What is the mechanism of action for Vaughan Williams classification Class 1 antiarrhythmic drugs?
Inhibits voltage-gated sodium channels
What is the mechanism of action for Vaughan Williams classification class 2 antiarrhthmic drugs?
Beta blockers
What is the mechanism of action for Vaughan Williams classification class 3 antiarrhythmic drugs?
Inhibits voltage gated potassium channels- prolonging action potential by prolonging repolarization
What is the mechanism of action for Vaughan Williams classification class 4 antiarrhthmic drugs?
Calcium channel blockers (L-type)
True/False: ablations and implantable devises are more effective and less harmful in some ways than drug therapy.
True, they have largely relegated drug therapy to a secondary role
What are the three ways that antiarrhythmic drugs work?
By reducing automaticity of abnormal tissues
Prolonging refractoriness
Slowing conduction
According to the ACLS guideline, what is the main antiarrhythmic drug for cardiac arrest algorithm?
Amiodarone- indicated for v fib or pulseless v tach
What is an alternative drug to amiodarone in the cardiac arrest algorithm?
Lidocaine
Wha class does amiodarone fall in?
Class 3
Which channels do amiodarone have an effect in?
Moderate calcium, alpha and beta receptor blockage
Mild fast Na+ channel
Strong voltage-gated K+ channel
What is the major effect of amiodarone?
Block K+ voltage gated channel and phase 3 (repolarization) of cardiac cells
What is the drug half life of amiodarone?
25-60 days half life
How is amiodarone eliminated?
Hepatic metabolism and elimination
What are major adverse effects seen in amiodarone?
Pulmonary- pneumonia is leading to pulmonary fibrosis – often fatal
Thyroid issues
Elevated liver enzymes
Skin discoloration (irreversible)
What are some drug interaction with amiodarone?
Inhibits o-glycoprotein and certain CYP450 enzymes causing high plasma levels of other drugs which are metabolized by those CYP450 enzymes or substrates of p-glycoprotein
What is the second line of drug in cardiac arrest algorithm?
Lidocaine
What does the stem -Caine tell you about the drugs mechanism of action?
Blocks Na+ channel
True/False: lidocaine can be given orally, IV and topically for cardiac arrhythmia
False; only IV bolus for cardiac arrhythmia
What class of Vaughan Williams classification does lidocaine belong to?
Class I
What is the preferred drug for bradycardia with a pulse?
Atropine
What is the mechanism of action for atropine?
Anticholinergic- blocks muscarinic receptors (M2)
How does atropine affect the heart?
Increase HR and AV nodal conduction
What is the first line drug for tachycardia with a pulse and no wide QRS?
Adenosine
Beta blockers
Calcium channel blockers
What is the half life for adenosine?
10 second half life
How does adenosine affect the heart?
Decrease HR
Decrease AV nodal conduction
Which ion channel does adenosine block?
L type calcium channels
What are alternative drug to adenosine?
Verapamil (L type calcium channel blocker)
Diltiazem (L type calcium channel blocker)
How does calcium channel blockers affect the heart?
Decrease contractility
Decrease heart rate
Decrease conduction velocity
How does calcium channel blocker affect vasculature?
Smooth muscle relaxation (vasodilation)
What does the stem -dipines have in common?
They are calcium channel blockers
Arterial vasodilator
Are versatile and diltiazem a dihydropyridine?
No
What are some dihydropyridines?
Nicardipine
Nifedipine
Amlodipine
What are the preferred drugs when there is a widen QRS in tachycardia with a pulse?
Procainamide
Amiodarone
Sotalol
What is the drug of choice for ventricular tachycardia?
Amiodarone
What are alternatives of amiodarone for treatment of ventricular tachycardia?
Class 1A agent: procainamide
Class 3 agent: sotalol
What are amiodarone good for?
Cardiac arrest (v fib)
Ventricular tachycardia
How is procainamide given?
IV and IM
Why isn’t oral procainamide available?
Had potential to cause drug induced lupus syndrome
What is the classification for sotalol?
Class III - voltage gated potassium channel blocker
What is an adverse effect of sotalol?
Proarrhythmia – induce v tach and v fib
True/False: sotalol has beta blocking ability
True
How does Torsades de Pointes rhythm occur?
Can be induced by drugs – prolonged QT intervals
What are the two class 3 antiarrhythmic drugs we learned?
Amiodarone
Sotalol
If QT interval becomes too prolonged with Class 3 K+ blockers, what could result?
Torsade de pointes – V tach and turn into V fib
If patient already has QT, should you give Class 3 drugs?
No!
Patients who have hypokalemia and hypomagnesia, what could result if given class 3 drugs?
Torsade de pointes
How to treat torsade de pointes?
Magnesium
Which drug to treat atrial tachycardia/SVT?
Adenosine
Verapamil
Diltiazem for a-fib
Which drugs to treat bradycardia?
Atropine
Dopamine
Epinephrine
Which drugs to treat V-tach/V-fib?
Amiodarone
Lidocaine
Procainamide
Sotalol
Magensium sulfate
List two class 1 drugs:
Procainamide
Lidocaine
List two class 3 drugs:
Amiodarone
Sotalol
List two class 4 drugs:
Verapamil
Diltiazem
Which class of drug are the beta blockers?
Class II
What class does atropine belong to?
None, they are not classified as they are anticholinergic drug
What is an antiarrhythmic effect of atropine?
It is used to treat bradycardia via anticholinergic effect thereby raising HR
