Where should the pulsed-wave Doppler sample volume be placed relative to the left atrial appendage entry into the left atrium?

• A. 1 cm distal
• B. 3 cm proximal
• C. 1 cm proximal
• D. 5 mm proximal

Answer: (C)

When using pulsed-wave Doppler to assess flow into the left atrial appendage (LAA), you want to capture the velocity as blood moves from the main left atrium into the LAA. Placing the sample volume about 1 cm proximal to the LAA ostium means you’re sampling from the left atrial side, just before the entry into the LAA. This location gives a clean, representative measurement of the LAA’s inflow (the emptying of the LAA toward the atrium is reflected at this boundary) and helps keep the Doppler beam aligned with the jet for accurate velocity.

If you place the sample inside the LAA (distal to the ostium) or too far back into the LA, flow becomes more complex and the measured velocity may be less reliable or not reflect the true LAA emptying velocity. The 1 cm proximal position is a practical, reproducible spot that yields meaningful velocity values for assessing LAA function and thromboembolism risk.