Antiarrhythmia Flashcards
What class of antiarrhythmic drugs that work on fast response fibers of the heart (heart muscle)? and what kind of arrhythmia does is treat?
Class I and III—>ventricular arrhythmia (fast response fibers)
What class of antiarrhythmic drugs that work on phase 0 and 4 of slow response fibers of SA and AV node?
Class II (beta blockers) and IV (Na channel blockers)
What class of antiarrhythmic drugs are used for SVT?
Class II and IV
What are all the antiarrhythmic drugs’ affects on EEG?
Class I and III—>prolonged QT (ventricular contraction)
Class II and IV—>prolonged PR (atrial contraction)
What are the symp and parasymp’s affect on slow response fiber?
Symp—>increase the slope of phase 0 and 4
Paraymp—>decrease the slope of phase 0 and 4
Vagal stimulation is useful for ventricular or supraventricular tachy?
SVT
Why is SA node the pacemaker of the heart?
Is has the fastest phase 4 (repolarization)
What else does K channel blocker prolong besides repolarization?
Effective refractory period (ERP) and action potential duration (APD)
How does the sodium channel change from the beginning to late phase 3? what is the resting state of sodium channel?
Beginning of phase 0—>M and h gate open (active state)
Late phase 0 to phase 3—>h gate closes (inactive state)
Then back to resting state—>M gate closes and h gate open
What state of the sodium channel does class I antiarrhythmic drug target?
Active and inactive state—>mainly inactive state
What are the characteristics of class Ia Ib and Ic drugs?
Ia–>block both Na and K channels—>prolonged QT—>torsades
Ib—>block Na channel in ischemic tissues of the heart/shorten APD
Ic—>proarrhythmia/use for SVT like a fib
Why don’t we use quinidine much anymore? and what enhance the toxicity of it?
It also blocks muscarinic receptor at heart—>increase HR
It blocks alpha 1—>vasodilate—>reflex tachy
Cinchonism—>GI upset and tinnitus
Hyperkalemia
What are the class Ia Ib and Ic drugs? Double quarter pounder/lettuce tomato mayo/more fries please
Ia—>disopyramide/quinidine/procainamide
Ib—>lidocaine/mexiletine
Ic—>moricizine/flecainide/propafenone
What causes torsades?
Drugs that block K channel—>prolonged QT
What are lidocaine and mexiletine used for?
Ventricular arrhythmia or tachy (post MI)
Digoxin induced ventricular arrhythmia
Mexiletine—>oral lidocaine
Which beta blocker is used IV for acute SVT?
Esmolol
What is the antiarrhythmic drug that treats all arrhythmia? and what are its side effects?
Amiodarone (contain iodine)
Pul fibrosis/blue skin/hypo or hyperthyroidism/hepatic necrosis
What else does sotalol block besides K channel?
Beta blocker
What is torsades de pointes? what class cause it? and what is the drug that most likely cause torsades? and how do we treat it?
QT prolongation—>ventricular tachy
Class I and III
Sotalol
Give Mg
What drugs should Long QT syndrome pt avoid?
Class I and III
What are the class III and IV drugs?
Class III—>amiodarone/sotalol/dofetilide/ibutilide
Class IV—>verapamil/diltiazam
What are the side effect of class IV and what drug interaction are there?
Verapamil—>constipation
AV block—>worsen with beta blocker or digoxin
Verapamil and quinidine displace digoxin
What is adenosine used for?
Work on adenosine receptor
SVT (DOC for PSVT)
Short half life—>not for chronic
What else can be used to treat PSVT besides adenosine?
Class II and IV (for SVT)
Carotid sinus massage/valsalva—>stimulate vagal
What other drugs can cause torsades?
Thioridazine/TCA
SUMMARY
Drugs that treat SVT and VT?
SVT:
class II and IV/adenosine/digoxin
VT:
class I and III
How to treat a fib?
Class II and IV for rate control + anticoagulant
Flecainide for rhythm control
