Anti-arrhythmics Flashcards
What is the cardiac pacemaker
SA node
what is the cardiac gatekeeper
AV node
how do anti-arrhythmic drugs work
affect specialized ion channels or affect sympathetic tone
Ia MOA
moderate block of both open Na and K channels
slow phase 0 depolarization
prolong action potential and slow conduction
Ia drugs
DQP: Disopyramide, Quinidine, Procainamide
Ia uses
ventricular tachy-arrhythmias
Paroxysmal recurrent afib
Wolff-Parkinson-White syndrome (Procainamide)
Ib MOA
mild blocking or inactivating sodium channels
shorten phase 3 repolarization
decrease duration of AP
Ib drugs
LPM: Lidocaine, Phenytoin, Mexiletine
Ib uses
ventricular tachycardias
Ic MOA
block open Na channels
markedly slow phase 0 depolarization
Ic drugs
FP: Flecainide
Propafenone (avoid in HF and MI)
Ic uses
paroxysmal a-fib
II MOA
block catecholamines
block AV node
decrease slope of phase 4 depolarization
prolong repolarization in AV node –> block reentry
II drugs
Propranolol
II uses
Tachyarrhythmia supraventricular
III MOA
blocking IKr
prolong phase 3 repolarization without altering phase 0
III drugs
Amiodarone Sotalol Ibutilide Dofetilide (initiated in hospital, mandates testing every 3 months to check K, Mg, SCR and EKG) Dronedarone
III uses
Wolff-Parkinson-White syndrome (Sotalol)
Ventricular arrhythimias
atrial tachyarrhythmias
IV MOA
block L-type calcium channels
decrease AV node conduction
increase refractory period
similar to class II but does not block adrenergic system
IV drugs
Non-dihydrophyridine
CCBs
Verapamil
Diltiazem
IV uses
prevent recurrence of paroxysmal supraventricular tachycardias
control ventricular rate in afib
rate classes control rate?
Class II, IV
digoxin
which classes control rhythm
Ia, c, III
what are non-pharmacologic choices?
ablation
pacing
DI’s of Quinidine
warfarin
digoxin
DI’s of Disopyramide
glaucoma
indications of Disopyramide
only paroxysmal supraventricular tachycardia
CI of Mexiletine
3rd degree AV block
indications of Mexiletine
ventricular arrhythmias
commonly as an add on to Amiodarone and not sole agent
BB DI’s
severe sinus bradycardia or heart block
Amiodarone, Dronedarone, Sotalol, Dofetilide CI’s
iodine hypersensitivity, hyperthyroidism, 3rd degree AV heart block
(Dronedarone lacks iodine and therefore thyroid side effects)
which class has the highest risk of proarrhythmias?
class I
which class has anticholinergic effects?
IA
Adenosine MOA
acts on adenosine receptors (GPCR) to decrease adenylyl cyclase to decrease cAMP
side effect of Adenosine
transient hypotension and chest pain (within 15 seconds)
Atropine MOA
competitieve inhibitor of muscarinic acetylcholine receptors
indication of Atropine
bradycardia
side effects of Atropine
blurry vision, dry mouth, tachycardia “dry as a bone, red as a beet, hot as a hare, blind as a bat, mad as a hatter”
antidote to Atropine
Physostigmine
Digoxin MOA
inhibit the Na/K ATPase in myocardium
decrease membrane sodium gradient
decrease sodium-calcium exchange
increase intracellular calcium
indications for Digoxin
Afib, atrial flutter with RVR, heart failure
which anti-arrhythmics cause constipation
Verapamil and diltiazem
