Anti-arrhythmics Flashcards
Rapid depolarization due to influx of Na ions.
Action potential -> cell depolarizes and contraction begins
Phase 0
Early rapid depol due to K+ moving out of the cell
Contraction is in process
Phase 1
Plateau phase mainly due to inward mvmt of Ca+ into muscle cell
Phase 2
Repolarizaion, as K+ moves out of cell
Phase 3
K+ flows out and Na+ seeps into cell (return to resting level)
Phase 4
Sympathetic stimulation increases the rate of pahse 4 depol, increasing HR
Interval during which a 2nd action potential cannot be initiated, no matter size
Absolute refarctory period
Interval following the relatiev refractory period when a second action potential is inhibited, but not impossivle
Relative refractory period
Electrical impulses travel through AV node slowly, but reach ventricles
Results in PR prolongation
1st degree heart block
Impulses travel slowly and occasionally get blocked, causing ventricles to beat out of sequence
2nd degree heart block
Atrial impulses do not reach ventricles so ventricles create their own impulse, cause them to beat out of sequence
Life threatening
3rd degree heart block
Torsades de Pointes typically occurs at QT interval > 500 ms.
What are some causes of TDP?
Hypokalemia
Hypomagnesemia
Drugs (see next slide/card)
Anti-arrhythmics that cause TDP?
Sotalol
Amiodarone
Quinidine
Abx that cause TDP?
Macrolides (Azithromycin!, Clarithromycin, Erythromycin)
Fluoroquinolones (Moxifloxacin)
Anti-nausea drugs that cause TDP?
Odansetron
Granisetron
Antidepressants that cause TDP?
Citalopram
Fluoxetine
Amitriptyline
Antipschotics that casue TDP?
Typical anti-psychotics (Haloperidol, chiefly)
Can sumatriptan cause TDP?
Yes
Supraventricular arrhythmias?
AFib (Fast/irregular, HF, Ischemic stroke)
Aflutter (Fast/regular, reentrant rhythm)
Paroxysmal SVTs can occur due to?
digitalis toxicity, caffeine intake, anxiety, alcohol, WP
V Tach?
More than 3 straight beats at a rate > 120
Lengthen refractory period
Decrease automaticity
Decrease conduction velocity
Class 1A (Na channel blocker)
Procainamide
Disopyramide
Quinidine
Weak Na channel blocker
Shorten phase 3 repolarization
Possess local anesthetic acitivity
Class 1B (Fast Na channel blocker)
Lidocaine
Mexiletine
Slow conduction velocity with little effect on refractory period
Useful in supraventricular and ventricular arrhythmias (caution w/ ventriculars, however?)
class 1C (potent Na channel blocker)
Flecainide
Propafenone
Block catecholamines
Lengthen refractory period
Decrease automaticity
Class 2 (beta b’s)
Prolongs phase 3
K channel blcoker
Class 3
Inhibits SA/AV node, prolonging refarctory period
SLows conduction
Decrease automaticity
Class 4 (CCBs)
Increase QRS and QT
Used for Atrial/Ventricular arrhythmias
class 1A
Procainamide
Disopyramide
Quinidine
Decrease QT interval
Used for ventricular arrhythmias
Class 1B
Lidocaine
Mexiletine
Increase QRS
USed for Atrial and ventricular arrhythmias
Class 1C
Flecainide
Propafenone
Decrease HR and increase PR
Used for Tachyarrhythmias caused by sympathetic activity and Supraventricular/ventricular arrhythmias
Class 2 (beta b’s)
Metoprolol
Atenolol
Propranolol
Esmolol
Increase QT interval
Used for Atrial and ventricular arrhythmias
(note that these DO NOT increase QRS like the class 1As… otherwise very similar)
Class 3 (K-channel blocker)
Amiodarone Sotalol (beta-ish) Ibutilide Difetilide Dronedarone