RVT Hemodynamics and Doppler Principles 5

Question 1

What is the primary cause of the 'to-and-fro' waveform pattern seen in a pseudoaneurysm neck on duplex ultrasound?

Accepted Answer

Bidirectional flow as blood enters during systole and exits during diastole

Answer

The neck of a pseudoaneurysm shows forward flow into the sac during systole and reverse flow back into the artery during diastole, creating the classic to-and-fro pattern.

Question 2

A tardus-parvus waveform pattern distal to an arterial obstruction is characterized by:

Accepted Answer

Delayed, rounded systolic peak with reduced amplitude and loss of diastolic reversal

Answer

Tardus-parvus (slow-small) describes the damped, delayed waveform seen downstream from a hemodynamically significant stenosis or occlusion.

Question 3

In renal artery duplex assessment, which indirect parameter best reflects significant proximal renal artery stenosis when direct visualization is limited?

Accepted Answer

Renal acceleration time and acceleration index

Answer

Acceleration time >70–100 ms and acceleration index <300 cm/s² in intrarenal segmental arteries are indirect indicators of significant proximal renal artery stenosis.

Question 4

Which parameter is used to calculate volume flow rate (mL/min) when performing duplex assessment of a dialysis access?

Accepted Answer

Time-averaged mean velocity and vessel cross-sectional area

Answer

Volume flow = time-averaged mean velocity (TAMV) × cross-sectional area (πr²) × 60, providing flow in mL/min.

Question 5

Harmonic imaging in vascular ultrasound primarily reduces which artifact?

Accepted Answer

Near-field clutter and side-lobe artifacts

Answer

Tissue harmonic imaging uses second-harmonic frequencies that are generated within tissue, reducing near-field clutter and side-lobe artifacts for improved image quality.

(RVT) Registered Vascular Technologist Practice Test

(RVT) Registered Vascular Technologist Practice Test

RVT Hemodynamics and Doppler Principles 5