A 76-year-old woman is brought to the emergency department by her son due to lethargy and confusion over the past 2 days. The patient has persistent atrial fibrillation and congestive heart failure and is on multiple medications. Recently, she has had nausea and decreased appetite. Today, she had 3 episodes of vomiting. The patient also reports vision difficulties. Temperature is 36.7 C (98 F) and blood pressure is 133/80 mm Hg. Laboratory results are as follows: ECG shows junctional escape rhythm at a rate of 48/min with occasional ventricular premature beats. Increased blood level of which of the following medications is most likely responsible for her symptoms?

Question

A 76-year-old woman is brought to the emergency department by her son due to lethargy and confusion over the past 2 days.  The patient has persistent atrial fibrillation and congestive heart failure and is on multiple medications.  Recently, she has had nausea and decreased appetite.  Today, she had 3 episodes of vomiting.  The patient also reports vision difficulties.  Temperature is 36.7 C (98 F) and blood pressure is 133/80 mm Hg.  Laboratory results are as follows:  ECG shows junctional escape rhythm at a rate of 48/min with occasional ventricular premature beats.  Increased blood level of which of the following medications is most likely responsible for her symptoms?

Quizplus · Accepted Answer

11ec160b_3b85_36c3_9249_8960dbb8db0a_MD0001_00 This patient with atrial fibrillation and congestive heart failure has signs and symptoms of digoxin toxicity. Although calcium channel blockers and beta blockers are the preferred treatments for patients with atrial fibrillation with rapid ventricular response, digoxin is a common second-line treatment that is particularly useful in patients with underlying systolic cardiac dysfunction. Its major effects are: Digoxin has a narrow therapeutic index, making toxicity relatively common. Symptoms of digoxin intoxication are fairly nonspecific and include nausea, abdominal pain, fatigue, dizziness, confusion, blurred vision, and abnormal color perception. Digoxin toxicity can cause a wide range of cardiac arrhythmias, including bradycardia and junctional escape beats due to increased AV nodal block. Hypokalemia can precipitate toxicity by increasing digoxin binding to Na-K-ATPase. However, elevated potassium is a sign of digoxin toxicity as inhibition of Na-K-ATPase pumps increases extracellular potassium. (Choice A) Amiodarone can cause pulmonary toxicity, thyroid dysfunction, cardiac arrhythmias, elevated liver enzymes, and visual disturbances. However, it does not cause hyperkalemia. (Choice B) Acute aspirin overdose presents with vertigo, tinnitus, vomiting, and diarrhea, whereas severe intoxication can lead to coma, hyperpyrexia, pulmonary edema, and death. (Choices D and F) Beta blocker and/or calcium channel blocker overdose usually cause profound bradycardia and hypotension (absent in this patient). In addition, nausea and vomiting are more common in digoxin overdose than in beta blocker overdose, which typically causes bronchospasm and hypoglycemia. (Choice E) Furosemide overdose causes volume depletion, along with electrolyte abnormalities such as hypokalemia and hypomagnesemia. (Choice G) Excess spironolactone can cause hyperkalemia, gynecomastia, impotence, and decreased libido. (Choice H) Valsartan is an angiotensin II receptor blocker. Overdose usually causes hypotension, renal failure, and hyperkalemia. Educational objective: Digoxin toxicity typically presents with cardiac arrhythmias and nonspecific gastrointestinal (nausea, vomiting), neurological (confusion, weakness), and visual symptoms. Elevated potassium is another sign of digoxin toxicity and is caused by inhibition of Na-K-ATPase pumps. __________ References: Mechanisms, manifestations, and management of digoxin toxicity in the modern era. (http://www.ncbi.nlm.nih.gov/pubmed/16555861)

A 76-Year-Old Woman Is Brought to the Emergency Department by Her