Final answer:
The nurse should assess for allergies to shellfish or iodine, the ability to lie prone for 30 minutes, and a history of reaction to nitrates before a patient undergoes a cardiac CTA with contrast.
Step-by-step explanation:
Before undergoing a cardiac CTA with contrast, a nurse should assess a patient for several critical factors to ensure the safety of the procedure. The nurse should check for any allergies to shellfish or iodine, as contrast agents often contain iodine, which can cause an allergic reaction in sensitive patients. Additionally, it is important to assess the patient's ability to lie prone for the duration of the test, which is usually about 30 minutes. A history of reaction to nitrates is also relevant, as these may be used during the procedure. The presence of body tattoos is less critical for a CT scan, as opposed to other imaging techniques, because tattoos do not interfere with CT imaging in the same way they may with MRI due to the metallic content in some tattoo inks.