Biomechanics Cardiovascular - Bruce

 
Created Nov 28, 2012
by austyn
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What is atherosclerosis What are consequences
Artery wall thickens - fatty tissue build up Reduced blood flow and nutrients Amputation, stroke,...
Cellular Mechanisms of Plaque
1. Excess LDL in arterial wall 2. LDL stimulate endothelial cells - adheasion molecules - latch...
Arterial Imaging Methods
1. Angiogram - x-ray based (0.25mm) 2. Intravascular Ultrasound IVUS - planning and post...
Atherosclerosis Treatment Options
Angioplasty, atherectomy, force focused angioplasty, cryoplasty, laser, radiation, local drug...
PTCA - percutaneous transluminal coronary angioplasty POBA - plain old balloon angioplasty...
medical devie that is inserted into clogged artery and inflated to high pressures to clear...
Angioplasty lumen enlargement happens from what combination?
1. plaque reduction (compression/embolisation) 2. axial plaque redistribution 3. vessel expansion
Describe two types of medical ballons
1. high pressure balloons - molded to inflated geometry, non/low compliant materials that retain...
Balloon Definitions  
Diameter: diameter at specific pressure Length: working length/length of body section burst...
Balloon materials
PET: polyethylene terephthalate - high tensile strength, low-medium compliance, high stiffness,...
Desired Ballon Qualities
1. smallest possible wall thickness 2. burst pressure > 15 bar 3. defined pressure &...
How balloons are made?
extrusion of material into a tube shape - blow molding 1. heating jaws to melt plastic 2. tubing...
Balloon mechanics
stress circumferential = pd/2t stress axial = pd/t coronary d = 2.5 mm valvuplasty...
Design Requirments for Balloon Catheter
1. low profile 2. flexible 3. pushable 4. high burst pressure 5. tensile strength 6. kink resistance 7....
Two main catheter designs
1. Over-the-wire (OTW) catheter (co-axial/dual-lumen design) peripheral procedures 2. Rapid...
Testing Requirements
1. Cyclic testing 10-40 cylcles of RPB (rated balloon pressure?) 2. Burst pressure - must tear...
Drug Eluting Balloons (DEBs) what are they coated with? what is concept?
coated with proprietary solution or dipped in paclitaxol assumption rapid release of drug into...
Application of DEB?
Coronary arteries - bifurcations, small vessels <2.5mmd, left main disease Peripheral arteries...
Angioplasty vs Surgery in Lower Extremity Lessions
Angioplast - short occlusions < 2 cm tibal, < 5cm iliac, < 10 cm superficial femoral...
What is RAS
- renal artery stenosis - arteries that feed kidneys! - occurs in 5% of pop - can lead to renal...
What is CAS what can happen? treatments? complications?
Caratoid arterial stensis - can develop stoeks - angioplasty as alternative to invasive carotid...
Protection devices during carotid arterial stenting
1. distal occlusion ballon - obstructs bloodflow as well as distal emboli, require aspiration...
What is atherectomy?
removal of atheroslerotic tissue by cutting/shaving tissue off inside of the artery
Problems with Balloon Angioplasty
1. restenosis ~30% cases - elastic recoil, negative vascular remodling maintain acute luminal...
Stent manufacturing steps
1. alloy tubes 2. laser cut stent pattern 3. grist blast - remove laser burrs 4. electropolish...
Stent requirements
1. high expandibility (ratio collapsed to expanded diameter) 2. wall thickness as small...
Stent Materials
1. plastically deformed alloys (316L/304 SS or CoCr alloy) 2. self expanding nitinol stents  3....
Nitinol
(superelastic 20x more that SS, spring loaded stent - biocompatible + corrosion resistant +...
Problems after stenting
1. cannot abolish restenosis - endothelial injury can create neointimal proliferation 2. ISR...


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