Figure 52-7 Heart rate and ST segment trends the evening before surgery from an ambulatory electrocardiographic monitor for a patient scheduled for femoropopliteal bypass. Notice the "mirror image" heart rate-related ST segment depression occurring at subtachycardic heart rates (about 85 beats/min). (Adapted from Frank SM, Beattie C, Christopherson R, et al: Perioperative rate-related silent myocardial ischemia and postoperative death. J Clin Anesth 2:326–331, 1990.)