5.1.3 Class II, III, IV Anti-arrhythmics

Question 1

Give some examples of Class II drugs and how they are taken

Answer 1

Propanolol- Oral/IV
Metoprolol- Oral/IV

Bisoprolol-Oral
Esmolol- IV only (very short acting T1/2)

Question 2

Why is esmolol IV only?

(Important hence why questioned again)

Answer 2

Very short acting, so you want it straight into blood stream

Question 3

What are the cardiac effects of Class II drugs?

Answer 3

Increased AP duration and refractory period in AVN to slow AV conduction velocity

Decreased phase 4 depolarisation

Question 4

ECG effects of Class II drugs?

Answer 4

Increased PR
Decreased HR

Question 5

What do you use Class II for?

Answer 5

Treating sinus and catecholamine dependent tachycardia

Converting re-entrant arrhythmias at AVN

Protecting the ventricles from high atrial rates in atrial flutter of atrial fibrillation

Question 6

What are the side effects of Class II drugs?

Answer 6

BLOCKER

Bronchospasm
Lethargy
Heart block
Erectile dysfunction
Raynauds

Mask tachycardia- compensatory
Hypotension

Question 7

When are Class II drugs not used?

Answer 7

Asthma
COPD
Liver failure
Partial AV block or acute heart failure

Question 8

What are some examples of Class III agents?

Answer 8

Amiodarone
Sotalol

Oral or IV

Question 9

What are the cardiac effects of Class III?

Answer 9

Decreased speed of AV conduction
Decreased phase 0 and conduction
Increased threshold
Increased AP duration
Increased refractory period
Decreased phase 4 (beta blocker and calcium blockers)

Question 10

What are the effects on ECG with Class III drugs?

Answer 10

Increased PR
Increased QRS
Increased QT
Decreased HR

Question 11

When do you use Amiodarone?

Answer 11

Very wide spectrum, effective for most arrhythmias

Question 12

What are the side effects of Amiodarone?

Answer 12

Pulmonary fibrosis
Hepatic injury
Increased LDL
Thyroid disease
Photosensitivity
Optic neuritis

Question 13

Why do you administer amiodarone in large veins?

Answer 13

Can cause thrombophlebitis therefore need to use a large vein

Question 14

What can cause torsade de pointes?

Answer 14

Prolonged QT

Question 15

How is sotalol taken?

Answer 15

Oral

Question 16

What are the cardiac effects of Sotalol?

Answer 16

Increased AP duration and refractory period in atrial and ventricular tissue

Slow phase 4 (as also a b blocker)

Slow AV conduction

Question 17

What are the ECG effects of sotalol?

Answer 17

Increased QT
Decreased HR

Question 18

When do you use sotalol?

Answer 18

Wide spectrum, supraventricular and ventricular tachycardia

Question 19

What are the side effects of sotalol?

Answer 19

Proarrhythmia
Fatigue
Insomnia

Question 20

Give some examples of Class IV agents and how they are taken

Answer 20

Verapamil- Oral or IV
Diltiazem- Oral

Question 21

What are the cardiac effects of Class IV drugs?

Answer 21

Slows conduction through AVN

Increases refractory period in AVN

Increased slope of phase 4 in SAN to slow HR

Question 22

What ECG effects are there with Class IV drugs?

Answer 22

Increased PR
Increased/decreased HR depending on blood pressure response and baroreceptor reflex

Question 23

When are Class IV drugs used?

Answer 23

Control ventricles during supraventricular tachycardia

Convert Supraventricular tachycardia (re-entry around AV)

Question 24

What are the side effects of Class IV drugs?

Answer 24

Caution when partial AV block- can get asystole if B blocker is on board

Caution when hypotension, decreased CO or sick sinus

GI problems, constipation