Antiarrhythmic pharmacology Flashcards Preview

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Flashcards in Antiarrhythmic pharmacology Deck (12):
1

Speed of upstroke proportional to...

Speed of conduction

2

EAD

When action potential is too long, Ca can reactivate and cause an Early after depolarization

3

DAD

Result from fast HR and B stimulation. Extra Ca in cell. So NCX works really hard. Is electrogenic, Na comes in and depolarizes cell.

4

Reentry

Cycling around tissue that has depolarized. Can increase wavelength to make this less possible.

5

Does the center of a reentry loop have to be anatomically defined?

No, can be functionally defined too.

6

Mechanisms of most the the important arrhythmias?

Are initiated by EAD/DAD and maintained by reentry.

7

Strategies for treating arrhythmias

Block Ca current to prevent EADS
block B adrenergic stimulation to decrease Ca in cells
Block Na channels to prevent DADs
Increase wavelength by prolonging action potentials

8

How to determine wavelength?

CV*APD. Increase in APD will increase wavelength and promote reentry termination.

9

Vaughan Williams Classification Systyem Class I

I: Blocks Na currents
A: Rate of unblock medium, IKr block strong. Medium reduction in upstroke velocity, prolong action potentials
B: Rate of unblock fast, IKr block weak. Small reduction in upstroke velocity. Small decrease in APD.
C: Rate of unblock slow, IKr weak. Large reduction in upstroke velocity. No change in APD.

10

Class II Antiarrhythmics

Beta blockers (propranolol). Will decrease HR. Prevent Ca overload and DADs

11

Class III Antiarrhythmics

Blocks IKr, prolongs APD. Amiodarone**

12

Class IV Antiarrhythmics

Blocks Ca channels. Decreases EADS and DADs by decreasing Ca2+overload. verapamil and diltiazem.