“One night on the sofa in my apartment, while studying the reams of wavy lines that make up EKGs, she puzzled over, then correctly identified, a fatal arrhythmia. All at once, it dawned on her and she began to cry: wherever this “practice EKG” had come from, the patient had not survived. The squiggly lines on that page were more than just lines; they were ventricular fibrillation deteriorating to asystole, and they could bring you to tears.”