Laser heart surgery - dead on the vine?
By DrRich
Medical science is actively exploring several new methods of treating coronary artery disease. Of these new therapies, one of the most promising has been direct myocardial revascularization (DMR). DMR uses a special laser tool to “drill” tiny holes into portions of heart muscle that are not getting sufficient blood flow (due to blockages in the coronary arteries supplying that muscle). These tiny holes, in theory, provide an alternate means of getting blood to the blood-starved muscle. Early results with DMR were very promising, leading several large biotech companies, high-profile medical centers, and well-known cardiologists to pursue this new technology with great vigor, investing significant time, money and prestige in delivering DMR to the clinical arena.
How is DMR done?
There are two major types of DMR: surgical DMR, and transcatheter DMR.
Surgical DMR has been an FDA-approved technique for several years. Surgical DMR is performed by cardiac surgeons in the operating room. A chest incision is made, the heart is exposed, the affected portion of heart muscle is identified visually, and the DMR laser tool is used to bore a series of tiny holes through that part of the muscle and into the cardiac chamber.
Transcatheter DMR, in contrast, is performed in the catheterization laboratory by cardiologists. In the transcatheter procedure a special catheter is inserted into the heart through a blood vessel. Using a high-tech mapping system to identify the affected portion of heart muscle, a series of laser holes are made into that affected portion, directly from inside the heart.
How is DMR supposed to work?
Leaving aside for the moment the question of whether DMR works at all, the most straightforward theory of how this procedure improves the heart is simply this: The new holes “drilled” into the heart muscle provide channels for the diffusion of blood directly into the blood-starved cardiac muscle.
What were the early clinical results?
Almost universally, early reports indicated that DMR significantly improved symptoms in many patients with severe coronary artery disease.
The usage of DMR has always been limited to patients who, in essence, had no other medical options. It has been offered only to patients whose heart disease was so severe that they were deemed not to be candidates for bypass surgery, angioplasty or stents, and their maximal drug therapy had proved insufficient for relieving their symptoms.
In using DMR to treat these difficult-to-manage patients, early results seemed extremely promising. Investigators reported many success stories, in which patients with refractory angina were remarkably improved after the procedure.
What does the improvement in the placebo group mean?
What causes the placebo effect is unknown. This phenomenon does, however, fit the growing perception within the medical profession that the mind has subtle, poorly understood, but important effects over the body.
As a general rule, it appears that the more desperate the patient, the more likely a novel treatment is to generate a placebo effect. Certainly the patients eligible for DIRECT had every right to feel desperate about their heart disease, and this may explain the magnitude of the placebo response observed in DIRECT.
Medical science is actively exploring several new methods of treating coronary artery disease. Of these new therapies, one of the most promising has been direct myocardial revascularization (DMR). DMR uses a special laser tool to “drill” tiny holes into portions of heart muscle that are not getting sufficient blood flow (due to blockages in the coronary arteries supplying that muscle). These tiny holes, in theory, provide an alternate means of getting blood to the blood-starved muscle. Early results with DMR were very promising, leading several large biotech companies, high-profile medical centers, and well-known cardiologists to pursue this new technology with great vigor, investing significant time, money and prestige in delivering DMR to the clinical arena.
How is DMR done?
There are two major types of DMR: surgical DMR, and transcatheter DMR.
Surgical DMR has been an FDA-approved technique for several years. Surgical DMR is performed by cardiac surgeons in the operating room. A chest incision is made, the heart is exposed, the affected portion of heart muscle is identified visually, and the DMR laser tool is used to bore a series of tiny holes through that part of the muscle and into the cardiac chamber.
Transcatheter DMR, in contrast, is performed in the catheterization laboratory by cardiologists. In the transcatheter procedure a special catheter is inserted into the heart through a blood vessel. Using a high-tech mapping system to identify the affected portion of heart muscle, a series of laser holes are made into that affected portion, directly from inside the heart.
How is DMR supposed to work?
Leaving aside for the moment the question of whether DMR works at all, the most straightforward theory of how this procedure improves the heart is simply this: The new holes “drilled” into the heart muscle provide channels for the diffusion of blood directly into the blood-starved cardiac muscle.
What were the early clinical results?
Almost universally, early reports indicated that DMR significantly improved symptoms in many patients with severe coronary artery disease.
The usage of DMR has always been limited to patients who, in essence, had no other medical options. It has been offered only to patients whose heart disease was so severe that they were deemed not to be candidates for bypass surgery, angioplasty or stents, and their maximal drug therapy had proved insufficient for relieving their symptoms.
In using DMR to treat these difficult-to-manage patients, early results seemed extremely promising. Investigators reported many success stories, in which patients with refractory angina were remarkably improved after the procedure.
What does the improvement in the placebo group mean?
What causes the placebo effect is unknown. This phenomenon does, however, fit the growing perception within the medical profession that the mind has subtle, poorly understood, but important effects over the body.
As a general rule, it appears that the more desperate the patient, the more likely a novel treatment is to generate a placebo effect. Certainly the patients eligible for DIRECT had every right to feel desperate about their heart disease, and this may explain the magnitude of the placebo response observed in DIRECT.
posted by Heart Scan @ 3:52 AM
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