Peripheral Arterial Hemodynamics Flashcards
Which is higher, systolic or diastolic velocity?
Systolic velocity.
Why is systolic velocity higher than disastolic velocity?
It is due to the heart pumping in systole and flow moving on its own momentum in diastole.
Do systolic velocities decrease or increase as the blood flows to the ankes?
It decreases.
Why is arterial flow pulsatile?
It is pulsatile primarily due to the pumping of the heart.
What do doppler velocity waveforms demonstrate?
Velocity changes throughout the cardiac cycle.
In normal LE and UE, flow reversal is primarily due to what?
The resistance of the distal vascular bed that the artery is feeding.
Are the distal vascular bed high or low resistance to flow at rest?
They are highly resistant to flow at rest.
What is the distal vascular beds resistance controlled by?
The resistance is controlled by arterioles.
What happens to the arterioles duiring excersise?
They open up and resistance lowers to increase flow needed by the muscles to work.
What does the resistance of distal vascular beds determine?
It determines the diastolic portion of velocity waveform.
What is resistance created by?
Arterioles.
What type of resistance is need to feed the brain, kidney, and liver?
Low resistance.
What is low resistance also known as?
Continuous flow.
What causes arterioles to open to reduce resistance and increase flow as necessary?
- Proximal obstruction.
- Inflammation
- Excerise
- Anything that may cause decreased peripheral resistance.
When does velocity change in peripheral arteries?
Velocity changes around a stenosis and occlusion.
How is the pressure and velocity at a stenosis?
Lower pressure, and higher velocity.
How is pressure and velocity post-stenosis?
Higher pressure, lower velocity than in stenosis.
What are the charactersistics of a pre-stenosis changes?
- not predicatable
- May be:
- Normal triphasic may indicate minor stenosis or good collaterals.
- No diastolic flow (high resistance)
- Biphasic or monophasic if proximal disease is present.
What are the characteristics of in-stenosis changes?
- velocity increases at least double pre-stenosis.
- Waveform is likely to have spectral broadening.
What are the characteristic of post-stenosis changes?
- velocities decrease along the artery distal to the stenosis.
- Intially post-stenoic turbulence is present.
- spectral broadening
- may have reversed flow under the peak.
- feathered peak velocities in waveform
- Father distal to stenosis, waveform will be different than pre-stenosis if it significant
- biphasic
- monophasic
How do pre-occlusive wave form look like?
- May have no diastolic flow.
- May have diastolic flow if good collaterals exist distal to the sample value.
- Velocity may be low.
What do in-occlusion waveforms look like?
- No doppler signal, no color.
- B-mode usually shows echoes.
how do post-occlusion waveforms looks like?
- Almost always has monophasic shape.
- low velocity.
What does aterial systole of a wave indicate?
indicates the inflow patency or obstruction.
What does the distalic portion of the wave indicate?
It indicates the resistance of the distal vascular bed.
How is high restsistance wave demonstrated?
Diastolic flow at baseline or below.
How is low resistance wave demonstrated?
It has a foward flow throughout the cycle. It indicates proximal obstruction or post-excersise or med.
How is NORMAL high resistance characterized?
High resistance waveforms has diastolic flow on or below the baseline.
Where are normally high resistance arteries located?
- LE ARTERIES
- UE ARTERIES
- ECA (goes to face)
- SMA pre-eating.
What is NORMAL low resistance characterized as?
Low resistance waveforms demonstrate continuous flow above the baseline.
Where is there normal low resistance waveform?
- ICA
- VERT (feeds the brain)
- CELIAC
- RENAL