Arrhythmia definition
Arrhythmia of the heart
Arrhythmia symptoms
Arrhythmia medication
Arrhythmia of the heart
Arrhythmia symptoms
Arrhythmia medication
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ARRHYTHMIA
Arrhythmia is disturbances in cardiac rhythm (i.e abnormality in site of origin of impulse, its rate, regularity or conduction).
Types of arrhythmia
1) Tachyarrhythmia :- Arrhythmia with increased heart rate
2) Brady arrhythmia :- Arrhythmia with decreased heart rate
Drugs used to restore normal rhythm are known as anti-arrhythmic drugs.
CLASSIFICATION
I (A) e.g :-quinidine , procanamide , disopyramide ,
I (B) e.g :- lidocaine , phenytoin , tocainide
I (C) e.g :- encainide , flecainide , propafenone
II beta-blockers- e.g :- propanolol , metaprolol , esmolol
III potassium-blockers e.g :- amiodarone , bretylium , sotalol
IV calcium channel blockers e.g :- verapamil , nifedepine , amlodepine
Class I anti arrhythmic agents have membrane stabilising properties this agents act on the fast sodium channels and interfere with the process by which the depolarisation occurs.
Class I A have intermediate affinity for sodium channel.
Class I B have least affinity for sodium channel and dissociate rapidly.
Class I C agents have highest affinity for sodium channel and dissociate slowly.
The first line drugs used in treatment of -
TSVT (peroxy/prophylactic supra ventricular tachycardia - adenosine , verapamil
AV block - atropine
Atrial extra systole - quinidine
Atrial flutter or atrial fibrillation - verapamil
Ventricular extra systole or ventricular trachycardia - lidocaine
Wolf - parkinson's white syndrome - amipdarone or flecanide
TSVT (peroxy/prophylactic supra ventricular tachycardia - adenosine , verapamil
AV block - atropine
Atrial extra systole - quinidine
Atrial flutter or atrial fibrillation - verapamil
Ventricular extra systole or ventricular trachycardia - lidocaine
Wolf - parkinson's white syndrome - amipdarone or flecanide
ARRHYTHMIA SYMPTOMS
It includes -
Chest pain
Dizziness
Fainting
Light headedness
Palpitation or slow heart rate
Shortness of breath
Chest pain
Dizziness
Fainting
Light headedness
Palpitation or slow heart rate
Shortness of breath
ARRHYTHMIA MEDICATION/PHARMACOLOGY OF ANTI-ARRHYTHMIC DRUGS
QUINIDINE :- It is an alkaloid obtained from cinchona bark, it has direct cardiac depressant, anticholinergic and alpha adrenergic blocking effects.
PHARMACOLOGICAL ACTION OF QUINIDINE :
HEART : Supresses automaticity
Depresses excitability
Depresses ectopic foci
Decreases contractility
Prolongs effective refractory period
Slows conduction velocity
AV node : Enhances AV conduction and increases ventricular rate by vagolytic action. It depresses AV conduction by direct action.
ECG : Quinidine prolongs QRS complex and QT interval. BP : Fall in blood pressure. SKELETAL MUSCLE : Quinidine reduces skeletal muscle contraction, it also has antimalerial, antipyretic, oxytocic activity.
PHARMACOKINETIC : Absorbed from git, metabolized in liver, high plasma protien binding, about 20% excreted unchanged in urine.
ADVERSE EFFECTS :1. Diarrhoea
2. Thrombocytopenia.
3. Fall in blood pressure.
4. Hepatitis and fever rarely.
5. Large dose causes CINCHONISM.
Oral administration, bioavailability is about 30%. It can be given intravenously for rapid effect. It accumulates in fat, muscle, lungs, liver, skin, etc. and has a long half life (1-2 months). Amiodarone is metabolized in the liver.
ADVERSE EFFECTS 1. Hypotension
2. Peripheral neuropathy.
3. Pulmonary fibrosis
4. Nausea, hepatitis
5. Photosensitivity.
6. Corneal deposits
7. Hypothyroidism, hyperthyroidism.
VERAPAMIL It blocks both activated and inactivated L-type Ca2+ channels - depresses calcium mediated depolarization. Verapamil decreases conduction velocity and increases refractory period of AV node; useful in
PHARMACOLOGICAL ACTION OF QUINIDINE :
HEART : Supresses automaticity
Depresses excitability
Depresses ectopic foci
Decreases contractility
Prolongs effective refractory period
Slows conduction velocity
AV node : Enhances AV conduction and increases ventricular rate by vagolytic action. It depresses AV conduction by direct action.
ECG : Quinidine prolongs QRS complex and QT interval. BP : Fall in blood pressure. SKELETAL MUSCLE : Quinidine reduces skeletal muscle contraction, it also has antimalerial, antipyretic, oxytocic activity.
PHARMACOKINETIC : Absorbed from git, metabolized in liver, high plasma protien binding, about 20% excreted unchanged in urine.
ADVERSE EFFECTS :1. Diarrhoea
2. Thrombocytopenia.
3. Fall in blood pressure.
4. Hepatitis and fever rarely.
5. Large dose causes CINCHONISM.
PROCAINAMIDE
Procainamide also have similar effect to those of quinidine but it has no anticholinergic and alpha adrenergic blocking effects.
PHARMACOKINETIC : Procainamide is well absorbed after oral administration. It can also be given by i.v. and i.m. routes. Metabolized in liver by acetylation. The major metabolite is n-acetyl procainamide. that has K+ channel blocking activity. NAPA is excreted in urine.
ADVERSE EFFECTS1. Hypotension and Heart block are main adverse effects.
2. Nausea, vomiting.
3. Confusion, depression, hallucination.
4. Long term therapy often produces lupus like syndrome with arthralgia and arthritis.
AMIODARONE
It is an iodine containing compound and structurally related to thyroid hormone, it has a broad spectrum of antiarrhythmic activity.
Procainamide also have similar effect to those of quinidine but it has no anticholinergic and alpha adrenergic blocking effects.
PHARMACOKINETIC : Procainamide is well absorbed after oral administration. It can also be given by i.v. and i.m. routes. Metabolized in liver by acetylation. The major metabolite is n-acetyl procainamide. that has K+ channel blocking activity. NAPA is excreted in urine.
ADVERSE EFFECTS1. Hypotension and Heart block are main adverse effects.
2. Nausea, vomiting.
3. Confusion, depression, hallucination.
4. Long term therapy often produces lupus like syndrome with arthralgia and arthritis.
AMIODARONE
It is an iodine containing compound and structurally related to thyroid hormone, it has a broad spectrum of antiarrhythmic activity.
- Amiodarone blocks potassium channels>>>increases duration of action potential>>>prolongs refractory period and suppresses abnormal automaticity.
- Blocks sodium channels in the inactivated state>>>decreases conduction mainly in the partially depolarized tissue.
- Blockade of sodium and potassium channels prolongs refractory period in the cardiac.
- It also has weak beta-adrenergic blocking and calcium channel blocking actions. It decreases heart rate and AV conduction.
Oral administration, bioavailability is about 30%. It can be given intravenously for rapid effect. It accumulates in fat, muscle, lungs, liver, skin, etc. and has a long half life (1-2 months). Amiodarone is metabolized in the liver.
ADVERSE EFFECTS 1. Hypotension
2. Peripheral neuropathy.
3. Pulmonary fibrosis
4. Nausea, hepatitis
5. Photosensitivity.
6. Corneal deposits
7. Hypothyroidism, hyperthyroidism.
VERAPAMIL It blocks both activated and inactivated L-type Ca2+ channels - depresses calcium mediated depolarization. Verapamil decreases conduction velocity and increases refractory period of AV node; useful in
- terminating reentry involving AV node.
- reducing ventricular rate in atrial flutter and fibrillation.
PHARMACOKINETICS:
Well absorbed through GI tract, highly bound to plasma protiens, metabolized in liver and excreted in urine.
ADVERSE EFFECTS
1. Constipation
2. Sinus bradycardia
3. Oedema
4. A-V block and headache rarely
Well absorbed through GI tract, highly bound to plasma protiens, metabolized in liver and excreted in urine.
ADVERSE EFFECTS
1. Constipation
2. Sinus bradycardia
3. Oedema
4. A-V block and headache rarely
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