Chap 130-133 Abdominal Aortic Aneurysm Flashcards
(62 cards)
What is definition of aneurysm?
50% increase in d compared to expected size (SVS)
>3cm
50% increase relative to adjacent normal size
what is ectasia?
intermediate stage of enlargement <50%
what is arteriomegaly?
diffuse continuous enlargement of multiple arterial segments dilated to >50% of normal
what is most significant RF for development of AAA? what are other RF?
smoking
age, maleness
famhx, white, DM
HTN increase rupture risk
What % of men >65 have AAA? women?
5%
1.7%
What % of TA have AAA?
What % of AAA have TA?
What % have iliac involvement?
what % of 1st degree family members have AAA?
50%
12%
40%
as high as 20%
What is the benefit from screening?
reduction of death (1 year and long-term)
not see for women
What is the benefit of intervention on small aneurysms <4.0?
What about with EVAR?
no benefit surveillance vs sx
no survival benefit at 20 months
What is LAPLACE’s law?
T=PR
What are some risk models used for estimating mortality with intervention on AAA? advantages/disadvantages?
glasgow aneurysm score
(open repair, good for elective or ruptured, poor external validity, performs poorly on high risk)
medicare model (open or EVAR)
Vascular governance
north west model
all the scoring systems for EVAR have ROC <70
What are advantages/disadvantages of EVAR over open in regards to outcomes?
more likely to DC home
lower mortality peri-op
Evar constant rupture risk after repair
more likely to have subsequent interventions
When should beta-blockers be started before AAA surgery?
one month. no benefit if not started before
What % of EVAR convert to open ?What is the mortality associated to open conversion after EVAR?
1.5% mort 12%
2% mort 10%
What are advantages/disad of transperitoneal approach?
more rapid, greatest flexibility
widest access
evaluation of intra-abdominal pathology
longer ileus
greater fluid loss
difficult exposure junta or pararenal
What are advantages/disad of retroperitoneal approach?
avoids hostile abdo good for junta/para less physiologic stress/less ileum good for obese inflam AAA/horseshoe kidney (lower LOS, cost and plum comps)
poor access to R renal and iliac
cannot eval intra-abdo pathology
more flank bulges/chronic wound pain
When do you consider preserving IMA?
signif SMA/celiac disease bilat hypo occlusion large IMA prior colonic resection sluggish back bleeding
What are renal or IV abnormalities encountered in AAA?
retro-aortic LRV circ LRV left-sided IVC accersory renal verin pre-aortic confluence of the iliac vein
What physiologic changes occur with aortic cross clamping?
10% increase in BP
if supracelia
preload increase if clamp prox to celiac as sphlanic cannot act as venous reservoir
increase after load and preload increase cardiac contractility and myocardial O2 demand
increase filling pressure
decrease EF
What are the consequences of unclamping?
reduction in PVR
reperfusion hyperemia
toxic metabolites, lactate, K, reactive O2 species, prostaglandins
What are the mechanism of renal injury in AAA repair
ischemia
emboli
renal vasoc even with infrarenal clamp
What are the rate of reintervention for bleeding? MI? resp comps? R insuff? dialysis? colonic ischemia?
1.2% 10% 20% 10% 0.5% (increase if pararenal) 1-5% (on histo 30%)
What are RF for colonic ischemia?
ligation of IMA, failure to revasc hypo, extensive iliofem dz, SMA stenosis, embolism, retractor injury, previous colonic resection
How does colonic ischemia present?
diarrhea, melena
left colon almost always affected
What are finding of CI on flex sig?
early petechial hemmorhage interspersed with areas of pale oedematous mucosa
late segmental erythema, +/- ulcerations and bleeding
with severe mucosa cyanotic, dusky, grey or black
