A nurse is reviewing a journal article about class IA antiarrhythmics. The article describes a drug that decreases depolarization and prolongs the refractory period. The nurse is most likely reading an article about which drug?
A) Quinidine
B) Lidocaine
C) Disopyramide
D) Flecainide
Ans: C
Feedback:
Disopyramide (Norpace) decreases depolarization of myocardial fibers, prolongs the refractory period, and increases the action potential duration of cardiac cells. Lidocaine (Xylocaine) decreases diastolic depolarization, decreases automaticity of ventricular cells, and raises the threshold of the ventricular myocardium. Quinidine depresses myocardial excitability or the ability of the myocardium to respond to an electrical stimulus. Flecainide (Tambocor) depresses fast sodium channels, decreases the height and rate of rise of action potentials, and slows conduction of all areas of the heart.
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