16 - Anti-arrhythmic drugs

Question 1

Arrhythmogenic mechanism:

pacemaker activity that originates anywhere tother than in the sinoatrial node

Answer 1

abnormal automaticity

Question 2

Arrhythmogenic mechanism:

conduction of an impulse that does not follow the defined path or reenters tissue previously excited

Answer 2

abnormal conduction

Question 3

ECG morphology of torsades de pointes:

Answer 3

polymorphic ventricular tachycardia, often displaying waxing and waning QRS amplitude

Question 4

Enumerate: Singh-Vaughan Williams Classification

Answer 4

• Class 1: sodium channel blockers
• Class 2: Beta-adrenoceptor blockers
• Class 3: potassium channel blockers
• Class 4: calcium channel blockers

Question 5

Action of Class 1 antiarrhythmics:

Answer 5

slow or block conduction in ischemic and depolarized cells and slow or abolish abnormal pacemakers;

use-dependent or state-dependent blockage of I_Na channels; some block I_k channels

Question 6

Enumerate: subdivision of group 1 antiarrhythmics and their effect:

Answer 6

• Group 1A prolongs the AP duration
• Group 1B shortens the AP duration
• Group 1C no effect on the AP duration

Question 7

Enumerate: Class 1A antiarrhythmics:

Answer 7

Disopyramide

Procainamide

Quinidine

DP the Quin!!!!

Question 8

Use of