Anti-arrhythmias

Question 1

Classes of anti-arrhythmias

Answer 1

Class 1: Na Channel blockers
Class 2: B-blocker
Class 3: K+ channel blockers
Class 4: Ca channel blockers

Question 2

Na Channel blockers

Answer 2

1A: procainamide — slow phase 0 depol
1B: lidocaine — shorten phase 3 depol, APD
1C: flecainide —slows phase 0 depol

All 3 subtypes reduce automaticity

Question 3

SE of flecainide

Answer 3

Increased mortality

Question 4

MoA of b-blockers (Propranolol)

Answer 4

Diminish phase 4 depol –> decrease automaticity, HR, contractility –> prolongs AV conduction

Question 5

Benefit of B-blocker

Answer 5

Only class that reduces mortality after MI (D/t sudden arrhythmic death)

Question 6

MoA of K channel blocker (Amiodarone)

Answer 6

BLockage of Ikr, Iks –> prolongs phase 3 depol

Question 7

PK of K channel blocker

Answer 7

After discontinuation, effects maintains for 1-3months due to time taken for 2nd 50% of drug to be eliminated (weeks)

Question 8

SE of K channel blocker

Answer 8

Symptomatic bradycardia, heart block

Question 9

MoA of Ca Channel blocker (verapamil, diltiazem, nifidepine)

Answer 9

Slows phase 4 depol, slows conduction in tissues dependent on Ca currents such as AV node

Question 10

SE of CCB

Answer 10

Hypotension

Question 11

Contraindication of CCB

Answer 11

Px with pre-existing decreased cardiac function (CHF)