All mesenteric duplex exams should be done with at least 6 hours of fasting, as prior literature is derived from fasting exam data. When comparing fasting to postprandial SMA velocities, the velocity increase in postprandial SMA is blunted compared to subjects with less than 70% stenosis. However, fasting mesenteric duplex is sensitive enough to identify stenosis; there is no role for routine postprandial studies to identify SMA stenosis.
Celiac Artery
- Celiac artery has low resistance pattern as it supplies low resistance organs, the liver and spleen.
- In medium arcuate ligament syndrome, velocity is lower during inhalation. This is due to the lowering of the diaphragm straightens out the celiac artery.
- Normal PSV is < 125 cm/s
- PSV > 200 cm/s is diagnostic for > 70% stenosis.
- EDV > 55 cm/s is diagnostic for > 50% stenosis in celiac artery.
- Reversed flow in the common hepatic artery is 100% predictive of severe celiac artery stenosis of occlusion
- Based on SVS guidelines, post celiac stent PSV >370cm/s or substantial increase from post-treatment baseline warrant further imaging.
SMA
- SMA spectra is high resistance in fasting state, but becomes low resistance in fed state.
- Replaced right hepatic artery (right hepatic artery originating from the SMA) prevalence is 17%. In this situation, the SMA waveforms would be low resistance since it is now supplying the liver.
- Normal PSV is also 125 cm/s
- PSV > 275 cm/s is diagnostic for > 70% stenosis.
- EDV > 45 cm/s is for >50% stenosis
- If SMA (or celiac) is supplying for other collaterals due to mesenteric disease, velocity throughout the vessel will increase without focal spectral broadening
- In a study examining patients after SMA stenting, the average velocity is 336 cm/s without signs of stenosis, suggesting post SMA stent normal range is 300s.
- Based on SVS guidelines, post SMA stent PSV >420 cm/s or substantial increase from post-treatment baseline warrant further imaging.
IMA
- High resistance pattern
Mesenteric Bypass Graft Duplex
In general, antegrade supraceliac aorta to mesenteric bypass peak systolic velocities are lower than that originating from retrograde inflow, such as from infrarenal aorta or iliac arteries.
Proximal anastomosis velocities:
- Supraceliac: 140s cm/s
- Infrarenal: 180s cm/s
- Iliac artery: 200s cm/s
However, their mid-graft velocities are in 140-160 cm/s range. There is no difference in graft velocities when comparing between saphenous vein vs prosthetic grafts, and there is also no difference whether the graft is bifurcated, single, or bypass to either SMA or celiac. In short, if you have a bypass graft, make sure your baseline velocity is 140-160 cm/s, and compare your future surveillance studies to your baseline value.
Post-treatment Follow-up Schedule
- Clinical follow-up and duplex ultrasound within 1 month of index procedure
- Clinical follow-up and duplex ultrasound at 6 month, 12 months, and yearly thereafter