Arrhythmia Drugs Flashcards
Anti-Arrhythmic Drug Classes
Class I: Na+ channel blockade
Class II: B-adrenergic receptor blocker
Class III: K+ DRK channel blockers
Class IV: Ca+2 channel blockers
Class I Subgroups
Class IA: moderate Na+ block (Increase in AP duration)
Class IB: mild Na+ block (Decrease in AP duration)
Class IC: marked Na+ block (No affect on AP)
Class IA Effects
- Increase AP duration (for reentrant Arrhythmias)
- Decrease slope of phase 4 (for automaticity arrhythmias)
- Increase threshold potentials (for automaticity arrhythmias)
Class IA Drugs
Quinidine
Procainamide
Disopyramide
Quinidine
- Class IA moderate Na+ block
- Flagship
- RISK OF TORSADES
- some GI distress
Torsades
Blockade of HERG K+ channels results in prolonged QT syndrome leading to Torsades and death
Procainamide
- Class IA moderate Na+ block
- LESS PRONOUNCED QT EXTENSION
- Fever/rash
- Mild ganglionic blocker
Disopyamide
- Class IA moderate Na+ block
- DECREASED CARDIAC INOTROPY
- can accumulate in renal dysfuncation leading to Torsades
Class IB Effects
- Decrease AP duration (for reentrant arrhythmias)
- Decrease slope of phase 4 (for automaticity arrhythmias)
- Increase threshold potentials (for automaticity arrhythmias)
Class IB Drugs
Lidocaine
Mexiletine
Lidocaine
- Class IB mild Na+ block
- ONLY IV INFUSION
- CNS side effects
Mexiletine
- Class IB mild Na+ block
- CAN BE ORAL
- CNS side effects
Class IC Effects
- NO effect on AP duration (for reentrant arrhythmias)
- Decrease slope of phase 4 (for automaticity arrhythmias)
- Increase threshold potentials (for automaticity arrhythmias)
Class IC Drugs
Flecainide
Propafenone
Flecainide
- Class IC marked Na+ block
- INCREASED RISK OF VENTRICULAR ARRHYTHMIAS
- CNS side effects
- Oral
Propafenone
- Class IC marked Na+ block
- WEAK B-BLOCKER
- CNS side effects
Class II Effects
- Decrease slope of Phase 4 depolarization (decrease automaticity)
- Block reentry by increasing effective refractory peroid (prolonged repolarization in AV node)
- Used for management of Supraventricular Arrhythmias
- Block catecholamine induces arrhythmias
Class II Drugs
-Propranolol
-Esmolol
-Metoprolol
-Timolol
-Acebatalol
(B-Blockers)
Class III Effects
- K+ DRK channel blocker
- Prolonged repolarization increases AP duration
- Effects reentrant arrhythmias
Class III Drugs
- Amiodarone
- Dronedarone
- Sotalol
- Dofetilide
- Ibutilide
Amiodarone
- Class I,II,III,IV effects
- Decreases sinus node firing, automaticity, reentrant circuits
- Vasodilation
- Negative Inotropy
- EFFECTIVE FOR VENTRICULAR AND SUPERVENTRICULAR TACHYARRHYTHMIAS
Amiodarone Side Effects
- 6hr absorption and 30-60day half-life
- Pulmonary and Cardiac toxicity
- Changes in thyroid function
- GI effects
- CNS Effects
- Torsades
Dronedarone
- Class III K+ blocker
- GI side effects
- NO TORSADES
- NO IODINE
Dofetilide
- Class III K+ blocker
- DANGEROUS TORSADES
- NO IODINE
Sotalol
- Class III K+ blocker
- B-BLOCKER
- TORSADES
Ibutilide
Boring, nothing here
Blaise Pascal on the Heart
“The heart has reasons that reason cannot know.”
Doesn’t that sum up Cardiology?
Class IV Effects
- Ca+2 channel blockers
- Decrease slope of phase 4 (for automaticity arrhythmias)
- Increase threshold potentials (for automaticity arrhythmias)
- Most active in nodes
- Increase refractory period
- Decrease conduction velocity
- Decrease heart rate
- Primary TX for AV nodal reentrant tachy
Class IV Drugs
- Diltizam
- Verapamil
Class IV Side Effects
- hypotension
- HF in patients with B-Blockers
Digoxin
- Decreases Na+-K+ ATP ase
- Used in HF to increase quality of life
- Enhances Vagal tone
- Used in Atrial ailments
- Termination at reentrant loops
Adenosine
- Rapid hyperpolarization
- VERY short half life (10 sec)
- Used to stop events and reset
- Acts on AV node
Let’s do this
http://m.youtube.com/watch?v=GPc7G0Cp91k
