Module 2: Mesenteric Vasculature

Question 1

what does splanchnic artery refers to

Answer 1

• vessels that supply the bowel with blood.

Question 2

what three arteries are included in splanchnic arteries

Answer 2

• celiac artery
• superior mesenteric artery
• inferiori mesenteric artery

Question 3

what is the first branch of the aorta and what are its branches

Answer 3

• celiac axis

- divides into left gastric, splenic, and common hepatic arteries

Question 4

what 5 organs are supplied by the celiac artery

Answer 4

• stomach
• liver
• pancreas
• duodenum
• spleen

Question 5

what is the doppler characteristics of the celiac artery

Answer 5

• low resistance waveform
• PSV 50-160cm/sec
• EDV = 55 cm/s

Question 6

where is the origin of the SMA

Answer 6

• 1-2cm distal to the origin of the CA

Question 7

what 4 organs are supplied by the SMA

Answer 7

• small intestine
• cecum
• ascending colon
• part of transverse colon

Question 8

what is flow in the SMA dependant on

Answer 8

• metabolic activity of the bowel

Question 9

what is the doppler flow of the SMA in the fasting state

Answer 9

• high resistance
• occasional reverse component
• PSV 110-177cm/s

Question 10

where is the origin of the IMA

Answer 10

• originates from the distal aorta 3-4cm above bifurcation heading to the left

Question 11

what are the 5 structures fed by the IMA

Answer 11

• left hand of the transverse colon
• descending colon
• iliac colon
• sigmoid colon
• part of rectum

Question 12

is the IMA easy or hard to see and if its easy to see what does that mean

Answer 12

• should be hard to see

- if easy to see may suggest SMA occlusion

Question 13

doppler flow of the IMA

Answer 13

• similar to SMA

Question 14

what are the 2 major collateral pathways in mesenteric vasculature

Answer 14

• pancreaticoduodenal arcade

- arc of riolan and marginal artery of Drummond

Question 15

what is the pancreaticoduodenal arcade

Answer 15

• links the celiac and SMA vie arterial branches that surround the duodenum and pancreas

Question 16

what is the arc of riolan and marginal artery of Drummond

Answer 16

• link the IMA and SMA via arterial branches

- the left colic-middle artery is common branch for collateralization in this group

Question 17

is splanchnic artery occlusion often symptomatic or asymptomatic

Answer 17

• asymptomatic

- due to potential for collateralization

Question 18

what are the 3 mechanisms of disease in the mesenteric vessels

Answer 18

• stenosis/occlusion
• acute mesenteric ischemia
• chronic mesenteric ischemia

Question 19

what condition can stenosis/occlusion cause

Answer 19

• acute or chronic bowel ischemia

Question 20

what can prevent acute or bowel ischemia when a stenosis/occlusion is present

Answer 20

• collateralization

Question 21

what vessel is important to interrogate before looking at the mesenteric vessel when stenosis is suspected

Answer 21

• aorta

- any narrowing or aneurysmal disease in the aorta may encroach on the origins of the celiac and mesenteric vessels

Question 22

what exam is the gold standard for diagnosing stenosis

Answer 22

• arteriography

Question 23

what reduction in vessel diameter is considered to be clinically significant

Answer 23

• > /= 70%

Question 24

what PSV in the celiac and the SMA considered a clinically significant stenosis

Answer 24

• CA PSV >/= 200cm/s

- SMA >/= 275cm/s

Question 25

what PSV ratio between the artery and aorta will indicate > 70% stenosis

Answer 25

>3.5

Question 26

when is occlusion of the CA indirectly considered as a diagnosis

Answer 26

- reversal of flow is seen in the gastroduodenal or common hepatic arteries

Question 27

what other condition can cause stenosis type symptoms in the celiac artery other than atherosclerosis

Answer 27

- compression o the celiac axis by the median arcuate ligament of the diaphragm

Question 28

how does the median arcuate ligament compression of the celiac axis mimic a stenosis and who is commonly effected

Answer 28

- ligament lies superior to CA origin and affects flow with respiration - deep inspiration there is no obstruction and on expiration and quiet respiration the stenotic appearance returns - younger patients

Question 29

what is acute mesenteric ischemia

Answer 29

- sudden onset of abdominal symptoms - due to an embolic process that progresses to a life threatening condition - surgical emergency - CT/angio is preferred method of diagnosis

Question 30

what is chronic mesenteric ischemia

Answer 30

- postprandial pain that leads to the patient changing their dietary content and habits

Question 31

what is the best method of diagnosis for chronic mesenteric ischemia

Answer 31

- angiography

Question 32

what must occur for chronic mesenteric ischemia to happen

Answer 32

- at least 2 major arteries to the bowel to be involved with atherosclerosis

Question 33

in the sonographic assessment of chronic mesenteric ischemia is the celiac axis commonly scanned and why

Answer 33

- celiac axis is not affected post prandially therefore it is not usually scanned

Question 34

protocol for sonographic assessment of chronic mesenteric ischemia

Answer 34

- patient scanned pre and post prandially - in fasting state flow should be high resistance - 20-30 minutes after patient given calories the study is repeated, done sooner if patient is symptomatic - studies are then compared

Question 35

what is the normal result of an assessment for chronic mesenteric ischemia

Answer 35

- post prandial PSV and EDV increase | - EDV almost doubles

Question 36

what is the abnormal result of an assessment for chronic mesenteric ischemia

Answer 36

- low resistance pattern with high velocities seen in fasting state is positive, then no need to test post prandial - post prandial SMA and IMA remain high

Question 37

what is evaluating the flow changes in the bowel similar to

Answer 37

- exercise stress test

Question 38

why is the evaluation of bowel ischemia difficult to diagnose with ultrasound

Answer 38

- bowel ischemia is not always due to disease in the main celiac and mesenteric arteries

Question 39

what are 4 other causes of ischemia in the bowel

Answer 39

- hypotension - small vessel disease - emboli - venous obstruction