answers
In FAST response fibers - Electrolyte involved in phase 0 - CORRECT
ANSWERS ✔✔Na+ influx
In FAST response fibers - Electrolyte involved in phase 2 - CORRECT
ANSWERS ✔✔Ca+ influx, K+ outflux plateau
In FAST response fibers - Electrolyte involved in phase 3 - CORRECT
ANSWERS ✔✔K+ outflux (Ca+ drops off) rapid repolarization
In SLOW response fibers - Electrolyte involved in phase 0 -
CORRECT ANSWERS ✔✔Ca+(few Na+ channels in Nodal fibers)
In SLOW response fibers - Electrolyte involved in phase 3 -
CORRECT ANSWERS ✔✔K+ outflux repolarization
In SLOW response fibers - Electrolyte involved in phase 4 -
CORRECT ANSWERS ✔✔"Mainly Na+ (This is the pacemaker
current) aarapim. "
,Ectopic rhythm can result from - CORRECT ANSWERS
✔✔ischemia, electrolyte abnormalities, or heightened sympathetic
tone
If an early afterdepolarization is sustained - CORRECT ANSWERS
✔✔torades de pointes (QRS complexes of varying amplitudes)
ECG of a patient with an accessory pathway (bundle of Kent) -
CORRECT ANSWERS ✔✔"Wide QRS complexes, early ventricular
upstroke (also predisposed to re-entry loops) (Wolff Parkinson White
(WPW) syndrome) wolff-parkinson-white-accessory-bundle-bundle-
of-Kent "
MOA of quinidine - CORRECT ANSWERS ✔✔Blocks (open-
activated) Na+ channels: In SA Nodal tissue - Shift to a more positive
threshold and decrease the pacemaker slope (phase 4), In Ventricular
tissue - Decreases the phase 0 slope (depolarization) and block K+
channels prolongs repolarization (longer refractory period protected
from reentry currents): Anticholanergic (vagolytic effect faster
conduction through AV node)
Indications of quinidine - CORRECT ANSWERS ✔✔"atrial flutter or
fibrillation maintain normal sinus rhythm,Paroxysmal
supraventricular tachycardia, Premature atrial or ventricular
contractions, paroxysmal AV junctional rhythm 9"
,When taking this drug patients must be monitored for lupus (with
ANA) - CORRECT ANSWERS ✔✔Procainamide
Take with quinidine to prevent rapid ventricular response in patient
with atrial flutter - CORRECT ANSWERS ✔✔β-blocker or Ca2+
channel blocker
Which 1A antiarrhythmic for a patient on digoxin - CORRECT
ANSWERS ✔✔Procainamide (doesn't alter digoxin levels)
MOA of Lidocaine and Phenytoin - CORRECT ANSWERS ✔✔( 1B)
block of voltage-gated Na+ in ventricular myocytes (decrease phase 0
upstroke)
MOA of Encainide, Flecainide, Moricizine, Propafenone - CORRECT
ANSWERS ✔✔( 1C) block of voltage-gated Na+ channelsin
ventricular myocytes
MOA of Propranolol, Atenolol, Metoprolol... - CORRECT ANSWERS
✔✔( ) block β1-adrenergic receptors SLOW SA and AV nodal activity,
(decreases phase 4 slope)
, MOA of Ibutilide, Dofetilide, Sotalol, Amiodarone - CORRECT
ANSWERS ✔✔( I) Block K+ channels longer action potential
plateau and prolonged repolarization
MOA of Verapamil, Diltiazem - CORRECT ANSWERS ✔✔( IV)
Ca2+ channel blocker slows action potential upstroke in SA and AV
nodes
This 1A drug is associated with the development of Lupus,
hematotoxicity, but less likely to cause torsades - CORRECT
ANSWERS ✔✔procainamide
Antiarrhythmics of choice for post ischemic insults - CORRECT
ANSWERS ✔✔1B
Drug used for Supraventricular tachycardias, and post-MI
prophylaxis - CORRECT ANSWERS ✔✔antiarrhythmics (β-
blockers)
What does Quinidine do to AV node - CORRECT ANSWERS
✔✔increases conduction velocity (via anticholinergic effects)