A client was admitted to the cardiac observation unit 2 hours ago reporting chest pain. On admission, the client's electrocardiogram (ECG) displays sinus bradycardia (SB) with ST segment depression, but no ventricular ectopy. The client suddenly reports a sharp increase in pain, telling the nurse, "I feel like an elephant just stepped on my chest." The ECG now displays Q waves and ST segment elevations in the anterior leads. Which interventions should the nurse perform?