Cook Incorporated, a world leader in minimally invasive medical technology with a family of stents and stent-grafts, is sponsoring a clinical trial to test the safety and effectiveness of a new device for treating peripheral arterial disease. The clinical trial uses the Zilver® stent. Cook has coated this stent with paclitaxel and is studying its safety and effectiveness in treating PAD.

Paclitaxel is a drug approved for use as an anti-cancer agent and is being used successfully with coronary stents to reduce the risk of renarrowing of the coronary arteries. It's believed that paclitaxel, when used with the Zilver® stent, will help to keep arteries in the leg from renarrowing after a stent is used to reopen a blockage.

Is the Zilver® PTX™ Drug-Eluting Stent Trial right for you?

Only you and your doctor can determine the best treatment for your peripheral arterial disease. This information sheet provides details about the clinical trial and will help you talk with your doctor about what treatment is best for you.

Question and answer with the Zilver® PTX™ Drug-Eluting Stent Trial clinical trial principal investigator.

Dr. Michael Dake, national principal investigator for the Zilver® PTX™ Drug-Eluting Stent Trial and Professor and Chairman of the Department of Radiology at the University of Virginia Health System, recently talked with Cook about the importance of the trial and the new technology to treat peripheral arterial disease.

Q. As the study's national principal investigator, what do you hope to determine through Cook's Zilver® PTX™ trial of a drug-eluting peripheral stent?

A. Cook's trial is the first to use a drug-coated stent in the treatment of peripheral arterial disease. It is designed to evaluate the safety and effectiveness of the Zilver® PTX™ Stent versus a procedure called percutaneous transluminal angioplasty, or PTA. The medical community considers PTA the treatment of choice for patients with peripheral arterial disease. This trial is designed to prove that a drug-coated stent is going to be a better treatment than PTA.

Q. What is different about using a drug-coated stent in a peripheral artery compared to the highly successful drug-coated coronary stents that have been approved in the last few years?

A. Although the arteries in our heart and our leg are composed of the same tissue, they experience very different strains and challenges. In the legs, for example, exercise and walking put stresses on a stent that would not be present in the heart. In this clinical trial by Cook, paclitaxel will be attached to the stent in an effort to evaluate how effective it will be in treating peripheral arterial disease.

Q. What drug is being used to coat the Cook Zilver® PTX™ stent and how does it stop the artery from reclogging?

A. The Zilver® PTX™ stent uses the drug paclitaxel, one of the most popular and effective drugs used in coronary stents. It is intended to reduce the amount of tissue build-up inside the stent after it is placed and to reduce the risk of renarrowing of the artery.

Our bodies are very smart, but the ways that we can respond to injury are limited. When we put a balloon in the body, the vessel is injured, much like if we were to cut our finger. The body's response is to attempt to heal that through a series of events including clotting. The end result in some cases can be the renarrowing of the vessel by formation of a scar.

Paclitaxel on the stent is intended to heal the site of injury by limiting the response of the blood vessel so a scar that could renarrow the vessel does not occur.

Q. How do blockages occur in the peripheral arteries? Is it the same process as the coronaries?

A. Obstructions in arteries in our legs are much the same as blockages that occur throughout our circulatory system, including our heart and blood vessels that supply the brain. These blockages are caused either from dietary and lifestyle considerations or hereditary reasons. Whatever the cause, we get a buildup of plaque that narrows the vessel and obstructs blood flow.

Q. What happens when a stent is placed into a vessel, and why do you need to put a drug on it?

A. Drug-eluting stents combine a stent - a metal "scaffold" that props open a narrowed artery - with a drug used to stop the renarrowing of the blood vessel. This was first used in treating circulation problems in the heart, and the results have been phenomenal. As a result, drug-eluting stents have become the primary therapy for obstructions in coronary circulation. It is hoped that similar technology, used in the legs, will help those who suffer from peripheral arterial disease.

Q. How does paclitaxel work?

A. The drug works by limiting cell division. In the leg, this is important. As the vessel is injured and it heals, we want to promote healing but we don't want an overproduction of cells that could actually renarrow the vessel with a scar.

PAD develops most often as a result of the hardening of arteries (atherosclerosis) that occurs when cholesterol levels and/or scar tissue build up, causing the arteries to narrow and restrict blood flow. Because hardening of the arteries causes peripheral arterial disease in up to 30 million people worldwide, this treatment has huge potential for reducing the suffering in many patients.