Antiarrhythmics Flashcards Preview

Cardiovascular > Antiarrhythmics > Flashcards

Flashcards in Antiarrhythmics Deck (36):
1

What are the 4 classes of antiarrhythmic drugs?

  • Class 1 - Na channel blockers
  • Class 2 - beta-Blockers
  • Class 3 - K channel blockers
  • Class 4 - Ca channel blockers

2

What is the effect of Na channel blockers?

  • Slow or block conduction
  • Decrease slope of phase 0 depolarization 
  • Increase threshold for firing in abnormal pacemaker cells

3

What are the Class IA antiarrhythmics?

  • Quinidine
  • Procainamide
  • disopyramide 

4

What is the mechanism of action of Class IA drugs?

  • Increase AP duration
  • Increase effective refractory period
  • Increase QT interval

5

What kind of arrhythmias do Class IA drugs treat?

  • Affect both atrial and ventricular arrhythmias 
  • Especially good for reentrant and ectopic supraventricular and ventricular tachycardia

6

What is the toxicity of Class IA drugs?

  • thrombocytopenia
  • torsades depointes due to increased QT interval
  • procainamide - SLE like syndrome
  • quinidine - cinchonism (headache, tinnitus)

7

What are the Class Ib drugs?

  • Lidocaine
  • Mexiletine
  • Tocainamide 

8

What is the mechanism of class Ib drugs?

  • Decrease AP duration
  • Preferentially affect ischemic or deplarized Purkinje and venticular tissue

9

What kind of arrhythmias do class Ib drugs treat best?

  • Acute ventricular arrhythmias (esp post MI)
  • Digitalis induced arrhythmias

10

What is the toxicity of class Ib drugs?

  • Local anesthetic
  • CNS stimulation/depression
  • CV depression

11

What are the class IC drugs?

  • Flecainide
  • Propafenone 

12

What is the mechanism of Class IC drugs?

  • No effect on AP duration

13

When is Class IC drug useful?

  • V-tachs that progress to Vfib
  • Intractable SVT
  • Usually only used as last resort in refractory tachyarrhythmias 
  • For patients without structural abnormalities 

14

What is the toxicity of Class IC drugs?

  • Proarrhythmic, esp post-MI
  • Significantly prolongs refractory period in AV noce

15

When are class IC drugs contraindicated?

Post-MI

16

What are the Class II drugs?

  • Propranolol
  • Esmolol
  • Metoprolol
  • Atenolol
  • Timolol

17

What is the mechanism of Class II drugs?

  • Decrease cAMP
  • decrease Ca++ currents
  • Suppress abnormal pacemakers by decreasing slope of phase 4
  • AV node particularly sensitive
    • Prolongs PR interval

18

Which Class II drugs is shortest acting?

Esmolol

19

What is the clinical use of class II drugs?

  • V-tach
  • SVT
  • slowing ventricular rate during afib and atrial flutter

20

What is the toxicity of Class II drugs?

  • Impotence
  • exacerbation of asthma
  • CV effects (bradycardia, AV block, CHF)
  • CNS effects (sedation, sleep alterations)
  • May mask signs of hypoglycemia 
  • Metoprolol can cause dylipidemia
  • Tx overdose with glucagon

21

What are the class III drugs?

  • Ibutilide
  • Sotalol
  • Bretylium
  • Amiodarone
  • Dofetilide

"K IS BAD"

22

What is the mechanism of Class III drugs?

  • Increase AP duration
  • Increase ERP
  • Increase QT interval

23

When do Class II drugs tend to be used?

When other antiarrhythmics fail

24

What is the toxicity of Sotalol?

  • Torsades de pointes
  • excessive beta block

25

What is hte toxicity of ibutilide?

torsades de pointes

26

What is the toxicity of bretylium?

  • New arrhythmias
  • hypotension

27

What is the toxicity of amiodarone?

  • Pulmonary fibrosis
  • Hepatotoxicity
  • Hypothroidism/hyperthroidism
  • corneal deposites
  • skin deposits (blue/gray) resulting in photodermatitis 
  • neurologic effects 
  • constipation
  • CV effects (bradycardia, heart block, CHF)
  • Amiodarone has class I, II, III and IV effects 

28

What are the class IV drugs?

  • Verapamil
  • Diltiazem

29

What is hte mechanism of class IV drugs?

  • Decrease conductoin velocity
  • Increase ERP
  • Increase PR interval

30

What kind of arrhythmias are class IV drugs mainly used for?

Prevention of nodela arrhythmias 

31

What is the toxicity of class IV drugs?

  • Constipation
  • flushing
  • edema
  • CV effects (CHF, AV block, sinus node depression)

32

What is the mechanism of adenosine as an antiarrhythmic drug?

  • Increase K+ out of cells 
  • Hypoerpolarizes the cell and decreases ICA channel flow

33

When is adenosine used?

Drug of choice in diagnosing/abolishing supraventricular tachycardia 

34

What is the toxicity of adenosine?

  • Flushing
  • Hypotension
  • Chest pain

35

What drug blocks the effects of adenosine?

Theophylline

36

What is MG2+ use as an antiarrhythmic?

Effective in torsades de pointes and digoxin toxicity