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A new application in transmyocardial revascularization (TMR) laser technology may offer an alternative method of treatment to men and women with severe heart disease who are not candidates for coronary bypass surgery or balloon angioplasty. Cornell University Medical College has received FDA approval to begin a research program to evaluate the Helionetics/Acculase Excimer Laser Transmyocardial Revascularization (TMR) System, a minimally invasive procedure aimed at providing a source of blood flow to areas of ischemic or oxygen-starved heart muscle. Cornell is the only facility on the East Coast participating in this research program.

"Although there have been continued advances in the medical and surgical treatment of coronary heart disease, there exist a significant number of patients for whom cardiac surgery is not indicated because of diffuse atherosclerotic disease (multiple blockages); severe small vessel coronary disease; or multiple reoperations for coronary disease with poor results," said Dr. Todd Rosengart, Assistant Professor, Department of Cardiothoracic Surgery.

"For these patients, many of whom are diabetics, the Excimer Laser may offer a promising alternative."

A normal heart depends primarily on the coronary arteries to deliver its blood supply from the left ventricle cavity, the pumping chamber of the heart. In patients with heart disease, the coronary arteries are blocked preventing normal blood flow to the heart muscle. However, they still have a large supply of oxygenated blood in their left ventricular cavity. For a subset of patients who are not candidates for traditional cardiac surgery, which bypasses blocked arteries, surgeons have to create new pathways for the blood flow.

TMR uses laser energy to create these pathways through a series of 1mm channels from the outer surface of the heart through the heart muscle into the left ventricular cavity, allowing for an increased blood flow directly from this "blood-filled" chamber to the oxygen-starved areas of the heart muscle.

The presently available TMR technology CO₂ laser energy must be delivered via a series of mirrors and right angles. "And although studies have found the system to be both safe and effective, it is quite cumbersome and restricting to use," said Dr. Rosengart.

"By transmitting energy through flexible fiberoptics, the Excimer Laser allows surgeons the potential to develop less invasive procedures. This is a significant advantage over the CO₂ laser, the current TMR technology," he added.

Other potential advantages of the Excimer Laser include: 1) it lessens thermal effects which results in less scarring and a more favorable healing response; 2) allows for greater potential for long-term channel potency; and 3) reduces risk of air embolism and stroke.

The Cornell research team is led by Dr. Rosengart, O. Wayne Isom, M.D., Chairman, Department of Cardiothoracic Surgery; and Timothy Sanborn, M.D., Chief, Cardiac Catheterization Laboratory. Other surgeons participating in the Cornell program are Karl Krieger, M.D.; Samuel Lang, M.D.; Nasser Altorki, M.D.; Wilson Ko, M.D.; and Charles Mack, M.D.

"TMR is an exciting, new laser treatment for patients with coronary heart disease. The Excimer Laser holds the promise of being the most effective, safest and easiest laser system for doing TMR," said Dr. Sanborn.