Great Vessels

URR study guide

What are the 3 vessel wall layers?

• tunica intima (inner layer)

• tunica media (middle, muscular layer)

  • thicker in arteries

  • thinner in veins for flexibility of the lumen size due to varied flow volumes

• tunica externa (outer layer)
  
  
  

Common iliac arteries

• where are they located?

• what part of the body do they supply?

• doppler characteristic?

• at the aortic bifurcation - umbilicus level

• supplies blood to legs and pelvis

• high resistance waveform - triphasic

aortic segments (what are the parts of the aorta)

• ascending aorta

• aortic arch

• descending thoracic aorta

• descending abdominal aorta

Great vessels (image)

Indications to scan the aorta

• abdominal pain

• pulsatile mass

• aneurysm seen on x-ray

• follow up aneurysm

• trauma

What lab value can indicate active bleeding in the body, or that an aneurysm is leaking?

low hematocrit

How do you obtain a longitudinal view of the aorta and IVC in the same image?

• position patient in decubitus position

• use coronal approach to angle through the abdomen to visualize the aorta and IVC at the same time

Average Normal Aortic Measurements

Proximal = 2.0 - 2.6 cm

Mid = 1.6 - 2.4 cm

Distal = 1.1 - 2.0 cm

Iliacs = 0.6 - 1.4 cm

Doppler characteristics of the Aorta

• high resistance

• clean spectral window

• biphasic waveform above renal arteries

  • due to low resistance branches to organs

• triphasic waveform below renal arteries

  • supplies lower extremities

• occlusion can change resistance and pulsitility of waveform

• aneurysms can show increased turbulence

aortic flow above the renal arteries

• biphasic

• low resistance branches to organs

  • most organs have low resistance vascular beds that require continuous antegrade flow

aortic flow below the renal arteries

• triphasic

• supplies the lower extremities and pelvic

• the muscular tissues of the lower extremities have high resistance vascular beds

• normal diastolic flow will occur in 2 phases: diastolic flow reversal followed by a small amount of antegrade flow.

Aortic ectasia

• occurs when the aorta does not taper in size distally

• size of aorta remains constant from proximal to distal

• can be a precursor to aneurysm formation

AAA - abdominal aortic aneurysm

• what is it? measurements?

• caused by what?

• who’s at risk?

• focal dilation of the aorta

  • greater than 3 cm

  • increase in diameter greater than 50% between 2 adjacent segments

• commonly caused by atherosclerotic disease

• high risk for males, fam hx, smoking, CHTN

Types of aneursyms

(what’s the most common?

and most common location?)

• saccular

• fusiform

• berry (a saccular cerebral aneurysm)

• mycotic

most common = fusiform below the renal arteries

Aneurysm above the renal arteries requires immediate surgical intervention.

True or False? Why?

True

• the aorta segment above the renal arteries supplies vital organs

aneurysm below renal arteries

• most common location for fusiform aneursyms

• surgical intervention required if diameter is > 5.5 cm

What AP measurement indicates aneurysm in the common iliac artery?

greater than 1.5 cm

Follow up exams after AAA identified

• annual follow up on AAA = 4 - 4.4 cm diameter

• semiannual follow up on AAA > 4.5 cm

complications of aortic aneurysm

• rupture (most common)

• decreased flow to lower extremities

• blue toe syndrome with thrombus accumulation and embolization

• affects renal circulation and systemic blood pressure, if suprarenal or juxtarenal in location

• Large AAA can compress the IVC, causing reduced flow toward the heart and pedal edema

Which 2 structures guarantee a complete evaluation of the abdominal aorta?

• celic axis (complete evaluation of the proximal abdominal segment)

• iliac arteries (complete evaluation of the infrarenal abdominal segment)

What to do if you see an aneurysm?

• measure true lumen size if thrombus is present

• measure length of affected segment

• document AAA location related to renal arteries

• turn on color

  • turbulence seen with color and PW

  • Yin Yang Sign = swirling of blood in the body of the aneurysm

most common splanchic artery aneurysm

splenic artery

endovascular aortic repair

percutaneous stent or graft placement through groin

• if leak is present, native sac increases in size

blue toe syndrome

• embolic material lodges into the digital arteries of the toes leading to cyanosis of the distal tissues

Dissection

• how does it happen?

• Increased risk of what?

• most common where?

• What can occur in the false lumen?

• intimal layer tears and allows flow between the intima and media layers into a blind pocket (false lumen)

• causes weakened vessel wall

• risk of vessel rupture

• most common at aortic arch

• thrombosis can occur in false lumen → stenosis/occlusion and ischemia distal to dissection

Marfan syndrome

• what is it?

• how do patients with this syndrome appear like?

• associated with?

genetic disorder that affects the connective tissue of the heart, vessels and bones

• tall, thin, long extremities & fingers

• associated with aortic dissection, aneurysm, valve insufficiency

aortic dissection (image)

aortic dissection (image)

aortic dissection (image)

Aortic rupture

• measurement?

• symptoms?

• what can rupture cause?

• high risk if aneurysm > 7 cm in diameter

• back pain, hypotension

• hypovolemic shock due to sudden blood loss

pseudoaneurysm

• what is it?

• caused by?

• what does it look like?

• how is it treated?

• blood escapes all 3 vessel layers into surrounding tissues and is encapsulated within the tissues

• caused by trauma, invasive procedures

• round sac of blood connected to the vessel by a neck/stalk

• treated with compression of the stalk or thrombin injection

pseudoaneurysm sonographic appearance

• yin/yang sign, turbulent flow

• high resistance to-fro flow in stalk; low resistance to-fro flow in body

• rounded, anechoic structure adjacent to main artery

• color demonstrates connection between artery and structure

• depth is measured to the pseudo-aneurysm for needle selection with thrombin injection

AORTIC STENOSIS

• most commonly caused by?

• can be related to what?

• flow pattern

  • proximal to the stenosis?

  • distal to stenosis?

• what happens to velocity at the stenosis?

• What happens if the stenosis is suprarenal?

• caused commonly by atherosclerosis

  • also can be related to AAA thrombosis, arteritis

• higher resistance proximal to stenosis

• increased velocity at stenosis

• dampened waveform (tardus parvus) distal to stenosis

• if stenosis is suprarenal → causes renal ischemia → systemic HTN

Leriche Syndrome

• caused by?

• what part of the body does it affect?

• symptoms?

• flow pattern?

• related to?

AKA aortoiliac occlusive disease

• occlusion at the abdominal aorta above the bifurcation of the CIA

• bilateral symptoms and flow changes in the lower extremities

• symptoms:

  • fatigue, intermittent claudication with ischemic pain, absent or diminished femoral pulses, pallor, coldness

• low resistance, post-stenotic flow

• related to erectile dysfunction (bc internal iliac arteries supply blood to the male genitalia)

retroperitoneal fibrosis

• what is it?

• where does it occur?

• cause related to?

• what can happen to the IVC and gonadal veins?

AKA ormond disease

• idiopathic overgrowth of fibrous tissue around and atherosclerotic aorta

  • at the level of aortic bifurcation and inferior to the pelvis

• can be related to drugs, infection, malignancy or cancer therapy

• may compress IVC → bilateral pedal edema

• may compress gonadal veins → scrotal swelling

What is the normal AP diameter of the aorta?

What measurement indicates an aneurysm?

• normal = under 3 cm

• Aneurysm = > 3 cm in AP diameter

How should the aorta measure from proximal to distal?

At what level of the aorta should the largest diameter be measured?

• normal diameter of aorta should decrease from superior to inferior

• greatest diameter is at the level of the celiac axis

How do you accurately measure the AP diameter of the aorta?

measure from outer to outer wall