IBHRE Pharmacology and Drug Therapy

Question 1

Which class of antiarrhythmic drug works by blocking fast sodium channels?

Accepted Answer

Class I

Answer

Class I antiarrhythmic drugs block fast sodium channels, slowing phase 0 depolarization and conduction velocity.

Question 2

Amiodarone is primarily classified under which Vaughan Williams class?

Accepted Answer

Class III

Answer

Amiodarone is primarily a Class III antiarrhythmic that blocks potassium channels to prolong the action potential and refractory period.

Question 3

Which antiarrhythmic drug is contraindicated in structural heart disease due to increased mortality demonstrated in the CAST trial?

Accepted Answer

Flecainide

Answer

Flecainide (Class IC) is contraindicated in structural heart disease because the CAST trial showed it significantly increased mortality in post-MI patients.

Question 4

What is the primary mechanism by which adenosine terminates paroxysmal SVT?

Accepted Answer

Activates A1 receptors causing transient AV block

Answer

Adenosine activates A1 receptors on AV nodal cells, increasing potassium conductance and causing transient AV block that interrupts reentrant SVT.

Question 5

Ibutilide is primarily indicated for acute pharmacological conversion of which arrhythmia?

Accepted Answer

Atrial flutter and atrial fibrillation

Answer

Ibutilide is an IV Class III agent specifically approved for rapid pharmacological cardioversion of atrial flutter and atrial fibrillation.

IBHRE - International Board of Heart Rhythm Examiners Practice Test

IBHRE - International Board of Heart Rhythm Examiners Practice Test

IBHRE Pharmacology and Drug Therapy