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Vascular Conduits & Flow dynamics

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Presentation on theme: "Vascular Conduits & Flow dynamics"— Presentation transcript:

1 Vascular Conduits & Flow dynamics
Dr. Nalaka Gunawansa Consultant Vascular and Transplant surgeon National Institute for Nephrology, Dialysis & Transplantation –

2 Vascular Conduit ? An artificial channel / connection between two different vessels or parts of the same vessel.

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5 For steady laminar flow of a Newtonian fluid through a cylindrical tube, the flow rate is directly proportional to the pressure drop, fourth power of radius of tube and inversely to the length and viscosity of fluid

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8 Types of Vascular Conduits.
autologous Biological Cryo-preserved Dacron Prosthetic Polytetraflouroethylene (PTFE) Endografts - - stents/ stent grafts

9 Venous Conduits. Autologous-
Cryo preserved – cadaveric / xeno (porcine) Reversed Non-reversed In situ

10 Autologous venous conduits.
A venous graft taken from the patient's own body. eg – 1. Greater Saphenous vein – -Most frequently used autologous vein graft. 2.Lesser Saphenous vein – -used as an alternative to GSV where this is unsuitable or has been harvested previously. 3.Arm veins - -where there is no suitable leg vein available but there is a strong indication for the use of vein rather than prosthetic material -Cephalic and basilic veins Composite grafts

11 Cryo Preserved Venous Conduits
In infected fields Where the autologous vein is not available or not suitable. Dimethyl sulfoxiude and chondroitin sulfate are current cryoprotectants. Specific complications, - aneurysmal degeneration - late rejection leading to thrombosis

12 Vein graft handling Pre-operative mapping

13 Reversed / insituVenous Conduits
Insitu – Valves surgically destroyed with intraluminal cutting valvutome

14 Arterial Conduits internal mammary, radial and hypogastric arteries are the most durable and best performing vascular conduits. In cardiac bypass surgeries

15 Prosthetic Conduits Types - Polyethylene (PET) - Dacron
-Poly tetra fluro ethylene - PTFE Indications - Autologous unavailable/ non patent. - Replace the thoracic and abdominal aorta, arch vessels, the iliac artery, and common femoral arteries. for either aneurismal or occlusive disease Complications -Thrombosis -Compliance mismatch -Infection

16 Dacron Conduits Available in woven or knitted forms
woven material reduced porosity less leakage Stiffer knitted graft looser construction more flexible excessive blood leakage prevented by impregnation impregnated with Silver, Rifampicin, heparin to be used when there is high risk of graft infection.

17 Polytetraflouroethylene (PTFE) Conduits
Smooth surface – less thrombogenic than Dacron Prone to kinking external reinforcing rings to prevent kinking

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20 Endo – prosthetic grafts

21 The ‘ideal’ graft Non biodegradable Non thrombogenic Non carcinogenic
Cheap Long shelf life durable Pliable and allowing body movement Easy to handle / suture Self sealing Mechanically inert Hydrophobic Resistant to infection


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