Hemodynamics A
What does the term "hemodynamics" refer to?
The study of blood changes
What is the primary cause of pulsatile flow in an artery?
Cardiac cycle and heart rate
On spectral Doppler flow AWAY from the transducer is represented above or below the baseline.
Below baseline
Spectral Doppler displays what information about the blood flow?
Direction and velocity
Most common artifact associated with Doppler Imaging
Aliasing
Describe laminar flow, in the context of blood traveling in a blood vessel?
Discrete layers of blood
Separated layers and disturbed flow, describes what type of flow
Turbulent flow
Color Doppler is used to determine what regarding:
Blood flow direction
The main advantage of Pulse Wave Doppler is:
Site-specific sampling
What are the two types of Spectral Doppler used to evaluate the presence and direction of blood flow
CW and PW
What terms describes the chaotic spirals formed in turbulent flow?
Eddies or vortexes
How does blood travel in the vessel when the flow is described as parabolic laminar flow? (Where is the blood the slowest and where is the blood the fastest)
The outer edges travel slower and the inner core travels faster
Which type of Doppler presents the Doppler Shift and velocity information on a Velocity/Time graph?
Spectral Doppler
Disadvantage of Pulse Wave Doppler
List at least one
•Not useful for High-Velocity situations
•Subject to Aliasing, due to the low Niquest limit
What patient position would create higher blood pressure and increase venous return to the heart?
Trendelenburg
What condition is characterized by the abnormal narrowing of an opening or pathway?
Stenosis
What term refers to the relative thickness of fluid
Viscosity
What are the advantages of Continuous Wave Doppler:
List at least one
Ability to measure high velocities
Resistant to aliasing
Difference between transducer frequency and the Reflected frequency
Doppler Shift
In what position would you need to have the patient in to create equalized hydrostatic pressure within the body?
Truly supine position
In which type of laminar flow do all the layers travel at roughly the same velocity?
Plug flow
At what value in regards to the Reynolds number will turbulant flow occur?
When it exceeds 2000
In the Doppler Shift equation (DS = RF – FF), if the result is a positive number, it means the Red Blood Cell (RBC) is moving in what direction:
Toward the transducer
What describes the change in frequencies of a wave, secondary to the motion in the waves source.
Doppler Effect
What does the Wall Filter adjustment do for the Doppler signal
Eliminates low-velocity Doppler signals near the baseline.
What effect will a greater pressure gradient have on the fluid velocity?
Fluid will flow faster in the area with a greater pressure gradient
What creates a pressure gradient?
pressure difference between two areas of high and low pressure
What Doppler Shift angle would result in a lack of color (neither red nor blue) on the Color Doppler display?
90 degree angle
The Doppler Shift represents the difference between:
Transducer Frequency and Reflected Frequency
What three ultrasound machine adjustments can be made to reduce or eliminate aliasing?