Anti-Arrhythmics Flashcards
What do Class 1 anti-Arrhythmics act on?
Sodium channels
Class 1 AA’s are split according to how they affect the length of action potentials. What are the sub-groups?
1a: lengthens
1b: shortens
1c: stays the same
What are examples of 1a AA’s?
Quinidine
Procainamide
What effect does 1a have on cardiac activity?
Decreases conduction
Increases refractory period
Increases threshold
When is 1a used?
Maintains sinus rhythm in AF
Prevents tachycardia and fibrillation
What are ADRs of 1a?
Hypotension
Dizziness, confusion, insomnia
GI
What are examples of 1b?
Lidocaine
Phenytoin
What effects do 1b have on cardiac activity?
Increased threshold
Decreased phase 0 conduction in fast beating or ischaemic tissue
When is 1b used?
Ventricular tachycardia
What are ADRs of 1b?
Dizziness
Drowsiness
What are the effects of 1c on cardiac activity?
Increases threshold
Increased refractory period
When is 1c used?
Supra ventricular arrhythmias
Wolff-Parkinson-White syndrome
What are the ADRs of 1c?
Sudden death with chronic use
CNS and GI
What are class 2 agents?
Beta blockers
What are examples of class 2?
Propanolol
Acebutol
When are class 2 agents used?
Tachycardic arrhythmia
Protecting ventricles from high atrial rates
What are the ADRs of class 2?
Bronchospasm
Hypotension
Don’t use in partial AV block/ ventricular failure
What does class 3 do?
Block potassium channels
Prolong repolarization
What are examples of class 3?
Amiodarone
Sotalol
What are the cardiac effects of Amiodarone?
Increased refractory period
Increased threshold
Decreased AV conduction
What are the uses of Amiodarone?
Effective for most arrhythmias
What are the ADRs of Class 3?
Pulmonary fibrosis
Hepatic injury thyroid disease
Increased LDL cholesterol
What are the cardiac effects of Sotalol?
Increased refractory tissue
Slow AV conduction
What are the uses of Sotalol?
Supra ventricular and ventricular tachycardia
What are the ADRs of Sotalol?
Pro arrhythmia
Fatigue
Insomnia
What do class 4 agents do?
Calcium channel blocker
What are examples of class 4 agents?
Verapamil
Diltiazem
What are the cardiac effects of class 4 agents?
Slow AV conduction
Increased refractory period in the AV node
When are class 4 agents used?
Supra ventricular tachycardia
What are the ADRs of class 4 agents?
Caution with AV block
Caution with hypotension or decreased cardiac output
GI
How does adenosine work?
Binds to A1 receptors and activates potassium currents in SA node
Hyperpolarization
Decreases heart rate
Decreases calcium currents
How does Digoxin work?
Cardiac glycosides Enhances vagal activity Increases potassium currents, decreases calcium currents Increases refractory period Slows AV conduction and slows heart rate
When is Digoxin used?
Atrial fibrillation and flutter
What are the cardiac effects of atropine?
Block vagal activity to speed AV conduction and increased heart rate
What is atropine used for?
Vagal bradycardia
What is magnesium used to treat?
Tachycardia resulting from long QT
How can Arrhythmia come about?
Abnormal impulse generation
Abnormal conduction
After-depolarizations
Re-entry
