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
verapamil
non-dihydropyridine Ca channel blocker
diltiazem
non-dihydropyridine Ca channel blocker
amidarone
oral or IV
long T1/2: highly lipophilic
MOA: K channel blockade, Na(IA), Ca channel blockade, B-adrenergic blockade
Interacts w/ nuclear thyroid hormone receptors
use: Atiral, ventricular arrhythmias, IV for acute life-threatening arrhythmias (Ventricular tachycardia, ventricular fibrillation) has replaced lidocaine as drug of choice in cardiac resuscitation
CI: CYP3A4 inhibitor
AE: pulmonary fibrosis, gray-blue skin, corneal micro deposits (halos), hyper/hypothyroidism, muscle weakness, hepatitis
dronedarone
Non-iodinated congener of amidarone
use: Paroxysmal atrial fib, Maintenance of sinus rhythm following cardioversion
CI: decompensated CHF
sotalol
Non-selective B-blocker, K+ channel blocker
use: Atrial, ventricular, AV nodal
re-entrant arrhythmias
(including ventricular tachycardia)
CI: long QT interval, renal insufficiency. Asthma or COPD, Decompensated CHF, AV block, bradycardia
propranolol
Beta blocker
use: Suppress VPBs related to sympathetic activity
metoprolol
Beta blocker
use: Slow heart rate in supraventricular arrhthmias by blocking AV node
acebutolol
Beta blocker
use: Suppress ventricular premature beats related to sympathetic activity
esmolol
IV: ultra short duration
Beta blocker
use: Slows AV node cunduction for acute treatment of supraventricular arrhythmias
atenolol
Beta blocker
use: Rate control in atrial flutter and atrial fibrillation, Prevent recurrence of PSVT
flecanide
Class IC: Na channel blocker: Suppress automaticity, Increases effective refractive period in atria, ventricles.
CI: Structural heart disease, Increased mortality post-MI, LV dysfunction, CHD, sustained VT (proarrhythmic effect)
propafenone
Class IC: Na channel blocker and Beta blocking properties
use: a. fib/flutter w/out structural heart disease
lidocaine
IV (oral has 1st pass)
Class IB: Na channel blocker: Preferentially binds to Na+ channels in partially depolarized cells to suppress abnormal automaticity
Use: Acute ventricular tachycardia, Ventricular arrythmias
NOT effective for atrial arrythmia
AE: CNS
quinidine
Class 1A: Na channel blocker
use: Atrial and ventricular arrythmias
SE: QT prolongation, TDP, Ventricular tachycardia/fibrillation, syncope, Diarrhea, Autoimmune thrombocytopenia
disopyradine
Class 1A: Na channel blocker
SE: Vagolytic (Urinary retention, Dry mouth, Blurred vision), precipitates heart failure.
Class 1B
less than 1 second
rapid dissociation
effective anti-tachycardia drug
short AP
