What are the Causes of Arrythmia?
- -Abnormal generation of impulse
- Enhanced / ectopic pacemaker activity
- -Abnormal impulse conduction
- Conduction block
Name the types Antiarrhythmic drugs
- 1. Sodium channel blocker
- 2. Beta blocker
- 3. Prolonged repolarization
- 4. Calcium channel blocker
- Cardiac glycoside
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.
Name the Class II drugs
What are class II drugs?
CLASS II : Beta blockers :
Propranolol, Esmolol , Sotalol
Name the Class III drugs
CLASS III : Agents widening APD : K channel blockers :
Amiodarone, Bretylium, Sotalol, Ibutilide
Name the Class IV drugs
- CLASS IV : CCB :
- Verapamil, Diltiazem
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)
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.
What are the Adverse effects of Quinidine?
- -Precipitate torsades de pointes by prolonging QT interval- Diarrhea, Cinchonism
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.
-Prominent anti-cholinergic activity.
-Approved only for ventricular arrhythmia (not a first line).
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
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
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
Name the Class III drugs effect
- -It blocks K channels
- -Inhibit Ca channels
- -Block inactivated Na channels
What is Amiodarone and what are its adverse effects?
It is a class III drug
- -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.
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