Cardiac Arrhythmias

Question 1

Understand the basic ways in which arrhythmias may occur

Answer 1

Disturbances with:
Pacemaker impulse formation
Contraction impulse conduction

Question 2

Explain the Vaughan-Williams classification of anti-arrhythmic drugs

Answer 2

Class 1 - Na+ channel blockers
Class 2 - B-blockers
Class 3 - K+ channel blockers
Class 4 - Ca2+ channel blockers

Question 3

Describe the method of action and ADRs of class 1 anti-arrhythmic drugs

Answer 3

1a e.g. quinidine, procainamide
1b e.g. lidocaine, mexiletine
1c e.g. flecainide, propafenone
MOA - decreases phase 0, increase ERP
ADRs - proarrhythmic --> toursades des pointes, VF, sudden cardiac death

Question 4

Describe the method of action and ADRs of class 2 anti-arrhythmic drugs

Answer 4

E.g. metoprolol
MOA - decrease sympathetic stimulation at nodes, decrease phase 4
ADRs - bronchospasm

Question 5

Describe the method of action and ADRs of class 3 anti-arrhythmic drugs

Answer 5

E.g. Amiodarone
MOA - elongate phase 3, increase ERP
ADRs - pulmonary fibrosis, hepatic injury, thyroid disease

Question 6

Describe the method of action and ADRs of class 4 anti-arrhythmic drugs

Answer 6

E.g. Diltiazem, verapamil
MOA - decrease nodal firing
ADRs - torsades des pointes, VF