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?

• New onset angina: The client’s chest pain is unrelieved by rest and associated with ST depression on ECG. These features indicate myocardial ischemia without infarction, consistent with unstable angina. Since this is the client’s first episode, it is classified as new onset angina, which requires urgent evaluation and treatment.

• Troponin: Troponin is a specific cardiac biomarker that rises in response to myocardial cell injury or infarction. A normal troponin level in the setting of ST depression and chest pain suggests ischemia without necrosis, confirming the diagnosis of angina rather than myocardial infarction.

• ST elevation myocardial infarction: STEMI is diagnosed when there is ST elevation in two or more contiguous ECG leads, accompanied by elevated cardiac markers. The client’s ECG shows ST depression, not elevation, and his troponin is normal, making STEMI unlikely.

• Chronic stable angina: Chronic stable angina occurs with predictable exertion and is typically relieved by rest or nitroglycerin. This client’s pain worsened over 30 minutes and was not relieved by rest, indicating unstable rather than stable angina.

• prothrombin: Prothrombin time reflects clotting ability, not cardiac ischemia. While important in evaluating bleeding risks or anticoagulation status, it is not relevant in diagnosing angina or MI.

• INR: INR is used to monitor anticoagulation therapy, especially in clients on warfarin. It does not indicate myocardial injury or help confirm ischemia or infarction. The client’s INR is normal and unrelated to the chest pain evaluation.

A. It will no longer be necessary to take daily doses of anticoagulants: Clients with mechanical valves are at high risk for thromboembolism and require lifelong anticoagulation therapy. Stopping anticoagulants places the client at risk for valve thrombosis and systemic emboli such as stroke.

B. The client will need to take an antibiotic before dental procedures: Prophylactic antibiotics are recommended before dental procedures to prevent infective endocarditis in clients with mechanical heart valves.

C. Mechanical valves usually must be replaced within 7 to 10 years after insertion:
Mechanical valves are highly durable and often last 20 years or more. Unlike bioprosthetic valves, they do not require routine replacement unless complications occur.

D. Heparin injections will be required to decrease the incidence of clot formation:
Heparin may be used short-term postoperatively, but long-term anticoagulation for mechanical valves is typically managed with oral agents like warfarin.