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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. The pulsatility index (PI) is calculated as:

    Answer: (PSV − EDV) / mean velocity

    The Pulsatility Index = (Peak Systolic Velocity − End Diastolic Velocity) / Mean Velocity, providing a measure of downstream resistance.

  2. Which Doppler finding is most indicative of a hemodynamically significant proximal arterial stenosis?

    Answer: Monophasic, low-resistance tardus-parvus waveform distal to the stenosis

    A tardus-parvus (slow rise, small amplitude) waveform distal to a significant stenosis reflects the damped, delayed transmission of the pulse through the obstruction.

  3. Poiseuille's Law states that blood flow through a vessel is most sensitive to changes in which parameter?

    Answer: Vessel radius

    Flow is proportional to the fourth power of radius; halving the radius reduces flow 16-fold, making radius by far the most powerful determinant of vascular resistance.

  4. In a normal hepatic vein Doppler waveform, the waveform is expected to be:

    Answer: Triphasic with both antegrade and retrograde components reflecting cardiac pulsatility

    Normal hepatic veins transmit right atrial pressure changes, producing a triphasic waveform with S, D, and A waves including a brief retrograde A wave.

  5. The spectral window in a normal arterial Doppler waveform represents:

    Answer: The clear area below the spectral envelope indicating organized laminar flow

    The clear spectral window below the waveform envelope reflects the narrow, uniform velocity distribution of laminar flow where few cells travel at intermediate velocities.

  6. Elevated end-diastolic velocity (EDV) in an arterial waveform typically indicates:

    Answer: Low downstream vascular resistance (high diastolic demand)

    High EDV indicates continued forward flow throughout diastole, reflecting low downstream resistance from vasodilation, as seen in low-resistance organs like the kidney or brain.