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What are the Causes of Arrythmia?
- -Abnormal generation of impulse
- Enhanced / ectopic pacemaker activity
- After-depolarization
- -Abnormal impulse conduction
- Re-entry
- Conduction block
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Name the types Antiarrhythmic drugs
- 1. Sodium channel blocker
- 2. Beta blocker
- 3. Prolonged repolarization
- 4. Calcium channel blocker
- Miscellaneous:
- Cardiac glycoside
- Adenosine
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Name the Anti arrhythmic drugs in Class one.
What are Class one drugs called?
- Type A:
- Quinidine, Procainamide, Disopyramide
- Type B:
- Lidocaine, Mexiletine, Phenytoin
- Type C:
- Flecainide, Propafenone
Membran stabilizing drugs.
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Name the Class II drugs
What are class II drugs?
CLASS II : Beta blockers :
Propranolol, Esmolol , Sotalol
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Name the Class III drugs
CLASS III : Agents widening APD : K channel blockers :
Amiodarone, Bretylium, Sotalol, Ibutilide
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Name the Class IV drugs
- CLASS IV : CCB :
- Verapamil, Diltiazem
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What is the Mechanism of Class IA drugs?
Open / activated Na+ channel blockers –moderate delay in channel recovery time
-They prolong ERP and APD (try to keep it inactivated longer)
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What are the actions of quinidine?
-It blocks the sodium channel and also potassium channel.
-It has anti-muscarinic and alpha blocking action.
- Is an inhibitor of Cytochrome P450
-It increases the concentration of Digoxin by displacing it from tissue binding sites and prevents its excretion.
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What are the Adverse effects of Quinidine?
- -Precipitate torsades de pointes by prolonging QT interval- Diarrhea, Cinchonism
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What is Procainamide?
What are its adverse effects?
Class I A
- -Has anti muscarinic action
- -Used in ventricular tachycardia
-Adverse effects: SLE like syndrome consisting of arthralgia and arthritis specially in slow acetylators.
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-Prominent anti-cholinergic activity.
-Approved only for ventricular arrhythmia (not a first line).
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CLASS IB : Lidocaine
What is its Mechanism?
What is its Toxicity?
What is it used for?
Block Na channels
- -High first pass metabolism – not given orally
- -Toxicity:Drowsiness, nystagmus, and seizures (Neurological)
-Used to treat Ventricular arrythmia and digoxin induced arrhythmias
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Class I C
What is it?
Name one and its uses.
Na channel blockers
-Have negative inotropic effect and high pro-arrhythmogenic potential – sudden death
-Flecainide: indicated for atrial fibrillation and refractory ventricular arrhythmia
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Name the Class II drugs.
What are their effects?
- They are the Beta Blockers.
- Metoprolol, Esmolol, Sotalol, Acebutolol
- -Prolonged AV conduction
- -Deminish Phase 4 (decrease automaticity)
- - Used in Post MI and prophylaxis and SVT
- -Sotalol used in Life threatening ventricular arrythmias
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Name the Class III drugs effect
- -It blocks K channels
- -Inhibit Ca channels
- -Block inactivated Na channels
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What is Amiodarone and what are its adverse effects?
It is a class III drug
Adverse effects:
- -Pulmonary fibrosis, Hepatotoxicity
- -Skin pigmentation, Corneal deposits
- -Interferes with the thyroid function
- -Risk of rhabdomyolysis, which can lead to kidney failure or death, when simvastatin is used with amiodarone.
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What are Dofetilide and Ibutilide?
What do they cause?
What is special about them?
They are Class III K channel blockers
Artial flutter and fibrillation
Can reduce the hearts rythm in 30 mins
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