New Treatment Prevents Reclogging of Heart Vessels

A new gamma radiation treatment intended to prevent stented heart vessels from reclogging is now available at St. Luke's Episcopal Hospital, thanks to the cooperative efforts of medical specialists at St. Luke's, the Texas Heart Institute, and The University of Texas M. D. Anderson Cancer Center.

Despite major advancements in procedures and technology to keep blood flowing through diseased coronary arteries, the medical community has remained frustrated by the high percentage of reblockage, or in-stent restenosis that occurs in some patients treated with coronary artery stents - the tiny scaffolding devices designed to push back coronary artery plaque and keep vessels open.

The new treatment, the first intravascular brachytherapy, or radiation, system introduced in the United States for lesions up to and including 45 millimeters, was recently approved by the Food and Drug Administration, and follows extensive testing at the Texas Heart Institute and St. Luke's Episcopal Hospital.

"In-stent restenosis has been a very difficult condition to treat," said Dr. R. David Fish, director of Interventional Cardiology Research at the Texas Heart Institute at St. Luke's. "Our study results show the effects are strong with as much as a 60 percent reduction of event rates. We believe the effectiveness of this treatment will benefit thousands of patients for years to come."

Radiation oncologists at M. D. Anderson, long a world leader in the use of radiation for cancer treatment, provided expertise in employing the gamma radiation used in the new noncancer treatment.

"We were pleased to accept the invitation for collaboration with St. Luke's and Texas Heart Institute, and we are looking forward to making a significant contribution to patient care and research," said Dr. James D. Cox, professor and head of the Division of Radiation Oncology at M. D. Anderson Cancer Center. "This new venture allows our radiation oncologists and physicists to bring their advanced skills to a new type of patient care and explore new research opportunities. We remain committed to collaborations with colleagues in the Texas Medical Center and around-the-world efforts to improve patient care everywhere."

Gamma radiation, which has a 70-year history of proven effectiveness and safety in a wide range of medical applications and treatment, is being used rather than beta radiation because gamma radiation has greater penetration.

During the procedure, which is performed in the cardiac catheterization laboratory, the arterial system is entered in the groin and a catheter is threaded through the artery to the blockage. An angioplasty balloon is used to open up the blocked artery within the previously implanted stent. A one-to-two inch long radiation ribbon containing Iridium-192 is then sent through the catheter to cover the stented area of the artery. The ribbon is left in place for between 15 and 30 minutes, exposing the cells in the artery to the radiation.

The radiation therapy is designed to stop scar tissue from growing within the stent. Prior to this new technology, it has not been uncommon for patients whose stented vessels reclogged to undergo repeat procedures on the same vessel in a continuing effort to maintain adequate blood flow.

Since their introduction in 1994, stents, along with coronary balloon angioplasty, have enabled hundreds of thousands of patients to avoid coronary artery bypass procedures.

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©2006 Texas Medical Center

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