Antidysrhyrhmic Drugs

Question 1

Arrhythmias are always symptomatic. True or false?

Answer 1

False. They may be symptomatic or asymptomatic.

Question 2

Common symptoms of arrhythmia

Answer 2

sudden death
Syncopal attacks
Heart failure
Dizziness
Palpitations

Question 3

Factors precipitating arrythmias:

Answer 3

MS HIDI

Mechanical injury
Stretching
Hypoxia
Ischemia
Drugs (anti-arrhythmics etc)
Imbalance of electrolyte / pH imbalance

Question 4

Causes of Arrhythmias:

Answer 4

Atherosclerosis
Coronary artery spasms
Myocardial ischemia
Conduction block.

Question 5

Types of arrhythmias

Answer 5

2SE2A2PV

Sinus tachycardia: HR > 100bpm
Sinus bradycardia: HR < 60bpm
Extrasystoles
Atrial flutter
Atrial fibrillation
Paroxysmal atrial tachycardia
Paroxysmal ventricular tachycardia
Ventricular fibrillation

Question 6

Torsade de pointes occurs when

Answer 6

…a long QT causes undulating baseline/rapid asynchronous complexes on ECG.

Question 7

Atrial rate in atrial tachycardia

Answer 7

100 - 250 bpm

Question 8

What is so unique about PSVT?

Answer 8

Electrical signals, starting in the upper chambers fire irregularly, preventing the heart from having enough time to fill with blood before pumping out to the rest of the body

Question 9

What on an ECG is indicative of ventricular tachycardia?

Answer 9

Widened QRS

Question 10

What is the heart rate in ventricular tachycardia?

Answer 10

100 to 120bpm

Question 11

What is the heart rate in PSVT?

Answer 11

120 to 230

Question 12

Difference between V tach and V fib

Answer 12

In Vtach, spontaneous ventricular automaticity causes chaotic faster HR with widened QRS. Drugs like cocaine, meth, and structural heart dx are responsible.

In VFib, the ventricles contract rapidly and uncoordinatedly, causing sudden cardiac arrest and even death. It is caused by prior heart disease or electrolyte imbalance.

Question 13

The four parameters explained in the electrophysiology of the heart include:

Answer 13

Automaticity
conduction
Excitability
refractory period

Question 14

HIS/Purkinje fibres are specialised conducting tissues. True or false?

Answer 14

True

Question 15

What are the automatic cardiomyocytes?

Answer 15

• SAN
• AVN
• HIS/Purkinje

Question 16

Non-pacemaker AP occurs in how many phases?

Answer 16

5

Question 17

Give brief overview of events in Phases 0 to 4

Answer 17

0 - Na channels open (rapid depolarisation)
1 - Na channels close (early repolarisation)
2 - Ca channels open, fast K channels close (plateau)
3 - Ca channels close, fast K channels open (repolarisation)
4 - Resting potential

Question 18

What kind of abnormal conduction is seen in PSVT and WFW syndrome?

Answer 18

Reentry

Question 19

Give examples of conditions with micro entry circuit

Answer 19

Ventricular extrasystole
Ventricular tachycardia
V.fib

Question 20

What is a Conduction block?

Answer 20

Conduction from SA node to AV node could be slowed down by ischemia, causing partial to complete AV block or sick sinus.

Question 21

2nd degree AV block

Answer 21

Some supraventricular complexes are not conducted, missed beat.

Question 22

3rd degree AV block

Answer 22

No supraventricular complexes are not conducted, ventricles generate own impulse.

Question 23

What is the most common cause of conduction block?

Answer 23

Ischemia

Question 24

When are arrhythmias left untreated?

Answer 24

Simple arrhythmic agents e.g. Atrial extrasystole and ventricular extrasystole in a normal heart

Question 25

In what kind of arrhythmias are vigorous therapies required?

Answer 25

- Life threatening conditions like Ventricular tachycardia. - Arrhythmias causing hypotension , breathlessness or heart failure. - Marked palpitation as in PSVT, sustained V.tach, Atrial fib, torsades de pointes.

Question 26

What are the classes of antiarrhythmic drugs?

Answer 26

Class I to V

Question 27

Class 1A antiarrhythmics

Answer 27

D-Disopyramide P-Procainamide

Question 28

Class 1B antiarrhythmics

Answer 28

L-Lidocaine M-Mexiletine

Question 29

Class 1C antiarrhythmics

Answer 29

Propafenone Flecainide

Question 30

Class II antiarrhythmics

Answer 30

Esmolol Sotalol Propranolol

Question 31

Class III antiarrhythmics

Answer 31

Sotalol Amiodarone Dronedarone Dofetilide

Question 32

Class IV antiarrhythmics

Answer 32

Verapamil Diltiazem

Question 33

Class V antiarrhythmics

Answer 33

Adenosine Digoxin Magnesium sulfate

Question 34

Pharmacological action of quinidine

Answer 34

Decrease automaticity in purkinje fibers and other ectopic focus to extinguish extrasystoles and prophylaxis of re entrant arrythmias.

Question 35

How do class 1A drugs reduce membrane responsiveness?

Answer 35

Via anti-vagal action, it reduces the rate of 0 phase depolarization thereby reducing membrane responsiveness.

Question 36

ECG reading of class 1A

Answer 36

Increase PR and QR intervals, broaden QRS complex

Question 37

Pneumonic to know the drugs in anti-arrhythmic drugs and their classes

Answer 37

"Daring Paramedics Love Managing Potentially Fatal Episodes Since Patients Are Demanding Defibrillation Ventures Daily" D - Disopyramide P - Procainamide L - Lidocaine M - Mexiletine P - Propafenone F - Flecainide E - Esmolol S - Sotolol P - Propranolol A - Amiodarone D - Dronedarone D - Dofetilide V - Verapamil D - Diltiazem

Question 38

How many classes would amiodarone fit in?

Answer 38

Four - I, II, III, IV

Question 39

In what way is quinidine the opposite of digoxin?

Answer 39

It depresses myocardial contractility where digoxin increases it

Question 40

Lidocaine is effective for atrial tachyarrhythmia. True or false?

Answer 40

False. It affects ventricular re-entry only