Antiarrhythmics Flashcards
Class 2 antiarrhythmics
Beta blockers
Class 1 antiarrhythmics
Sodium channel blockers
Class 3 antiarrhythmics
Potassium channel blockers
Class 4 antiarrhythmics
Calcium channel blockers
Class 1a antiarrhythmics effect on heart
Sodium channel blockers Decrease conduction Increase refractory period Decrease automaticity - decrease slope of phase 4, fast potentials Increase threshold Quinidine has anticholinergic properties
Class 1a antiarrhythmics effect on ECG
Longer QRS, with or without long PR and long QT
Class 1a antiarrhythmics uses
Quinidine - maintain sinus rhythm in AF and flutter, to prevent recurrent tachycardia and AF
Procainamide - acute treatment of SV and ventricular arrhythmias
Quinidine
Class 1a antiarrhythmic
Oral or IV
Anticholinergic effect
Procainamide
Class 1a antiarrhythmic
Class 1a antiarrhythmics ADRs
Reduced CO Torsades de Points Dizziness, confusion, insomnia, seizure Lupus like syndrome GI
Class 1B antiarrhythmics effects on heart
Fast binding offset kinetics
No change in phase 0 in normal tissue (no tonic block), no ECG changes in these tissues
APD slightly decreases
Reduced phase 0 conductance in ischaemic or fast beating tissue
Increased QRS in these tissues
Class 1B antiarrhythmics uses
Acute VT and VF, especially during ischaemia
Not atrial or AV junctional arrhythmias
Lidocaine
Sodium channel blocker
Class 1B antiarrhythmic - IV only
Local anaesthetic
Phenytoin
Sodium channel blocker
Class 1B antiarrhythmic - oral
Anti epileptic
Class 1B antiarrhythmics ADRs
CNS- dizziness, drowsiness
Class 1c antiarrhythmic effects
Slow binding offset kinetics (>10s) Decreases phase 0 in normal tissue Decreases automaticity Increased threshold Increased APD Increased refractory period, especially in rapidly depolarising atrial tissue
Class 1c antiarrhythmic effects on ECG
Longer PR, long QRS, long QT
Class 1c antiarrhythmic uses
Super ventricular arrhythmias (fib and flutter)
Premature ventricular contraction
Wollf-Parkenson White
Flecainide
Class 1c antiarrhythmic
IV or oral
Propafenone
Class 1c antiarrhythmic
IV or oral
Class 1c antiarrhythmic ADRs
Proarrhythmic
Sudden death with chronic use
Increased ventricular response to supraventricular arrhythmias
CNS and GI
Class 2 antiarrhythmics effect
Beta blockers
Increase APD and refractory period in AVN, reduced AV conduction velocity
Class 2 antiarrhythmics effect on ECG
Longer PR interval
Lower HR
Class 2 antiarrhythmics uses
Sinus and catecholamine dependent tachyarrhythmias
Converting re entrant arrhythmias in AV
Protecting ventricles from high atrial rates
Propanolol
Beta blocker
Non selective
Oral or IV
Esmolol
Beta blocker
IV only
Class 2 antiarrhythmics ADRs
Bronchospasm
Hypotension
Class 2 antiarrhythmics contraindications
Ventricular failure
Partial AV block
Class 3 antiarrhythmics effects
Potassium channel blockers
Amiodarone
Potassium channel blocker
Amiodarone pharmacokinetics
Oral or IV
T1/2 3 months
Very lipid soluble - large volume of distribution
Amiodarone effects on heart
Increased refractory period Increased action potential duration Increased threshold Decreases phase 4 Decreased AV conduction speed
Amiodarone uses
Effective in most arrhythmias
Wolff Parkenson White
Amiodarone ADRs
Hepatic injury Pulmonary fibrosis Thyroid disease Increased LDLs Photosensitivity leading to sunburn Crystals laid down in eyes
Sotalol
Potassium channel blocker
Sotalol administration
Oral
Sotalol effects
Slow phase 4
Increased APD, refractory period in atrial and ventricular tissue
Slows AV conduction
Lengthens QT, decreases HR
Sotalol uses
Wide spectrum
SVT
VT
Sotalol ADRs
Insomnia
Fatigue
Proarrhythmic
Class 4 antiarrhythmics effects
Slow AV conduction
Increase refractory time in AVN
Increase slope of phase 4 in SA to slow HR
ECG shows longer PR, heart rate up or down depending on baroreceptor reflex
Class 4 anti arrhythmics uses
Control ventricles during SVT Convert SVT (reentry around AV)
Class 4 anti arrhythmics ADRs
GI
Caution in hypertension, low CO or sick sinus
Diltiazem
Class 4 anti arrhythmics
Oral
Adenosine mechanism
Binds A1 receptor
Activates potassium currents in AVN and SAN, causing hyperpolarisation
Reduces APD
Decreases calcium currents, slowing AV conduction
Adenosine pharmacokinetics
Short T1/2 (few seconds)
Rapid IV bolus
Atropine mechanism
Muscarinic antagonist
Blocks vagal activity, increasing heart rate
Atropine uses
Vagal bradycardia
Digoxin mechanism in antiarrhythmics
Enhances vagal activity
Slows AV conduction and HR
Magnesium antiarrhythmic
Treatment of tachycardia resulting from long QT
Atenolol
Beta 1 selective beta blocker
Bisoprolol
Beta 1 selective beta blocker
Carvedilol
Mixed beta 1 alpha1 antagonist
Digoxin used
Rapid atrial fibrillation