DC Pharmacology & Drug Administration 2

Question 1

A patient in atrial fibrillation is started on digoxin. Which electrolyte imbalance most increases the risk of digoxin toxicity?

Accepted Answer

Hypokalemia

Answer

Hypokalemia potentiates digoxin toxicity by increasing binding of digoxin to cardiac Na+/K+-ATPase.

Question 2

Which of the following best describes the mechanism of adenosine when used to treat supraventricular tachycardia (SVT)?

Accepted Answer

Transiently blocks AV node conduction via A1 receptor activation

Answer

Adenosine activates cardiac A1 receptors, transiently hyperpolarizing AV nodal cells and interrupting reentrant SVT circuits.

Question 3

A patient receiving IV amiodarone develops hypotension. The MOST likely cause is:

Accepted Answer

Vasodilation from the polysorbate 80 vehicle

Answer

IV amiodarone formulations contain polysorbate 80 and benzyl alcohol, which cause vasodilation and hypotension during rapid infusion.

Question 4

Procainamide is preferred over lidocaine for treatment of which rhythm in the setting of WPW syndrome?

Accepted Answer

Atrial fibrillation with rapid ventricular response via accessory pathway

Answer

Procainamide slows conduction in the accessory pathway, making it preferred over AV nodal blockers (which can accelerate conduction through the bypass tract) in WPW with AF.

Question 5

Which antiarrhythmic drug is contraindicated in patients with structural heart disease due to its proarrhythmic risk demonstrated in the CAST trial?

Accepted Answer

Flecainide

Answer

The CAST trial showed that flecainide (a Class IC drug) increased mortality in patients with structural heart disease by suppressing ventricular ectopy but increasing the risk of fatal arrhythmias.

(DC) Dysrhythmia Certification Practice Test

(DC) Dysrhythmia Certification Practice Test

DC Pharmacology & Drug Administration 2