Anti-Arrhythmia Drugs

Question 1

3 mechanisms for drugs to be anti-arrhythmic

Answer 1

decrease autmaticity
increase refractory period
decrease conduction velocity

Question 2

what are the five ways to decrease automaticity of a cell?

Answer 2

1. increase threshold potential
2. decrease phase 4 slope
3. increase AP duration
4. slow SA/AV node depolarization
5. increase maximum diastolic potential

Question 3

mechanism to increase the depolarization threshold and class of these drugs

Answer 3

block sodium channels

class 1 anti arrhythmics

Question 4

what are the subsets of class I antiarrhythmics and which of these also blocks potassium channels?

Answer 4

A,B,C

Class IA blocks potassium too

Question 5

rate class IA-C by increasing strength of Na block

Answer 5

B is weakest
A in the middle
C is strongest

Question 6

with potassium channel blocking…what is the greatest toxicity?

Answer 6

will lead to lengthened QT…so torsades

Question 7

name the class IA anti-arrhythmic and its function

Answer 7

Procainamide…Na and K blockers

Question 8

name the two class IC anti-arrhythmics and its function

Answer 8

Flecainide and Propafenone..Na blockers

Question 9

what is the warning with class IC drugs?

Answer 9

do not give to patients with structural heart abnormalities

Question 10

name the class IB anti arrhythmic and its function

Answer 10

lidocaine and Na blocker

Question 11

how do we decrease the phase 4 slope in the action potential of a nodal cell?

Answer 11

block the HCN channels

Question 12

what common drugs block the HCN channels?

Answer 12

beta antagonists

Question 13

class II anti-arrhythmics are what type of drug?

Answer 13

beta blockers

Question 14

how to increase length of the action potential?

Answer 14

block the K channels that are repolarizing the cells

Question 15

what class of antiarrhythmics block the K channels to lengthen the action potentials?

Answer 15

Class III and Class IA

Question 16

name the Class II anti arrhythmics to know

Answer 16

metoprolol, propanolol, atenolol, carvedilol

Question 17

how to slow depolarization of SA/AV node cells?

Answer 17

block calcium channels

Question 18

what class of anti arrhythmics blocks calcium channels?

Answer 18

class IV

Question 19

what are the two calcium channel blockers of class IV to know for cardiac muscle?

Answer 19

verapamil and diltiazem

Question 20

what other effect can calcium channel blockers have?

Answer 20

decrease smooth muscle tone so they can treat hypertension

Question 21

how do we increase the maximum diastolic potential and what does this actually mean?

Answer 21

the repolarization drops lower…do this via stimulating K+ influx to the cell

Question 22

what is the drug that does a good job at increasing the maximum diastolic potential?

Answer 22

adenosine brings in more K+

Question 23

how must we administer adenosine and why?

Answer 23

IV bolus because its naturally occurring and has receptors all over so need it to get to the heart fast

Question 24

name the two classes of drugs that will cause the AP to lengthen

Answer 24

class IA
class III
BOTH POTASSIUM BLOCKERS

Question 25

name the four classes of drugs that will slow recovery of Na channels

Answer 25

class IA,B,C
adenosine

Question 26

name the four classes of drugs that will slow recovery of Na channels or Ca channels

Answer 26

class IA,B,C
adenosine is Ca channels

Question 27

the class IABC and adenosine all slow recovery of the Na channels…what is the effect this has on the AP?

Answer 27

the AP will not be lengthened like it is with potassium block…rather the recovery of the Na channels just takes longer and causes the cells to be refractory

Question 28

three mechanisms to slow conduction velocity through the AV node

Answer 28

block Ca channels
block HCN channels
increase K+ influx

Question 29

what three classes/drugs can be nodal (AV) blockers?

Answer 29

class II (HCN) IV (Ca) and adenosine (K+)

Question 30

name the four class III anti arrhythmics

Answer 30

amiodarone, dronedarone, dofetalide, sotalol