Class I antiarrhythmics Flashcards Preview

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Flashcards in Class I antiarrhythmics Deck (14)
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1
Q

What are some commonalities to the functions of class I antiarrhythmics?

A

the all decrease the slope of phase 0 of the AP and slow conduction. they incr. the threshold for firing in abnormal pacemaker cells.
toxicities are all worsened by hyperkalemia
they are all state dependent (selectively depresses tissue that is frequently activated)

2
Q

list the class Ia antiarrhythmics

A

quinidine, procainamide, disopyramide

3
Q

Mechanism of class Ia antiarrhythmics

A

decrease the slope of phase 0 and prolong the AP. increase the effective refractory period and increase QT interval.

4
Q

Use for Class IA antiarrhythmics

A

atrial and ventricular arrythmias, esp. re-entrant and ectopic SVT and VT

5
Q

toxicity of class IA antiarrhythmics

A

procainamide: SLE-like syndrome
cinchonism (headache and tinnits with quinidine), heart failure with disopyramide. all can cause thrombocytopenia, torsades de points

6
Q

list the class IB antiarrhythmics

A

lidocaine, mexiletine (phenytoin)

7
Q

mechanism of the class IB antiarrhythmics

A

shorten the AP duration. decrease the slope of phase zero. especially effect ischemic or depolarized Purkinje/ventricular tissue

8
Q

class IB uses

A

acute ventricular arrhythmias, esp. post-MI. digitalis-induced arrhythmias. (it is the best post-MI)

9
Q

toxicity of class IB antiarrhythmics

A

CNS stimulation/depression; CV depression

10
Q

list class IC antiarrhythmics

A

Flecainide, propafenone

11
Q

mechanism of class IC anti-arrhythmics

A

prolongs the refractory period in the AV node. minimal effects on AP duration

12
Q

clinical use of class IC anti-arrhythmics

A

supraventricular tachycardia, including afib. only as a last resort in ventricular tachycardia

13
Q

toxicity of class IC anti-arrhythmics

A

proarrhythmic, esp. post-MI. it is contraindicated in structal and ischemic heart disease

14
Q

When is Mg used as an antiarrhythmic?

A

torsades de points and digoxin toxicity