Cardiac Arrhythmias

Question 1

What are the different classes of anti-arrhythmic drugs?

Answer 1

Class I - block Na+ channels
Class II - β-blockers
Class III - block K+ channels
Class IV - calcium channel blockers

Question 2

What are the action of drugs used for abnormal action potential generation?

Answer 2

Decrease phase 4 slope in pacemaker cells

Raises threshold for action potential

Question 3

What are the actions of drugs used for abnormal conduction of action potential?

Answer 3

Decrease conduction velocity

Increased effective refractory period so cell can’t be depolarised again

Question 4

What causes arrhythmias to occur?

Answer 4

Automatic or triggered activity
Re-entry due to a scar, anatomy of AV node
WPW

Question 5

What are examples of class IA anti-arrhythmics?

Answer 5

Quinidine

Procainamide

Question 6

What are the effects of class IA ant-arrhythmics on cardiac activity?

Answer 6

Decreased conduction
Increased refractory period
Decreased automaticity
Increase threshold for action potential

Question 7

What are the uses of class IA anti-arrhythmics?

Answer 7

Quinidine; maintains sinus rhythm in AF and atrial flutter, and prevents recurrence

Procainamide; acute IV treatment of SVT and ventricular arrhythmias

Question 8

What are examples of class IB anti-arrhythmics?

Answer 8

Lidocaine

Mexiletine

Question 9

What are the effects of class IB anti-arrhythmics on cardiac activity?

Answer 9

Slightly decreased ADP
Increase threshold for action potential
Decrease phase 0 conduction in fast beating or ischaemic tissue

Question 10

What are some side effects of class IA anti-arrhythmics?

Answer 10

Hypotension - reduced CO 
Proarrhythmic - increased QT interval 
Dizziness, confusion, insomnia, seizure 
GI Sx 
Lupus-like syndrome

Question 11

What is a use of class IB anti-arrhythmics?

Answer 11

Acute ventricular tachycardia

Question 12

What are some side effects of class IB anti-arrhythmics?

Answer 12

CNS effects - dizziness, drowsiness

Abdo upset

Question 13

What are some examples of class IC anti-arrhythmics?

Answer 13

Flecainide

Propafenone

Question 14

What are the effects of class IC anti-arrhythmics on cardiac activity?

Answer 14

Decreased phase 0
Decreased automaticity
Increased APD

Question 15

What are the used of class IC anti-arrhythmics?

Answer 15

Supraventricular arrhythmias - fibrillation and flutter
Premature ventricular contractions - ventricular ectopics
Wolff-Parkinson-White syndrome

Question 16

What are some side effects of class IC anti-arrhythmics?

Answer 16

Pro-arrhythmic and sudden death - esp w/ chronic use and structural heart disease
Increase ventricular response to supraventricular arrhythmias - need to body IC AVN
CNS and GI effects

Question 17

What are some class II anti-arrhythmics?

Answer 17

Propranolol
Bisoprolol
Metoprolol
Esmolol

Question 18

What is the MOA of class II anti-arrhythmic drugs?

Answer 18

β-blockers

Increase refractory period in AV node to slow AV conduction
Decreases phase 4 depolarisation

Question 19

What is the MOA of class III anti-arrhythmic drugs?

Answer 19

Prolongs depolarisation

Increases refractory period

Question 20

What is the MOA of class IV anti-arrhythmic drugs?

Answer 20

Calcium channel blockers
Slows conduction through AV node
Increases refractory period in the AV node

Question 21

What are class II anti-arrhythmic drugs used for?

Answer 21

Treat sinus and catecholamine dependent tachycardia
Wolff-Parkinson-White syndrome
Slows AV conduction to protect ventricles from high atrial rates

Question 22

What are the side effects of class II anti-arrhythmic drugs?

Answer 22

Bronchospasm

Hypotension

Question 23

What are some examples of class III anti-arrhythmic drugs?

Answer 23

Amiodarone

Sotalol

Question 24

What is amiodarone used for?

Answer 24

Effective for most arrhythmias

Question 25

What are some side effects of amiodarone?

Answer 25

``` Pulmonary fibrosis Hepatic injury Inc LDL Thyroid disease Photosensitivity ```

Question 26

What is sotalol used for?

Answer 26

Supraventricular and ventricular tachycardia

Question 27

What are some side effects of sotalol?

Answer 27

Proarrhythmic Fatigue Insomnia

Question 28

What are some examples of class IV anti-arrhythmic drugs?

Answer 28

Verapamil | Diltiazem

Question 29

What are some uses of class IV anti-arrhythmic agents?

Answer 29

Control ventricles in supraventricular tachycardia

Question 30

What are some side effects of class IV anti-arrhythmic drugs?

Answer 30

Can get asystole if also using a β blocker | GI upset - constipation

Question 31

What is the MOA of adenosine as an anti-arrhythmic drug?

Answer 31

Slows AV conduction | Activates K+ channels => hyperpolarisation => decrease Ca2+ current => inc refractory period

Question 32

What is adenosine as an anti-arrhythmic used for?

Answer 32

Convert re-entrant supraventricular arrhythmias | Diagnosis of coronary artery disease

Question 33

What is the MOA of ivabradine as an anti-arrhythmic?

Answer 33

Blocks funny current in sinus node | Therefore slows sinus node w/o affecting BP

Question 34

What are some uses for ivabradine?

Answer 34

Reduce sinus tachycardia | Reduce HR in heart failure and angina - avoids BP drop

Question 35

What is the MOA of digoxin?

Answer 35

Enhances vagal activity | Slows AV conduction and slows HR

Question 36

What is digoxin used for?

Answer 36

Reduces ventricular rates in atrial fibrillation or flutter

Question 37

What is the MOA of atropine?

Answer 37

Selective muscarinic antagonist Blocks vagal activity to speed AV conduction and increase HR

Question 38

What is a use of atropine?

Answer 38

Treats vagal bradycardia

Question 39

What drugs are used in AF to control rate and rhythm?

Answer 39

Rate control: Bisoprolol, verapamil, diltiazem Rhythm control: Sotalol, flecainide with bisoprolol, amiodarone

Question 40

What drugs are used to treat WPW?

Answer 40

Flecainide | Amiodarone

Question 41

What drugs are used in re-entrant SVT?

Answer 41

Acute (IV) Adenosine, verapamil, flecainide ``` Chronic (oral) Bisoprolol, flecainide Sotalol Flecainide, procainamide Amiodarone ```

Question 42

What drugs are used for ectopic beats?

Answer 42

First line: bisoprolol Flecainide, sotalol, amiodarone

Question 43

What drugs are used to treat sinus tachycardia?

Answer 43

Ivabradine Bisoprolol, verapamil