2. A vascular bypass (or vascular graft) is a surgical
procedure performed to redirect blood flow from
one area to another by reconnecting blood vessels.
or
Conduits used to replace the diseased or blocked
blood vessels are called vascular grafts.
It can be either arteries , veins or capillaries
3.
4. Artery is a blood vessel that takes
oxygenated blood from the heart to all parts of the
body.
Veins are bloodvessels that carry blood toward
the heart
Capillaries are the smallest of the body's blood
vessels
5. Blood vessels became narrower on Atheroscelerosis
It is a disease in which plaque builds up inside our
arteries.
Plaque is made up of fat, cholesterol, calcium, and
other substances found in the blood.
It may leads to heart attack, stroke or even death
6.
7. Blood vessels undergo abnormal buldge , called
Aneurysm
it is a localized, blood-filled balloon-like bulge in
the wall of a blood vessel.
8.
9. Based on size, grafts can be classified as large
caliber, medium caliber and small caliber grafts .
Large calibre vascular grafts: Grafts with diameter
greater than 8 mm are considered as large diameter
The resistance to blood flow is low in large diameter
grafts, hence the occurrence of thrombosis is less
10. Medium calibre vascular grafts: Grafts with
diameter ranging 6-8 mm but greater than 5 mm
are regarded as medium diameter grafts
Small calibre vascular grafts: Grafts whose
diameters are lower than 5 mm are considered as
small diameter grafts
11. Based on origin, grafts can be classified as natural and
synthetic.
. Natural Grafts: Usually autologous grafts such as sephenous
vein from the leg, internal mammary artery and radial artery
from arm are most preferable options during vascular
surgery .
These grafts possess physiological properties akin to the
native vessel and are considered as gold standard
The lack of availability of these grafts due to various factors
such as prevalence of other vascular diseases and need for
multiple grafts are major concerns in vascular surgery
12.
13.
14. Synthetic grafts: Synthetic prosthetic grafts are
being employed as grafts during vascular surgery.
Polymers such as expanded TEFLON (ePTFE),
polyethylene terephthalate (Dacron) (PET) and
polyurethane (PU) are employed for vascular graft
applications
18. characteristics of ideal graft
should be biocompactable
Non thrombogenic
Suturable
Durable
Non toxic
19. Must not cause undesirable reactions
Diamension and mechanical properties are similar
to natural materials
Strong enough to undergo repeated punctures,
resistant to infections
20. Biomaterials used for vascular graft
Expanded teflon
Dacron (PET)
Poly urethanes
22. Less prone to thrombosis and infection
Increased porosity
Better adhesion
Improved pliability in comparison with dacron
graft
23. Sold under trade name dacron
Chemical inertness
Biocompactable
Available in either knitted or woven form ,which
therefore reduces blood leakage
24. PET grafts are available with a protien coating either
collagen / albumin
Promote endothelization with no calcification
Chance of thrombus formation
25.
26.
27. Generally formed by the reaction between
diisocyanates and alcohols
It is not commonly used
TPU has high shear strength,elasticity and
transparency
Probability for thrombosis is similar to that of teflon
Durable