Anti-arrhythmics Flashcards
Class IA
Intermediate
[T]>1 second
Prolongs AP duration due to K+ channel blocking properties
Use: ventricular and atrial arrhythmia
Class IB
less than 1 second rapid dissociation effective anti-tachycardia drug short AP duration Use: ventricular arrhythmias
Class IC
[T]>10 seconds
Dissociation very slow
Pronounced slowing of depolarization
A. Fib, SVT
carotid massage
vagal activation
atropine
vagal blocker
dofetilide
K channel blocker
use: a. fib (interrupts reentry)
ibutilide
IV
K channel blocker
use: a. fib or flutter
mexilitine
oral
Class IB: Na channel blocker
SE: GI distress
procainamide
IV
Class 1A: Na channel blocker
use: Atrial and ventricular arrhythmias, Short term-treatment (e.g., post-op atrial fib), WPW
SE: drug induced lupus (more likely in slow acetylators), torsades
Class I: Na channel blockers
Bind during open and inactivated states, Phase 0 depolarization is slowed (slowed conduction velocity and suppression of ectopic pacemakers in atrial and ventricular myocytes), Slowed conduction though re-entrant circuits, Reduced availability of Na+ channels (increases membrane voltage required for a new depolarization): Inceased Effective Refractory Period (ERP).
Vary based on rate of dissociation [T] from Na channel
Class II: beta blockers
MOA: Electrophysiologic effects: reduces enhanced automaticity related to catecholamines and ischemia, Slows AV node conduction by blocking pos influence of catecholamines (blocks exercise- induced increase in vent rate in atrial fib)
Use: Reduces atrial and ventricular arrhythmias in patients with CHD (improves survival).
PVCs in pts w/ and w/o structrual heart disease
SVT, rate control a. Fib and flutter
Class III: K channel blockers
MOA: Suppress ectopic pacemakers, Interrupt re-entry, Extended AP b/c phase 2 and 3 repolarization delayed: Increases ERP (making it harder for ectopic pacemakers to fire and for re-entry to be sustained)
SE: QT interval prolonged: early after depolarization and torsades
Use: a. Fib and flutter
Ventricular tachycardia for amid arose and sotalol
Class IV: Ca channel blockers (Non-dihydropyridines)
MOA: Reduce SA node automaticity, Reduce AV node conduction, Little effect on electrophsiology of fast conduction tissues (atrium and ventricle) under normal conditions.
SE: SA block, AV block, Impaired myocardial contractility, Hypotension
CI (due to prolonged PR): CHF, sinus bradycardia, AV block
Use: rate control in a. Fib, prevent nodal arrhythmias (SVT)
adenosine
IV: T1/2 10s
MOA: Blocks AV node to terminate acute PSVT
Diagnostic for PSVT: Reverts: confirms diagnosis, If not: other cause of atrial flutter
AE: chest tightness, transient asystole, reoccurrence of PVST
digoxin
vagal activation
MOA: Antiarrythmic effects mediated via increased vagal nerve activity, Na/K ATPase inhibition with calcium overload, Reduces SA node automaticity, Reduces AV conduction, Controls ventricular rate in supraventricular arrhythmias., Interrupts reentry in AV node,
Increased normal automaticity, Delayed afterdepolarizations
use: APB, VPB, paroxysmal atrial tachycardia with block, ventricular tachycardia