Unit 4 - Abdominal Vascular Pathology

IVC thrombus

• usually occurs from propagation of thrombus from another origin

  • thrombus propagation from lower limbs = most common

• can develop secondary to obstructive processes that reduce IVC flow

sono feats:

• distention pre-obstruction and continuous flow (instead of pulsations or respiratory variations)

  • blockage obstructs any reflections from cardiac contractions or changes w respiration

• absence of flow if occluded

• presence of material within vein lumen

  • echogenicity varies w age of clot

iliac vein thrombus:

• difficult to diagnose bcuz manual compressions by sonographer aren’t possible at this lvl

• so we rely on indirect findings such as: loss of phasicity in the CFV

fistulas

• aortocaval fistula (aorta to IVC fistula) can occur spontaneously or from trauma

• usually a complication of an abdominal aortic aneurysm (AAA)

• portocaval fistulas (bw vena cava and portal venous system) may be surgically created to relieve portal HTN

may-thurner syndrome

• aka iliac vein compression syndroms (IVCS)

• lt. common iliac vein is compressed bw the rt. common iliac artery and the underlying vertebral body

• pts. usually present w left iliofemoral DVT or chronic left lower extremity pain & edema

• may see loss of phasicity in lower venous sys

neoplastic obstruction

• IVC flow obstruction caused by primary tumors that typically propagate from hepatic or renal veins

  • rare

• extrinsic tumors can also cause compression or invasion into IVC (abdo tumors along midline)

sono feats:

• visualization of intraluminal tumor

  • tumor will demonstrate blood flow within, thrombus wont

• visualization of extrinsic tumor mass that compresses & obstructs IVC

• variable echogenicity

• dilation of IVC and tributary veins below lvl of obstruction

• continuous flow below the point of obstruction

This patient most likely has which of the following pathologies?

may-thurner syndrome

IVC filter

• device placed into IVC percutaneously, just below the renal veins, to trap any lower extremity venous thromboemboli before they reach the heart and lungs

• percutaneous placement is through common femoral or jugular vein » doesn’t significantly obstruct blood flow

• indicated when a pt. has known lower extremity venous thrombosis, or at risk for redeveloping thrombosis, and anticoagulation therapy is contraindicated

• most devices consist of thin metal struts joined at one end to form the shape of a cone

sono findings:

• should be situated below renal veins

• metal struts appear as echogenic lines

• should have pulsatile flow in VC above the filter, and phasic flow below

What is the most common pathology affecting the inferior vena cava?

thrombus propagation

Which of the following matches with the findings below?

neoplastic IVC obstruction

While performing a post-IVC filter sonogram, it is important to _______.

• rule out IVC propagation

• assess for echogenic material within filter

• ensure device tip is below renal veins

What can you conclude from this image of an IVC filter?

there’s IVC perforation from the filter

• filter strut extends outside IVC

This image was taken from a patient during a routine IVC filter follow-up ultrasound. What can you conclude? This image was taken from a patient during a routine IVC filter follow-up ultrasound. What can you conclude? 

there’s thrombosis within IVC

What is the purpose of the device imaged below?  

(This image shows vascular filling through the arteries only.)

• offer alternative treatment for when antocoagulant therapy is contraindicated

• prevent pulmonary embolism

• break up deep venous thrombosis emboli

While scanning a patients' left lower leg, you notice the common femoral vein flow is continuous without any respiratory variation. What do you suspect this patient may have?

may-thurner syndrome

Which of the following is associated with extrinsic compression of the inferior vena cava?

neoplasm

atherosclerosis

• intimal thickening that causes narrowing and hardening of the arteries » leading to stenosis

• common sites for plaque build-up:

  • near the origin of the renal arteries (infrarenal most common)

  • bifurcation into common iliac arteries

• men>women

• inc. chance w age

complications:

• aneurysm

• emboli

• occlusion

direct sono findings:

• narrowed luminal diameter or absence of flow

• VR > 2.0 = stenosis >50%

• post-stenotic turbulence

indirect sono findings:

• monophasic CFA spectral tracings (normal CFA tracings are triphasic)

• PSV </= 45cm/s

arterial occlusion

• can lead to tissue ischemia and gangrene

• emboli can cause acute occulision in distal arteries

LeRiche’s Syndrome:

• occlusion of the abdo aorta that also involves the iliac bifurcation

• collateralization to the leg is through epigastric vessels

• may see tardus parvus waveforms in femoral arteries

abdominal aortic aneurysm (AAA)

• localized weakening and thinning of an arterial wall » causing dilatation of all 3 layers

• may rupture into IVC » causinf massive A-V fistula OR rupture into duodenum w upper GI bleeding (RARE)

• males>females

• most found inferior to renal arteries

• commonly associated w:

  • iliac, femoral, and popliteal aneurysms

• ectatic: mild enlargement of aorta

• cigarette smoking is a risk factor

parameters:

• ~1.5x normal caliber (compared to adj. segment) is considered aneurysmal or >/= 2cm (outer-outer wall)

two AAA types:

FUSIFORM

• most common

• usually infrarenal

• all 3 layers bulge out symmetrically

• may contain thrombus

SACCULAR

• focal outpouching/asymmetric dilatation

• rare, least common

• assoc. w/ infection

treatment:

• recommended once 5-5.5cm diameter reached

• treatment is imperative at 6cm » risk for rupture inc.

sono findings:

• possibly turbulent color dopp flow within aneurysm

• dec. velocities and may show lower resist.

iliac artery aneurysms

• often involved w aneurysmal dilatation of the lower abdo aorta

• considered aneurysmal when diameter inc. by 50% compared to adj. segment OR >/= 1.5cm

  • 3.5cm = intervention recommended

• usually associated w atherosclerotic disease

• often found bilaterally

• can cause compression on ureters » can lead to hydronephrosis

dissection

• abdo aorta dissection is most often from an intimal tear descending from the thoracic aorta

• usually stops at an aortic branch origin or at lvl of atherosclerotic plaque

• more common in African Americans, Caucasians 2nd

• male:female » 3:1

sono findings:

• membrane may be seen appearing to divide the artery into 2 compartments » showing diff. flow rates and/or direction in each

• visible membrane appears to flutter or move w/ blood flow

DeBakey classification:

• DeBakey I = starts at prox. ao. origin » down to abdo aorta (MOST COMMON)

• DeBakey II = starts at prox. ao. origin

• DeBakey III = starts post-left SCA (2ND MOST COMMON)

Standord classification:

• Stanford A = starts at prox. ao. (MOST COMMON)

• Stanford B = starts post-left SCA (2ND MOST COMMON)

pseudoaneurysm (PSA)

• usually preceded by arterial cannulation in rt. common femoral artery

• often pulsatile, palpable mass

sono findings:

• large, hypo mass

• connected to artery by tract or neck

• high velo. to-and-fro waveform in neck

• “ying-yang” flow within mass

• occasionally there’s flow disturbance within artery at the site of defect

aortic bypass grafts

• traditional method of aortic aneurysm repair, but not commonly used anymore

• functions for ~10ys+

three types:

• simple tube grafts:

  • limited to aorta only

  • AAA opened longitudinally » graft places inside » native aorta wrapped around graft

  • isolates graft » lessening chance of infection

• end-to-side

• end-to-end

  • extravascular connections » graft connects prox. and dist. arteries outside vessel lumen

sono assessment post-op:

• assess for pathological fluids and PSA formation at anastomotic sites

sono findings:

• examine full length of graft & all anastomotic sites

• should measure the graft diameter

• grafts generally have a textured or tram track appearance

  • they’re also echogenic

• graft velo. compared to baseline study

• very high or very low velo. are indicative of stenosis/graft failure

endovascular aortic repair (EVAR)

• aka endograft, stent-graft, or transluminally placed endovascular graft

• graft placed transluminally through small femoral incisions (via femoral arteriotomy) and deployed remotely

• comprised of intravascular metallic stents

• fenestrated grafts are for placements that involve overlapping aortic branches

  • these grafts have strategically placed holes where branch origins would be covered by the graft otherwise

purpose:

• exclude aneurysm sac from the effects of blood press. and flow » eliminating risk of rupture

advantages:

• less invasive then standard surgical repair

most common types:

• bifurcated (most common)

• straight tube

• uni-iliac

contraindications for EVAR:

• aneurysm tortuosity

• excessive prox. neck diameter (graft may migrate)

• limited prox. neck length

• severe iliac artery disease

• marked iliac artery tortuisity

vascular complications:

• infection, PSA, stenosis, thrombosis, dissection, AVF

possible graft complications:

• graft migration, twisting/kinking

• incomplete stent deployment, graft “limb” separation, stent fracture

• endoleaks:

  • blood flowing outside of the endovascular graft and into the aortic aneurysm sac

• endotension:

  • inc. in aneurysm size in the absence if endoleak

categories of endoleaks

type I - attachment leak

• leak is ar prox. or distal end of graft or endograft iliac limbs

• color flow shows jet at point of leak

type II - branch leak

• retrograde flow from aortic branches into aneurysmal sac

• may or may not see inflow from IMA, lumbar, internal iliac arteries, etc.

type III - device related

• leaking through the body of the graft, from graft-to-graft connections, or through a graft defect/hole

• may or may not be able to identify by u/s

type IV - unidentified site

• microleak through graft material (porosity blush)

• not seen by u/s

EVAR ultrasound