Treatment of Arrhythmias

Question 1

What 3 factors contribute to the spontaneous electrical discharge of the SAN?

Answer 1

o Decrease in K+ outflow
o “funny” Na+ current
o Slow inward Ca2+ current

Question 2

Which area of the heart are atrial dysrhythmias associated with?

Answer 2

Supraventricular

Question 3

Which area of the heart are junctional dysrhythmias associated with?

Answer 3

AV node

Question 4

What are the 4 broad categories of event that dysrhythmias usually arise from?

Answer 4

Heart block
After depolarisations (early or delayed)
Circuit re-entry
Ectopic pacemaker activity

Question 5

Which class of arrhythmia treatment do potassium channel blockers belong to?

Answer 5

Class 3

Question 6

Which class of arrhythmia treatment do calcium channel blockers belong to?

Answer 6

Class 4

Question 7

Which class of arrhythmia treatment do sodium channel blockers belong to?

Answer 7

Class 1

Question 8

Which class of arrhythmia treatment do beta-adrenoreceptor channel blockers belong to?

Answer 8

Class 2

Question 9

Sotalol

Answer 9

Class 2

Question 10

Verapamil

Answer 10

Class 4

Question 11

Disopyramide

Answer 11

Class 1a

Question 12

Flecainide

Answer 12

Class 1c

Question 13

Amiodarone

Answer 13

Class 3

Question 14

Lignocaine

Answer 14

Class 1b

Question 15

What are the two important arrhythmia treating drugs that are ‘unclassified’?

Answer 15

Adenosine

Digoxin

Question 16

What type of dysrhythmias are very effectively tackled by verapamil?

Answer 16

SVT

AF

Question 17

How does diltiazem differ from verapamil?

Answer 17

Diltiazem has a greater effect on smooth muscle calcium channels

Question 18

Think back to the different phases of heart muscle contraction:

Phase 0: rapid depolarisation (F-type Na+ open)
Phase 1: partial repolarisation (F-type Na+ close)
Phase 2: plateau (Ca2+ open)
Phase 3: repolarisation (Ca2+ close, K+ open)
Phase 4: stable (pacemaker potential)

Which phases do each of the classes of anti-arrhythmic drugs target?

Answer 18

CLASS 1: Phase 0 (rapid depolarisation)

CLASS 2: Inhibit action of beta agonists, which act on Phase 2 (plateau) and Phase 4 (pacemaker potential)

CLASS 3 & 1a: Phase 3 (repolarisation)

CLASS 4: Phase 2 (plateau)

Question 19

NOTE:

Answer 19

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