A patient's heart monitor shows HR 78 with progressive lengthening of the PR interval over time. What is the most appropriate action for the nurse to take next?

Rationale: A. Progressive lengthening of the PR interval indicates a first-degree or potentially worsening second-degree AV block. Notifying the provider is essential to prevent further conduction deterioration and potential progression to complete heart block, which can be life-threatening. B. Increasing activity could exacerbate bradycardia or AV block symptoms (e.g., dizziness, syncope) and is unsafe in this context. C. Beta-blockers like metoprolol can further slow AV conduction, potentially worsening the block, so giving it without provider consultation is unsafe. D. Atropine is indicated for symptomatic bradycardia, but this patient currently has a normal HR (78) and is asymptomatic. Immediate administration is not warranted; the priority is assessment and provider notification.