A nurse is caring for a client who has pericarditis and reports feeling a new onset of palpitations and shortness of breath. Which of the following assessments should indicate to the nurse that the client may have developed atrial fibrillation?

Rationale: A. Differences in blood pressure between arms can indicate vascular issues such as aortic dissection or coarctation of the aorta, but they do not indicate a cardiac rhythm disturbance like atrial fibrillation. B. Variations in lung sounds suggest pulmonary conditions such as consolidation, atelectasis, or pleural effusion, not arrhythmias. C. These minor temperature discrepancies reflect measurement technique or peripheral circulation differences and are not associated with cardiac rhythm problems. D. A pulse deficit occurs when the apical heart rate (measured at the apex of the heart) is faster than the radial pulse rate (felt at the wrist). This happens in atrial fibrillation because some atrial contractions are ineffective and fail to generate a palpable peripheral pulse. Detecting a pulse deficit is a reliable clinical sign of AF and helps quantify the severity of the irregular ventricular response.