Antiarrhythmic drugs Flashcards
What action do calcium channel blockers have on the heart?
Slows conduction through the AV node
For arrhythmias originating above the AV node
What is the hierarchy of pacemaker cells?
SAN
AVN
Bundle of his
purkynje fibres
What is the main sodium channel blocker that acts ONLY on ventricular action potentials?
Lidocaine
What are the main sodium channel blockers that acts on atrial and ventricular action potentials?
Procainamide
Quinidine
What can cause an arrhythmia?
Structural/ electrical remodelling
Haemodynamics
Endocrine issues
What is the definition of automaticity?
Spontaneous rhythmic depolarisation of cells in the conduction system
What are afterdepolarisations?
Oscillations during repolarisation
Can trigger sibsequent action potentials
Where do supraventricular arrhythmias originate?
In SAN, atrial myocardium or AVN
Where do ventricular arrhythmias originate?
Bundle of His
Purkynje system
Ventricular myocardium
What are class I antiarrhythmic drugs?
Sodium channel blockers
What are class II antiarrhythmic drugs?
Beta blockers
What are class III antiarrhythmic drugs?
Potassium channel blockers
What are class IV antiarrhythmic drugs?
Calcium channel blockers
What are the 3 main Na channel blockers?
Lidocaine
Procainamide
Quinidine
What is the main beta blocker?
Atenolol
What are the main potassium channel blockers?
Sotalol
Amiodarone
What is the main calcium channel blocker?
Diltiazem
What is quinidine used for?
Horses with atrial fibrillation
What is procainamide used for?
Supra/ventricular arrhythmias in small animals
What is lidocaine used for?
Life threatening ventricular arrhythmias
What do beta blockers do?
Reduce HR - slow conduction
Decrease heart contraction
Reduce spontaneous depolarization
What arrhythmia are beta blockers used for?
Arrhythmias mediated by sympathetic tone
What shouldnt you do/use beta blockers for?
Dont use in heart failure
Slowly wean
What do potassium channel blockers do?
Prolong refractory period and action potential duration
Suppress tachyarrhythmias
What are potassium channel blockers used for?
Supra/ventricular arrhythmias
What do calcium channel blockers do?
Reduce automaticity, slow AVN conduction, prolong refractory period
What are calcium channel blockers used for?
Supraventricular tachyarrhythmias eg. atrial fibrillation, atrial tachycardia
What is digoxin?
A parasympathomimetic
Decreases SAN firing
Slows AVN conduction
What is digoxin used for?
Atrial fibrillation
