AAA - Abdominal Aortic Aneurysm Flashcards
(50 cards)
Define: What is an AAA?
Abnormal dilatation of aorta becoming >3cm or >50% of normal diameter
What is the normal diameter of the aorta?
Ranges from 2-3.5cm depending on where it is (more distal typically is smaller diameter)
What is meant by a true AAA? How does that differ from false?
A true AAA is one that contains all 3 layers of the vessel wall whereas in a false it is only some of the layers => extravasation of blood into an aneurysmal sac
What is the pathogenesis of AAA?
Transmural inflammation causing abnormal collagen remodeling
=> Loss of elastin and smooth muscle cells
=> Aortic wall thinning => weaker => expansion
At what level is the celiac trunk and what branches does it give off?
Left gastric
Common hepatic
Splenic
T12
At what levels does the aorta give off the superior and inferior mesenteric arteries
L1
L3
At what level does the aorta bifurcate? What does it bifurcate into?
L4
Bifurcates into the left and right common iliac (which then each split into internal and external) as well as a median sacral artery
At what level does the aorta pierce the diaphragm?
T12
What arteries do the suprarenal arteries stem from?
Superior suprarenal comes off the (inferior) phrenic artery (T12)
Middle suprarenal comes directly off the aorta (T12) at the level of the celiac
Inferior suprarenal comes off the renal arteries (L1)
Please state the branches of the abdominal aorta superiorly to inferiorly
Phrenic
Celiac Trunk (T12)
Suprarenal artery
Renal arteries
Superior mesenteric (L1)
Gonadal Arteries
Inferior Mesenteric (L3)
Bifurcation (L4)
At what level is the horseshoe kidney typically located? Why?
L3 as it gets stuck on the inferior mesenteric artery
What are the 2 etiological types of AAA?
Which is the more common one?
Fusiform (more common) => Degenerative => normal pathogenesis of abnormal collagen remodeling and loss of elastin
Saccular => infective (bacteremia, endocarditis, mycotic aneurysm)
What classification is used to classify the location of the aneurysm? (go into detail)
Which is the most common type and name it.
Crawford Classification
Type 1: Origin of left subclavian -> Suprarenal
Type 2: Subclavian -> Bifurcation
Type 3: Distal thoracic -> bifurcation
Type 4: All Under Diaphragm
95% of AAA are infrarenal => Type 4
What are the modifiable and non-modifiable risk factors of PVD (Peripheral vascular disease)?
Modifiable: Smoking, HTN, dyslipidemia, hypercholesterolemia, previous stroke/MI, Hyperhomocysteinemia
Non-modifiable: Male, Age >55, Family Hx
What aortic diameter is an indication for surgery?
Diameter >5.5 or expansion rate of 0.5cm/6 months
What are the RF for AAA and its rupture?
1) PVD RF especially smoking (x10) and HTN (x2)
2) Collagen/Elastin Defects: Marfan’s or Ehlers Danlos Syndrome
3) Diameter >5.5 or expansion rate of 0.5cm/6 months
4) Aortitis (from bacteremia, endocarditis, mycotic aneurysm)
5) Other: Diabetes, GCA, Polyarteritis nodosa, Coarctation of the aorta
An aorto-enteric fistula may be caused primarily by AAA itself or secondarily post-op (especially EVAR). What is the cause of primary aorto-enteric fistula? (not a disease, physiologically)
What can this lead to? (2)
A long-standing leak causes the formation of the aorto-enteric fistula. This leads to
1) Upper GI bleed
2) High output HF
Where does an aorto-enteric fistula leak into?
Retroperitoneal space or sometimes into the bowel causing a GI bleed
What is the retroperitoneum
Space behind the abdomen. This is the space where most of the ecchymosis happens in AAA as a leak or a ruptured AAA accumulates blood there showing bruising.
Why should we ask about urinary symptoms when taking a history for AAA?
AAA may compress ureter => urinary frequency
Aorto-ureteric fistula => Haematuria
50% of AAA patients are found incidentally on exam or imaging while asymptomatic. What are the clinical features of AAA that you would like to elicit in a history? (incl those with rupture)
1) Sudden Onset Abdominal/back/flank pain
2) Emboli: Blue Toe syndrome, Distal aneurysms (popliteal and femoral), Acute limb ischemia
3) Aorto-enteric fistula =>Upper GI bleed malaena +/- hemoptysis
4) !!!Urinary sx: Frequency and haematuria
5) Rupture
=> Hypotension => syncope, tachycardia, tachypnoea, reduce UO…
=> Anaemia sx
=>Ecchymosis -> Retroperitoneal hematoma/ruptured AAA
Dont forget to ask for RFs
What % of patients with AAA have popliteal or femoral aneurysms?
25%
What is seen in this image?
What may cause this (2)
Image showing retroperitoneal ecchymosis typically seen in ruptured AAA and hemorrhagic pancreatitis. This leads to having the Grey Turner sign in the second image
In this picture there is Cullen’s sign which is periumbilical. This has the same causes + ectopic pregnancy
50% of AAA patients are found incidentally on exam or imaging while asymptomatic. On exam, what would indicate an AAA?
Inspection: Going down to the level of the abdomen and checking for pulsations
Palpation: A pulsatile mass above and left of umbilicus