In the medical and surgical field, especially incardio-vascular diseases, medical textiles play a major role.Polytetrafluroethylene (PTFE) and Polyester fibre are the most commonly usedfibres in cardio-vascular implants. Polydioxanone is also used in the making ofsutures. The characteristic properties of these fibres are as follows:

Polytertafluroethylene (PTFE): This is a synthetic fluropolymer. Ithas varied applications. It has a very low coefficient of friction and is usedin the machinery industry also. PTFE is very commonly known by the brand nameTeflon by the trademark DuPont. FEP(fluorinated ethylene-propylene) and PFA (perfluoroalkoxy polymer resin) areco-polymers of PTFE and they have the same qualities as PTFE.

Properties:

• Low coefficient of friction
• Dielectric properties
• High radio frequency
• Cannot be cross linked like an elastomer
• High resistivity
• High melting point [327C (620.6F)]
• No adverse effects on human body

Polyester: This is a polymer with ester functional group as a main chain.It is available in many forms, but is commonly used as PET (polyethylene terephthalate).PETis also available in the forms known as polycarbonate and plant cuticles orcutin. Polyesters are easily flammables at high temperatures. Due to itswrinkle resistant capacity, it is widely spun together with other naturalfibres. Its one widespread application in the medical field is the making ofheart valves.

Properties:

• Wrinkle resistance
• Heat resistance
• Good mechanical properties
• Polymerization and cross linking is possible

Polydioxanone: Polydioxanone is used for biomedicalapplications. It is a colorless crystalline biodegradable polymer, which iscommonly available in PDS (poly-p-dioxanone) or PDO (polydioxanone) form. Thisis widely used for the making of sutures in medical applications. The otherareas in the medical field where the application of polydioxanone can be seenare plastic surgery, tissue engineering, cardiovascular, orthopedics and drugdelivery.

Properties:

• Good flexibility
• Property of glass transition temperature
• Shape memory properties
• Biodegradability

Application of polytetrafluoroethylene,polyester fibre and polydioxanone in cardio-vascular diseases:

Polytetrafluoroethyleneis used for the making of vascular grafts and heart valves.Polytetrafluoroethylene sutures are used with or without chordal replacement inthe repair of mitral valve for myxomatous disease. PTFE sutures are used in thesurgery of patients who have prolapse of the anterior leaflet, prolapse of posterior leaflet or prolapse of both the leaflets of the mitral valve. PTFE isespecially used in implantable prosthetic heart valve rings. This ring has a semi-impermeableor impermeable coated cover on the surface to protect tissue ingrowth. Prostheticheart valves are made of non-thrombogenic, blood compatible materials which comprise of titanium and pyrolytic carbon with hinge mechanisms. These kind of prosthetic valves are surrounded by the suturing ring. This suturing ring is sewed to the valvebody by the surgeon.

This is done after the removal of the diseased or damaged part of the heart valve and the prosthetic suturing ring is sewed to the peripheral tissue of the natural heart valve orifice. Proper manufacturing is needed so that rotation between the valve body and the suturing ring is possible in respect with each other when force is applicable. Surgeons can adjust the valve body by disk orientation so that the heart valve can function without any interference of the surrounding heart tissues. Sometimes overgrowth is seen in the suturing ring fabrics. To avoid this, Biolite carbon film coating is applied on valve suturing rings of some heart valves like Bjoke-Shiley valve and Omnicarbon valve. This coating increases the biocompatibility of the suturing ring without reducing its surface porosity.

Polyester fibre is normally used in aortic valve surgery. The tubing of polyester fibre is replaced at the place of the constricted artery in people who have blockages in the main peripheral artery. This draws blood out from the heart by the aorta. This can make permanent bypass for blood flow. The aortic grafts made from polyester fibre are also widely used by surgeons. These prosthetic devices made from polyester fibre are also used in blocked vessels by arteriosclerotic plaques. These fibres do better work than donated tissues because these have lesser risk of stimulated rejection.

Polydioxanone helps in achieving the effect of invisible wound closure, so that the wound closed by the suture is not visible at the time of healing and after healing. The barbed suture works on the sub dermal level. Surgical knots are not required for the strength of the tissue and this knotless configuration reduces the possibility of scars. Bi-directional barbed sutures can be applied in many surgical procedures like tendon repair, dermal tissue approximation and internal wound closure.

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