Class I

Question 1

Harmful effects of Class I

Answer 1

Increase defib thresholds(esp IC)
Impair myocardial contractility (IC)
May cause pro arrhythmia 
Increase RR interval
Reduce effectiveness of antitachycardia pacing (IC)

Question 2

Beneficial effects of Class I

Answer 2

?reduce episodes of non-sustained VT
?reduce episodes of sustained VT
?improve efficacy of antitachy pacing
?prevent syncope during vent tachyarrhythmias

Question 3

Name Class IA drugs

Answer 3

Quinidine
Proclainamide
Disopyramide

“The queen proclaims dis pyramid “
IA = active, so potential for more duration

Question 4

How do Class IA work?

Answer 4

Bind and partially close gate h so when gate m opens not as many Na ions get in
Phase 0 not as steep and conduction velocity is slower
Increases refractory period

Question 5

How do Class IB drugs work?

Answer 5

Little effect on conduction velocity

Decrease action potential duration and refractory periods

Question 6

Name Class IB drugs

Answer 6

Lidocaine
Mexilitine
Tocainamide

“I Buy lidy’s mexican tacos”
IB = bored, so decrease action potential duration

Question 7

How do Class IC drugs work?

Answer 7

Profound effect on conduction velocity (decrease)

Minimal effect on refractory periods

Question 8

Name Class IC drugs

Answer 8

Encainide
Propafenone
Flecainide

“I Can eat a profane amount of fries”