Class I Antiarrhythmics

Question 1

what are the subdivisions of Class I Antiarrhythmics?

Answer 1

IA
IB
IC

Question 2

Name the Class I Antiarrhythmics and mention under which subdivision they fall

Answer 2

Class IA
Quinidine (“Dining prom queen”)
Procainamide (“Prom King”)
Dysopyramide (“Disapears!”)

Class IB
Lidocaine (“you lied ,your’e DEAD to me”)
Mexilitine (Mexican flag)
Phenytoin (“Friendly towing employee”)

Class IC
Flecainide (“blondy on 3rd floor eating cornFLAKES”)
Propafenone (“purple phone”)

Question 3

Class I Antiarrhythmics MOA

Answer 3

-block open or inactivated Na+ channels
(“soloist holding open peanut butter jar with inactivating spoon in it “)

-affect the Na+ dependent cardiac action potential​
(“Illuminated atria, ventricles, and His-perkinje system”)

**-“use dependence”** – class I antiarrhythmics have a **greater** effect on **rapidly depolarizing** tissues 
("Heart tipping mic stand") 

-decrease the slope of phase 0 upstroke (slows conduction of the cardiac AP) AP will almost look tipped over with a decreased slope
(“Soloist tipping mic stand”)

-widen the QRS complex on the ECG
(decreased AP conduction velocity)
(“Wide QRS shaped crack”)

**no action at the SA and AV nodes**

Question 4

Class IA properties

Answer 4

-have an intermediate binding affinity to the Na+ channel
(“Prom queen lightly holding peanut butter jar”)

-block K+ channels prolonging phase 2 and 3 of the cardiac action potential 􏰀prolonged refractory period

• increased AP duration
  (“prom queen pushing away the banana curtain”)

Question 5

Class IA Antiarrhythmics can treat

Answer 5

-Supraventricular and Ventricular Arrhythmias
(“Illuminated top and bottom of IA heart:”)

-WPW syndrome
(“wpw highschool sign with 3 wolfs”)

Question 6

Class IA Antiarrhythmics Side Effects

Answer 6

-quinidine toxicity can cause cinchonism
(syndrome of tinnitus, headache, dizziness)
(“tin cans around prom queen”)

-quinidine can cause thrombocytopenia
(“Broken plates around prom queen”)

-procainamide can cause a lupus–like syndrome raising an ANA titer
(“Prom king’s lupus wolf”)

-dysopyramide can exacerbate heart failure
(negative ionotrophy)
(“Darts in failing heart balloon”)

-can cause QT interval prolongation
(Precipitates torsades)
(“Twisted torsades streamer”)

Question 7

Class IB properties

Answer 7

-have a low binding affinity for the Na+ channel

• Decreased AP duration
  (“Pulling the curtain”)

​-shorten phase 2 and 3 of the cardiac action potential􏰀 shortened refractory period so no chance for torsades de pointes
(“Pulling the curtain”)

-has a greater tendency to work with ischemic heart
(“Broken illuminated IB heart”)

[because of the reduced resting membrane potential delays sodium channel transition from inactive back into resting state resulting in increased drug binding]

(“Dropped peanut butter jar”)

Question 8

Class IB Antiarrhythmics can treat…

Answer 8

-treat ventricular arrhythmias-especially in ischemic tissues
(“Illuminated and cracked bottom of heart”)

-treat ischemia induced ventricular arrhythmias one of the most common causes of death in the acute period following an MI
(sign says “you lied your’e “DEAD” to me”)

Question 9

Class IB Antiarrhythmics Side Effects

Answer 9

-cause neurological problems-parasthesias, tremor, convulsions.

(“friendly towing trucker has brain hat”)

Question 10

Class IC Antiarrhythmics Properties

Answer 10

-strong binding affinity for the Na+ channel
(“blonde dude in bed tightly holding peanut butter jar”)

(strong use dependence, drastic slowing of the phase 0 upstroke)

• dramatic effect on QRS duration, , no change in AP Duration
  (prolongs ERP in AV node)
  (“3rd floor has untouched potassium curtain”)

-do not affect the cardiac action potential duration
(“3rd floor has untouched potassium curtain”)

Question 11

Class IC Antiarrhythmics treat …

Answer 11

-treat supraventricular (A.Fib) and ventricular arrhythmias
(“Illuminated top and bottom of heart”)

-treat atrial fibrillation (and flutter)
(“Irregularly Irregular signal”)

-can restore and maintain normal sinus rhythm in A. Fib and Flutter
(“blonde dude uses remote controller to convert the signal”)

Question 12

Class IC Antiarrhythmics are contraindicated when …

Answer 12

-contraindicated in patients with history of structural or ischemic heart disease

(proarrhythmic effects)

(“box next to cornflakes box says “Healthy Hearts Only”!”)