Final answer:
The priority nursing intervention for a patient with STEMI receiving alteplase is to monitor for signs of bleeding, due to the risk posed by the clot-dissolving mechanism of the medication.
Step-by-step explanation:
The priority nursing intervention when a client is diagnosed with an ST segment elevation myocardial infarction (STEMI) and is receiving a tissue plasminogen activator, such as alteplase, is to monitor for signs of bleeding. Alteplase is a thrombolytic agent that helps in dissolving the blood clot that has caused the myocardial infarction by converting plasminogen to plasmin.
While this medication can be lifesaving, it also poses a significant risk for bleeding due to its mechanism of breaking down clots. Therefore, continuous monitoring for signs of bleeding is crucial. Other interventions, such as having heparin sodium available, may also be important, but the immediate risk of bleeding makes monitoring for bleeding the priority.