Final answer:
The nurse should reassess the pulse for 1 full minute upon detecting an irregular radial pulse to confirm the irregularity and observe any patterns.
Step-by-step explanation:
When a patient's radial pulse has an irregular rhythm, the nurse's priority action would be to reassess the pulse for 1 full minute. This allows the nurse to confirm the irregularity and note any pattern to the irregularity, which may provide important diagnostic information. Assessing for a pulse deficit or reviewing documentation might follow based on the findings from the reassessment. Waiting without immediate reassessment is generally not advised, as timely evaluation is critical to determining the cause of the irregular rhythm and responding appropriately.