conduits used to replace diseased or blocked blood vessels

1. JESIYA SUSAN GEORGE
MSC BPS
CBPST KOCHI

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

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

7.  Blood vessels undergo abnormal buldge , called
Aneurysm
 it is a localized, blood-filled balloon-like bulge in
the wall of a blood vessel.

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

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

15. Teflon graft

16.  Porosity
 Compliance
 Biodegradability
 suturable

17.  Dialtion
 Suture failure
 Defects in the graft
 Bleeding and infection

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

21.  Great tensile strength
 Mechanical toughness
 Durability
 Inert
 Highly hydrophobic

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

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