Vascular Hemodynamics Principles Flashcards

The parvus et tardus waveform pattern distal to a stenosis is characterized by:

Answer: Reduced peak velocity and prolonged systolic acceleration time

Parvus (small amplitude) and tardus (slow rise) describes the dampened, delayed waveform seen downstream from a significant proximal stenosis.

Which vessel wall property primarily determines the capacitance function of the arterial system?

Answer: Medial smooth muscle compliance

The elastic recoil of medial smooth muscle allows large arteries to store and release energy, buffering pulsatile flow.

In venous hemodynamics, which maneuver is used to assess valve competence during duplex ultrasound?

Answer: Valsalva maneuver

Valsalva maneuver increases intra-abdominal pressure and abolishes normal venous flow; reflux upon release indicates valve incompetence.

Portal hypertension is most commonly associated with which Doppler finding in the portal vein?

Answer: Reversal of portal venous flow (hepatofugal)

Hepatofugal (away from the liver) portal flow reversal is a hallmark of severe portal hypertension caused by cirrhosis.

Which equation directly describes the relationship between pressure gradient, flow, and resistance?

Answer: Ohm's law analog (ΔP = Q × R)

The hemodynamic analog of Ohm's law states that pressure gradient equals flow multiplied by resistance (ΔP = Q × R).

A toe-brachial index (TBI) is preferred over ABI in diabetic patients because:

Answer: Medial calcification of tibial arteries causes falsely elevated ABI

Medial calcification in tibial arteries of diabetic patients makes them non-compressible, producing falsely elevated ABI values.

Which type of plaque morphology on ultrasound is associated with the highest embolic stroke risk?

Answer: Heterogeneous plaque with hypoechoic (lipid-rich) component

Heterogeneous plaques with hypoechoic (lipid-rich or hemorrhagic) components are more vulnerable to rupture and embolization.