02 - anti-arrythmics

Question 1

1. how do class 1 anti-arrhythmics work?

Answer 1

1. inhibit fast sodum channels -> inhibit rate of spontaneous depolarization

Question 2

(lidocaine)

1. what class?
2. drug of choice to treat what?

Answer 2

1. class 1
2. life-threatening ventricular arrythmias

Question 3

(procainamide)

1. what class?
2. prolongs refractory period in both the atria and ventricles, decreases myocardial excitability, anticholinergic effects
3. used when?

Answer 3

1. class 1
2. used IV for lidocaine-refractory ventricular arrythmias

Question 4

(mexilitene)

1. what class?
2. what is it?

Answer 4

1. class 1
2. oral version of lidocaine for dogs

Question 5

(quinidine)

1. what class?
2. prolongs duration of action potential and refractory period in both atria and ventricle
3. indication?

Answer 5

1. class 1
2. atrial fibrillation

Question 6

(beta blockers - class II)

1. mechanism?

Answer 6

1. adrenergic receptor antagonists

(adrenergic = adrenaline -> so this will slow things down a little)

Question 7

(propranolol)

1. what class?
2. best for what?

Answer 7

1. beta blockers - class II
2. supraventricular arrythmias

Question 8

(atenolol, metoprolol, esmolol)

1. what class?
2. best for?
3. what is the drug of choice for feline arrhythmias?

Answer 8

1. beta blockers - class II
2. supraventricular arrhythmias
3. atenolol

Question 9

(class III - anti-arrhythmics)

1. mechanism?
2. greatest effect where in heart?

Answer 9

1. block K channels -> prolong refractory period, ^ duration of action potential
2. ventricular muscle

Question 10

(solatol)

1. what class?
2. indication?

Answer 10

1. combo of class II and class III
2. refractory ventricular arrythmias

Question 11

(amiodarone)

1. what class?
2. mech of action?
3. reserved for what?

Answer 11

1. class III
2. structural analogue of thyroid hormone
3. refractory ventricular tachycardia

Question 12

(calcium channel blockers - class IV)

1. mechanism?

Answer 12

1. block influx of calcium through through slow calcium channels during plateau of action potential

Question 13

(Diltiazem)

1. what class?
2. incidations?

Answer 13

1. class 4
2. supraventicular tachyarrhythmias, hypertrophic cardiomyopathy

Question 14

(verapamil)

1. what class?
2. greatest effect on what?

Answer 14

1. class 4
2. effect on AV node (increased refractory period, decreased automaticity and AV conduction)