Outside Reading 8

One summer day in 1996, Hans Ohlin, the fifty-year old chief of coronary care at the University of Lund Hospital in Sweden, sat down in his office with a stack of two thousand two hundred and forty electrocardiograms. Each test result consisted of a series of wavy lines, running from left to right on a letter size page of graph paper. Ohlin read them alone so that he would not be disturbed and scanned them one at a time, seperating them into two piles according to whether or not he thought that the patient was having a heart attack at the time the electrocardiogram was recorded. To avoid fatigue and inattention, he did his work over the course of a week, sorting through the EKGs in shifts no longer than two hours. He wanted no careless errors because the stakes were too high. Hans was going head to head with a computer. The electrocardiogram is one of the most common of diagnostic tests performed more than fifty million times a year in the United States alone. Electrodes are placeed on the skin to puck up the low-vlotage electrical impulses that travel through the heart muscle, and then those impulses are reflected in the waves on a EKG printout. The theory behind an EKG is that in a heart attack a portion of the muscle dies, causing the electrical impulses to change course when they travel around the dead tissue. Sometimes those changes are obvious more than they are subtle or in medical argot, "nonspecific".