RVT Prep - Mesenteric Vessels

What are the indications for mesenteric vessel evaluation?

Post-prandial pain, abdominal bruit, recent weight loss, sitophobia, diarrhea, nausea and vomiting

What are the limitations for mesenteric evaluation?

Open abdominal wounds/drains/sutures/staples, patient not NPO, overlying bowel gas, patient cooperation

Which vessels are evaluated in a mesenteric exam?

Proximal abdominal aorta, celiac axis, common hepatic artery, splenic artery, superior mesenteric artery, inferior mesenteric artery

What is the celiac axis?

Anterior branch of aorta, originates within first 2 cm below diaphragm, normally 1-3 cm in length

What are the branches of the celiac axis?

Common hepatic artery, left gastric artery, splenic artery

What should be evaluated in the celiac axis?

• Transverse view to evaluate origin and bifurcation (T/bird/seagull sign)

• Longitudinal view to evaluate Doppler

What is the typical sonographic appearance of the celiac axis?

Low resistance waveform, normal PSV < 2 m/s

What is the effect of occlusion on the celiac axis?

• May cause increased velocity and resistance

• May cause retrograde flow through the gastroduodenal artery or common hepatic trunk

What is the left gastric artery?

• The smallest branch of the celiac axis that travels anterior and cephalad

• Supplies the stomach and pylorus

What is the common hepatic artery?

• Right branch of celiac axis

• Supplies blood to the liver, gallbladder, and stomach

• Branches into proper hepatic artery (liver) and gastroduodenal artery (pancreas and duodenum)

What percentage of blood to the liver is supplied by the hepatic artery?

20-30%

What are indications to examine the common hepatic artery?

Chronic liver disease, liver transplant, trauma

What are the anatomic variants of the common hepatic artery?

It can also originate from the SMA or aorta

What should be evaluated in the common hepatic artery?

• Transverse view to evaluate origin and area around porta hepatis

• Longitudinal view to evaluate doppler

What is the typical sonographic appearance of the common hepatic artery?

• Low resistance, tortuous flow

• Monophasic with antegrade diastolic flow

What is the normal value to rule out portal HTN in the hepatic artery?

RI > 0.78 implies portal HTN

What can cause increased flow velocities in the common hepatic artery?

Cirrhosis, metastasis, lymphoma

What is the splenic artery?

• Largest branch of the celiac axis

• Supplies blood to spleen, pancreas, and fundus of stomach

What should be evaluated in the splenic artery?

• Transverse view to evaluate origin and proximal portion

• Distal segment best evaluated through splenic hilum

• Longitudinal view to evaluate doppler

What is the typical sonographic appearance of the splenic artery?

Low resistance, tortuous flow (most tortuous artery in the body)

Which vessel is the most common site of aneurysm in a visceral vessel?

Splenic artery

What is the superior mesenteric artery?

• Anterior branch of aorta that originates 1-2 cm below the celiac axis

• Supplies jejunum, ileum, cecum, ascending colon, transverse colon, duodenum, and pancreatic head

What should be evaluated in the superior mesenteric artery?

• Transverse and longitudinal views (anterior to aorta and posterior to pancreas)

• Pre and post-prandial flow

What is the typical sonographic appearance of the superior mesenteric artery?

• Pre-prandial: high resistance flow with minimal flow in late diastole, peaked waveform

• Post-prandial: low resistance flow with continuous flow is diastole, rounded waveform

How can you tell if stenosis is present in the superior mesenteric artery?

If there is no change in resistance from pre to post-prandial evaluation

What is the inferior mesenteric artery?

• Originates 3-4 cm above the aortic bifurcation on the left anterolateral aspect of aorta

• Supplies distal colon and proximal rectum

What is the typical sonographic appearance of the inferior mesenteric artery?

• Pre-prandial: High resistance with minimal late diastolic flow

• Post-prandial: Low resistance with increased diastolic flow

What is important about the inferior mesenteric artery?

Provides collateral flow in the presence of SMA obstruction, IMA is easily identifiable by ultrasound then SMA stenosis/occlusion should be suspected

What is the time difference between the pre and post-prandial evaluation?

20-30 minutes or when the patient has symptoms, the time should be documented

What are the collateral pathways that can form for mesenteric vessels?

• Pancreaticduodenal arcade

• Arc of Riolan

• Marginal artery of Drummond

What is the gold standard for mesenteric evaluation?

Arteriography

What is the normal mesenteric/aortic PSV ratio?

1.0

What is the abnormal mesenteric/aortic PSV ratio?

> 3.0 indicates significant stenosis

What is the effect on mesenteric branches if SMA is occluded?

• Celiac artery may demonstrate increased flow, increased velocity, and normal spectral window

• IMA can increase in size and flow without post-stenotic turbulence

What is the effect on the SMA if the celiac axis is occluded?

SMA can demonstrate increased flow velocity without post-stenotic turbulence

What is the difference between compensatory flow and stenosis?

• Compensatory flow: increased velocity + spectral window

• Stenosis: increased velocity + post-stenotic turbulence

What are possible treatments for mesenteric stenosis/ischemia?

Angioplasty, stent placement, bypass graft

What is median arcuate ligament syndrome?

• Intermittent extrinsic compression of the celiac axis

• Caused by diaphragm moving superiorly and the median arcuate ligament pinching the celiac axis

What is the typical sonographic appearance of median arcute ligament syndrome?

• Intermittent increased PSV in celiac axis with respiration maneuvers

• Velocities will increase with expiration and return to normal on inspiration

What is Wilkie syndrome?

• AKA superior mesenteric syndrome

• Acute angulation and reduction in distance between the aorta and SMA caused by diminished fatty tissue around the SMA from severe weight loss

What are the symptoms of Wilkie syndrome?

Early satiety, recurrent episodes of abdominal pain, vomiting

What are conditions related to Wilkie syndrome?

Anorexia nervosa, malabsorption, malignancy, increased spinal lordosis, short ligament of Treitz, abnormally inferior SMA origin