antiarrhythmic Drugs

Question 1

What 2 classes of drugs are used to lower rate ?

Answer 1

class II: beta-blockers

class IV: Ca2+ blockers

Question 2

What 2 classes of drugs are used to correct rhythm?

Answer 2

class I: Na+ channel blocker

class III: K+ channel blocker

Question 3

Class I drug name + specifics

Answer 3

Class I : Na+ channel blocker

Ex: flecanide, lidocaine, propaferode

Question 4

Class II drug name + specific

Answer 4

Class II: Beta blocker

Ex: metoprolol, etc.

Question 5

Class III drug name + specific

Answer 5

Class III: K+ channel blocker

Ex: amiodarone, sotalol

Question 6

Class IV drug name + specific

Answer 6

Class IV: Ca2+ channel blocker

verapamil, dilitazem

Question 7

How do class I drugs work broadly?

Answer 7

Na+ blockers that prevent phase 0 upstroke

Question 8

How do class II drugs work broadly?

Answer 8

prevent B1 which decreases contractility and lowers HR

Question 9

How do class III drugs work broadly?

Answer 9

K+ channel blocker that prevents repolarization

Question 10

How do class IV drugs work broadly?

Answer 10

Ca2+ channel blocker

decreases the plateau phase (myocyte) or upstroke phase (SA/AV)

Question 11

This drug is suppresses spontaneous depolarization of SA and AV node via A1 receptor and is helpful in breaking and diagnosing a re-entry SVT.

Answer 11

adenosine

Question 12

What receptor does adenosine work on?

Answer 12

a1

Question 13

Which drug blocks Na/ATPase? What is its result?

Answer 13

Digoxin

Increases intracellular Ca2+ which increases LV contractility

Question 14

What class III agent is iodinated and can lead to hypothyroidism?

Answer 14

amiodarone

Question 15

Class IB agent gist and example

Answer 15

Blocks Na+ only channels which shortens the QT interval

ex: lidocaine

Question 16

Class 1A drug that has associated lupus-like syndrome

Answer 16

Procainamide

Question 17

How do sodium channel blockers work?

Answer 17

phase 0 of myocyte normally has Na+ entering the cell to depolarize it

if we block the sodium channel, the cell cannot depolarize and rhythm will be interrupted

Question 18

What type of rhythm control is better to treat re-entry tachycardia?

Answer 18

class I

Na+ channels are not in the NA/AV action potential so this won’t slow the AV node which could be a problem in re-entry tachy

Question 19

What is normally first line treatment for PSVT?

Answer 19

valsalva

then, adenosine

Question 20

How do valsalva maneuvers work?

Answer 20

they decrease preload due to increased pressure

baroreceptor will compensate for increase in pressure by slowing heart rate

Question 21

How do K+ channel blockers work?

Answer 21

normally potassium flows out of cell during repolarization

cell will struggle to repolarize if K+ channels are blocked

leads to increased action potential period and refractory period

Question 22

What 2 phases does calcium channels work on?

Answer 22

1) phase 2 of myocytes

2) phase 0 of AV/SA

Question 23

Phase 2 effects of class 4 drugs

Answer 23

contraction normally occurs during the plateau

decreased plateau time = decreased contraction

Question 24

Phase 0 effects of class 4 drugs

Answer 24

prevents depolarization in SA/AV cells

Question 25

What are 2 effects of digoxin?

Answer 25

1) Increase contractility (by blocking Na+/ATPase you have more intracellular calcium which will lead to an influx of Ca2+)

2) Decrease heart rate through stimulating the parasympathetic system