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Emergency Medicine Resident
University of Chicago
AAEM/RSA Publication Committee Member
The Case:
A 68-year-old male with a history of heart failure presents with weakness, confusion, and visual disturbances including yellow/green halos and scotomas. Digoxin is on the list of current medications. Vitals are notable for bradycardia with a HR of 55. The patient is awake but confused.
The Clinical Decision-Making:
While your differential diagnosis may include calcium channel toxicity, beta blocker toxicity, sick sinus syndrome, clonidine toxicity, organophosphate poisoning, and other potential diagnoses, digoxin toxicity should be at the top of the list.
You quickly recall how digoxin works: it inhibits the Na/K ATPase, causing intracellular sodium levels to rise. Sodium is then exchanged for calcium via a Na/Ca transporter. The intracellular calcium concentration is thus increased, thereby increasing contractility. Furthermore, digoxin also may increase vagal tone and can lead to bradyarrhythmias.
