A 60-year-old woman with hypertension, diabetes mellitus, and intermittent
atrial fibrillation presents with nausea, diaphoresis, dizziness, and global
weakness that has lasted 1 hour. She denies chest pain, dyspnea, syncope,
vomiting, diarrhea, blood loss, and headache; there is no vertigo. Medications
include acetaminophen, digoxin, diltiazem, glipizide, hydrochlorothiazide,
irbesartan, metformin, pioglitazone, and warfarin.