Chapter 83 - Lower extremity aneurysms Flashcards
M:F ratio of LE true aneurysms
30:1
Association of AAA with other peripheral aneurysms
Femoral: 50-90%
One popliteal 30-50%
Bilateral popliteal 70%
Chance of bilateral aneurysms in femoral and popliteal
Femoral: 25-50%
Popliteal 50-70%
Rate of femoral or popliteal aneurysm in men or women with aortic aneurysms
14% in men
no association in women
Normal size of CFA
Men 1.0 cm
Women 0.8 cm
Indicated diameter for repair in CFA aneurysm
- 5 cm according to largest reported series 172 patients
3. 5 cm according to Lawrence
Risk for CFA true aneurysms
1) men
2) age >70
3) smoking
4) HTN
Cause of CFA true aneurysm
1) degenerative
2) atriomegaly
3) Behçet
4) Parkes Weber syndrome
5) Wegener granulomatosis
distribution of true aneurysms in the femoral segment
CFA 81%
SFA 14%
PFA 5%
Clinical presentation of true femoral aneurysm
Asymptomatic 30-40%
Pain 30-40%
Lower extremity ischemia (embolization) 65%
Pain associated with femoral aneurysm
localized tenderness
compressive neuropathic pain
leg edema
Indication for treatment of femoral aneurysm
1) all symptomatics
2) > 2.5 cm (controversial, maybe 3.5 cm according to Lawrence)
Natural history of femoral pseudoaneurysm
Less than 2-3cm may thrombose spontaneously
Closure rate higher if less than 1.8 cm
Will not close if on anticoagulation
Duplex Sen and Spe for pseudoaneurysm
Sensitivity 94%
Specificity 97%
Ultrasound guided compression of femoral pseudoaneurysm first introduced in
1991
Ultrasound guided compression of femoral pseudoaneurysm technique
1) compression maintained 10-20 min
2) repeat if flow still present
3) bed rest 6 hours
4) repeat DUS 24-48 hours
Success rate of ultrasound guided compression; what if anticoagulated, time needed to compress and recurrence rate
66-86%
<40% if anticoagulation
Compression time 30-44 min
Recurrence 4%
Contraindication for ultrasound guided compression of pseudoaneurysm
1) ischemic skin
2) infection
3) puncture site above inguinal ligament
4) severe pain
5) large hematoma
Complication types and rate after ultrasound guided compression of pseudoaneurysm
2-4%
1) rupture
2) femoral vein thrombosis
3) femoral artery thrombosis
4) vasovagal
Ultrasound-guided thrombin injection first described by
Cope in 1990’s using angiographic guidance
Kang modified using ultrasound guidance
Thombin MOA
Converts fibrinogen to fibrin
Clot formation bypassing heparin/warfarin effects
How to prepare thrombin
Bovine or human thrombin mix with NS
Ultrasound-guided thrombin injection technique
1) US to identify cavity
2) local
3) puncture with 22 or 25 gauge needle
4) inject slowly via 3ml syringe over 10-15 seconds (1000 IU/ml): total dose ~ 1000 Units
5) bed rest 1 hour
6) repeat US 24 hours
Ultrasound-guided thrombin injection success rate
96-100%
second injection in 7% cases
Contraindication to bovine thrombin
1) allergy
2) infection
3) pregnancy
Relative
1) wide channel/neck
Indication for open surgical repair of femoral pseudoaneurysms
1) ruptures
2) failure or contraindication to compression or thrombin
3) skin ischemia
4) AVF
Open repair techniques for femoral pseudoaneurysms
1) direct repair
2) patch angioplasty
Complication following open repair of femoral pseudoaneurysms
Wound complication: 4-8%
Mortality 2.9%
SFA aneurysm (isolated)
Elderly men age 75.7 years
middle third of artery
mean diameter at presentation 8.4 cm
Clinical symptom of SFA aneurysm
Pulsatile tender thigh mass 59%
Rupture 42%
Distal ischemia 13%
When to fix SFA aneurysms
2.5 cm or greater
SFA aneurysm treatment outcome
Limb salvage 88%
5- year survival 62%
Graft patency 85%
Rate of synchronous aneurysm in PFA aneurysms
70%
most common popliteal
PFA indication to repair
Whenever present since natural history unknown
Dissecting out PFA
1) vertical incision
2) start at CFA bifurcation
3) extent inferiorly and slightly laterally
4) sartorius and rectus femoris reflected laterally
5) divide crossing venous branches
6) preserve femoral nerve branches
Persistent sciatic artery prevalence
0.01-0.05%
Sciatic artery origin
Umbilical artery in embryology
at month 3 it regresses and becomes part of the inferior gluteal artery
Aneurysm formation in persistent sciatic arteries
40%
Symptoms of persistent sciatic artery aneurysm
1) enlarged butt mass
2) local compressive symptoms
3) distal ischemia
Repair of persistent sciatic artery aneurysm
Interposition graft without aneurysm resection given risk of sciatic nerve injury
Normal diameter of popliteal artery
0.5-1.1 cm
Size threshold for popliteal artery aneurysm
1.5 cm
some say 2cm
really need to know that popliteal artery size varies from proximal to distal
Popliteal artery aneurysm as a percentage of total peripheral aneurysms
70%
Popliteal artery aneurysm epidemiology
1) 7.4/100,000 men; 1/100,000 women
2) 50% have bilateral PAAs
3) 30-50% have AAA
4) 50% have another aneurysm somewhere in 10 years
Pathogenesis of popliteal artery aneurysms
Degenerative not atherosclerotic
1) disruption and fragmentation of elastic lamellae
2) decreased vascular SMC and increase pro-apoptotic signals
also mechanical stress because of the location
Growth of popliteal artery aneurysms
< 20 mm: 1.5 mm/year
20-30 mm: 3 mm/yr
>30 mm: 3.7 mm/yr
Risk factors for popliteal artery aneurysm growth
hypertension
Rupture risk of popliteal artery aneurysm
2.5%
high rate of limb loss
Rate of LE complication in patients with popliteal artery aneurysms
32-74% in 5 years
Rate of rupture in popliteal artery aneurysms
2% (0-7%)
Symptoms of popliteal artery aneurysm rupture
1) swelling
2) edema
3) popliteal vein thrombosis 14%
Imaging modality in popliteal artery aneurysm
1) DSA helps with outflow but limited in terms of mural thrombus misleading
2) US easy
3) CTA MRA best
Risk of ALI and limb loss in popliteal aneurysm > 2cm
30-40%
When to repair popliteal artery aneurysms
1) symptomatic
2) asymptomatic 2-2.5 cm with thrombus
3) Extensive thrombus
4) occlusion of tibial vessels
Endovascular treatment of popliteal aneurysm criteria
1) proximal and distal landing 2cm
2) landing zone size consistency
3) no tortuosity
4) not extremely large aneurysm which could kink stent
5) cannot do in people who hyperflex knee routinely
6) must be on antiplatelet after
7) single vessel runoff has lower patency rate
Endovascular treatment for popliteal aneurysm technique
1) oversize 10-15% viabahn
2) ACT > 250
3) maximal 1 mm size differential between grafts if more than 1 used
4) avoid landing graft at the bend of the popliteal artery (few cm above actual knee joint; determined by doing angiogram with knee bent)
5) 2-3 cm overlap between stents
6) plavix indefinitely
John Hunter 1785 on popliteal aneurysm
Ligation of a coachman popliteal aneurysm
Medial vs posterior approach benefits in popliteal aneurysm
Medial: more proximal and distal exposure
easier positioning
Best for small fusiform aneurysms
Posterior: better for large saccular aneurysms
allow ligation of tributaries
Allow excision of the mass effect
Medial approach to popliteal aneurysm rate of failed thrombosis
30%
What needs to be divided to gain proper access to the popliteal aneurysm via medial approach
Medial head of the gastrocnemius muscle
Posterior popliteal artery approach
1) Prone
2) Lazy S from medial proximal to lateral distal
3) palpate distal to adductor canal
4) Separate semimembranosus and semitendinosus from long head of bicep femoris
5) dissect on anterior surface of aneurysm to avoid injury to nerves (lateral posterior to aneurysm)
6) dissect down to two heads of the gastroc
Percentage of popliteal aneurysm that have acute ischemia on presentation
30%
Rate of patients without runoff after acute ischemia and popliteal thrombosis
25-45%
Rate of tpa infusion
2 mg/hr or less
Heparin infusion in sheath during tpa infusion
500 Units/hr
PTT and fibrinogen checks in tpa infusion
PTT < 50
fibrinogen > 200 mg/dL (if it drops below then stop or reduce dose; stop if < 150 mg/dl)
Chance of thrombolysis in restoring runoff in popliteal thrombosis
77% at least 1
Preoperative thrombolysis in popliteal thrombosis in amputation rates
96% down to 69%
Limb salvage in popliteal aneurysms and primary patency
asymptomatic vs symptomatic
Asymptomatic
Limb salvage 92%
Primary patency 87%
Symptomatic
Limb salvage 80%
primary patency 52%
Predictor of endovascular graft failure in popliteal aneurysm
Single vessel runoff
Patency of endograft in popliteal aneurysm
primary patency 5 year 70%
secondary 76%
better >80% if treated with plavix
Open vs endo repair of popliteal aneurysm
Open = longer LOS, higher 30d complication, better 3yr primary patency
No difference in secondary patency or amputation rates
Reasons to choose endo over open for popliteal aneurysm
1) good anatomy
2) does not bend knee more than 90 degrees routinely
3) can take plavix >4-6 weeks
Tibial and pedal artery aneurysms key points
1) rare without trauma
2) treatment: bypass if distal ischemia, ligation, coil embolization, observation and wait for spontaneous thrombosis