CHICAGO (AP) _ A heart-monitoring procedure used more than a million times a year during major operations serves no benefit and may actually raise the risk of heart attacks, researchers say.
Right heart catheterization _ in which a thin, flexible tube is inserted into a neck vein and guided into the right side of the heart _ is used on patients with a history of heart trouble during major, non-cardiac operations such as hip replacements and gall bladder removal.
It has been used on patients for 30 years to monitor the heart for everything from fluid pressure to oxygen content.
However, researchers at Brigham and Women's Hospital in Boston found no benefit to the procedure and said the risk of heart attacks and other cardiac problems was three times greater among patients who had it than among those who did not.
The procedure should be re-evaluated, the researchers said. Their study, which appeared in Wednesday's Journal of the American Medical Association, supports earlier findings.
It is unclear whether the procedure itself causes problems or whether information provided by the monitoring leads to overly aggressive corrective treatments that may harm patients, said Dr. Thomas Lee, an associate professor at Harvard Medical School who led the study.
``Some old-time clinicians feel that younger doctors get hypnotized by the numbers from high-tech monitoring devices, and overreact and treat minor fluctuations in numbers from the catheter,'' Lee said.
It is also possible that patients who underwent catheterization simply were sicker than the study's data indicated, he said.
The National Heart, Lung and Blood Institute is now conducting two studies on the use of right heart catheterization.
``I don't think it's dangerous, but the study shows we have some real work to do to say which patients can really benefit from it,'' Lee said.
Lee said there are no other safer procedures that monitor heart function to the same extent. Without a catheter, doctors simply keep track of blood pressure and heart rate, as well as oxygen saturation.
The study involved 4,059 patients _ 221 had the monitoring procedure and 3,838 did not _ 50 and older who underwent major elective non-cardiac operations at Brigham and Women's Hospital between 1989 and 1994.
Researchers came up with 215 matched pairs of patients who did and did not undergo the procedure but had similar medical risks. Those who underwent the procedure had a threefold greater risk of cardiac problems.
The findings appear to support a 1996 study that found patients who underwent right heart catheterization had a 21 percent greater risk of death in the succeeding 30 days. That study prompted calls for more research and a government moratorium on the procedure. The Food and Drug Administration did not issue a moratorium but did recommend clinical trials.
In an editorial accompanying Lee's study, Dr. James Dalen of the University of Arizona Health Sciences Center, editor of the Archives of Internal Medicine, said that given the risks and expense of right heart catheterization, it should not routinely be used.
Dr. Ann Thompson, president of the Society of Critical Care Medicine, said the study could have missed crucial differences between patients in the matched pairs.
``I just don't believe that the problem, with rare exceptions, is with the catheter,'' said Thompson, a professor of anesthesiology, critical care medicine and pediatrics at the University of Pittsburgh. She said it is possible that the fault lies with the surgeons using the catheter.