypertension?
These vessels are dilated
When there is portal venous hypertension what happens to the spleen?
splenomegaly with dilated splenic radicles
What does the liver look like when there is portal venous hypertension?
small liver with irregular surface
larger liver with abnormal texture
What does TIPS stand for?
Transjugular Intrahepatic Portosystemic Shunt