Mesenteric vessels USA and Eval

Indications for mesenteric study

Post-prandial pain

Abdominal bruit

Recent weight loss

Fear of food/eating

Diarrhea

N/V

Celiac Axis

Anterior branch of the aorta

Originates from the aorta within the first 2cm below the diaphragm

Normally 1-3cm in lengt

Superior to body of pancreas

Celiac branches

CHA, Left gastric A, Splenic A

In some patients the celiac artery and SMA may share a

Common trunk

Celiac Doppler

Low resistance waveform because it feeds organs requiring constant flow

Pattern does NOT change after eating

Normal PSV → <200cm/s

Abnormal PSV → >200cm/s (70-99% stenosis)

Abnormal EDV → >55cm/s (>50% stenosis)

Celiac occlusion leads to retrograde flow in the ________________ to supply blood to the CHA

Gastroduodenal artery

____ may also demonstrate retrograde flow in a celiac occlusion to send blood back to the spleen

CHA

Left gastric artery

Smallest branch of CA

Travels anterior and cephalad

Supplies the stomach and pylorus

Not usually seen sonographically due to coarse and structures supplies

Anatomy of the CHA

Right branch of the celiac axis

Supplies blood into the liver, GB and stomach

Branches into the proper hepatic artery which enters the liver and the GDA that supplies the pancreas and duodenum

Hepatic artery supplies 20-30% of blood to liver

Indications to scan the common hepatic artery

Chronic liver disease

Liver transplant

Trauma

Anatomic variant of CHA

Hepatic artery originates from SMA

Hepatic artery originates from aorta

CHA is best visualized in what plane

Trans

Doppler of Hepatic artery

Low resistance

Flow velocities increases with cirrhosis, mets, lymphoma

RI >0.78 = Portal HTN

Splenic artery anatomy

Largest branch of celiac

Tortuous course posterior to the body of the pancreas

MOST tortuous artery in body

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

MOST COMMON SITE FOR VISCERAL ANEURYSM

US of splenic artery

Origin and proximal portion best visualized in transverse

Distal segment best evaluated through the splenic hilum from left lateral window

Travels posterior and superior to the pancreas body/tail

Doppler of splenic artery

Low resistance

Tortuous, may normally find areas of high PSV

SMA anatomy

Anterior branch of AO that originates about 1-2cm below the celiac axis

Runs parallel to aorta posterior to body of pancreas

Supplies blood to jejunum, ileum, cecum, ascending colon, proximal 2/3 trans colon

Communicates with celiac artery via pancreaticoduodenal arcade

Terminates near ileocecal valve

US and Doppler of SMA:

Pre-Prandial: High resistance flow with minimal flow in late diastole; peaked waveform

Post-prandial: Low resistance flow with continuous flow in diastole and more rounded waveform

No resistance change if stenosis present

PSV can also increase normally after eating

IMA

3-4cm above the aortic bifurcation, on the left anterolateral aspect of the aorta and courses inferiorly to the left

IMA provides blood supply to distal colon and proximal rectuM

Provide potential for collateral flow

Can be located in trans inferior to renal arteries

IMA Doppler

High resistance with minimal later diastolic flow

If IMA is EASILY identified on ultrasound, SMA stenosis or occlusion should be suspected

IMA dilutes due to compensatory flow related to an SMA stenosis

Mesenteric ischemia

Patient experiences reproducible pain after eating due to bowel ischemia caused by stenosis

Post-prandial evaluation should be performed 20-30mins after meal

Abnormal SMA and IMA post-prandial flow = High resistance/no change

Diagnosed with stenosis/occlusion of TWO OR MORE of the 3 major arteries

Collateral pathways that can form with mesenteric ischemia

Pancreaticoduodenal arcade (MOST COMMON)

Arc of Riolan

Marginal artery of Drummond

Mesenteric PSV/Aortic PSV Ratio is usually:

1.0

Abnormal Mesenteric PSV/Aorta PSV ratio =

>3.0

Abormal SMA Doppler

PSV >275cm/s = 70% stenosis

EDV >45cm/s = 50% stenosis

Abnormal IMA Doppler

PSV >200cm/s = stenosis

EDV >25cm/s = stenosis

If flow in the SMA and IMA is low resistance with increased diastolic flow even in a fasting patient =

Capillary beds are constantly vasodilated due to ischemia

Compensatory flow can sometimes mimic___________

Stenosis

Compensatory flow = increased _______ and spectral window

Velocity

Treatment for mesenteric ischemia

Angioplasty, stent, bypass graft

SMA Stenosis

Median arcuate ligament syndrome

Can be mistaken for celiac stenosis with mesenteric stenosis

Intermittent extrinsic compression of the celiac axis

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

Rarely causes symptoms, but may see pain with expiration

USA Median arcuate ligament syndrome

Intermittent increased PSV in celiac axis with respiration maneuvers

SMA syndrome is also known as

Wilkie syndrome

SMA syndrome

Acute angulation of SMA causes compression and obstruction of the third part of the duodenum

An angle less than 22 degrees indicates compression is likely

Measurement of the aortomesenteric angle can demonstrate the risk of compression syndromes

Requires surgical intervention

If a patient suffers from severe weight loss, the latty tissue around the SMA is diminished, causing …

Acute angulation and reduction in distance between the aorta and superior mesenteric artery

Symptoms of SMA syndrome

Early satiety, recurrent episodes of abdominal pain, vomiting

What artery is visualized coursing anterior to the main portal vein

Common hepatic artery

What is the difference between a waveform from a stenotic vessel and one from a vessel with compensatory flow?

A spectral window is present with compensatory flow, but not with stenosis

What causes stenosis in median arcuate ligament syndrome

Compression

The aortomesenteric angle is used to predict the risk of:

Compression