This section is intended as an adjunct reading to accompany Moerman's article "Physiology and Symbols: The Anthropological Implications of the Placebo Effect" cited at the end of this article. Additional sources are cited also.
I. BILATERAL INTERNAL MAMMARY ARTERY LIGATION
This was a surgical technique used to increase the blood flow to the heart musculature in the days before angioplasty and the coronary arterial bypass surgery.
The goal of the surgery was to increase the blood flow to the heart. Instead of a bypass as we know it today, the surgeons would ligate (tie off) blood vessels in the chest wall thereby forcing more blood to flow through the accessory branches of the internal mammary artery that went from the chest wall to the heart musculature. Think of it as analogous to closing off the Borman Expressway to force all traffic southbound onto Broadway!
In the Moerman article, a procedure called BIMAL is described. To understand it, examine the anatomical diagram shown at the right.
The internal mammary artery is the one that descends behind the ribs close to the midline. As the article says, the access is easy and can be done under local anaesthesia.
One question that is often asked is, if you tie off an artery, what happens to the tissue downstream? The answer is that the body is very effective in providing collateral circulation. At first their might be some localized ischemia (restriction in blood flow), but the arterioles and capillaries from other arterial sources quickly adapt and provide blood circulation. From an anatomical standpoint, this surgery would seem to be of only limited benefit.
The ineffectiveness of this procedure was revealed by two double blind studies as cited in the Moerman article. In a double blind study, the patients are not told whether the surgery was done 'for real' or was a 'sham.' Furthermore, the investigators evaluating each patient were denied information about 'for real' or 'sham.' Double blind methodology is imperative in clinical studies, especially is studies of drugs.
Another frequently asked question is, how can you do surgery and ethically do nothing? In a surgery such as this, patients sign a release. They are promised surgery and told only that it may--or may not be beneficial. Remember, this was minor surgery with no entry into the chest cavity.
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Studies of the results of the BIMAL surgery revealed that it offered the same relief from angina pain as the sham surgery. The surgery worked, but not for the reasons it was performed. How can that be? Results from placebo pills is one thing, but placebo effects from cold steel and surgery?
Biomedicine (heart surgery included) unintentionally uses powerful symbols that enhance its effectiveness. For example, a pill may symbolize medical powers to cure inside the body. Surgery, lab tests, and diet regimens may likewise be used as ritual symbols. Medical costumes and paraphernalia symbolize professional expertise. Such symbols increase trust and expectancy and, indirectly, may increase healing effectiveness. Much of what is called the placebo effect may in fact be related to symbolic healing.
Perhaps the foremost reason why we participate in health care as we do is because it makes sense to us. We admire technology and it is what we expect of doctors and hospitals. It certainly matters how a medical procedure works or at least why the surgeon is convinced that it works. After all, that is what he/she tells the patient!
Coronary bypass surgery, the current treatment for a patient with severe angina pain is virtually a cosmic event. Moerman points out that it has a metaphorically dramatic outline. The patient is rendered unconscious. The heart, the source of life, wracked with pain is stopped. By any measure, the patient is dead. The surgeon reconfigures the circulation of the heart and the patient, Christlike, is reborn.
Following surgery, 85% of patients have a complete or dramatic relief with a coronary arterial bypass. At the end of one year, 85% of the blood vessel transplants remain open. Some patients remain significantly improved even in spite of closure of the bypass.
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How effective is coronary arterial bypass surgery? It is highly effective, the mortality rate is only about 1.5%. About 85% of patients have dramatic--or complete relief of symptoms. At the end of one year, 85% of grafts remain open. Exercise test results show a positive correlation between patency (open vessels) and exercise tolerance.
Is there symbolism and metaphor with bypass surgery? Apparently so. Some patients improve in spite of graft closure!
Statistics show that bypass surgery shows longer survival rates that noninvasive medical care. Nitroglycerine tablets placed under the tongue gives relief from angina (pain) in minutes. How does it work? It is a smooth muscle relaxer and a vasodilater. But--placebos give relief for 70-90% of enthusiastic people, 30-40% for skeptics.
..... CJ'97
Resources
Berkow, R. ed. The Merck Manual Rahway: Merck and Company, 1992.
Davis, G. and Park, E. The Heart Washington: U.S. News Books, 1981.
Freund, P and McGuire, M. Health, Illness and the Social Body. Englewood Cliffs: Prentice Hall, 1991.
Moerman, D. "Physiology and Symbols: The Anthropological Implications of the Placebo Effect" The Anthropology of Medicine, Romanucci-Ross, L., Moerman, D., and Tancredi, L., eds. Westport: Bergin & Garvey, 1997 pp 240-253.