Chapter 14

After beginning drug therapy to suppress ventricular tachycardia, a man reports cold intolerance and lethargy, and his thyroid-stimulating hormone level is found to be elevated. Which drug is most likely responsible for this adverse reaction? (A) procainamide (B) dronedarone (C) dofetilide (D) verapamil (E) amiodarone

A woman is placed on an antidysrhythmic drug that dissociates very slowly from ventricular sodium channels. Which electrocardiographic finding results from this property? (A) prolonged \(\mathrm{PR}\) interval (B) shortened PR interval (C) prolonged QRS duration (D) prolonged \(Q T\) interval (E) sinus bradycardia

A man is administered a drug that selectively blocks the rapidly activating delayed rectifier channels. Which electrocardiographic change should guide dosage adjustments with this drug? (A) QT prolongation (B) QRS widening (C) PR prolongation (D) \(T\) wave inversion (E) heart rate

A woman with supraventricular tachycardia is given an intravenous bolus of adenosine. What is the mechanism by which this drug acts to terminate the dysrhythmia? (A) increased chloride influx (B) increased cyclic guanosine monophosphate (C) increased calcium influx (D) increased potassium efflux (E) decreased sodium influx

Which drug should be avoided in persons with asthma? (A) sotalol (B) diltiazem (C) flecainide (D) quinidine (E) lidocaine