COMTEX) B: Laser heart drill provides long-term relief from chest pa
B: Laser heart drill provides long-term relief from chest pain
NEW ORLEANS, Nov 14, 2000 (AP WorldStream via COMTEX) -- AP Medical Editor
Using a laser to drill tiny holes in the heart seems to produce years of relief
from disabling chest pain, even though experts still cannot explain for sure why
it works.
The procedure, called transmyocardial revascularization, or TMR, became
available for routine use in the United States last year. However, some doctors
remain skeptical and wonder if the apparent benefit is an illusion.
The latest U.S. findings, released Tuesday, came from the first long-term
follow-up of patients getting the treatment. It found that the benefits last at
least five years and often longer.
The patients were treated with a carbon dioxide laser developed by PLC systems
of Franklin, Massachusetts, which sponsored the review. The findings were
presented by Dr. Keith Horvath of Northwestern University Medical Center at a
meeting in New Orleans of the American Heart Association.
The procedure is intended primarily for patients who cannot undergo balloon
angioplasty or coronary bypass surgery, the two leading procedures for
increasing blood flow to the heart muscle when clogged arteries choke off the
supply.
Doctors rate the intensity of chest pain, known as angina, on a scale of 1 to 4.
Before treatment, the patients' average angina scores were 3.7.
One year after treatment, their scores had improved to 1.5. And after an average
of five years of follow-up, they were virtually unchanged at 1.6. Seventeen
percent of the patients had no chest pain at all after five years. Some still
felt fine eight to nine years after the procedure.
The treatment requires doctors to open the chest, expose the heart and use the
laser to burn 10 to 50 holes in the heart. Doctors once thought that the holes
served as new blood channels. But this idea has been largely rejected, since the
holes quickly fill in after the treatment.
Proponents now say they think it works by prompting the heart to improve its own
blood supply. They say the drilling probably triggers the release of growth
proteins, and these force the muscle to sprout new blood vessels, which carry in
oxygen and relieve the pain.
Another idea is that the damage caused by the laser destroys nerves in the
heart. Pain goes away, even though the underlying problems remain.
However, during a session at the heart meeting, Dr. David Faxon of the
University of Chicago raised another often-mentioned possibility.
"Why couldn't the results be an enormous placebo effect?" he asked Horvath.
The patients knew they were undergoing a major procedure that doctors believed
would help them. Perhaps, the thinking goes, the patients simply imagined their
improvement.
Such illusions are common in medicine, especially with treatments intended to
stop pain. Recently doctors tested a competing form of the treatment that uses a
laser on a tube threaded into the heart to drill holes from the inside out.
Patients were randomly assigned to get real laser treatment or make-believe
therapy. Those who got the laser improved dramatically, but so did patients
receiving the mock drilling.
However, Horvath replied that a placebo effect should have worn off long ago.
"We saw improvement that people cannot will to happen," he said.
By DANIEL Q. HANEY
Copyright 2000 Associated Press, All rights reserved |
