Anti-Arrhythmics intro Flashcards Preview

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Flashcards in Anti-Arrhythmics intro Deck (11):
1

Membrane potential when Na+ inactivation gates close:

What is the significance?

-75 to -55 mV

***if AP is evoked at -60 mV --> fewer Na+ channels available than if evoked at -80

2

factors that lead to arrhythmias do so by disturbing? (2 things)

1. impulse formation

2. impulse conduction

3

More important phase in determining pacemaker cell impulse formation:

diastolic interval phase 4 ( > action potential; phase 0 and 3)

4

Hyperpolarizing the diastolic interval of the pacemaker cell will _________ pacemaker.

slow

5

Two ways to hyperpolarize pacemaker diastolic interval:

1. vagal discharge (Ach)

2. Beta blockers (inhibit NE)

6

Five ways to speed pacemaker diastolic interval:

1. hypOkalemia

2. Beta stimulation

3. Positive chronotropic drugs

4. fiber stretch

5. acidosis

7

Afterdepolarizations?

Early and delayed

slides 28-30

8

Class I drugs?

Na+ channel blockers

-alter AP duration and kinetics of Na+ channel blockade

9

Class II drugs?

Beta blockers

-blockade of SNS effects in heart

10

Class III drugs?

K+ channel blockers

-prolongation of effective refractory period

11

Class IV drugs?

Ca2+ channel blockers

-slows conduction where depolarization is Ca2+ dependent