Arterial Hemodynamis Class 8 Unit 16 COPY Flashcards
Systolic velocity is ________ than diastolic velocity
Higher
Why is systolic velocity higher than diastolic velocity?
Because of the heart pumping in systole and flowing moving on it’s own momentum in diastole .
Does systolic velocity increase or decrease, as the blood flows to the ankles?
It decreases.
When viewing in ultrasound of the peripheral arterial flow, what characteristic is usually found within the waveform?
Peripheral arterial flow is pulsatile, due to the pumping of the heart.
Doppler velocity waveforms demonstrate what?
Demonstrate velocity changes, throughout the cardiac cycle
In the peripheral arteries (le and ue), how is the velocity pattern demonstrated on doppler?
Velocity pattern is forward in systole, with a sharp upstroke, and narrow peak, followed by a short reversal of flow.
(Looks more triaphasic )
In the normal le and ue, flow reversal is primarily due to what?
The resistance of the distal vascular bed that the artery is feeding.
In normal le and ue arteries, what is the resistance controlled by?
Arterioles
During exercise, what happens to the arterioles?
Arterioles open, which causes the resistance to decrease, and increases the flow needed for the muscles to work.
What determines the diastolic portion of the velocity waveform?
Resistance of distal vascular bed
Is there a high or low resistance, in the vessels feeding the brain, kidney, and liver?
Low resistance
Peripheral arteries normally _________ resistance at rest.
High
Why do arterioles open?
to reduce resistance and increase flow as needed.
When do arterioles open?
- During a proximal obstruction in the artery.
- inflammation
- exercise
- anything that may cause decreased peripheral resistance.
Normal mean velocities in the peripheral arteries
These are not criteria, just average velocities
Come back to this and put the chart
When do velocities usually change in the peripheral arteries?
Usually around the stenosis and occlusion
What does peri-stenosis mean?
Around the stenosis
During peri-stenotic flow changes, as velocity increases, pressure ____________ .
decreases
During peri-stenotic flow changes, as velocity decrease distally, pressure _________.
increases
In a peri- stenotic, when the velocity decreases , and pressure increases, is the pressure higher than the inflow (initial) pressure?
no, its not as high as the inflow pressure.
arterial velocity changes & waveforms
come back to put the image
what has to happen to the velocity in a artery, in order to say there is a stenosis in it?
velocity increases at least double the pre-stenosis.
Is pre stenosis predictable?
no
In pre stenosis, if there is a triphasic waveform on Doppler, what may this indicate?
minor stenosis, or good collateralss
During pre stenosis, does the Doppler signal have diastolic flow?
no
During pre stenosis, a biphasic or monophasic doppler signal indicates ____________.
proximal disease present
When you turn on Doppler in the stenosis, how will the waveform look?
it will have a spectral broadening
put in image 11
During post -stenosis, what happens to the velocities?
they decrease along the artery distal to the stenosis
During post-stenosis, what is present on the doppler waveform?
- initially turbulence is present
- may have reversed flow under the peak
- feathered peak velocities in the peak
(put image 12)
how will you know if the stenosis is significant, when viewing the waveform on doppler?
when moving distal from the pre stenosis, if it shows biphasic or monophasic waveform, you know its a significant.
List characteristics that a PRE -occlusive doppler waveform may have in ultrasound
- may have no diastolic flow
- may have diastolic flow if good collaterals exist to the sample volume
- velocity may be low
List characteristics that IN - occlusion doppler waveform may have in ultrasound
- no doppler signal
- b- mode usually shows echoes
List characteristics that POST occlusion doppler may have in ultrasound
- almost always has a monophasic shape
- low velocity
In systole, the systolic portion of the wave indicates what?
indicates the inflow patency or obstruction
what does a slow upstroke indicates in systole?
a significant proximal obstruction
In diastole, the diastolic portion of the wave indicates what?
the resistance of the distal vascular bed
what does a high resistance wave demonstrate?
the diastolic flow, which can be at the baseline or below the baseline
what does a low resistance wave demonstrate?
- forward flow throughout the cycle, about the baseline
- indicates proximal obstruction or post exercise or meds
which arteries are normally high resistance?
- le arteries
- ue arteries
- eca
- sma
which arteries are normally low resistance?
- ica
- vert
- celiac
- renal
What are some normal situations that change the resistance of the arterioles?
-exercise
(changes arteries from high resistance to low resistance, so flow can increase and help muscles work)
- eating
( changes the superior mesenteric artery from normally high resistance to low resistance to help digestion)
- post ichemia
(normal high resistance to low resistance )
we see this when you come in from cold and fingers, toes and cheeks, may be low resistance to encourage flow
Peripheral arteries distal to a significant obstruction will become low resistance, due to what?
arterioles opening to encourage flow
The CCA will change from low to high resistance, proximal to an _________ occlusion, due to distal resistance,
ICA
ICA will change from a low to high resistance proximal to an intracranial ________ occlusion, due to distal resistance.
ICA
terminology : waveform patterns
slide 20 post
terminology:waveform patterns
slide 21 post
The systolic portion of the arterial waveform is affected by what?
A proximal obstruction, which may cause it to have a slow upstroke.
The diastolic portion of the arterial waveform, demonstrates what?
the distal resistance.
What is a characteristic of a high resistance waveform?
have diastolic flow at or below the baseline
What is a characteristic of a low resistance waveform?
have forward flow throughout the cardiac cycle
Do velocities increase or decrease, from the aorta to the ankles ?
They decrease
what type of a waveform should you see with a normal le doppler signal ?
triphasic signal
The normal triaphasic signals can become biphasic or monophasic under what conditions?
- excercise
- inflammation
- proximal significant obstruction
- close proximity occlusion.
in stenos the velocity is at least ________ the pre stenosis velocity.
2 times
what is the flow pattern for post stenotic ?
turbulence, and further downstream a change in the waveform shape
what are some recognizable flow patterns in the waveforms?
- triphasic
- biphasic
- monophasic
- stenotic
- turbulent
- staccato
- pendulum
- bruit
