We propose to evaluate left ventricular regional wall motion by gated blood pool tomographic (SPECT) imaging at rest, during maximal exercise, 15 and 30 minutes after termination of exercise. Myocardial perfusion (O-15 water) and metabolic (F-18 deoxyglucose) studies will be performed utilizing positron emission tomography (PET). Absolute regional myocardial blood flow (ml/min/gm) will be assessed at rest, during maximal exercise, 15 and 30 minutes post-exercise along with myocardial fluorodeoxyglucose utilization 45 to 90 minutes post-exercise. Patients afflicted with conditions that limit their capacity to perform an adequate exercise study will undergo pharmacological stress study with dobutamine. Normal subjects will also be studied in order to create a control database.