75 y/o M with a past medical history of atrial fibrillation presents to the ED not feeling well for several days. He has some diarrhea but has continued to take his medications. He is mildly hypotensive. While IV access is established, you are shown his ECG….

Whats the problem with this ECG?

—The patient has a regular rhythm! But how would a patient with afib have a regular rhythm?

He is in complete heart block. The patient neglects to tell you he is on digoxin. While the atrial rhythm is fibrillation, the ventricular rhythm is a junctional escape rhythm. Dig is an av nodal blocking agent and given the patients dig toxicity, there is a lack of conduction through the AV node and the patients regular junctional escape rhythm has taken over.

The patient recovered with IV hydration and normalization of his digoxin levels.

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