AAA Flashcards
AAA screening recommendations
The new recommendations of surveillance intervals for patients with AAA were published in 2018 from the Society of Vascular Surgery:
1) imaging at 3-year intervals for AAA diameter between 3.0 and 3.9 cm;
2) imaging at 1-year intervals for AAA diameter between 4.0 and 4.9 cm; and
3) imaging at 6-month intervals for AAA diameter between 5.0 and 5.4 cm.
This was based on the meta-regression analysis by Thompson et al. They studied the AAA growth rate based on aneurysm diameter and the time to 10% probability of reaching a diameter of 5.5 cm. For an aortic diameter greater than 2.5 cm but less than 3 cm, it is now recommended to rescreen at 10 years.
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
List local factors associated with development of anastomotic aneurysm.
Arterial wall degen
Suture line disruption
Prosthetic graft failure
Infection/inflammation
Technical factors
Mechanical stress
List systemic factors associated with anastomotic aneurysm.
Smoking
DLP
HTN
Anticoagulation
Vasculitides
Generalized arterial weakness
What are indications for treatment for anastomotic aneurysm?
>2.5cm
symptomatic
Is endovascular better then open repair for anastomotic aneurysms?
endo can offer lower mortality and morbidity rates with high success rates in certain patients
What are the causes of primary AEF?
aneurismal aorta (most common)
foreign body
tumor
radiation
infection
GI dz
What portion of the duodenum is involved in AEF?
3rd or 4th
Where do secondary AEF and AEE occurs?
AEF suture line
AEE on graft
What are the causes of secondary AEF?
infection pulsatile pressure (graft non compliant) technical error (injury to bowel)
what is the classic triad for secondary AEF?
GI bleeding
abdo pain
pulsatile mass
11%
What is the classic feature of a secondary AEF?
herald bleed
What are findings on CT scan that indicate AEF?
Effacement of fat planes around aorta
Perigraft fluid and soft tissue thickening,
ectopic gas,
tethering of adjacent thickened bowel loops toward aortic graft, rarely extrav
What are signs of AEF on endoscopy?
need to see 3-4th portions
visualization of graft
ulcer
erosion with adherent clot
extrinsic pulsatile mass
What are the most common bacteria for primary AEF?
salmonella
klebsiella
What are the most common bacteria for secondary AEF?
s.aureus
What are repair options?
graft excision without replacement if enough ollaterals
insitu graft replacement
neo-aortoiliac procedure
extra-anatomic revasc
endovascular (as bridge)
What grafts can be used for replacement?
allograft
synthetic graft
silver coated dacron
antibiotic impregnated grafts
What are the result of operative repair for AEF?
mortality 30%
amputation 10%
3 yr survival 50%
What are most common complications after PCI?
bleeding/hematoma
PSA
AVF
dissection
thrombosis
What are RF for complications after endo procedure?
larger sheath
interventional procedures
previous cath
small BMI
female
uncontrolled HTN
GIIbIIIa
increased age
What are indications for intervention for femoral hematoma?
hemo instability
persistent anemia
skin necrosis
nerve compression
severe pain
What nerves can be affected in the retroperitoneal space (4)?
lateral cutaneous nerve of the thigh
genitofemoral nerve
femoral nerve
nerve to cremaster muscle
What does the lateral cutaneous nerve of the thigh innervate?
innervates skin on lateral thigh
What does the genitofermoral nerve innervate?
sensation upper anterior thigh
sensation anterior scrotum/mons
What does the femoral nerve innervate?
sensation ant/medial thigh/medial chin/arch of foot
extends knee
What does the nerve of the cremaster muscle innervate?
cremasteric reflex
What are signs/symptoms of RPB?
non-specific groin/back pain
oliguria
numbness weakness LE
ecchymosis flank (grey turner)
ecchymosis umbilicus (cullens)
What is natural hx of AVF from endovascular procedure?
30-80% resolve spontaneously within 1 year (most within 1 month)
What are treatment strategies for PSA?
US compression
US guided thrombin
observation
surgical
Endovascular
what is success of thrombin injection for PSA? describe procedure.
95-100%
Anesthetize skin
Fill sac with 0.1-0.2ml of thrombine
Direct needle away from inflow of the PSA
If perist then another dose
Check distal pulses and repeat US in 24-48 hours
Recurrence 3%
What are indications for surgical intervention on PSA?
Infected
Hemo instability
Skin necrosis
Distal limb ischemia
Neurologic defecit
Failure of US treatment
Large aneurysm >5cm with wide necks
What causes thrombosis after endovasclar procedure?
large sheath
aggressive compression
closure device failure
What are methods of nerve injury in brachial access?
hematoma
direct damage
schema from arterial thrombosis
What are different types of closure devices and give an e.g.?
collagen based (angioseal) suture based (per close) metal/disk based (star close)
What is the evidence for closure devices?
MA
no difference in complication rate then with compression alone
What are active and passive closure devices?
active
suture/clip
extravascular prothrombotic matrix
passive (faciliatate compression)
external patches with prothrombotic coating
assisted compression
What were the rates of life threatening hemorrhage in TOPAS and STILE trial?
13%
6%
At what fibrinogen levels do you alter thrombolysis management?
<100 stop
List ways to assess graft latency intra-operatively.
inspection
palpation
arteriography
doppler
duplex
angioscopy
IVUS
What b/w to send off before initiating heparin in thromboses grafts?
Plt
Functional activated protein C resistance
Anticardiolipin antibodies
ATIII
Protein S
HITT assay
What are RF for graft thrombosis?
Single vessel runoff high rate of graft failure
Below knee target
DM
Preop tissue loss
BMI >35
Early revision
African American
smoking
failure to go to surveillance
What are the critical elements for sustained flow in bypass graft?
Inflow
Outflow
Conduit
Operative technique
Coagulation profile
What are 30 day causes of graft thrombosis?
technical error
graft thrombogenicity
poor runoff
obstructive venous disease
What are 18 month causes of graft failure?
neointimal hyperplasia
vein graft structural abnormalities
What are 5 year causes of graft failure?
vein or prosthetic graft structural abnormalities
progressive athero
What are indications for angioplasty for intimal hyperplasia?
Post CTD to bridge to OR
High risk for OR
Difficult to approach surgically
