the narrowing of blood vessels

issue in cardiovascular surgery

20-30% for stents

use drug eluting stents

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

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

designed to extend life several months while heart donor found

Transcutaneous energy transfer

energy resupply through skin

ex: abiocor

viral vector targets receptor cells

effective

mutatgenesis can occur

healthy cells from retina used to replace damaged parts of retina

can be combined with gene therapy

Polylactic Acid

used as scaffold in growing retinal stem cells

location in brian

brain is enormously complex

device/brain interface between convuluted topology and biomaterial

signal/noise separation

reconstructive: restore original function

cosmetic: restore, enhance appearance

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

cant use saline

less realisitic shape

width, projection = parameters

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

smooth- reduced risk of leakage

in armpit

reduced capsular contracture

high risk of injury bc senstive structure in armpit

beneath breast

hides scar, precision implant

yes breast feeding

around areola

desirable

hides scar, precise implant

low bleeding.

high risk of no breast feeding

Between pectoralis, gland

easier surger, faster recovery, no muscle interference

more capsular contracture, looks more artificial 

between pect. major, pect. minor

looks more real, less capsular contracture

longer recovery, harder to reverse

myofibroblast + collagen + blood vessels

severity rated 1-4 on "Baker Scale"

flexibility to conform to facial expression

UV resistance

Shade/tone matching

Easy removal

Easy cleaning

Ultra High Molecular Weight Polyethylene

for porous facial implants

temporary porous biomaterial to facilitate skin regrowth

 double layered

polymethyl methacrylate

confers UV resistance

lens made of PMMA

fastening haptics made from polypropylene fiber

any irregularity from natural heart rhythm 

congenital

blood pressure, stress, caffiene, etc

R. ventricle,

R. Atrium

mesh allows for tissue ingrowth

spearhead design improves stability in tissue

inner: silicone into which fluid is pumped

middle: fabric which allows for and control direction of expansion

outer: silicone prevents tissue ingrowth

surgery contamination

implants harboring bacteria

foreign body reactions

biofilm formation

addressed using antiobiotic elutants

liquid

solid

fabric

hydrogel

critical moleculare weight...

point at which molecular entanglement becomes dominant. 

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

interweaving of polymer molecules at joints called "knots"

dependent on MW, concentration

restricts molecular motion

transparent

biocompatible

UV absorbtive

no oxygen permeability needed

promotes communication between inside, outside of implants

tissue ingrowth

fasten implants

promote growth factor production + release

uses 1 knot

faster,

allows for propogation of infection by capillary action

if one part breaks, entire suture can unravel

many knots

takes longer

if one part breaks, the rest is fine

will contain infection

non-absorbable suture fibers 

disadvantages, advantages

permanent wound support (good for implants)

foreign body remains

suture sinus can develop

suture extrusioon

no permanent foreign body 

strength decreases with time

degradation products can induce tissue rxns

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

being replaced with super critical carbon dioxide

adv: soft pliable, low cutting, good know security

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

more rigid, more mechanical irritation

poor knot security

provoke less tissue response, dont harbor bacteria

allows 1:1 suture:needle ratio

polytetraflouroethylene PTFE

[-CF2-CF2-]

knotless, self anchoring, always monofilament

often used in cosmetics

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

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

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

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

achieve by interweaving absorbable/non-absorbable fibers

body wall defects (pelvic floor, hernia)

gastric bypass

tracheal reconstruction

mesh erosion into surrounding tissue can cause inflammation

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

eroded mesh-- granuloma formation

non-woven= random, moveable fibers

fused joints- reduce movability

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

used with antibiotic Polygenum Chinensis

Nitric oxide, NO

effects, usage

vasodilatory

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

absorb 20-30x weight in water

low mechanical strength, high tissue compatibility

respond stimulus with changes in swelling, permability, mechanical strength

temperature, pH, light, magnetic field, metabolite sensitivities

Lower Critical Solution Temperature

above: materials swell

below: materials shrink

therefore: point at which drug is released

2-10 micrometers

drug release capability

can be injected unlike hydrogels

stress σ = force/area

strain ε : elongation of material/orginal length

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

=slope of stress vs. strain plot

indication of ability of object to absorb impact energy

=area under stress vs. strain curve

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

65% co, 30% cr

low elongation

10-11x more rigid than bone

Chromium oxide sfc layer protects against corrosion

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