Chap 92-96 Grafts and Stents Flashcards Preview

Vascular Surgery > Chap 92-96 Grafts and Stents > Flashcards

Flashcards in Chap 92-96 Grafts and Stents Deck (49):
1

What manoeuvres can improve SVG latency during harvest?

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

2

What are advantages/disadvantages for reversed vein graft?

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

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

3

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

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

valve lysis required

4

What are advantages/disadvantages in-situ vein graft?

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

5

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

age <0.7
if 3RF need for contralteral vein 25-50%

6

What is ideal SVG size for bypass?

3.5 best
<3 highest risk of failure

7

What are different types of valvulotomes?

Mills
expandable
fixed

8

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

No

9

What configuration should most arm vein be implanted?

reversed as most have wall to thin for valve lysis

10

Which is the most commonly used arm vein?

cephalic

11

What is the top three choice for bypass conduit?

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

12

What can you do to elongate the LSV?

harvest the Giacomini in continuity

13

What is the latency for popliteal vein? SFA artery?

similar to SVG
1 year patency 60%

14

What is the most common cause of early graft failure?

technical at anastomosis

15

what is the failure rate of graft caused by atherosclerosis?

4% annual loss

16

What are intraoperative ways to assess graft patency?

doppler
palpation
angio
flowmeter
duplex
angioscopy

17

What are intra-operative duplex criteria for bypass grafts?

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

18

What to do if moderate stenosis identified?

papaverine and rescan
consider angio

19

What are postoperative duplex criteria?

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

20

How to manage post-op mod stenosis?

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

21

How to manage post op severe stenosis

repair

22

What other index is concerning for graft stenosis?

ABI drop of >0.15

23

Name different types of prosthetic grafts?

Dacron
ePTFE
hybrid stent
polyurethane

24

How much does dacron increase in size after implantation?

10-20%

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