Antiarrhythmic Drugs

Question 1

Different Channel Expression

Answer 1

Different regions have different expression, so drugs affect them differently

Question 2

Class I Drugs General Action

Answer 2

Block Na channels

Question 3

Class II Drugs

Answer 3

Beta blockers, mainly act on phase IV

Question 4

Class III Drugs

Answer 4

Block K channels: prolong AP and refractory period (suppress re-entry) (prolong QT interval)

Question 5

Class IV Drugs

Answer 5

Ca channel antagonists - impair impulse propagation in nodal and damaged areas

Question 6

Subclass IA Drugs (potency, graphical action, 3 examples)

Answer 6

High/intermediate potency prolong depol and repol (prolong QT interval): quinidine, procainamide, disopyramide

Question 7

Subclass IB (potency, graph action, 2 examples)

Answer 7

Lowest potency, shorten repol and thus QT interval. Lidocaine and mexiletine

Question 8

Subclass IC (potency, graph action, 2 examples)

Answer 8

Most potent so prolong depol/QRS no effect on repol/QT. Fecainide, propafenone

Question 9

Use of 1A (3 points)

Answer 9

AF or VT, NOT SVT. Can’t use w/ CHF. Quinidine dangerous so use rarely, cautionary w/ CAD

Question 10

Use of 1B (2)

Answer 10

VT, can use w/ CAD or CHF

Question 11

Use of 1C (2)

Answer 11

AF or SVT, but not with CAD or CHF. Cause sudden death w/ ischemia so use in populations not at risk for that

Question 12

Use of Disopyramide

Answer 12

Occasionally pts w/ vagal Afib

Question 13

Use of Lidocaine

Answer 13

Acute IV use in VT/VF

Question 14

Class III Graph Effect and Important Monitoring

Answer 14

Slightly prolong depol and repol - monitor bc don’t want QT too long

Question 15

4 Class 3 Drugs

Answer 15

Amiodarone
Sotalol (? - or class II?)
Dofetilide
Dronedarone

Question 16

Amiodarone

Answer 16

Multichannel blocker, all 4 classes that can be used for pretty much any life threatening arrhythmia, even w/ CHF and CAD. But has crazy half life and horrible side effects

Question 17

Sotalol

Answer 17

Good for arrhythmias, but can’t use in CHF bc BB

Question 18

Torsades

Answer 18

Polymorphic proarrhythmia associated w/ drugs that prolong QT (IA, III)

Question 19

2 Drug Choice for Premature Atrial/Nodal/Vent Depol

Answer 19

None, maybe BB is symptomatic

Question 20

4 Drug Choice for Afib/flutter/PSVT

Answer 20

AV nodal blockers to control vent response: Adenosine, class II, IV, digoxin (except for WPW)

Question 21

3 Drug Choice for VT

Answer 21

Amiodarone, III, I

Question 22

4 Drug Choice for VF

Answer 22

Amiodarone, Lidocaine, III, I

Question 23

2 Acute Drug Choice for Tosades

Answer 23

Mg, Isoproterenol

Question 24

CYP3A4

Answer 24

Necessary to clear Class IV (Ca channel blockers like verapamil), inhibited by grapefruit juice

Question 25

Digoxin ANS Mech

Answer 25

Increases vagal tone, inhibiting AV nodal conduction

Question 26

Adenosine

Answer 26

Acutely treats paroxysmal supraventricular tachycardia