Chap 92-96 Grafts and Stents Flashcards

1
Q

What manoeuvres can improve SVG latency during harvest?

A

limited touch
limit distention pressure <150mmHg
blood solution less damaging to endothelium
Heparin/papverin

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2
Q

What are advantages/disadvantages for reversed vein graft?

A

valve lysis not required
options for anatomic/non-anatomic placement

potential size mismatch at anastomoses
hemodnamic effect of intact valves
valves can complicate thrombectomy

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3
Q

What are advantages/disadvantages for non-reversed vein graft?

A

improved vein to artery size match
options for anatomic/non-anatomic placement

valve lysis required

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4
Q

What are advantages/disadvantages in-situ vein graft?

A

limited skin incision
reduced manipulation of the vein
improved size match
subcutaneous position assists in graft revision

valve lysis required
subcutaneous position risk for exposure with wounds infection
length limitation for proximal anastomosis

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5
Q

What are risk factors for future contralateral leg intervention at time of ipso bypass?

A

age <0.7

if 3RF need for contralteral vein 25-50%

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6
Q

What is ideal SVG size for bypass?

A

3.5 best

<3 highest risk of failure

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7
Q

What are different types of valvulotomes?

A

Mills
expandable
fixed

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8
Q

Do intact valves in reversed vein adversely effect long-term latency?

A

No

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9
Q

What configuration should most arm vein be implanted?

A

reversed as most have wall to thin for valve lysis

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10
Q

Which is the most commonly used arm vein?

A

cephalic

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11
Q

What is the top three choice for bypass conduit?

A

GSV
arm vein
LSV (third due to difficult harvest and limited length

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12
Q

What can you do to elongate the LSV?

A

harvest the Giacomini in continuity

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13
Q

What is the latency for popliteal vein? SFA artery?

A

similar to SVG

1 year patency 60%

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14
Q

What is the most common cause of early graft failure?

A

technical at anastomosis

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15
Q

what is the failure rate of graft caused by atherosclerosis?

A

4% annual loss

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16
Q

What are intraoperative ways to assess graft patency?

A
doppler
palpation
angio
flowmeter
duplex
angioscopy
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17
Q

What are intra-operative duplex criteria for bypass grafts?

A

normal<125
Moderate 125-180 ratio 2-3
Severe >189 w spectral broadening, ratio 2.5-5 repair
high-grade >300, ratio >5

low flow <40, low PVR–consider anticoag

lowfloe, high PVR–consider AVF, alternate target

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18
Q

What to do if moderate stenosis identified?

A

papaverine and rescan

consider angio

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19
Q

What are postoperative duplex criteria?

A

normal 150, ratio <1.5
Mild >150, ratio 1.5-2
mod (50-75% >180, ratio >2.5, rescan leave alone if stable
severe (>75%), >300ratio >3.5 repair

low -flow <40, repair

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20
Q

How to manage post-op mod stenosis?

A

rescan in 4-6 weeks if not progression continue observation 3 month interval

21
Q

How to manage post op severe stenosis

22
Q

What other index is concerning for graft stenosis?

A

ABI drop of >0.15

23
Q

Name different types of prosthetic grafts?

A

Dacron
ePTFE
hybrid stent
polyurethane

24
Q

How much does dacron increase in size after implantation?

25
What are failure modes of prosthetic grafts?
blood interface (no antithrombotic mechanisms) infection compliance
26
What cells adhere to graft wall
Complement, coagulation cascade, plt, neutrophils and macs adhesion
27
Why is graft infection bad with prosthetic?
biofilm reduces abx effectiveness 50% amp rate 50% mortality
28
How does compliance influence failure?
stiff graft can lead to area of excessive mechanical stress which can lead to IH
29
What is anti-pot/anti-coag after prothetic graft?
ASA (lowers graft occlusion by 40%) | warfarin doubles bleeding events so only if at high risk of occlusion
30
Name options for cryopreserved grafts for bypass.
``` cryo SVG HUV CFA bovine carotid artery bovine mesenteric vein ```
31
How can cryopreservation effect allografts?
vessel can become less compliant can have micro changes to histology of intima diminished vasodilatory function
32
What is overall latency of cryo grafts?
its poor but limb salvage rate better then expected | likely du to repeated revasc attempts or situational perfusion enhancement
33
What aortic stent design features help prevent graft failure?
positive fixation column support friction
34
What are examples of positive fixation?
hook barbs anchors supplemental staples
35
What is column support?
long iliac sealing zone to help prevent infrarenal migration
36
What are some anatomical features that can lead to graft limb occlusion?
``` iliac injury calcification tortuosity stenosis limb oversizing ```
37
How much overlap between components?
2-3 cm infrarenal | 5-7cm thoracic
38
What are mechanism of failure of aortic stent grafts?
``` migration neck dilation fracture limb occlusion sac expansion ```
39
What is the definition of stent migration?
movement of more then 10mm or any movement with new type I/need of secondary procedure
40
What are some graft complication specific to thoracic?
retrograde type A | compression (with excessive oversizing)
41
Name some AAA devices.
``` aneurx medtronic excluder gore zenith cool powerlink engologix talent medtronic ovation trivascular ```
42
Name thoracic devices.
cTag gore talent medtronic Tx2 cook alpha cook
43
What are some stent interaction with vessel wall?
``` vessel injury fluid dynamics (oversizing leads to areas of low wall shear stress which leads to IH) strut characteristics (flow over struts can cause areas of low wall shear stress) ```
44
What are advantages/disadvantages of BE stents?
high radial force high radio-opacityno oversizing needed high precision ``` requires delivery sheath can't treat lesion with variable diameter low flexibility not resistant to external compression risk of dislodgment off balloon ```
45
What are advantages/disadvantages of SE stents?
high flexibility no delivery sheath needed treats lesions with variable diameter resistant to compression low radio-opacity oversizing needed low radial force
46
What is the definition of radial force?
force required to produce a 50% reduction in the luminal diameter of the stent
47
What differences in radial force between stainless steel and nitinol stents?
SS relies on design for radial force | nitinol relies on inherent nature of the metal
48
What are the differences in open and closed cell stents?
closed cell every stent wire interconnected. less flexible | may prevent distal embolization
49
``` Which stent to use: concern about embolization fresh thrombus high external forces ostial lesions venous heavily calcified infrainguinal dialysis branch points long iliac lesio ```
``` covered covered SE BE SE oversized BE SE SE BE SE (calibre change ```