Cardiac Drugs Flashcards
Name a class II drug
Propranolol, atenolol; beta-blockers
What is a class IA drug?
Procainamide, quinidine, disopyramide
Decrease conduction and automaticity and increase threshold and refractory period.
Name the 4 mechanisms of generating arrhythmias
Automatic
Triggered
Conduction block
Re-entrant
What is the rationale and goal when prescribing anti-arrhythmic drugs?
Restore sinus rhythm and prevent further issues.
What are the effects of Class II cardiac drugs?
Decrease phase 4 depolarisation (catecholamine dependant)
Increase acute phase depolarisation and refractory period in AV node to slow AV conduction velocity.
Increase PR interval and decrease heart rate.
What conditions would Class II drugs be prescribed for?
Treating sinus and catecholamine tachycardia
Converting re-entrant arrhythmia at AV node
Slow AV conduction in AF or flutter- preventing ventricles from doing the same.
What are the side effects of Class II drugs?
Bronchospasm
Hypotension
Not used in partial AV block or acute HF
What is a class 1B agent?
Lidocaine, mexiletine
increased threshold and decrease phase 0 in fast beating /ischaemic tissue
Used for VT
What is a class 1C drug?
Flecainide and propafenone
Decrease phase 0 in normal tissue and automaticity
increase APD and refractory period in rapidly depolarising atrial tissue
What class is amiodarone and how does it work?
Class III
Increase refractory period, apd and threshold
Decrease phase 0 and conduction, decrease phase 4 and AV conduction speed.
What class is sotalol and how does it work?
Class III
Increases APD and refractory period in atrial and ventricular tissue
Slow phase 4 and AV conduction
Name a class IV agent and how they work?
Slow conduction through AV
Increase refractory period in AVN and slope of phase 4 SAN to slow HR
What is the effect of atropine?
Blocks vagal activity to speed AV conduction and increase HR.
What is the mechanism of action of digoxin?
Enhances vagal activity, slows AV conduction and HR.
What is the mechanism of action of ivabradine?
Blocks funny current expressed in the SAN - no effect on blood pressure.
What is the mechanism of action of vernakalant?
Blocks atrial specific potassium channels and therefore slows atrial conduction and increases in potently with higher heart rates.
What is the mechanism of action of adenosine?
Binds A1 receptors and activates potassium currents in AV and SA node. Decreased APD and causes hyperpolarization - decreasing heart rate.
Decreases calcium currents and therefore increases refractory period in AVN.
What are the side effects of a class 1a drug?
Hypotension Proarrhythmia GI upset Lupus like syndrome High dose induces Dizziness/confusion/ insomnia/seizure
What are the side effects of a class 1b drug?
Abdominal upset
CNS effects like dizziness and drowsy
What are the side effects of 1c agents?
Pro arrhythmias
CNS and gastro effects
Increased ventricular response to SVT
What are the side effects of soltalol?
Proarrythmia
Fatigue
Insomnia
What are the side effects of amiodarone?
Pulmonary fibrosis Hepatic injury Increased LDL Thyroid disease Photosensitivity Optic neuritis
What side effects and cautions are there for class 4 drugs?
GI upset
Caution:
Partial AV block - with a beta blocker leads to asystole
Hypotension, decreased CO and sick sinus
