The Practice of Electrocardiography (PDF)

Electrocardiography is a mature discipline, so familiar to both doctors and patients that it's hardly noticed, one of those tests that have always been there, like the white count and hemoglobin, not something one has to think about much, or question. To some extent this view is valid, but it overlooks some important points. Like the white count and hemoglobin, electrocardiograms are produced by technicians using mechanical devices that turn out numbers, but there is a difference. The white count and hemoglobin are reported as single values to be interpreted by the doctor who knows the patient and ordered the test, but the graph produced by an EKG machine represents millions of numbers displayed as XY plots, a message written in a language different from one's own. It requires transla­ tion, and this means that the translator must not only know the lan­ guage, but also be able to assess the effects on it of the many factors that may have modified its meaning between origin and delivery. There is potential for harm to the patient, as well as for help, in every facet of the process, and to lose sight of this, to see the tracing as a single whole, would be like seeing words as units without con­ sidering the letters that compose them. When we read, we do recog­ nize whole words, patterns, but, having learned the letters first, revert to this base intuitively when we encounter a new word, or one that is misspelled.