Cardiac Dysrhythmia

Question 1

Class IA anti-Arrhythmic drugs Mechanism

Answer 1

Block Both Sodium & Calcium channels:
* Slows Phase 0 –> slow Excitability & Conductivity
* Slow Phase 4 –> Low Automaticity
* Long Phase 3 –> Long Action potential duration & Refractory Period

Affects all, thus broad spectrum

Question 2

Enumerate Class IA anti-Arrhythmic drugs

Answer 2

• Quinidine
• Procainamide
• Disopyramide

Question 3

Uses of Class IA anti-Arrhythmic drugs

Answer 3

• Atrial Fibrillation
• Ventricular tachycardia

Question 4

Class IB anti-Arrhythmic drugs Mechanism

Answer 4

Blockes Inactivated Na+ channels —> low Phase 4 —> Low Automaticity

• No effect on conductivity (AVN)
• Not effective in Atrial fibrillation (Narrow spectrum)

Question 5

enumerate Class IB anti-Arrhythmic drugs

Answer 5

• Lidocane
• Phenytoin
• Mexiletine

Question 6

Uses of Lidocane (Class IB)

Answer 6

1. Emergency ventricular arrhythmia without heart block
2. Myocardial infarction
3. Digitalis induced arrhythmia
4. Local & General Anesthetic
5. Cardiosurgeoury or Catheter

Question 7

What to consider when giving Lidocane

Answer 7

decrease its dose in liver disease & drugs lowering hepatic blood flow

Question 8

the only Class IB drug can be used in Ventricular Arrhythmia with heart block

Answer 8

Phentoyin (may decrease AV conduction)

Question 9

Class IC anti-Arrhythmic drugs Mechanism

Answer 9

Block Activated Na+ channels —> Slow phase 0 —> slow Excitability & conductivity

Question 10

Class IC anti-Arrhythmic drugs Example

Answer 10

• Flecainide
• Encainide
• Propafenone

Question 11

Contraindication of Flecainide/Encainide/propafenone

Answer 11

• Heart failure
• left ventricular Hypertrophy
• CHD

Beta blocking, negative inotropic, pro arrhythmic

Question 12

uses of Flecainide/Encainide/propafenone (Class IC)

Answer 12

• Atrial fibrillation
• Ventricular tachycardia

broad spectrum

Question 13

Class II anti-Arrhythmic drugs Mechanism

Answer 13

Beta blockers:
* depress all Cardiac properties

Question 14

Enumerate Class II anti-Arrhythmic drugs

Answer 14

Beta blockers:
* Esmolol
* propranolol
* Atenolol
* Metoprolol

Question 15

Class II anti-Arrhythmic drug reducing risk of bronchospasm (most widely used)

Answer 15

Metoprolol

Question 16

Class II anti-Arrhythmic drug used in Acute arrhythmia emergency and is metabolised by RBCs

Answer 16

Esmolol

Question 17

Mechanism of action of Class III anti-Arrhythmic drugs

Answer 17

K+ Channel blockers –> Long Phas 3 –> long refractory period & Period of depolarization

Question 18

Enumerate Class III anti-Arrhythmic drugs

Answer 18

• Amiodarone
• Dronedarone (less side effects than amiodarone)
• Bretylium
• Sotalol (actually beta blocker)

Question 19

which class II drug belongs to Class III

Answer 19

Sotalol

Question 20

Uses of Amiodarone

Answer 20

Severe & refractory supraventricular & ventricular arrhythmia

Question 21

Adverse effects of Amiodarone

Answer 21

• Pulomary inflammation & fibrosis
• Thyroid dysfunction
• skin discoloration
• corneal deposits

Question 22

Enumerate Class IV anti-Arrhythmic drugs

Answer 22

calcium channel blockers:
* Verapamil
* Diltiazem

Question 23

uses of Class IV anti-Arrhythmic drugs

Answer 23

• reentrant supraventriuclar tachycadia
• decrease ventricular rate in Atrial flutter & fibrillation

Question 24

Drug of choice in Atrial flutter/Fibrillation

Answer 24

Digoxin

Question 25

Drug of choice in Superaventricular tachycardia

Answer 25

* Adenosine * Verpamil (class IV ca2+ blocker)

Question 26

drug of choice in Sustained ventricular tachycardia

Answer 26

Lidocane

Question 27

drug of choice in Ventricular Fibrillation

Answer 27

Lidocane

Question 28

drug of choice in Digitalis induce ventricular tachycardia

Answer 28

Lidocane

Question 29

Drug of choice in Torse De pointes

Answer 29

Magnesium