Coronary Artery Disease as Clogged Pipes

Abstract

A recent advertisement on the back cover of a special health issue of the New York Times Magazine section read “Ironic that a plumber came to us to help him remove a clog.”1 The ad referred to doctors in the cardiac catheterization laboratory as “one kind of pipe specialist,” and noted that the patient in the ad returned to work “just 2 days after having his own pipes cleaned out.” Although the image of coronary arteries as kitchen pipes clogged with fat is simple, familiar, and evocative, it is also wrong. Conceptual models help us to make sense of a complex world. In both research and clinical practice, our conceptual models inform our decisions about which outcomes to measure, which confounders to adjust for, and which patients are likely to benefit from a particular treatment. For example, the model of cervical cancer as the consequence of infection with certain strains of human papilloma virus has led to the development of a vaccine to prevent cancer. However, when a conceptual model is flawed, as in the case of the clogged pipes analogy, we are supposed to discard it and replace it with a more accurate one. In Structure of Scientific Revolutions , Kuhn observed that such paradigm shifts do not occur easily.2 Instead, scientists cling tenaciously to the old, accepted model, despite its inability to explain observed phenomena. In medicine, too, misconceptions embedded in an outdated model may linger for years, influencing physicians’ practice and patients’ expectations. Simple models, especially those we have worked for years to get the public to understand, may be the hardest to abandon. The clogged pipe analogy of stable coronary heart disease has been particularly difficult to dislodge. This representation had its origins in the 1970s, when researchers observed that the degree of coronary …