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Hemodynamics and Vascular Flow Principles Flashcards

6 cards from real ARDMS SPI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 Hemodynamics and Vascular Flow Principles flashcards as text

  1. What is the primary acoustic effect that enables Doppler ultrasound to detect moving blood cells?

    Answer: The Doppler effect: frequency shift in echoes from moving reflectors

    Moving red blood cells shift the frequency of the returning echo relative to the transmitted frequency; this Doppler frequency shift is proportional to velocity.

  2. The Doppler equation shows that detected frequency shift is zero when the angle between the beam and flow direction is:

    Answer: 90 degrees (perpendicular)

    At 90 degrees, the cosine of the angle equals zero, making the Doppler frequency shift zero regardless of actual velocity; Doppler is therefore unusable at this angle.

  3. Which clinical finding is associated with markedly increased peak systolic velocity (PSV) at a focal arterial segment?

    Answer: Focal arterial stenosis with hemodynamic significance

    Flow accelerates as it passes through a stenotic segment due to reduced cross-sectional area, causing a focal jet with markedly elevated PSV.

  4. Spectral broadening without a visible spectral window in a peripheral artery most likely indicates:

    Answer: Post-stenotic turbulence or intrinsic vessel disease

    Turbulence downstream of a stenosis produces cells moving at many different velocities simultaneously, filling the spectral window and causing broadening.

  5. The continuity equation in hemodynamics states that flow rate is conserved, meaning:

    Answer: Cross-sectional area × velocity is constant at any point along a vessel

    The continuity equation (Q = A × V) states that volumetric flow rate equals cross-sectional area times velocity and is conserved, so a smaller area requires higher velocity.

  6. A post-stenotic waveform showing low PSV, slow systolic acceleration time, and absence of the early diastolic reversal component is described as:

    Answer: Tardus-parvus

    Tardus-parvus (Latin: slow-small) describes the dampened, delayed, monophasic waveform seen distal to a hemodynamically significant stenosis or occlusion.