Chapter 23: Cardiac Rhythm

Question 1

MOA of Class IA Anti-arrhythmics

Answer 1

Block Na + channels
Block K+ channels
in ventricular myocytes
–> decreases conduction velocity thru myocardium

Question 2

Class IA have what effect on AP duration, refractory period, and QT interval?

Answer 2

Increases all 3

Question 3

Class IB effect on AP duration?

Answer 3

Decreases AP duration

Question 4

What is Class IC MOA and effect of AP duration?

Answer 4

Marked (most) block of Na+ channels

Does not change AP duration

Question 5

What are Class II drugs?

Answer 5

B-blockers…LOL!

Question 6

MOA of Class III? Effect on AP duration, QT and refractory period?

Answer 6

K+ channel blockers

Increase AP duration
Increase refractory period
Increase QT interval

Question 7

When do you use Class III?

Answer 7

When other anti-arrythmics fail

Question 8

Class IV MOA? What do they do to conduction velocity, refractory period, and PR interval?

Answer 8

Ca2+ channel blockers

decrease conduction velocty
increase refractory
increase PR interval

Question 9

Adenosine MOA?

Answer 9

opens G protein coupled K+ channel and suppress Ca dependent AP
–> increases K OUT of cell….suppress Ca AP

= inhibits SA node, atrial, and AV nodal conduction

Question 10

Name the class IA drugs

Answer 10

quinidine
procainimide
disopyramide

Question 11

Name the class IB drugs

Answer 11

Lidocaine
Mexiletine
Phenytoin

Question 12

Name the class IC drugs

Answer 12

Flecainide

Propafenone

Question 13

Name the class III drugs

Answer 13

Ibutilide
Dofetilide
Sotalol
Bretylium
Amiodarone
Dronedarone

Question 14

Name the class IV drugs

Answer 14

Verapamil

Diltiazem

Question 15

Quinidine toxicity?

Answer 15

cinchonism (impaired hearing, headache, dizziness)

Question 16

Procainamide toxicity?

Answer 16

lupus like syndrome (almost all chronic users get this…think increase ANAs)

Question 17

Disopyramide toxicity?

Answer 17

heart failure

Question 18

All class IAs can cause what serious adverse effect?

Answer 18

Torsades des pointes

Question 19

What should be used in conjunction with quinidine?

Answer 19

An agent that will slow AV nodal conduction

- Ca channel blocker or B blocker

Question 20

What drug may be used in hypertrophic cardiomyopathy because it decreases cardiac contractility?

Answer 20

dispyramide

Question 21

Quinidine induced ____ toxicity may occur in a fraction of patients

Answer 21

digoxin

Question 22

What is the drug used to maintain normal sinus rhythm after conversion of atrial flutter?

Answer 22

procainamide

Question 23

What is the class IA drug for paroxysmal supraventricular tachycardia? What if this fails?

Answer 23

quinidine (class IA)

if fails, try a class IC --> used as last resort drugs
= Flecainide or Propafenone

Question 24

_____ suppresses purkinje automaticity without affecting the SA node

Answer 24

Lidocaine

Question 25

Clinical use of lidocaine/mixiletine?

Answer 25

Ventricular arrythmias in context of MI, cardiac manipulation or cardiac glycosides

Question 26

Class IB has an effect on what type of tissue?

Answer 26

INJURED/DISEASED myocardium

Question 27

What drug is used for local anesthesia of skin or mucous membranes?

Answer 27

lidocaine

Question 28

Clinical use of phenytoin?

Answer 28

tonic-clonic seizures status epilepticus non epileptic seizures

Question 29

IB is Best ____ | IC is Contraindicated _____

Answer 29

post MI | post MI/structural heart disease

Question 30

What drugs are associated with excessive mortality and nonfatal cardiac arrest? (restrict these drugs to people who have failed other measures)

Answer 30

Class IC = flecainide propafenone

Question 31

What type of drug would you give to decrease the likelihood for mortality and re-infarction after MI?

Answer 31

B blockers!

Question 32

Ibutilide clinical use?

Answer 32

conversion of atrial fibrillation/atrial flutter to normal sinus rhythm

Question 33

What must you do if giving ibutilide? Why?

Answer 33

monitor QT interval during administration Bc 2% develop torsades des pointes and need cardioversion

Question 34

Sotalol clinical use?

Answer 34

life threatening ventricular arrhythmias when patients can't tolerate amiodarone

Question 35

Adverse effects of sotalol? So don't use in pts that have a hx of __?

Answer 35

bradycardia | bronchospasm --> dont use in pts with asthma!!

Question 36

When v. arrythmias don't respond to lidocaine or defibb, what drug should you try?

Answer 36

Bretylium (no effect on atrial tissue)

Question 37

What drugs targets the entire lipid membrane and can thus be considered a multi-class anti-arrhythmic?

Answer 37

amiodarone

Question 38

Co-administration of amiodarone with what drug would decrease amiodarone levels?

Answer 38

phenytoin

Question 39

Amiodarone toxicity?

Answer 39

severe pulmonary toxicity thyroid dysfunction (40% iodine by weight) Corneal deposits Blue-gray skin discoloration photosensitivity

Question 40

Which of the class III drugs can cause torsades des pointes?

Answer 40

sotalol | ibutilide

Question 41

Drug used for a fibb/a flutter that is similar to amiodarone, but has a shorter half life and less thyroid toxicity?

Answer 41

dronedarone

Question 42

Don't use dronendarone in patients with what?

Answer 42

systolic heart failure!

Question 43

What is the drug of choice for paroxysmal supraventricular tachycardia?

Answer 43

adenosine

Question 44

Is adenosine short or long acting? What are the toxicities?

Answer 44

VERY short acting - 15sec Facial flushing Chest pressure Diaphoresis

Question 45

Do not use adenosine to treat ____

Answer 45

atrial fibb or atrial flutter

Question 46

Ranolazine is used to treat ____

Answer 46

chronic angina pectoris --> freq used in conjunction with nitrates or B blockers