Chapter 65 - Biologic grafts Flashcards

1
Q

Cryoprotectants

what are they and examples

A

Protect cell viability and improve stability during freezing process

Dimethylsulfoxide
Glycerol

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2
Q

Mechanism of cryoprotectants

A

Enter cellular cytoplasm and decrease vapor pressure gradient between intracellular and extracellular components

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3
Q

Rapid freezing rate and storage temperature for cryopreserved grafts

A

5C/sec

-102 to -196C

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4
Q

Cryopreserved vein vs fresh vein differences in histological response

A

Endothelial loss
Minimal re-endothelilization
accumulate low-density lipoprotein cholesterol at a faster rate

diminished endothelial vasodilation function

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5
Q

Structurally modified biologic grafts

A

1) bovine carotid artery
2) bovine mesenteric veins
3) human umbilical vein

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6
Q

Thawing allograft

A

Submersion in warm water bath 37-42C for 20 minutes

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7
Q

Human umbilical vein graft key points

A

1) shipped in 50% ethanol
2) does not tolerate traction or clamp
3) vein and dacron mesh both need to be sewn into the anastomosis
4) low molecular weight dextra to prevent thrombosis

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8
Q

Cryo GSV for lower leg bypass patency

A

30-37% 1 year

very poor

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9
Q

Cryo GSV for LE bypass aneurysm rate

A

25-44% in 2 years

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10
Q

Concern for using cryo FV in dialysis access

A

1) good for preventing infection
2) higher risk of pseudoaneurysm
3) allosensitization so do not use in kidney transplant candidates

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11
Q

Use of cryopreserved arterial allografts in lower extremity

A

Low patency
high pseudoaneurysm
too short need more segments
no advantage over cryo vein

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12
Q

Infected aortic replacement with cryograft

morbidity
delayed mortality
aneurysm

A

18-55% morbidity

2-14% delayed mortality in 4 years with rupture

aneurysm 8%

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13
Q

Human umbilical vein graft results

aneurysms
patency to popliteal/tibial

A

Aneurysm: 0-57%
Popliteal 49-57%
Tibial 19-61%

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14
Q

Complication with umbilical vein grafts

A

1) infection
2) stenosis
3) thrombosis
4) dissection
5) pseudoaneurysm

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15
Q

Bovine carotid arteries key points

A

harder to excise due to increased fibrosis

expensive

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16
Q

bovine mesenteric vein xenografts key points

A

poor primary patency and high occlusion rate

not used for infrainguinal bypass

17
Q

Benefit of tissue-engineered vascular grafts

A

1) eliminate immunogenicity

2) against infection

18
Q

tissue engineered vascular graft manufacture

A

1) living fibroblast from human biopsy samples
2) wrapped in stainless steel mandrel
3) fuse for 10 weeks to mature
4) autologous endothelial cells used to seed and precondition the conduit 7 days prior to surgery