Vascular graft

conduits used to replace diseased or blocked blood vessels

1. VASCULAR GRAFT 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 Definition

3. Blood vessels

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 ARTERIES ,VEINS & CAPILLARIES

5. Blood vessels became narrower on Atheroscelerosis I t 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 WHY NEW BLOOD VESSELS?

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

7. 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 Classification of vascular graft

8. 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

9. 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

10. 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

11. Teflon graft

12. Porosity Compliance Biodegradability suturable Characteristics of Vascular Grafts

13. Dialtion Suture failure Defects in the graft Bleeding and infection Graft failure

14. characteristics of ideal graft should be biocompactable Non thrombogenic Suturable Durable Non toxic

15. Must not cause undesirable reactions Diamension and mechanical properties are similar to natural materials Strong enough to undergo repeated punctures, resistant to infections

16. Biomaterials used for vascular graft Expanded teflon Dacron (PET) Poly urethanes

17. Great tensile strength Mechanical toughness Durability Inert Highly hydrophobic Why ePTFE??

18. Less prone to thrombosis and infection Increased porosity Better adhesion Improved pliability in comparison with dacron graft

19. Sold under trade name dacron Chemical inertness Biocompactable Available in either knitted or woven form ,which therefore reduces blood leakage PET??

20. PET grafts are available with a protien coating either collagen / albumin Promote endothelization with no calcification Chance of thrombus formation

21. 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 Poly urethanes??