AntiArrhythmics Flashcards
What are Class I Na Channel Blockers?
Class of drugs that inhibit Na influx through cell membranes, slowing depolarization, decreasing cell excitability, and decreasing conduction velocity.
What is the most common Class IA Na Channel Blocker?
Procainamide
What effects does Procainamide have?
- Depresses conduction
- Prolongs refractory period
- Vagolytic
- Negative inotropy
- Increases PR interval and QRS interval
- Increases QTc by 30% or 0.5 seconds
What are the indications for Procainamide?
- Ventricular tachycardia
- PVCs
- Atrial fibrillation
What is the metabolism process for Procainamide?
Acetylation results in the formation of N-acetylated procainamide (NAPA), which also has antiarrhythmic effects.
What cautions should be noted for Procainamide?
- Trimethoprim may increase NAPA levels
- Contraindicated in complete heart block
- Long term use may lead to positive nuclear antibody test (ANA) and SLE symptoms
What are some adverse reactions associated with Procainamide?
- Hypotension
- Arrhythmia
- Vomiting
- Neutropenia
- Lupus-like syndrome (positive ANA test)
What is the mechanism of action for Class IB Na Channel Blockers?
Acts rapidly, high affinity for open and inactivated Na channels with rapid unbinding during diastole, affecting QRS minimally.
What is the most common Class IB Na Channel Blocker?
Lidocaine
What is the primary effect of Class IC Na Channel Blockers?
Slows conduction in cardiac tissue by altering transport across fast Na channels.
What is the most common Class IC Na Channel Blocker?
Flecainide
What are the indications for Flecainide?
- Prevention of ventricular tachycardia
- Suppression of SVT
- Effective against reentry SVT, flutter, fibrillation, WPW
What are the cautions for using Flecainide?
- Contraindicated in complete heart block
- Can increase digoxin levels
- Use with beta blockers may cause negative inotropic effect
What is the mechanism of action for Class II Beta Blockers?
Blocks stimulus to beta 1 and beta 2 adrenergic stimulation.
What is the most common non-selective beta blocker?
Propranolol
What are the side effects of Propranolol?
- Hypotension
- May potentiate Ca channel blockers
What distinguishes Atenolol from other beta blockers?
More selective for beta 1 receptor competitive block.
What is the half-life of Esmolol?
10 minutes
What is the primary use of Sotalol?
Treatment of SVT and VT in neonates and infants.
What is the primary action of Class III K Channel Blockers?
Inhibit potassium efflux through cell membranes, prolonging action potentials and repolarization.
What are the properties of Amiodarone?
- Possesses properties of all 4 classes of antiarrhythmics
- Slows conduction
- Beta blocking activity
- Ca channel antagonist
What are the major side effects of Amiodarone?
- Bradycardia
- AV block
- Pulmonary fibrosis
- Torsades de Pointes
What is the mechanism of action for Adenosine?
Vagotonic, depresses Ca influx, increases K conductance, slows AV node conduction.
What is the half-life of Adenosine?
10 seconds
