The New England journal of medicine
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Whether human coronary arteries undergo compensatory enlargement in the presence of coronary disease has not been clarified. We studied histologic sections of the left main coronary artery in 136 hearts obtained at autopsy to determine whether atherosclerotic human coronary arteries enlarge in relation to plaque (lesion) area and to assess whether such enlargement preserves the cross-sectional area of the lumen. The area circumscribed by the internal elastic lamina (internal elastic lamina area) was taken as a measure of the area of the arterial lumen if no plaque had been present. ⋯ The lumen area did not decrease in relation to the percentage of stenosis (lesion area/internal elastic lamina area X 100) for values between zero and 40 percent but did diminish markedly and in close relation to the percentage of stenosis for values above 40 percent (r = -0.73, P less than 0.001). We conclude that human coronary arteries enlarge in relation to plaque area and that functionally important lumen stenosis may be delayed until the lesion occupies 40 percent of the internal elastic lamina area. The preservation of a nearly normal lumen cross-sectional area despite the presence of a large plaque should be taken into account in evaluating atherosclerotic disease with use of coronary angiography.
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In patients with pulmonary disease, the diffusing capacity for carbon monoxide has been used to predict abnormal gas exchange in the lung. However, abnormal values for arterial blood gases during exercise are likely to be the most sensitive manifestations of lung disease. We compared the single-breath diffusing capacity for carbon monoxide at rest with measurements of gas exchange during exercise, including arterial oxygen tension, the alveolar-arterial difference in oxygen tension, the arterial-end-tidal difference in carbon dioxide tension, and the dead-space/tidal-volume ratio in 276 current and former shipyard workers. ⋯ In contrast, of 96 men who had abnormal gas exchange during exercise, only 14 had a diffusing capacity for carbon monoxide below 70 percent of predicted. Neither the type nor the degree of abnormality in gas exchange could be predicted from the diffusing capacity. We conclude that diffusing capacity for carbon monoxide at rest is a specific but insensitive predictor of abnormal gas exchange during exercise and that, if indicated, measurements of arterial blood gases should be obtained during exercise.
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We compared the specialty listings of physicians in the Yellow Pages of the 1983 Hartford, Connecticut, telephone book with the board certifications in specialties of the American Board of Medical Specialties as listed in the American Medical Association directory or the Marquis Directory of Medical Specialists. There were 1179 listings by 946 physicians under 61 specialty headings in the Yellow Pages. We found that a mean of 12 percent of "specialists" listed in the Yellow Pages were not board-certified in a specialty, although they had had ample opportunity to obtain board certification. We conclude that specialty advertising in the Yellow Pages is potentially misleading to consumers and that member boards of the American Board of Medical Specialties should consider ways to diminish this possible misrepresentation.