Biomechanics Cardiovascular - Bruce

28 cards


 
  
Created Nov 28, 2012
by
austyn

 

 
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1
What is atherosclerosis
What are consequences
 
Artery wall thickens - fatty tissue build up
Reduced blood flow and nutrients
Amputation,...
2
Cellular Mechanisms of Plaque
 
1. Excess LDL in arterial wall
2. LDL stimulate endothelial cells - adheasion molecules...
3

Arterial Imaging Methods

 

1. Angiogram - x-ray based (0.25mm)
2. Intravascular Ultrasound IVUS - planning...

4

Atherosclerosis Treatment Options

 
Angioplasty, atherectomy, force focused angioplasty, cryoplasty, laser, radiation, local drug...
5
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...
6

Angioplasty lumen enlargement happens from what combination?

 
1. plaque reduction (compression/embolisation)
2. axial plaque redistribution
3....
7

Describe two types of medical ballons

 
1. high pressure balloons - molded to inflated geometry, non/low compliant materials that retain...
8

Balloon Definitions
 

 

Diameter: diameter at specific pressure
Length: working length/length of body section

9

Balloon materials

 
PET: polyethylene terephthalate - high tensile strength, low-medium compliance, high stiffness,...
10

Desired Ballon Qualities

 
1. smallest possible wall thickness
2. burst pressure > 15 bar
3. defined pressure...
11
How balloons are made?
 
extrusion of material into a tube shape - blow molding
1. heating jaws to melt plastic
12
Balloon mechanics
 

stress circumferential = pd/2t
stress axial = pd/t
coronary d = 2.5...

13
Design Requirments for Balloon Catheter
 
1. low profile
2. flexible
3. pushable
4. high burst pressure
5. tensile...
14
Two main catheter designs
 
1. Over-the-wire (OTW) catheter (co-axial/dual-lumen design) peripheral procedures
2....
15
Testing Requirements
 
1. Cyclic testing 10-40 cylcles of RPB (rated balloon pressure?)
2. Burst pressure -...
16
Drug Eluting Balloons (DEBs)
what are they coated with?
what is concept?
 
coated with proprietary solution or dipped in paclitaxol
assumption rapid release of...
17
Application of DEB?
 
Coronary arteries - bifurcations, small vessels <2.5mmd, left main disease
Peripheral...
18
Angioplasty vs Surgery in Lower Extremity Lessions
 
Angioplast - short occlusions
< 2 cm tibal, < 5cm iliac, < 10 cm superficial...
19
What is RAS
 
- renal artery stenosis - arteries that feed kidneys!
- occurs in 5% of pop
- can...
20
What is CAS
what can happen?
treatments?
complications?
 
Caratoid arterial stensis
- can develop stoeks
- angioplasty as alternative to...
21
Protection devices during carotid arterial stenting
 

1. distal occlusion ballon - obstructs bloodflow as well as distal emboli, require aspiration...

22
What is atherectomy?
 
removal of atheroslerotic tissue by cutting/shaving tissue off inside of the artery
23
Problems with Balloon Angioplasty
 
1. restenosis ~30% cases - elastic recoil, negative vascular remodling maintain acute luminal...
24
Stent manufacturing steps
 
1. alloy tubes
2. laser cut stent pattern
3. grist blast - remove laser burrs
25
Stent requirements
 

1. high expandibility (ratio collapsed to expanded diameter)
2. wall thickness...

26
Stent Materials
 
1. plastically deformed alloys (316L/304 SS or CoCr alloy)
2. self expanding nitinol...
27
Nitinol
 
(superelastic 20x more that SS, spring loaded stent - biocompatible + corrosion resistant +...
28
Problems after stenting
 
1. cannot abolish restenosis - endothelial injury can create neointimal proliferation
2....

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