CAHE ABDOMEN II- ABDOMINAL VASCULAR PATHOLOGY

Terms in this set (98)

origin of the aorta

at the left ventricle

Aortic hiatus of diaphragm

where the aorta becomes the abdominal aorta

location/position of aorta

-retroperitoneal
-anterior to spine & left of midline

what is the best window to perform color flow of the renal vessels?

-coronal image
-transducer = slightly angled toward midline to see IVC anterior to aorta & renal arteries

what is the spectral waveform of the aorta dependent on?

where the waveform is obtained

proximal aorta waveform

lower-resistance waveform due to its low-resistance terminal bed, the liver, spleen and kidneys

distal aorta waveform & common iliac arteries

high-resistance waveform (triphasic) with reversal of flow in early diastole b/c they supply normally high-resistance lower extremities

aorta velocities

typically 40- 100 cm/speak systolic velocity (PSV)

atherosclerotic disease

occurs when arterial wall becomes thick & stiff from plaque buildup in arterial wall

what is atherosclerosis a specific form of?

arteriosclerosis

what does atherosclerotic disease lead to?

restriction of blood flow to organs and tissues in body resulting in high BP

normal healthy arteries

flexible and elastic

buildup of fats, cholesterol, calcium and other substances within arterial wall that can restrict blood flow

a small piece of a blood clot that breaks off from thrombus & travels through blood vessels until it reaches vessel too small to pass through

ultrasound features of atherosclerosis

-luminal irregularities
-aortic wall calcifications
-tortuosity (twisting)

luminal irregularities in sonogram of aorta

aortic wall calcification appearance

sharp, HYPERechoic, can display shadowing

causes of atherosclerosis

1. elevated BP
2. high cholesterol
3. high triglycerides
4. smoking
5. diabetes
6. inflammation from systemic diseases
7. family history of heart disease & lack of exercise

abdominal aortic aneurysm (AAA)

localized dilation of abdominal aorta

usually greater than 3 cm

OR

more than 1.5 times diameter of proximal unaffected part of aorta

what might cause an aneurysm?

the force of blood pushing against walls of an artery COMBINED with damage/injury to artery's walls

location of aneurysm formation

majority of AAAs occur BELOW the kidneys (infrarenal)

AAA clinical findings

-evidence of pulsatile abdominal mass
-abdominal bruit
-back pain
-abdominal pain
-lower extremity pain

AAA complications

-distal embolism
-infection
-dissection
-rupture

what other aneurysm are commonly associated with aortic aneurysms?

-iliac & popliteal artery aneurysm

most common cause of aneurysm in united states

atherosclerosis

what type of aneurysms are most AAAs?

AAA risk factors

-atherosclerosis (most common cause)
-tobacco use
-hypertension
-trauma
-COPD & positive family history for AAA
-marfan syndrome
-inflammation of media & adventitia (rheumatic fever etc.)

what should be measured if aneurysm is present?

measure length of dilation & note position of renal arteries in relation to aneurysm

what planes are used to measure aneurysm?

-transverse ( depth & AP)
-longitudinal (length & AP)

what should sonographer determine if there is an aneurysm?

-whether renal arteries & iliac arteries are involved in aneurysm
-clot or thrombus formation carefully assessed

what is important to distinguish between in the aorta?

between aortic ectasia & an aneurysm

when does aortic ectasia occur

when aorta increases both in transverse diameter & in vertical length

implies diffuse dilation of vessel

techniques to measure aneurysm

-measure max diameter of aneurysm outer to outer
-transducer = perpendicular to aorta

what is the correct plane to measure aortic aneurysm?

-sagittal plane, perpendicular to long axis of vessel @ widest point

-length x transverse x AP

3 classification of aneurysms

1. true aneurysm
2. false aneurysm
3. dissecting aneurysm

involve all 3 layers of aorta & most common cause of artheriosclerotic disease

2 types of true aneurysms

1. fusiform
2. saccular

fusiform aneurysm (spindle shape dilation)

bulges out on BOTH sides of aorta & affects entire circumference of artery

most common presentation of AAA

is fusiform dilatation

saccular aneurysm

localized spherical out-pouching of vessel wall

false aneurysm (pseudoaneurysm)

a tear in vascular wall of aorta leading to hematoma which is walled off by surrounding tissue

*not lined by ALL 3 layers & very rare in aorta*

what does a pseudoaneurysm result from?

some type of injury to artery- interventional procedures, surgery or trauma

common site for pseudoaneurysm development

within groin @ level of femoral artery following heart catheterization

clinical findings of pseudoaneurysm

pulsatile mass in area of puncture location

sonographic findings of pseudoaneurysm

perivascular hematoma that contains swirling blood & has neck connecting it to vessel

Color Doppler with pseudoaneurysm

demonstrates turbulent flow within the mass

"ying-yang" sign

spectral waveform with pseudoaneurysm

-obtained from the neck of pseudoaneurysm

-displays a high velocity, bidirectional or "to-and-fro" signal

correction of pseudoaneurysm techniques

1. surgical repair
2. prolonged compression repair
3. ultrasound guided thrombin injection repair

thrombi- blood clots

-commonly seen in very large aneurysms
-eccentric in location
-causes narrowing of vessel lumen

appearance of acute vs. chronic clots

-acute clots (fresh clots) = hard to see, less echogenic

-chronic clots = more echogenic

rupture of aortic aneurysm classic symptoms

- sever abdominal pain
-hypotension
-DECREASED heamtocrit
-expanding abdominal mass

mortality rate of an aortic aneurysm rupture

sonographic appearance for aortic rupture

an abdominal aneurysm with an adjacent hematoma

when should intervention be considered for an AAA?

once AAA reaches size of 5.5 cm

dissecting aneurysm (aortic dissection)

a separation of the intima from aorta wall creating a flap causing blood flow on both sides

how many lumens are there in an aortic dissection?

2- a true one & false one divided by the "intimal flap"

true lumen of aortic dissection appearance

-round or oval
-strong systolic doppler velocity
-thrombus = rare

false lumen of aortic dissection appearance

-shaped like a crescent
-sluggish or no doppler velocity
-thrombus = common

where does a dissection most often occur?

in the thoracic aorta

what might an aortic dissection be associated with?

what happens to the outer diameter in a aortic dissection?

diameter of aorta is increased & false lumen opens in the media layer

causes of aortic dissection

-most idiopathic
-hypertension
-connective tissue disorders (marfan's)
-coarctation of the aorta
-takayasu arteritis
-trauma

congenital narrowing of a short section of the aorta

takayasu arteritis

-an idiopathic, progressive obliterative arteritis involving chronic inflammation of aortic arch
-fibrosis & marked luminal narrowing of aorta/branches

aortic dissection clinical findings

-intense chest pain
-hypertension
-abdominal pain
-lower back pain

what needs to be identified sonographically for an aortic dissection?

2 channels of flow using 2D or color flow doppler

what may be noted sonographically for an aortic dissection?

a linear intimal flap within aortic lumen & might be visualized swaying in current of passing blood

what needs to be determined sonographically for an aortic dissection?

-extent of dissection in either direction
-the velocity of flow & existence of turbulent flow

mycotic aneurysms

aneurysm caused by infection

small saccular aneurysm commonly located in cerebrum (brain vessels)

surgical repair of AAA

repaired surgically with resection or grafts

endovascular repair of AAA

with percutaneous insertion of aortic stent grafts where residual aneurysm sac remains- surrounding aortic stent graft

aortic endograft appearance

echogenic walls

median arcuate ligament syndrome

a vascular compromise due to compression "pinching" of celiac trunk by the low attachment of median arcuate ligament of diaphragm resulting in vascular narrowing

location of vessel in median arcuate ligament syndrome

-the median arcuate ligament of diaphragm lies anterior to abdominal aorta
-just proximal to origin of the celiac truck

how can the pinching be relieved for median arcuate ligament syndrome

patient assumes upright position or takes a deep breath

ruling out median arcuate ligament syndrome

obtain Doppler readings during inspiration/expiration & in supine and upright positions

-characterized by compression of 3rd (transverse) portion of duodenum against aorta by the SMA

-results in complete or partial duodenal obstruction

what angle does the SMA form with abdominal aorta?

approx 45 degrees

sonographic findings of SMA syndrome

-measure angle b/w vessels to see if reduced
-use color doppler of SMA

formation of IVC

union of common iliac veins near level of umbilicus @ level of 5th lumbar vertebra

IVC measurement

less than 2.5 cm

doppler waveform of distal IVC

-demonstrates pulsatility from reflected right atrial pressure

-proximal IVC = phasicity similarly seen in lower extremity veins

doppler waveform of proximal IVC

demonstrates phasicity similar to lower extremity veins

what does color-flow imaging of the IVC reveal?

directional variations associated with respirophasicity in the distal segment of vein

dilation of IVC

caused by obstruction leading to enlargement of IVC

most common cause of dilation of IVC

right-sided heart failure

-most common vascular problem affecting IVC

most common findings of IVC thrombosis

-IVC enlargement
-absence of flow
-thrombus noted with IVC lumen

acute thrombus sonographic appearance

-completely anechoic or HYPOechoic
-free-floating tail may be seen

sonographic appearance of IVC thrombus over time

becomes more echogenic & may calcify producing acoustic shadowing

what does the doppler spectral waveforms demonstrate for IVC thrombus

-continuous, nonphasic flow patterns with partial obstruction of the caval lumen

may be associated with renal cell carcinoma & carcinomas of adrenal gland

used for pulmonary embolus to trap emboli that could travel upstream

preferred location of IVC filter

in the iliac bifurcation below renal veins

nutcracker syndrome

compression of LRV between the aorta and SMA

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