4-ANTIARRHYTHMIC DRUGS
CARDIAC ARRHYTHMIAS
• All arrhythmia Result From
• 2-Abnormalities of impulse formation
• 2-Abnormalities of impulse conduction.
• 3-Both.
Types of arrhythmia :
1. Sinus tachycardia.
2. Sinus bradycardia
3. Extra systoles
4. Atrial flutter
5. Atrial fibrillation
6. Paroxysmal atrial tachycardia
7. Paroxysmal ventricular tachycardia
8. Ventricular fibrillation
9. Heart block
8. Bundle branch block
N.B.
Wolf-Parkinson-White Syndrome (WPW):
• accessory atrioventricular pathway which conduct more
ANTIARRHYTHMIC DRUGS
• Non-pharmacological treatment are preferred because:
• 1-Arrhythmogenic effect of the drugs used in treatment of
arrhythmias.
• 2-Efficacy of these methods.
Non Pharmacological techniques
• Ablation technique..
• Implantable cardiovector defibrillator .
• Artificial pacemaker.
A-Mechanistic Classifications
CLASS I (SODIUM CHANNEL BLOCKERS)
Ia:
Ib:
Quinidine
Lidocaine
CLASS II (BETA-BLOCKERS)
CLASS III (POTASSIUM CHANNEL BLOCKERS)
Amiodarone
CLASS IV
• Calcium channel blockers e.g. verapamil, diltiazem( not nifidipine cus it will caus reflex
sympathetic stimulation )
• Potassium channel openers ( indirect C.C.B) e.g. adenosine
B-Therapeutic Classification of Antiarrhythmic Drugs
• Supraventricular arrhythmias:
verapamil
digoxin
beta-blockers
• Ventricular arrhythmias:
Lidocaine
• Supraventicular and ventricular arrhytmias:
Amiodarone
Quinidine
CLASS Ia ANTIARRHYTHMICS
QUINIDINE.
• Pharmacodynamics
Fast sodium channels blocker
atropine like action
alpha receptor blocking effect
Pharmacological Effects
Effects on the cardiovascular system
Cardiac effects
-ve inotropic effect.
↓ excitability
↓ automaticity
ENHANCE conductivity in the A-V node ( cus it has atropine like
effect) and bundle of His
^ this effect is dangerous can cause paradoxical techacardiya causin death
Effect on blood vessels and BP:
vasodilatation
hypotension with large dose
Therapeutic Indications
Atrial fibrillation (of less than 6 months duration).
Patient should be digitalized before quinidine?
to prevent the possible occurrence of "Paradoxical tachycardia".
Atrial flutter
less active than in atrial fibrillation
can be used when digitalis fails.
Paroxysmal atrial tachycardia.
Extrasystoles. Atrial and ventricular.
Ventricular tachycardias.
Maintenance of sinus rhythm
after successful direct current cardioversion.
Side Effects and Toxicity
1.
2.
3.
4.
5.
6.
Idiosyncrasy : abnormal individual response
Cinchonism: ‫ حس إن أجراس تدق باذنه وجاي من اسم الشجرة‬ringing of the ear
Embolism
Paradoxical tachycardia.
Quinidine syncope.
Hypotension: particularly if given intravenously.
Precautions before giving QUINIDINE
1- @ 1st give testing dose
2-digoxin (digitalize the heart)
3-give anti coagulant
4-u shouldn't give QUINIDINE for Old standing atrial fibrillation
( AF) more than 6 months
Contraindications
1.
2.
3.
4.
5.
6.
Complete A.V block
Old standing atrial fibrillation.
Congestive heart failure.
Hypotension.
Hypersensitivity.
Myasthenia gravis.
PROCAINAMIDE
Pharmacological Effects
Similar to quinidine
It has
weak anticholinergic effects.
has a ganglion blocking effect.
It doesn’t have alpha blocking activity
Therapeutic Uses
more in Ventricular arrhythmias
CLASS Ib ANTIARRHYTHMICS
LIDOCAINE**
the least cardio toxic of antiarrhythmic
Therapeutic Uses
Ideal drug for treatment of ventricular arrhythmias .
*Given IV only
PHENYTOIN (DIPHENYLHYDANTOIN, DPH)
1-treating epileptic seizures
2-ventricular arrhythmias.
• ADVERSE EFFECTS
GUM HYPERPLASYIA
gingival hyperplasia
CLASS II
BETA-ADRENOCEPTOR BLOCKERS
‫يستعمل في حاالت معينة‬
Therapeutic Uses : Supraventricular arrhythmias
drug of choice for chest pain and arrhythmias of mitral valve prolapse
CLASS III
AMIODARONE* ‫سؤال عن هذا الدواء‬
‫*ال يخلو امتحان من‬
• POTASSIUM CHANNEL BLOCKERS
• Broad-spectrum antiarrhythmic drug ( all types of arrhythmia )
Adverse Effects
1.
Corneal microdeposists
2.
disturb thyroid function
3.
photosensitivity
4.
pulmonary fibrosis
5.
myopathy
6.
peripheral neuropathy
7.
hepatotoxicity
CLASS IV
CALCIUM CHANNEL BLOCKERS
verapamil and diltiazem
• MECHANISM OF ACTION: delaying conduction in A.V node
OTHER ANTIARRHYTHMICS
DIGOXIN: Delay conduction in A.V node
ADENOSINE
MAGNESIUM SULFATE
• ELECTRIC SHOCK THERAPY
•
Direct current electric shock will depolarize the heart , then S.A node will work , after that
give quinidine
CLINICAL APPLICATIONS OF ANTIARRHYTHMIC DRUGS
Atrial Fibrillation
• Emergency Treatment
Digitalis IV is the drug of choice.
Cardioversion
• Non-emergency Treatment
Digitalis is given orally.
Quinidine
Atrial Flutter
• Emergency Treatment
Cardioversion
I.V. digitalis
• Non-Emergency Treatment
Digitalis is given orally
Wolf-Parkinson-White (WPW) Syndrome
• Amiodarone ,sotalol
• Cardioversion.
Junctional Tachycardias
• Vagotonic maneuvers ..( stimulate vagal nerve)
• I.V. verapamil
• ADENOSINE
Ventricular Tachycardia
• Emergency Treatment
• Lidocaine ( IV) is the first choice
• I.V. amiodarone
• Cardioversion
• Prophylaxis
• I.V. drips quinidine (72 hrs)
• Oral quinidine should be continued for at least 3 months
especially if there is acute myocardial infarction.
Torsade de pointes
MAGNESIUM SULFATE
Artificial pacemaker
Ventricular fibrillation
Lidocaine
procainamide
amiodarone
Bradyarrhythmias and Heart Block
Cardiac pacemaker
Atropine I.V. .
Hydrocortisone I.V. ( if there’s inflammation in conducting tissue)