When Dr. Jeffrey Snell looks at a patient, he sees the complex network of veins and arteries as the route to clearing clogged heart arteries, preventing strokes and keeping bulging vessels from rupturing -- all without major surgery. Doctors long have used the winding maze of blood vessels in the vascular system to identify and treat blockages in the arteries that feed blood to the heart. Now an arsenal of newly miniaturized devices and sophisticated digital imaging equipment allow doctors to treat other complicated conditions with minimally invasive procedures where only local anesthesia is needed. The fast-growing discipline, known as endovascular therapy, could replace up to 70 percent of conventional surgeries by the end of the decade, by some estimates. Mike in Brazil Forty years ago, University of Oregon radiologist Charles Dotter devised catheters that could be guided through blood vessels to clear blocked arteries. The technique, called angioplasty, was slow to catch on, but is now performed more than a half-million times a year in the United States. "Today, the technique is used to open blockages all over the body, treat aneurysms and other things," said Dr. Barry Katzen, director of the Baptist Cardiac & Vascular Institute in Miami. "Charles Dotter predicted this would happen." Katzen said doctors and patients tend to prefer less-invasive treatments, which reduce the risk of heart attacks, blood loss and time spent in the hospital. He predicts the market for endovascular therapy will increase by 50 percent to 9.5 million procedures in the next five years. 8th street latinas That will prove a boon to a number of companies that make the catheters, balloons, and tiny wire mesh tubes, known as stents, that prop open vessels. Dr. Alexander Arrow, a medical technology analyst with Lazard Freres & Co., estimated the market for noncoronary stents at $610 million and growing at an 11 percent clip. Coronary stents, a $3 billion market, could potentially expand to $5.4 billion by 2007.