Question

When discussing class IB antiarrhythmics, which of the following would the nurse identify as an effect? Select all that apply.

A) Shortening of the action potential duration
B) Depression of cardiac conduction
C) Prolongation of the action potential
D) Slowing of repolarization
E) Increase in cardiac conduction

Answer 1

Class IB antiarrhythmic drugs lead to a shortening of the action potential duration and depression of cardiac conduction. Potassium channel blockers, like amiodarone and procainamide, are not class IB antiarrhythmics but affect the repolarization phase of the action potential by prolonging it.

Step-by-step explanation:

When discussing class IB antiarrhythmic drugs and their effects, the nurse would identify the following:

• A) Shortening of the action potential duration
• B) Depression of cardiac conduction
• C) Prolongation of the action potential (not typically associated with class IB antiarrhythmics)
• D) Slowing of repolarization (not typically associated with class IB antiarrhythmics)
• E) Increase in cardiac conduction (not typically associated with class IB antiarrhythmics)

Potassium channel blockers, such as amiodarone and procainamide, affect the phase 3 of the action potential, which is the repolarization phase. They impede the movement of K+ through voltage-gated K+ channels, which would lead to a prolongation of the repolarization phase and consequently an elongation of the action potential duration, not a shortening as seen with class IB antiarrhythmics. However, it's vital to distinguish that potassium channel blockers are not class IB antiarrhythmics but can affect similar areas of the action potential. Class IB antiarrhythmics notably shorten the action potential duration and depress cardiac conduction without significantly affecting the rate of repolarization.