Module 2: Mesenteric Vasculature Flashcards
what does splanchnic artery refers to
- vessels that supply the bowel with blood.
what three arteries are included in splanchnic arteries
- celiac artery
- superior mesenteric artery
- inferiori mesenteric artery
what is the first branch of the aorta and what are its branches
- celiac axis
- divides into left gastric, splenic, and common hepatic arteries
what 5 organs are supplied by the celiac artery
- stomach
- liver
- pancreas
- duodenum
- spleen
what is the doppler characteristics of the celiac artery
- low resistance waveform
- PSV 50-160cm/sec
- EDV = 55 cm/s
where is the origin of the SMA
- 1-2cm distal to the origin of the CA
what 4 organs are supplied by the SMA
- small intestine
- cecum
- ascending colon
- part of transverse colon
what is flow in the SMA dependant on
- metabolic activity of the bowel
what is the doppler flow of the SMA in the fasting state
- high resistance
- occasional reverse component
- PSV 110-177cm/s
where is the origin of the IMA
- originates from the distal aorta 3-4cm above bifurcation heading to the left
what are the 5 structures fed by the IMA
- left hand of the transverse colon
- descending colon
- iliac colon
- sigmoid colon
- part of rectum
is the IMA easy or hard to see and if its easy to see what does that mean
- should be hard to see
- if easy to see may suggest SMA occlusion
doppler flow of the IMA
- similar to SMA
what are the 2 major collateral pathways in mesenteric vasculature
- pancreaticoduodenal arcade
- arc of riolan and marginal artery of Drummond
what is the pancreaticoduodenal arcade
- links the celiac and SMA vie arterial branches that surround the duodenum and pancreas
what is the arc of riolan and marginal artery of Drummond
- link the IMA and SMA via arterial branches
- the left colic-middle artery is common branch for collateralization in this group
is splanchnic artery occlusion often symptomatic or asymptomatic
- asymptomatic
- due to potential for collateralization
what are the 3 mechanisms of disease in the mesenteric vessels
- stenosis/occlusion
- acute mesenteric ischemia
- chronic mesenteric ischemia
what condition can stenosis/occlusion cause
- acute or chronic bowel ischemia
what can prevent acute or bowel ischemia when a stenosis/occlusion is present
- collateralization
what vessel is important to interrogate before looking at the mesenteric vessel when stenosis is suspected
- aorta
- any narrowing or aneurysmal disease in the aorta may encroach on the origins of the celiac and mesenteric vessels
what exam is the gold standard for diagnosing stenosis
- arteriography
what reduction in vessel diameter is considered to be clinically significant
- > /= 70%
what PSV in the celiac and the SMA considered a clinically significant stenosis
- CA PSV >/= 200cm/s
- SMA >/= 275cm/s
what PSV ratio between the artery and aorta will indicate > 70% stenosis
> 3.5
when is occlusion of the CA indirectly considered as a diagnosis
- reversal of flow is seen in the gastroduodenal or common hepatic arteries
what other condition can cause stenosis type symptoms in the celiac artery other than atherosclerosis
- compression o the celiac axis by the median arcuate ligament of the diaphragm
how does the median arcuate ligament compression of the celiac axis mimic a stenosis and who is commonly effected
- 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
what is acute mesenteric ischemia
- 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
what is chronic mesenteric ischemia
- postprandial pain that leads to the patient changing their dietary content and habits
what is the best method of diagnosis for chronic mesenteric ischemia
- angiography
what must occur for chronic mesenteric ischemia to happen
- at least 2 major arteries to the bowel to be involved with atherosclerosis
in the sonographic assessment of chronic mesenteric ischemia is the celiac axis commonly scanned and why
- celiac axis is not affected post prandially therefore it is not usually scanned
protocol for sonographic assessment of chronic mesenteric ischemia
- 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
what is the normal result of an assessment for chronic mesenteric ischemia
- post prandial PSV and EDV increase
- EDV almost doubles
what is the abnormal result of an assessment for chronic mesenteric ischemia
- 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
what is evaluating the flow changes in the bowel similar to
- exercise stress test
why is the evaluation of bowel ischemia difficult to diagnose with ultrasound
- bowel ischemia is not always due to disease in the main celiac and mesenteric arteries
what are 4 other causes of ischemia in the bowel
- hypotension
- small vessel disease
- emboli
- venous obstruction
