Abdominal Aortic Aneurysm
Where is the most common site for an AAA?
*infra-renal* aorta - below origin of the renal arteries
Aneurysm - define
*irreversible* dilation of an artery at least 1.5 times its normal diameter
What is the average growth rate for aneurysms per year?
0.4 cm/yr (or less)
What should we be rapidly doing to treat a patient for a suspected ruptured AAA?
1. 2 large bore peripheral IVs 2. baseline labs 3. foley catheter 4. type and cross 5. notify attending 6. notify vascular attending 7. call the OR
What are some indications for repair of an AAA? (4)
1. AAA > 5 cm, those > 80 yo should wait > 6 cm 2. ruptured AAA 3. rapidly expanding (> 0.5/year) 4. evidence of distal embolization
What are some etiologies of a dissecting aneurysm? (4)
1. HTN 2. Marfan's syndrome 3. Blunt trauma 4. during cannulation w/ coronary bypass
What are some possible complications associated with AAA surgery? (7)
1. MI 2. Renal failure 3. Colon ischemia 4. Spinal cord ischemia 5. Aortoenteric fistula 6. Graft infection 7. Impotence
What vessels are clamped during an AAA repair?
1. R & L common iliac arteries 2. Aorta
What are 3 common bacterial causes of a mycotic aneurysm?
1. Syphilis 2. Salmonella 3. Staphylococcus
What is the normal diameter of the abdominal aorta?
2 cm
Studies have shown that repair of an aneurysm greater than ______ cm prolongs patient survival.
6
What is the mortality rate for a ruptured AAA?
90%
At what size does the AA become an aneurysm?
>/= 3 cm
What is the most common *type* of aneurysm?
Degenerative
How can AAA surgery lead to renal failure?
Hypotension due to blood loss can lead to acute tubular necrosis - blood loss from rupture - decreased BF to kidney from clamps during surgery
What is Blue Toe Syndrome?
It occurs when the patient presents with discolored toes (blue/purple) due to embolization somewhere in the body
What is the number 1 cause of death in patients undergoing elective AAA repair?
MI
If a patient has an AAA where else should you suspect they may have another aneurysm?
Popliteal artery - be sure to check for the popliteal pulse
If a patient has CAD and they also want to undergo an elective AAA repair, what needs to be done first?
Preoperative coronary revascularization or at least a cardiac work up
How do patients with a dissecting aneurysm describe their pain as?
TEARNG
What is Laplace's Law
Tension = pressure x diameter
T or F: Endovascular grafts have been shown to increase patient survival with repair of an AAA.
True
T or F: Vascular disease is a BODY WIDE process.
True
What is the imaging procedure of choice for an AAA?
U/S
How should we unclamp the vessels post AAA repair? Why?
Unclamp one leg at a time - b/c severe hypotension may occur - b/c lactic acid and wastes would rush throughout the body and possibly cause an arrhythmia or death (metabolic wash out)
When does an aneurysm rupture?
When the stress on the arterial wall exceeds strength of the arterial wall - like a balloon popping
If a patient with a known aneurysm presents to the ER with syncope and abdominal pain, but is stable what should you send them for?
an emergent CT scan - IV contrast only
What is a mycotic aneurysm?
an infected aneurysm
At the induction of anesthesia in a patient with a ruptured AAA what should you be prepared for?
be ready for BP crash
What symptom is evidence of colon ischemia post AAA surgery?
bloody diarrhea
What might we see on a plain x-ray of a patient with a AAA?
calcification of the aneurysm
Why do pregnant women get aneurysms?
due to the hemodynamic stress of pregnancy - it is reversible... (which goes against the definition of an aneurysm..)
How are AAA usually found?
incidentally on PE or imaging study that was performed for other reasons
True aneurysm - define
involves all layers of the arterial wall
False aneurysm - define
involves only a portion of the vessel wall
What vein crosses over the abdominal aorta to empty into the IVC?
left renal vein - this is an important landmark - DO NOT SACRIFICE IT
Are AAA more common in males or females?
males
What is a traumatic aneurysm?
occurs when there is a focal defect in the arterial wall with local bleeding contained by surrounding tissues
Define a dissecting aneurysm
occurs when there is a longitudinal splitting of the layers of the arterial wall
Anterior spinal syndrome - define
paraplegia that follows surgery to the lower thoracic aorta in which the greater medullary artery of Adamkewisc is disrupted - PERMANENT
A patient who presents to the ER with the complaint of syncope and severe abdominal pain has a what until proven otherwise?
ruptured AAA
Which artery is the most common to have an aneurysm in a pregnant woman?
splenic artery aneurysm - very hard to find on imaging
If a patient has a known aneurysm and presents to the ER w/ syncope and abdominal pain and is clearly unstable what should you do?
take them directly to the OR
What is a CT/CTA helpful for evaluating in a patient with an AAA?
the AAA relation to the renal and iliac arteries
What type of patient should we without question give IV fluids to with a ruptured AAA?
those who are unstable! - if they are awake you should hold off
Why would we get an MRI/MRA on a patient with an AAA?
to evaluate the aneurysm characteristics for consideration of endovascular repair
How do aneurysms of pregnancy usually present?
with rupture and shock