***Veins have thinner media layer to allow flexibility of lumen size with varied flow volume***

• Trunk artery
• Arises from left ventricle
• Courses inferior through chest and enters the abdomen through the diaphragm
• Located anterior and to the left of the spine and to the left of the IVC
• Most posterior abdominal vessel
• More posterior than the IVC until the umbilicus level where it lies more anterior than the IVC
• Distributes oxygenated blood to organs and limbs
• In most cases branches of the aorta are named after the organs they are feeding

Paired Branches:

• Suprarenal arteries - supply adrenal glands
• Renal arteries - supply kidneys
• Gonadal arteries - supply ovaries/testicles
• Lumbar arteries
• Common iliac arteries

Unpaired Branches:

• Celiac Axis - 1st abdominal branch of aorta, supplies blood to common hepatic artery, splenic artery and left gastric artery
• Superior Mesenteric Artery(SMA)
• Inferior Mesenteric Artery (IMA)
• Median Sacral Artery

Anterior Branches: from superior to inferior

• Celiac Axis
• Superior Mesenteric Artery(SMA)
• Inferior Mesenteric Artery (IMA)
• Gonadal Arteries
• Median Sacral Artery

Lateral Branches: from superior to inferior

• Suprarenal Arteries
• Renal Arteries
• Common Iliac Arteries

• Bifurcation at L3-4 vertebra, umbilicus level
• Supplies legs and pelvis
• High resistance flow
• Above the umbilicus, abdominal arteries are posterior to veins
• Below the umbilicus, the abdominal/pelvic arteries are anterior to the veins
• Evaluated for arterial pathology in longitudinal and transverse planes

• 2.5MHz to 6.5MHz adult probe
• 4MHz to 8MHz pediatric probe
• Patient must be NPO 8-12hrs prior to the exam to best visualize the abdominal vasculature
• Multiple patient positions can help view the aorta behind gas containing bowel loops
• Supine, oblique and decubitus positions may all be necessary for optimal evaluation
• A transverse view can demonstrate a transverse image of both great vessels on the same image
• To obtain a longitudinal view of the aorta and IVC on the same image:
  • Position the patient in a decubitus position
  • Use a coronal approach to angle through the abdomen to visualize the aorta and IVC simultaneously
  • A right coronal approach will demonstrate the aorta as the posterior vessel on the image
  • A left coronal approach will demonstrate the IVC as the posterior vessel on the image
• Right posterior oblique position can be especially helpful for evaluating the distal aorta bifurcation into the common iliac arteries
• Identifying the celiac axis guarantees a complete evaluation of the proximal segment
• Identifying the aortic bifurcation guarantees a complete evaluation of the infrarenal segment
• 2D, Color and Doppler evaluation of proximal, mid and distal segments with iliac arteries

• Best anatomic landmark in abdomen
• Longitudinal - hollow tube anterior to spine
• Transverse - circular structure to the left of the comma shaped IVC
• Gradual tapering as it courses distally
• Becomes more anterior in the abdomen as it courses distally

• High resistance
• Clean spectral window
• Biphasic above renal arteries due to low resistance branches to organs
• Triphasic below renal arteries; supplies lower extremities which cause an increase in resistance
• Occlusive disease may change resistance and pulsatility of waveform
• Aneurysmal disease may show increased turbulence, especially with color Doppler

 

• Embolic material lodges in digital arteries in toes leading to cyanosis of the distal tissues
• Causes: Thrombus in an aortic aneurysm, arteritis, ulcerated atherosclerotic lesions, some angiography procedures

• Intimal layer tears and allows flow between the intima and media layers into a blind pocket (false lumen)
• Remaining lumen (true lumen) is decreased in size due to flap with blood flow beneath it
• Causes weakened vessel wall, risk of vessel rupture
• Thrombosis can occur in the false lumen which can cause a significant stenosis/occlusion in the vessel and ischemia distal to the dissection
• Most commonly occurs in the aortic arch due to the shearing forces of the blood as it rounds the curve of the arch
• Surgical intervention required immediately due to significant risk of rupture
• Debakey Classification:
  • Type I - involves ascending and descending aorta
  • Type II - involves ascending aorta; associated with Marfan syndrome; least common
  • Type III - involves the descending aorta (below the origin of the left subclavian artery); lowest mortality rate
• Marfan syndrome:
  • Genetic disorder that affects connective tissue of the heart, vessels and bones
  • Patients are usually very tall with a thin frame, long extremities and fingers
  • Abraham Lincoln is believed to have had Marfan syndrome
  • The aortic root and arch are the most commonly affected blood vessel (DeBakey Type II)
  • Aortic dissection, aneurysm and valve insufficiency are commonly associated with this disorder
  • Mitral valve prolapse and valve insufficiency are common with this disorder

• Linear echogenicity seen in the lumen of the vessel, separating it into two channels; one channel is a blind ended pocket
• Color flow demonstrates two lumens, both with turbulence
• Bidirectional flow seen in false lumen

Aortic Rupture:

• Significant risk of rupture in aneurysms >7cm in diameter
• Back pain and hypotension
• Critical finding
• Varied sonographic appearance
• Irregular hypoechoic areas near an aortic aneurysm
• Hematomas can displace surrounding structures

• Most commonly caused by atherosclerotic changes
• Can also be related to AAA thrombosis or arteritis
• Resistance will increase proximal to the stenosis
• Causes increased velocity at the site of the stenosis
• Distal to the stenosis the flow will be dampened with tardus parvus waveforms possible
• Effects will be similar to coarctation with increased brachial pressures and decreased bilateral ankle pressures
• If the stenosis is superior to the renal artery origins, renal ischemia will activate the renin-angiotensin system causing systemic HTN

• AKA aortoiliac occlusive disease
• Due to occlusion of the abdominal aorta just above the site of its bifurcation
• Causes bilateral symptoms and flow changes in the lower extremities
• Symptoms include fatigue of both lower limbs, intermittent bilateral claudication with ischemic pain, absent or diminished femoral pulses and pallor or coldness of both lower extremities
• Doppler waveforms will demonstrate low resistance, post-stenotic flow changes throughout both legs

• AKA Ormond disease
• Most commonly occurs at the level of the aortic bifurcation and inferiorly in pelvis
• Idiopathic(usually) overgrowth of fibrous tissue around an atherosclerotic aorta
• Can be related to drugs, infection, malignancy or cancer therapy
• May lead to ureteral obstruction causing hydronephrosis
• May compress the IVC causing bilateral pedal edema
• May compress the gonadal veins causing scrotal swelling

• Soft tissue mass surrounding great vessels
• Hypoechoic
• Smooth borders