Chap 130-133 Abdominal Aortic Aneurysm Flashcards
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
What is the rate of aorta-enteric fistula after AAA? sexual dysfunction? abdo wall hernias? RP bulge? SBO at 4 years?
1.6% 50% 30% 30-50% 25%
what are most common bacteria for infected AAA?
staph, salmonella, strep, E.Coli
What are signs of infected AAA on CT scan?
periaortic soft tissue mass, stranding of fluid, signs of destruction of the surrounding tissue
50% have contained rupture
What % of type II resolve with 6-12months?
80%
eurostar says no association with rupture
What is the yearly rupture rate for EVAR?
1% per year
Name some EVAR RCT and describe their results
EVAR-1, Dream, OVER
mortality higher for open then EVAR but no difference at 2 years. reintervention rate higher in EVAR
What are techniques to fix type I endoleak?
proximal extension palmaz snorkel aorto-uni with fem fem fenestrated
What factors affect migration?
increased angulation of neck, short neck, neck thrombus, large diameter, neck dilation, sac shrinkage
How often doe limb occlusion occur? what are risk factors?
5% 4 years
AI dz,
small distal aorta <14mm, tortuous iliacs
What are consequences of IA embolization?
pelvic ischemia
buttock claudication 50%, necrosis, colorectal ischemia 2%, erectile dysfunction 2%
paraplegia if bilat 3%
What is the rate of Type I endoleak with snorkel?
5% (50% require tx)
30d mort 4%
What are bladder pressure measurements for abdominal compartment syndrome?
When is a laparotomy indicated?
grade I 10-15mmHg
grade II 16-25mmHg
grade III 26-35mmHg
grade IV >35mmHg
grade III-IV
What are common venous anomalies encountered during open surgery for AAA?
retro-aortic renal 1-3%
circumaortic 0.5-1.5%
Left sided vena cava <1%
duplicated IVC 1-3%
What is the evidence for AAA screening?
RCT
>65, 40% reduction in AAA mortality
MA
44% in AAA mortality
What growth rate for AAA is concerning?
> 1cm/year
How does family history effect rupture rate of AAA?
higher rupture rate if have a family hx of AAA
What cutoff for cardiopulmonary exercise testing predicts high risk after AAA?
10-15 ml/kg/min
What level of wall tension is high risk for AAA rupture?
> 40N/cm
<30 is low risk
What non-IFU related scenarios favour open >EVAR?
EVAR>opan
horsehoe kidney with multiple arteries
require IMA latency
redo
abdo stoma
wall defects
poor pulmonary
What are renal abnormalities that can be encountered during AAA repair?
horseshoe
pancake
crossed-fused renal ectopia
all of these usualy have multiple RA
What adjuncts can be used to protect kidneys during AAA?
cold hyperosmolar crystalloid
HTK solution
saline with mannitol
cooling kidney by 30% reduces metabolic demands by half
List collateral pathways that supply colon.
marginal artery meandering artery GDA middle sacral hypo (lateral sacral, middle rectal, superior rectal, obturator)
What is repair threshold for iliac aneurysm?
3-3.5cm
Which graft does not have suprarenal fixation?
Gore, aorfix
What were results of EVAR-1?
RCT open vs EVAR
30d mort 1.7 vs 4.7 (E vs O)
secondary more common in EVAR
no diff at 6 years
What were the results of the DREAM trial?
RCT peri-op mort 1.2 vs 4.6 in EVAR vs OPEN combined MACE and mort favoured EVAR no diff at 6 years
What were the results of the OVER trial?
peri-op mort 0.5 vs 3% E vsO
no diff at 2 years
From eurostar data which graft had
highest migration/endoleak
highest rate of limb occlusion
aneurs, talent
zenith
What is the rate of ED in EVAR?
20% for unilateral embolization
What are mortality rates for rAAA?
2/3 before hospital
50% with open
30% with EVAR
What are some management considerations for rAAA?
permissive hypotension
avoid hypothermia
cell saver
blood in room
What are outcomes for rAAA?
bleeding
colinic ischemia
10%
40% open, 20% EVAR
What features indicate high peri-op mortality for rAAA?
cardiac arrest
liver failure
MOF
What are SVS guidelines for pre-op workup for AAA?
EKG
NIST if 3 or > RF for CAD
Ideally how long to wait after PCI?
4-6 weeks for BMS
12months for DES
What are screening recommendations for AAA?
One-time screening for
men >65 yo
55 yo if fam hx of AAA
women >65 with fam hx of aaa or who have smoked
Re-screening not recommended if >65yo and aortic diameter <2.6cm
When do increase surveillance to q6months?
> 4.5cm
What are signs and symptoms of aortocaval fistula?
machinery murmur
high output failure
limb edema
hematuria
