17 Jun 2002
US researchers have shown that transmyocardial revascularization (TMR) - a surgical procedure that uses a laser to drill holes in the heart - can alleviate angina (chest pain) in the majority of sufferers for at least five years.
A second study could open the door to a non-surgical form of the laser procedure.
TMR uses a carbon dioxide laser to make multiple channels in the heart for blood to flow through. Although no-one is sure exactly why or how the procedure helps to reduce chest pain, it has proved to be effective over the short-term. The results of a new study indicate that TMR is also effective for longer periods of time. Researchers report that 60% of the patients in their study who have undergone TMR have had relief from chest pain for at least five years.
"Whatever symptom relief these patients have had at up to one year seems to be holding true for up to five years," said Keith Horvath, lead researcher of the TMR study and assistant professor of cardiovascular surgery, Northwestern University Medical School, Chicago. "We have a significant number of patients who have experienced pain relief for as long as eight to nine years following TMR surgery."
There are several theories as to why TMR is effective in curbing chest pain. It could be that the laser channels provide a new source of blood to the heart. Another theory is that TMR triggers angiogenesis - the stimulation of new blood-vessel growth. Yet another theory is that nerves in the affected area of the heart are destroyed, numbing the heart and thus relieving chest pain.
A non-surgical form of TMR, which uses a different type of laser than surgical TMR, could be available to patients in about six months' time, according to second study. In percutaneous TMR (PTMR), a catheter is placed under the skin and is then threaded up through the aorta (the heart's main blood vessel) to the inner lining of the heart wall. A holmium:YAG laser is placed on the tip of the catheter. Cardiologists use fluoroscopy to get a detailed view of the heart and to help guide the laser during the procedure.
Horvath says that one major advantage of surgical TMR compared with PTMR is that the heart is exposed, allowing the laser to create channels through the full thickness of the heart rather than just the inner surface of the heart muscle. In the future, TMR could be used in combination with coronary bypass surgery to provide chest-pain relief in areas of the heart that have widespread blockages.