6 Anti-arrhythmics

Question 1

Procainamide

Class, MoA, Phase

Answer 1

Procainamide
Class 1A
Na+ channel blocker
Slows Phase 0 depolarisation

Phase 0: influx of Na+

Question 2

Lidocaine

Class, MoA, Phase

Answer 2

Lidocaine
Class 1B
Na+ channel blocker
Slows Phase 0 depolarisation, shortens Phase 3 repolarisation and APD

Phase 0: influx of Na+, Phase 3: slower K+ going out

Question 3

Flecainide

Class, MoA, Phase

Answer 3

Flecainide
Class 1C
Na+ channel blocker
Slows Phase 0 depolarisation

Phase 0: influx of Na+

clinical uses: refractory ventricular tachycardias that tend to progress to VFib

Question 4

Metoprolol, Propanolol

Class, MoA, Phase

Answer 4

Metoprolol, Propanolol
Class 2
beta blockers
Suppresses Phase 4 depolarisation

Phase 4: automaticity

clincial uses: supraventricular tachycardia
AFib

Question 5

Amiodarone

Class, MoA, Phase

Answer 5

Amiodarone
Class 3
K+ channel blocker
Prolongs Phase 3 repolarisation

Phase 3: slower K+ going out

Clinical uses: maintain normal sinus rhythm in patients with AFib
prevent ventricular tachycardia

adverse effect: bradycardia, heart block

Question 6

Verapamil, Diltiazem

Class, MoA, Phase

Answer 6

Verapamil, Diltiazem
Class 4
Non-DHP Ca2+ channel blockers
Prolongs Phase 4 depolarisation and action potential

Phase 4: automaticity

Uses: supraventricular tachycardia
HTN
Angina

Contraindication: HF, hypotension

Question 7

Adenosine

half-life, indication

Answer 7

Adenosine
half-life <10 seconds
use for supraventricular tachycardia emergency