The nurse is caring for a patient that suffered from a myocardial infarction. While monitoring the patient's EKG for signs of a myocardial infarction, the nurse may observe which of the following?
• Myocardial infarctions cause cardiac tissue hypoxia leading to ST-elevation, pathological Q-wave, and T-wave inversion
• Prolonged PR interval is seen with a first-degree block
• U waves represent the repolarization of the Purkinje fibers or papillary muscles. U-waves may be present in healthy patients, but may be a sign of electrolyte imbalances
• An irregular PR interval is seen in second degree blocks