What is the effect of median arcuate ligament compression on celiac artery velocity during normal respiration?

• A. Velocity decreases
• B. Velocity increases
• C. Velocity remains constant
• D. Velocity becomes pulsatile with no change

Answer: (B)

Dynamic compression of the celiac axis by the median arcuate ligament causes a respiration-dependent stenosis. As the diaphragm moves upward during expiration, the MAL tightens over the origin of the celiac artery, narrowing the lumen. To pass the same amount of blood through a smaller opening, the flow velocity must rise, so Doppler shows an increased peak systolic velocity. During inspiration the diaphragm descends and the ligament relaxes away from the artery, easing the compression and reducing velocity toward baseline. So, with normal respiration, the velocity tends to rise during expiration when the compression is greatest.