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Biomedical Devices
Quiz 1
85
Biology
Undergraduate 4
03/04/2012

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Term
Restinosis
Definition

the narrowing of blood vessels

issue in cardiovascular surgery

20-30% for stents

Term
To cure restinosis:
Definition

use drug eluting stents

use anticancer, immunosuppression drugs coating on stents to prevent tissue in-growth

Term
Abiocor
Definition

2001: 1st implantable artificial heart, replaces left ventrical, left atrium

designed to extend life several months while heart donor found

Term
T.E.T.
Definition

Transcutaneous energy transfer

energy resupply through skin

ex: abiocor

Term
price: heart valves
Definition
$3,000-$5,000
Term
Percutaneous/transcatheter heart valve
Definition
no need for open heart surgery- implanted via catheter
Term
blindness: Gene therapy
Definition

viral vector targets receptor cells

effective

mutatgenesis can occur

Term
blindness: stem cell therapy
Definition

healthy cells from retina used to replace damaged parts of retina

can be combined with gene therapy

Term
PLA
Definition

Polylactic Acid

used as scaffold in growing retinal stem cells

Term
brain pacemaker
Definition
external electric signal sent to brain to control epilepsy
Term
Neural implants
Definition
accept brain signals for speech movement, etc
Term
challenges- brian implants
Definition

location in brian

brain is enormously complex

device/brain interface between convuluted topology and biomaterial

signal/noise separation

Term
Carbon Nanofibers (CNF) properties
Definition
used as supple scaffold for stem cell growth due to bending under weight of cell
Term
two types of biomaterials:
Definition

reconstructive: restore original function

 

cosmetic: restore, enhance appearance

Term
Breast implant: teardrop shape
Definition

anatomically correct, 3 parameters of size: height, width, projection

cant use saline

Term
breast implant: round
Definition

less realisitic shape

width, projection = parameters

Term
Breast implant: smooth v textured surface
Definition

textured- dull appearance. microprojections allow for tissue ingrowth-- less rippling

 

smooth- reduced risk of leakage

Term
breast implant: axilarry incision
Definition

in armpit

reduced capsular contracture

high risk of injury bc senstive structure in armpit

 

Term
breast implant: imframmery incision
Definition

beneath breast

hides scar, precision implant

yes breast feeding

Term
breast implant: periareolar
Definition

around areola

desirable

hides scar, precise implant

low bleeding.

high risk of no breast feeding

Term
breast implant: implantation (saline)
Definition
collapsed implant is inserted, filled with saline 
Term
breast implant: subglandular
Definition

Between pectoralis, gland

easier surger, faster recovery, no muscle interference

more capsular contracture, looks more artificial 

Term
breast implant: subpectoral implant
Definition

between pect. major, pect. minor

looks more real, less capsular contracture

longer recovery, harder to reverse

Term
capsular contracture
Definition

myofibroblast + collagen + blood vessels

severity rated 1-4 on "Baker Scale"

Term
requirements of silicone maxofacial device
Definition

flexibility to conform to facial expression

UV resistance

Shade/tone matching

Easy removal

Easy cleaning

Term
UHMWPE
Definition

Ultra High Molecular Weight Polyethylene

 

for porous facial implants

Term
DuoDerm
Definition

temporary porous biomaterial to facilitate skin regrowth

 double layered

Term
artificial eye biomaterials
Definition

polymethyl methacrylate

confers UV resistance

Term
Interocular Lens biomaterials
Definition

lens made of PMMA

 

fastening haptics made from polypropylene fiber

Term
snowflake degeneration
Definition
opacification in IOL 
Term
Denture biomaterial
Definition
PMMA
Term
disadvantage of ball and cage heart valves
Definition
alters blood flow (hemodynamics) resulting in erythrocyte destruction, increased risk of thrombosis
Term
arrhythmia (causes)
Definition

any irregularity from natural heart rhythm 

congenital

blood pressure, stress, caffiene, etc

Term
single chamber pace maker
Definition
planted in right ventricle
Term
double chamber pace maker
Definition

R. ventricle,

R. Atrium

 

Term
pacemaker leads
Definition

mesh allows for tissue ingrowth

 

spearhead design improves stability in tissue

Term
3 layers of penile implant cylinders
Definition

inner: silicone into which fluid is pumped

middle: fabric which allows for and control direction of expansion

outer: silicone prevents tissue ingrowth

Term
cylinder aneurism
Definition
overexpansion of cylinder prevents deflation
Term
increases in infection post surgery due to:
Definition

surgery contamination

implants harboring bacteria

foreign body reactions

biofilm formation

 

addressed using antiobiotic elutants

Term
4 forms of biomaterials
Definition

liquid

solid

fabric

hydrogel

Term
η
Definition
=viscosity
Term
MWc
Definition

critical moleculare weight...

point at which molecular entanglement becomes dominant. 

when viscosity greater than critical molecular weight, viscosity= MW^3.4

Term
molecular entanglement
Definition

interweaving of polymer molecules at joints called "knots"

 

dependent on MW, concentration

 

restricts molecular motion

Term
Toric lense
Definition
corrects for astigmatism
Term
requirements of IOL biomaterial
Definition

transparent

biocompatible

UV absorbtive

no oxygen permeability needed

Term
modular hip implant
Definition
ball and socket are separate for better integration
Term
roles of porosity in fabric
Definition

promotes communication between inside, outside of implants

tissue ingrowth

fasten implants

promote growth factor production + release

Term
affect of porosity on growth factor release, healing
Definition
increases both
Term
continuous suture
Definition

uses 1 knot

faster,

allows for propogation of infection by capillary action

if one part breaks, entire suture can unravel

Term
Interrupted suture
Definition

many knots

takes longer

if one part breaks, the rest is fine

will contain infection

 

Term

non-absorbable suture fibers 

disadvantages, advantages

Definition

permanent wound support (good for implants)

 

foreign body remains

suture sinus can develop

suture extrusioon

Term
absorbable suture dis/advantages
Definition

no permanent foreign body 

 

strength decreases with time

degradation products can induce tissue rxns

Term
use of ethylene oxide
Definition

sterilization of sutures... releases toxic gas, long process. 

 

being replaced with super critical carbon dioxide

Term
braided suture fibers
Definition

adv: soft pliable, low cutting, good know security

 

disadv: tissue drag, high tissue rxn, harbor/transport bacteria

Term
monofilament sutures
Definition

more rigid, more mechanical irritation

poor knot security

 

provoke less tissue response, dont harbor bacteria

Term
gortex structure
Definition

allows 1:1 suture:needle ratio

polytetraflouroethylene PTFE

[-CF2-CF2-]

 

 

 

 

 

 

 

 

Term
barbed suture fibers
Definition

knotless, self anchoring, always monofilament

often used in cosmetics

 

Term
disadvantages of suture knots
Definition

compromised blood flow-- tissue necrosis

high tension-- scarring

bulky knots can lead to suture extrusion or stich abscesse

high pressure can result in enzymatic degradation

Term
barb geometry
Definition

length cut=depth of cut/ sin (180 - cut angle)

 

large cut angle, lower depth, lower length = higher strength

Term
weft vs. warp
Definition
in braided fabrics warp under tension, weft not
Term
ideal porosity
Definition

fabric not initiall porous so patient doesnt loose blood, eventually becomes porous to allow for tissue ingrowth

 

achieve by interweaving absorbable/non-absorbable fibers

Term
uses of vicryl mesh
Definition

body wall defects (pelvic floor, hernia)

gastric bypass

tracheal reconstruction

Term
pelvic floor reconstruction
Definition
after historectomy, vaginal prolapse can occur bc uterus holds vagina in position. mesh used to reattach vagina
Term
reconstructive bariatric surgery
Definition
aka gastric bypass
Term
complications with surgical mesh
Definition

mesh erosion into surrounding tissue can cause inflammation

 

sacral osteomyelitis (bone infection in spine) following pelvic floor reconstruction

 

eroded mesh-- granuloma formation

Term
felt fabric structure
Definition

non-woven= random, moveable fibers

fused joints- reduce movability

 

Term
PEA nano fiber production
Definition

C.C. Chu's Lab- using electrospin extrusion. 

 

used with antibiotic Polygenum Chinensis

Term

Nitric oxide, NO

effects, usage

Definition

vasodilatory

impregnated into PEA, resulted in more rapid loss of weight (?)

Term
hydrogels
Definition

absorb 20-30x weight in water

low mechanical strength, high tissue compatibility

 

Term
charged hydrogels
Definition
based on (+) arginine
Term
temperature senstive hydrogel
Definition
swells as low temp, shrinks at high temp... releases drug at low temp
Term
intelligent hydrogel
Definition

respond stimulus with changes in swelling, permability, mechanical strength

 

temperature, pH, light, magnetic field, metabolite sensitivities

Term
LCST
Definition

Lower Critical Solution Temperature

 

above: materials swell

below: materials shrink

therefore: point at which drug is released

Term
hydrogel microspheres
Definition

2-10 micrometers

drug release capability

can be injected unlike hydrogels

Term
bFGF
Definition
basic fibroblast growth factor
Term
vEGF
Definition
Vascular endothelial Growth Factor
Term
heparin
Definition
protects bFGF, VEGF from proteolytic degradation
Term
Stress vs. Strain
Definition

stress σ = force/area

 

strain ε : elongation of material/orginal length

Term
modulus of elasticity
Definition

tendency of an object to be deformed elastically when a stress is applied

=slope of stress vs. strain plot

Term
toughness
Definition

indication of ability of object to absorb impact energy

 

=area under stress vs. strain curve

Term
creep
Definition

tendency of a solid material to move slowly or deform under constant stress

 

 

Term
stress relaxation
Definition
describes how polymers relieve stress under constant strain
Term
cobalt based alloys
Definition

65% co, 30% cr

low elongation

10-11x more rigid than bone

Chromium oxide sfc layer protects against corrosion

Term
Stainless Steel alloys
Definition

63% Fe, 17% cr, 12% Ni

low carbon steel to prevent formation of carbides which deplete Cr, preventing chromium oxide layer from forming

high elongation

9x more rigid than bone

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