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Laser Heart Surgery or transmyocardial revascularization is a recent advance in minimally invasive heart surgery. TMR uses a "cold beam" excimer
laser and a unique laser delivery system to create open channels in the heart. This technique is utilized to drill 10 -30 holes from a dying heart muscle to the left ventricle. Although these holes in the heart close, they are said to trigger the growth of new heart in the heart through a process called angiogenesis. Thus, oxygenated blood flows through these new vessels from the left ventricle to heart muscle that had not been receiving proper oxygen or nutrients due to an occlusion in the coronary arteries. The TMR procedure has advanced over the years from open heart surgery to minimally invasive surgery to recent catheter techniques. Laser Heart Surgery offers a solution to problems of angina (chest pain) and can delay or prevent mycardial infarct. Besides providing oxygenated blood to obstructed heart muscle, TMR is said to improve the pumping action of the left ventricle and result in a reduction of anginal or cardiac pain. Moreover, TMR is a minimally invasive heart surgery that may prove to be an alternative to angioplasty or cornary artery bypass.
View a TMR procedure on real video
Laser Mechanics
"USS' "cold beam" TMR system creates a clean, open channel in a controlled motion, vaporizing the tissue as it advances without causing significant thermal damage. The laser is attached to a state-of-the-art delivery system that synchronizes the laser's penetration rate with its ability to create a channel and employs a unique delivery technology that allows controlled access from any direction. A mechanically-controlled delivery assures consistent, reproducible channeling." [61]
TMR Laser
Angina Pain is caused by arteriosclerosis, an accumulation of fatty deposits in the arteries. These deposits often impede blood and oxygen flow to heart muscle tissue. The result of this oxygen and nutrient depletion is angina or chest pain. Angina is often exacerbated by stress and exertion. The
symptoms of angina include among other things, crushing chest pain and angina. Angina cannot be ignored and often requires immediate treatment. Currently three million Americans are afflicted with angina pain. [62]Recent Advances in Laser Heart Surgery
Although Laser Heart Surgery was a relatively pain-free and straightforward procedure with patients going home the same day, recent advances (4/12/99) in this technique have eliminated surgical techniques altogether. A catheter is now used to insert the laser into the left ventricle thus TMR is now a treatment rather than a surgery. The FDA was been wary of approving this technique for general use with a panel voting against the use of this laser technique, but recently (9/22/98) the FDA approved the use of this technique on patients with frequent and severe angina.
Recently the New England Journal of Medicine published the results of two clinical trials designed to test the efficacy of transmyocardial revascularization. Both trials reported that TMR produced less uncontrollable chest pain and an increased quality life than
traditional medical therapy (vasodilation pills). Dr. O.H. Frazier from the Texas Heart Institute in Houston, and colleagues in the transmyocardial Carbon Dioxide Laser Revascularization Study Group reported that 72% of TMR patients had considerably less chest pain, while only 13% of those patients undergoing medical therapy alone experienced significantly less chest pain. Quality of life in the surgery group also improved 38%, compared with 6% in the medically-treated group, but the death rate for the two groups remained similar. A study conducted by Dr. Keith Allen from the Indiana Heart Institute in Indianapolis, and investigators from 17 other medical centers, showed similar results as the Texas Heart Institute study. Dr. Allen's trial showed that 73% of TMR patients had considerably less chest pain with only 47% of those patients undergoing medical therapy exhibiting similar results. The quality of life in the laser surgery group was also 75% higher than that of the medical therapy group. [63]
Conventional Medical therapy
Conventional medical therapy for angina includes the use of vasodilators and a sound diet and lifestyle. Individuals afflicted with angina should not smoke, should exerice regularly and should avoid fatty foods. After maintaining a healthy lifestyle, the next best treatment option for angina pain is the use of drugs. Drugs like nitrates, beta-adrenergic blockers, and calcium channel blockers lower blood pressure and increase blood flow by dilating blood vessels.
For a complete listing of conventional angina treatment visit:
Patients
TMR is recommended for patients who have severe angina pain (Class IV) and who cannot be treated by conventional medical therapy. TMR is often a last resort for older patients who have undergone bypass or other cardiologic interventional techniques. Some patients may have small arteries or widespread blockages that cannot be treated with bypass surgery, and for them laser surgery is a viable option. There are certain
guidelines and criteria a patient must meet to be eligible for this surgery.Future of Laser Surgery
In analyzing the future of laser surgery it is important to note the marked quality of life improvement that patients claim this procedure provides over conventional therapy. Jack Harren of West Palm Beach Florida explained the potential benefits of TMR when he described how TMR substituted his use of conventional medical therapy. "I used to take three to four nitroglycerin tablets a day. Now I take that many a year." Although these clinical manifestations seem significant, they are entirely subjective and may be the result of a placebo effect. The important fact remains that the death rates for both procedures are very similar, and as of now laser surgery does not improve exercise stress tests or blood flow. It has not even been proved that TMR stimulates the growth of new blood vessels. Moreover, TMR is not a risk free procedure, containing mortality rates of anywhere between 5 -20%. Thus at this point, the procedure is not a necessity rather a luxury for those individuals who do not want to deal with the hassles of conventional medical therapy. Drs. Richard Lange and L. David Hillis from the University of Texas Southwestern Medical Center in Dallas suggest that before the use of transmyocardial revascularization is embraced enthusiastically objective evidence of its (effectiveness) should be strong." If objective data on TMR's effectiveness is ever presented, it may go on to replace angioplasty and CABG in older patients who cannot deal with the rigors of these procedures. "This is for people with no options who are miserable with their angina," said Dr. Oesterle in a press release. As of now however, it remains a risky substitute for clinically sound procedures.
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5/3/2000
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