22 - Antiarrhythmics Flashcards
in the SA node, (ion) is important for depolarization. in the ventricular muscle cells, (ion) is important for depolarization
SA node - Ca
ventricle - Na
classes of antiarrhythmics w/ mechanism
1 - Na channel blockers
2 - beta blockers
3 - K channel blockers
4 - Ca channel blockers
subclasses of class 1 antiarrhythmics
1a - increases refractory period, intermediate rate of binding
1b - rapid binding, decreases refractory pd
1c - slow binding, unchanged refractory pd
examples of class 1 antiarrhythmics
1a - quinidine
1b - lidocarine
1c - flecainide
class 1 antiarrhythmic side effects
quinidine - cinchonism, SA/AV block or asystole, Vfib, anticholinergic, anti alpha cholinergic, inc digoxin levels
lidocaine - CNS effects include drowsiness, slurred speech, confusion, convulsions (think about anesthetics)
flecainide - c/i in pts w/ CAD/CHF b/c proarrhythmic side effects
how do beta blockers work as an antiarrhythmic
dec slop of phase 4 depolarization
prolongs repolarization, prolongs refractory pd
ex of class 3 antiarrhythmics
amiodarone (mostly class 3, but also 1, 2 and 4) sotalol (class 2 and 3) ibutylide dofetilide
how do class 3 antiarrhythmics work
by blocking K channel, prolong refractory pd
ex of class 4 antiarrhythmics
verapamil
diltiazem
-dipines are selective for vascular smooth muscle
how do ca channel blockers prevent arrhythmias?
slow action potential upstroke in SA and AV nodes
SEs of amiodarone
pulm fibrosis
hypo/hyperthyroidism
ocular and liver tox
must monitor lung, liver, thyroid function
which antiarrhythmic for which type of arrhythmia?
Supraventricular?
VT, Vfib?
prevent SCD?
supraventricular - Class 2, 4
VT/VF - amiodarone
SCD - amiodarone, class 2
when is adenosine useful as antiarrhythmic?
conversion of paroxysmal SVT to normal sinus rhythm
66 yo w/ MI. Which is appropriate prophylactic antiarrhythmic therapy? lidocaine metoprolol flecainide quinidine verapamil
metoprolol
which antiarrhythmic causes thyroid dysfunction?
amiodarone
