DEVICE REDUCES PROCEDURE'S INVASIVENESS

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A Cincinnati medical device manufacturer produces an endoscopic vein harvesting system, made mostly with engineering thermoplastics, to ease side effects of coronary artery bypass surgery.

Ethicon Endo-Surgery Inc.'s procedure involves a few 1-inch leg incisions through which endoscopic instruments and fiber-optic scopes are inserted to locate, dissect and extract a healthy vein.

Traditionally, a vein-extraction incision results in a long scar, usually with prolonged pain and risk of infection and often extending from the ankle to the groin.

Worldwide, about 500,000 patients per year undergo heart bypass grafting procedures, extracting the great saphenous vein from a leg and using it to connect the aorta to the coronary artery, bypassing blockages. Since April, surgeons have used the Ethicon procedure in about 3,500 procedures.

Surgeons' concern about open vein harvesting drove the effort that began in 1994 to create a less-invasive procedure.

The system uses multiple components simultaneously and requires easily manipulated instruments that are long and thin but strong enough to resist a surgeon's force.

``We had plastics in mind from the outset of this project,'' said Gary Knight, the Ethicon senior design engineer who asked Dow Plastics for guidance on incorporating standard engineering plastics into a high-end product.

Ethicon is a unit of health-care giant Johnson & Johnson.

Dow Plastics, a business group of Dow Chemical Co., exhibits the solution in Booth 1047 at the Medical Design & Manufacturing West show Feb. 11-13 in Anaheim, Calif.

Dow's Calibre MegaRad polycarbonate resins are used for the transparent blunt tips of two instruments that dissect and retract the subcutaneous tissue of the leg.

The shaft of each device is made with 304 stainless steel.

Polycarbonate resins with a strength-inducing glass filler form the instrument handles.

``The internal portion of the handles contains a good deal of intricate structural ribbing,'' said Karen L. Winkler, senior applications development engineer for Dow in Midland, Mich.

Optical scopes are inserted into the handle.

Pellethane polyurethane elastomers in the scope-holding clip provide flexibility in holding different scopes in place throughout the procedure.

The vessel dissector is made of glass-filled Isoplast polyurethane, and the handle and trigger of the clip applier is formed with glass-filled Calibre resins.

Each device is disposable through incineration. Knight said a reusable metal design could cost 10 times more to produce and maintain.