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Vascular Class #20
Terms in this set (49)
What is an abdominal aortic aneurysm?
dilation of all 3 walls
What are the four types of AAA?
Explain a fusiform AAA
diffuse circumferential (even) dilation of arterial segment
Explain a saccular AAA
localized out-pouching of an artery
Explain a dissecting AAA
small tear in the intima allowing blood to form a cavity b/w intima and media; false lumen is formed
Explain a mycotic AAA
due to infection; could be any type of AAA but not due to pressure only infection
What is the most common location of a fusiform AAA?
infra-renal (below renal arteries)
What is the cause of a dissecting aneurysm?
idiopathic & Marfan's syndrome
What is the most common location of a dissecting AAA?
What is the US appearance of a dissecting AAA?
double channel with vibrant intimal flap
What is the most common site of an AAA?
-common iliac arteries
What are causes of aneurysms?
-giant cell arteritis (inflammatory disease of blood vessels)
-infections (mycotic aneurysm)
What are symptoms of an AAA?
-abdominal, back or groin pain
-palpable pulsatile abdominal mass
-30-60% are asymptomatic and discovered incidentally
When is surgical intervention used for AAA?
repair when aneurysm is equal to or greater than 5 cm or smaller than 5 cm but growing at a rate of greater than 1 cm/year
When is an AAA considered an aneurysm?
at 3 cm (considered aortic ectasia less than 3 cm)
Normal measurement for prox AO?
Normal measurement for mid AO?
Normal measurement for distal AO?
Normal measurement of AO before bifurcation?
How are thrombus and aneurysms related?
higher chance to form thrombus at aneurysm
What causes an aneurysm to form a thrombus?
normal low velocities at wall become stagnant in diastole
What is the US appearance of a thrombus caused by aneurysm?
echogenic mural thrombus
What forms the portal vein?
SMV & splenic vein
What are the branches of the right portal vein?
anterior & posterior branches
What are the branches of the left portal vein?
medial & lateral branches
How does the portal vein course in the liver?
intra-segmentally (within lobes)
What is the main portal vein normal diameter?
Characteristics of normal portal flow
-low velocity 20-40 cm/s
-no filling defects with color doppler
-hepatopetal direction toward liver
-normal flow direction in potential collaterals
What is portal hypertension?
elevated pressure in the portal-venous system due to increased impedance of flow through the liver
What are causes of portal hypertension?
pre-hepatic, intra-hepatic & post-hepatic
What causes pre-hepatic portal hypertension?
-thrombosis of portal or splenic vein
-extrinsic compression of portal vein
What causes intra-hepatic portal hypertension?
What causes post-hepatic portal hypertension?
-hepatic vein obstruction (Budd-Chiari)
What are complication of portal hypertension?
In what percentage of cases of portal hypertension does retrograde flow in gastric vein occur?
Increased pressure in the gastric vein may cause
-esophageal & stomach varices
-varices under left lobe of liver
-varices near spleen
Left gastric vein is also known as what?
Name the 3 porto-systemic shunts
-retrograde flow in left gastric vein
-recanalized ligamentum teres (hepatofugal flow)
-splenorenal shunt (flow from splenic vein to left renal vein)
What is a transjugular intrahepatic porto-systemic shunt?
aka TIPS; stint placed in liver b/w portal & hepatic vein
What is the purpose of TIPS?
decompression of portal venous system
What does the hepatic veins do?
drain blood from liver into IVC
What does the right hepatic vein divide?
right lobe into anterior & posterior segments
What does the middle hepatic vein divide?
right and left lobe
What does the left hepatic vein divide?
left lobe into medial & lateral segments
Where are hepatic veins largest?
near the IVC & diaphragm
What is Budd-Chiari syndrome?
hepatic venous outflow obstruction
What are the causes of Budd-Chiari syndrome?
-injury and inflammation
What is the direction of flow in the hepatic veins?
hepatofugal (away from liver)
What are the US finding of Budd-Chiari syndrome?
-no visualization of right hepatic vein with grey scale or color
-discontinuity b/w main hepatic vein and IVC
-reversed flow in hepatic veins
-presence of intrahepatic collaterals
-IVC; no flow, slow flow, bi-directional flow & narrowing
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