Cardiac Arrhythmias Flashcards
What are the different classes of anti-arrhythmic drugs?
Class I - block Na+ channels
Class II - β-blockers
Class III - block K+ channels
Class IV - calcium channel blockers
What are the action of drugs used for abnormal action potential generation?
Decrease phase 4 slope in pacemaker cells
Raises threshold for action potential
What are the actions of drugs used for abnormal conduction of action potential?
Decrease conduction velocity
Increased effective refractory period so cell can’t be depolarised again
What causes arrhythmias to occur?
Automatic or triggered activity
Re-entry due to a scar, anatomy of AV node
WPW
What are examples of class IA anti-arrhythmics?
Quinidine
Procainamide
What are the effects of class IA ant-arrhythmics on cardiac activity?
Decreased conduction
Increased refractory period
Decreased automaticity
Increase threshold for action potential
What are the uses of class IA anti-arrhythmics?
Quinidine; maintains sinus rhythm in AF and atrial flutter, and prevents recurrence
Procainamide; acute IV treatment of SVT and ventricular arrhythmias
What are examples of class IB anti-arrhythmics?
Lidocaine
Mexiletine
What are the effects of class IB anti-arrhythmics on cardiac activity?
Slightly decreased ADP
Increase threshold for action potential
Decrease phase 0 conduction in fast beating or ischaemic tissue
What are some side effects of class IA anti-arrhythmics?
Hypotension - reduced CO Proarrhythmic - increased QT interval Dizziness, confusion, insomnia, seizure GI Sx Lupus-like syndrome
What is a use of class IB anti-arrhythmics?
Acute ventricular tachycardia
What are some side effects of class IB anti-arrhythmics?
CNS effects - dizziness, drowsiness
Abdo upset
What are some examples of class IC anti-arrhythmics?
Flecainide
Propafenone
What are the effects of class IC anti-arrhythmics on cardiac activity?
Decreased phase 0
Decreased automaticity
Increased APD
What are the used of class IC anti-arrhythmics?
Supraventricular arrhythmias - fibrillation and flutter
Premature ventricular contractions - ventricular ectopics
Wolff-Parkinson-White syndrome
What are some side effects of class IC anti-arrhythmics?
Pro-arrhythmic and sudden death - esp w/ chronic use and structural heart disease
Increase ventricular response to supraventricular arrhythmias - need to body IC AVN
CNS and GI effects
What are some class II anti-arrhythmics?
Propranolol
Bisoprolol
Metoprolol
Esmolol
What is the MOA of class II anti-arrhythmic drugs?
β-blockers
Increase refractory period in AV node to slow AV conduction
Decreases phase 4 depolarisation
What is the MOA of class III anti-arrhythmic drugs?
Prolongs depolarisation
Increases refractory period
What is the MOA of class IV anti-arrhythmic drugs?
Calcium channel blockers
Slows conduction through AV node
Increases refractory period in the AV node
What are class II anti-arrhythmic drugs used for?
Treat sinus and catecholamine dependent tachycardia
Wolff-Parkinson-White syndrome
Slows AV conduction to protect ventricles from high atrial rates
What are the side effects of class II anti-arrhythmic drugs?
Bronchospasm
Hypotension
What are some examples of class III anti-arrhythmic drugs?
Amiodarone
Sotalol
What is amiodarone used for?
Effective for most arrhythmias
What are some side effects of amiodarone?
Pulmonary fibrosis Hepatic injury Inc LDL Thyroid disease Photosensitivity
What is sotalol used for?
Supraventricular and ventricular tachycardia
What are some side effects of sotalol?
Proarrhythmic
Fatigue
Insomnia
What are some examples of class IV anti-arrhythmic drugs?
Verapamil
Diltiazem
What are some uses of class IV anti-arrhythmic agents?
Control ventricles in supraventricular tachycardia
What are some side effects of class IV anti-arrhythmic drugs?
Can get asystole if also using a β blocker
GI upset - constipation
What is the MOA of adenosine as an anti-arrhythmic drug?
Slows AV conduction
Activates K+ channels => hyperpolarisation => decrease Ca2+ current => inc refractory period
What is adenosine as an anti-arrhythmic used for?
Convert re-entrant supraventricular arrhythmias
Diagnosis of coronary artery disease
What is the MOA of ivabradine as an anti-arrhythmic?
Blocks funny current in sinus node
Therefore slows sinus node w/o affecting BP
What are some uses for ivabradine?
Reduce sinus tachycardia
Reduce HR in heart failure and angina - avoids BP drop
What is the MOA of digoxin?
Enhances vagal activity
Slows AV conduction and slows HR
What is digoxin used for?
Reduces ventricular rates in atrial fibrillation or flutter
What is the MOA of atropine?
Selective muscarinic antagonist
Blocks vagal activity to speed AV conduction and increase HR
What is a use of atropine?
Treats vagal bradycardia
What drugs are used in AF to control rate and rhythm?
Rate control:
Bisoprolol, verapamil, diltiazem
Rhythm control:
Sotalol, flecainide with bisoprolol, amiodarone
What drugs are used to treat WPW?
Flecainide
Amiodarone
What drugs are used in re-entrant SVT?
Acute (IV)
Adenosine, verapamil, flecainide
Chronic (oral) Bisoprolol, flecainide Sotalol Flecainide, procainamide Amiodarone
What drugs are used for ectopic beats?
First line: bisoprolol
Flecainide, sotalol, amiodarone
What drugs are used to treat sinus tachycardia?
Ivabradine
Bisoprolol, verapamil
