Antiarrythmia Drugs Flashcards
Molecular mechanism of action of Lidocaine (aka Lignocaine)?
Inactivates voltage gated Na+ channels
What tissues/organs does Lidocaine/Lignocaine act on?
Nerves, cardiac muscle
What physiological effects does Lidocaine/Lignocaine have on the body?
Decreases conduction in excitable tissue
Potential side effects of Lidocaine/Lignocaine?
CNS activation/depression, hypotension
What type of anti-arrhythmic drug increases the negative inotropic effect of beta blockers?
Lidocaine/Lignocaine
Mnemonic for Class I-IV anti-arrhythmic drugs?
“NaB a Pot (of) Milk”
- Na+
- Beta blockers
- K+
- CCB’s
Example of Class 1 anti-arrhythmic drug?
Class I (Na+ channel blockers) = Flecainide
Example of Class 2 anti-arrhythmic drug?
Class 2: Beta blockers: Atenolol
Example of Class 3 anti-arrhythmic drug?
Class 3: K+ channel blockers
Amiodarone
Dronedarone
Example of Class 4 anti-arrhythmic drug?
Class 4: CCB
Verapamil
Lignocaine (Class 1b antiarrythmic drug) has what type of effect on action potential duration?
Shortens AP duration
Flecainide (Class 1c anti-arrhythmic drug) has what type of effect on action potential duration?
No effect on AP duration
Class 1 antiarrythmics… the faster the heart rate, the ________ the block.
Greater
(So they inhibit tachycardias, but allow normal heart rates)
Which anti-arrhythmic drug is indicated for paroxysmal (intermittent) AF?
Flecainide (Na+ channel blocker)
What is the drug of choice in WPW syndrome?
Flecainide (Na+ channel blocker)
What is the main contraindication for Flecainide?
Established IHD
What investigation should be ordered after starting a patient on Flecainide? (Or changing the dose?)
ECG- Can cause QT prolongation
List 4 main side effects of Flecainide
- QT prolongation (pro-arrhythmia)
- Increases pacing threshold (ie pacemaker needs to deliver more energy to activate contraction)
- Dizziness
- Blurred vision
Class Ic antiarrhythmic agent used to manage atrial fibrillation and paroxysmal supraventricular tachycardias
Flecainide
Common indications for this class II antiarrythmic drug include AF (reduces the ventricular rate, and in paroxysmal AF, to maintain sinus rhythm), and supraventricular tachycardia to restore sinus rhythm
Atenolol (Beta blocker)
MOA of Atenolol?
Act via Beta-1 adrenoreceptors in the heart to reduce force of cardiac contraction and speed of conduction
Contraindications/warnings for Atenolol?
Avoid in asthma
NEVER GIVE BETA BLOCKERS TO SOMEONE IN ACUTE HEART FAILURE! Contraindicated in heart block and severe hypotension
Common adverse effects of Atenolol
Fatigue, cold extremities, HA, GI upset
Drug treatment recommended for management of ectopic beats?
Low dose beta-blocker such as Propranolol
Class 1c anti-arrythmics such as ____________ and beta blockers can be used as second line management for __________________ (as they are less effective, but less toxic than Amiodarone)
Flecainide
Paroxysmal AF
Mechanism of action of Class III anti-arrythmic (Amiodarone)?
Potassium channel blocker
** Prolongs the action potential (QT PROLONGATION)
Stabilises ventricular and atrial myocytes. Slows AV node conduction. Blocks accessory pathways.
This class III anti-arrythmic is used in a wide range of sustained tachyarrhythmias including AF, atrial flutter, supraventricular tachycardia, VTach, and refractory Vfib. It is generally only used if other tx (drugs or electrical cardioversion) are ineffective or contraindicated
Amiodarone
Dronedarone
Contraindications/warnings for amiodarone
Severe hypotension
Heart block
Active thyroid disease