ARDMS SPI Hemodynamics and Vascular Flow Principles 1 — Questions and Answers
Question 1: Laminar flow in a vessel is characterized by:
- Random, chaotic movement of blood cells in all directions
- Concentric layers of blood moving at different velocities with fastest flow centrally (Correct answer)
- Uniform velocity across the entire vessel lumen
- Retrograde flow near the vessel walls
Correct answer: Concentric layers of blood moving at different velocities with fastest flow centrally
In laminar flow, blood moves in concentric layers (parabolic profile) with the fastest velocity at the center and slowest near the walls due to friction.
Question 2: Turbulent flow on a spectral Doppler waveform appears as:
- A narrow, well-defined spectral envelope
- Spectral broadening with filling in of the spectral window (Correct answer)
- Increased pulsatility with sharp systolic peaks
- Absence of diastolic flow
Correct answer: Spectral broadening with filling in of the spectral window
Turbulence causes blood cells to move at many different velocities simultaneously, resulting in spectral broadening and filling in of the normally clear spectral window.
Question 3: According to the Bernoulli principle, as blood flows through a stenosis, what happens to velocity and pressure?
- Velocity decreases, pressure increases
- Velocity increases, pressure decreases (Correct answer)
- Both velocity and pressure increase
- Both velocity and pressure decrease
Correct answer: Velocity increases, pressure decreases
Energy conservation (Bernoulli principle) dictates that at a stenosis, the cross-sectional area decreases so velocity must increase while pressure drops.
Question 4: The resistivity index (RI) is calculated as:
- (PSV − EDV) / PSV (Correct answer)
- (PSV + EDV) / 2
- PSV / EDV
- (PSV − EDV) / EDV
Correct answer: (PSV − EDV) / PSV
The Resistivity Index = (Peak Systolic Velocity − End Diastolic Velocity) / Peak Systolic Velocity, reflecting downstream vascular resistance.
Question 5: A high-resistance Doppler waveform pattern is typically found in which vessel?
- Internal carotid artery (ICA) at rest
- Hepatic vein
- Femoral artery at rest (Correct answer)
- Renal artery
Correct answer: Femoral artery at rest
The femoral artery at rest supplies skeletal muscle which has high resting vascular resistance, producing a triphasic high-resistance waveform.
Question 6: What hemodynamic effect does a vessel with increased compliance (elasticity) have on the Doppler waveform?
- Higher peak systolic velocity
- Dampened pulsatility and smoother waveform (Correct answer)
- Increased resistivity index
- Sharper systolic upstroke
Correct answer: Dampened pulsatility and smoother waveform
A compliant vessel absorbs systolic pressure energy by expanding, then recoils in diastole, dampening pulsatility and producing a smoother, less pulsatile waveform.
ARDMS SPI Hemodynamics and Vascular Flow Principles 1
Laminar flow in a vessel is characterized by: