<aside> ⚠️ Trap 3 (SVT Termination): Thinking that all rate control agents can terminate SVT. Reality: Adenosine's transient hyperpolarization is key for terminating AV nodal reentrant tachycardias (AVNRT/SVT).
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A 35-year-old male smoker presents with recurrent episodes of chest pain that are characteristically worse at night and often associated with elevated troponin levels, despite normal coronary angiography. He has a history of smoking and is being evaluated for Prinzmetal (variant) angina. The physician suspects vasospasm as the underlying cause. Which class of antianginal agents should be prioritized to treat this condition?
Answer: D. ** Prinzmetal angina is a vasospastic disease. The goal of treatment is to induce vasodilation. Non-dihydropyridine calcium channel blockers (e.g., Verapamil, Diltiazem) are effective vasodilators and are appropriate for rate control in associated arrhythmias. Triptans (serotonin receptor agonists) cause vasoconstriction and should be avoided. Non-selective beta-blockers can also cause vasoconstriction by blocking $\beta_2$ receptors, making them contraindicated. Dihydropyridine CCBs primarily target vascular smooth muscle but are less effective for rate control compared to the non-dihydropyridines.
A patient with chronic atrial fibrillation (AFib) and a history of severe heart failure is started on amiodarone for rhythm control. The physician notes that the patient has been taking several other medications, including an SSRI antidepressant. After two weeks, the patient develops generalized blue discoloration of the skin and reports mild nausea. What is the most likely cause of this clinical picture?
Answer: D. ** Amiodarone contains significant amounts of iodine. The blue discoloration (skin turning blue/blue tears) is a known, though uncommon, side effect due to the reaction between iodine and collagen in the skin. While amiodarone can cause thyroid dysfunction (Jod-Basedow phenomenon), the specific finding of generalized blue skin points directly to the iodine content itself.
A patient with chronic heart failure (CHF) is started on digoxin for symptom management. The nurse notes that the patient has been taking a thiazide diuretic, and the lab results show a serum potassium level of $5.8 \text{ mEq/L}$ and an elevated creatinine kinase. Which finding represents the most immediate risk associated with this medication regimen?