Exam 7: Anti-arrhythmics Flashcards
Name 2 Class 1A Antiarrhythmics
Quinidine
Procainamide
Name one Class 1B Antiarrhythmic
Lidocaine
Name one Class 1C Antiarrhythmic
Flecainide
Name 3 Class II Antiarrhythmics
Propranolol
Acebutolol
Esmolol
Name 2 Class III Antiarrhythmics
Amiodarone
Dofetilide
Name 2 Class IV Antiarrhythmics
Verapamil
Diltiazem
Name an Antiarrhythmic used in treating SVT
Adenosine
What channels do Class I Antiarrhythmics generally affect?
Sodium
Quinidine and a Procainamide metabolite also block K channels
Main Mechanism of Class I Antiarrhythmics
Blockage of Na channels, especially during 0 phase (Depolarization) and phase 4 (pacemaker phase), lengthens action potentials, slowing conduction velocity and decreases their rate of spontaneous firing.
Main Mechanism of Class IA Antiarrhythmics
Na channel inhibition during 0 phase slows conduction velocity
Intermediate speed of interaction with 0 phase Na channels
K channel inhibition during phase 3 (repolarization) increases the length of refractory periods.
Main mechanism of Class 1B Antiarrhythmics
Less of a conduction slowing effect in phase 0 via Na channel inhibition
Rapidly interact with phase 0 Na channels
They inhibit Late Acting Na Channels, which decreases AP duration and refractory period (opposite of Class 1A)
Main Mechanism of Class 1C Antiarrhythmics
Marked inhibition of Na channels in phase 0 results in dramatic slowing of conduction velocity
Little to no affect on ERP (effective refractory period)
What is an affect that all Class I Antiarrhythmics share to varying degrees?
Increase the threshold of excitability
Quinidine Mechanism and Uses
Class IA Antiarrhythmic
Inhibits Na channels (slowing conduction rate) and K channels (Increasing length of ERP)
Recently increased use for V Fib in Brugada Syndrome and A Fib in Short QT syndrome
Quinidine Adverse Effects (3)
Can cause arrhythmias (Especially Torsades)
GI problems
Cinchonism (OD)- Kind of like Atropine poisoning (Increased HR, decreased BP,