Which of the following most likely caused this patient’s symptoms? A 72-year-old man who receives treatment forcongestive heart failure (CHF) presents to theemergency department with vomiting, abdominalpain, and changes in his color vision. He is confused and does not remember the names ofhis medications. His heart rate is 36/min.

Recent increase in his furosemide dosage

The correct answer is D. This patient presents with symptoms of digoxin toxicity. Severe bradycardia in a patient with complete heart block is a sign of severe digoxin toxicity. Digoxin toxicity is fairly common given the narrow therapeutic range of this medication, which is commonly prescribed for CHF. An increase in furosemide would result in increased potassium secretion in the nephron, which could cause hypokalemia, a state that potentiates the effects of digoxin and results in bradycardia Answer A is incorrect. A decrease in digoxin dosage would not cause an overdose of digoxin and would not cause any changes in the patients ECG Answer B is incorrect. Verapamil, a calcium channel blocker, does not directly affect digoxin levels. However, increased levels of a calcium channel blocker will impair renal clearance in general and digoxin clearance specifically, thus resulting in digoxin toxicity. A reduced dosage of verapamil would not affect digoxin nor directly change the patients ECG Answer C is incorrect. Enalapril, an angiotensin- converting enzyme inhibitor, has no direct or indirect effect on digoxin levels and would not produce any changes in the patients ECG.