Medicine: The Machine Is Fallible

Now that the electrocardiograph has become a standard fixture in consulting rooms, doctors and patients often feel that a checkup is incomplete without its routine ceremonial—daubing with salty goo, taping on electrodes, and letting the machine make wavy lines on squared paper. Confidence in this useful machine has gone too far, says Dr. Francis F. Rosenbaum of Milwaukee. Sometimes it sounds a false alarm, sometimes its "all's well" gives a false sense of security.

By itself, says Dr. Rosenbaum, the electrocardiograph cannot tell the heart's whole story. If the graph shows a minor deviation...