A 44-year-old man complains of shortness of breath and palpitations after exertion. He has a systolic murmur at the left sternal border and cardiac apex that becomes louder when he stands up. He is diagnosed with obstructive hypertrophic cardiomyopathy and paroxysmal atrial fibrillation and begins treatment. The image below depicts changes in the action potential of ventricular muscle cells before and after medication administration. Black curve = Before administration of medication Red curve = After administration of medicationThe patient is most likely being treated with which of the following medications?

Question

A 44-year-old man complains of shortness of breath and palpitations after exertion. He has a systolic murmur at the left sternal border and cardiac apex that becomes louder when he stands up. He is diagnosed with obstructive hypertrophic cardiomyopathy and paroxysmal atrial fibrillation and begins treatment. The image below depicts changes in the action potential of ventricular muscle cells before and after medication administration.  Black curve = Before administration of medication Red curve = After administration of medicationThe patient is most likely being treated with which of the following medications?

Quizplus · Accepted Answer

Eductional Objective: The class IA antiarrhythmics (quinidine, procainamide, and disopyramide) are sodium channel-blocking agents that depress phase 0 depolarization.  They also prolong repolarization due to moderate potassium channel- blocking activity, increasing action potential duration in cardiac myocytes.

A 44-Year-Old Man Complains of Shortness of Breath and Palpitations