2006年VOA标准英语-Cardiologists Debate Safety of Heart Stents（在线收听）

By Carol Pearson
Washington, DC
08 November 2006
 
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Heart stents are lifesaving medical devices that help prevent heart attacks.  Most of these stents are coated with various drugs, but mounting data suggest drug-coated stents can pose significant risk. 

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A stent is a tiny mesh tube, usually made of metal, that is inserted into an artery so more blood can flow through. 

Various drugs, such as antibiotics, can be used to coat the stents. About 6 million people worldwide have drug-coated stents implanted in an artery. Cardiologists are now debating whether these stents can cause potentially fatal blood clots.

Dr. Michael Lincoff explains. "The clot forms in the stent, closes the stent off and the blood stops down the artery.  And so that area of the heart muscle has a heart attack."

Heart attacks are due to a blocked artery. Stents can help provide a clear passageway  
  
Some research suggests drug-coated stents may be responsible for 6,000 heart attacks in the U.S. each year.  Dr. Craig Smith of the Mayo Clinic says, "Even though there's considerable debate about the magnitude of the risk involved, it seems to be greater than was appreciated before."

Drug-coated stents prevent the buildup of scar tissue in the artery.  But the stents have direct contact with the blood stream, and can allow clots to form.

Dr. Lincoff says for patients with a drug-coated stent it's critical to remain on blood thinning drugs that help prevent clots from forming. "By far, the majority of these blood clotting events that are happening in patients who have stopped one or both blood thinning medications."

The debate over drug-coated stents may one day be moot.  Scientists are now testing a stent that can be absorbed into the artery wall once the stent does its job.  This type of stent may prove to be a safer alternative to the other stents currently available.