Antiarrhythmics Flashcards
What is the mechanism of action of class IV antiarrhythmics?
Inhibits L-type calcium channels
Prolong refractory period of pacemaker cells, prolongs depolarization
What are the therapeutic uses of atenolol?
Substitute for propranolol when compliance is a problem
Supraventricular and ventricular tachycardias, atrial fibrillation
What are the therapeutic uses of diltiazem?
Sustained and non-sustained supraventricular arrhythmias
Atrial fibrillation
What is the mechanism of action of class II antiarrhythmics?
Inhibit beta adrenergic receptors
What are the pharmacological effects of beta blockers?
Blocks sympathetic stimulation
Increase conduction time
Decrease the discharge rate of the SA node
Decreases automaticity of subsidiary pacemakers
What is the mechanism of action of class III antiarrhythmics?
Inhibits K channels
Phase 3- decreased K influx, prolongs action potential, prolongs refractory period
What are the actions of quinidine on the autonomic nervous system?
Decreases parasympathetic tone
Enhances sympathetic tone
Alpha-adrenergic antagonist
How does mexiletine differ from lidocaine?
It is slowly metabolized by the liver and effective after being given PO
What are the therapeutic uses of lidocaine?
Ventricular tachyarrythmias (especially from ischemic myopathy)
How does procainamide differ from quinidine?
In the same class of antiarrhythmics
Has fewer effects on the autonomic system
Why are class IC antiarrhythmics not often used in veterinary medicine?
They are highly proarrhythmic
Digoxin belongs to which class of antiarrhythmics?
It does not fit into the class I-IV scheme
What class of antiarrhythmics does quinidine belong to?
Class IA
What is the mechanism of action of digoxin?
Increases vagal tone
What are the therapeutic uses of propranolol?
Decrease ventricular response in atrial fibrillation
Re-entrant supraventricular tachyarrhythmias
Digoxin-induced ventricular arrhythmias
Cats- arrhythmias due to thyrotoxicosis
What are the therapeutic uses of digoxin?
Chronic tx of supraventricular tachyarrhythmias
Atrial fibrillation in dogs
What are the therapeutic uses of esmolol?
Acute therapy of supraventricular tachycardia (super short acting)
Diltizaem and amlodipine belong to which class of antiarrhythmics?
Class IV
What are the therapeutic uses of procainamide?
Atrial tachyarrhythmias (ex. acute atrial fibrillation)
Ventricular tachyarrhythmias
True or false:
Amiodarone is considered to have lower efficacy compared to other antiarrhythmics.
False. It shares properties with all classes of antiarrhymics and is considered to have high efficacy.
Lidocaine belongs to which class of antiarrhythmics?
Class IB
What are the therapeutic uses of amlodipine?
Systemic hypertension in dogs and cats
What are the therapeutic uses of sotalol?
Arrhythmogenic right ventricular cardiomyopathy in boxers
Sustained refractory ventricular tachycardias, supraventricular tachycardias
Most effective at slow heart rates
What effect do both amiodarone and sotalol have on all cardiac tissue?
Increases the effective refractory period
