An arrhythmia is a disorder of the heart rate (pulse) or heart rhythm. The heart can beat too fast (tachycardia), too slow (bradycardia), or irregularly.
Causes
Arrhythmias are caused by problems with the heart's electrical conduction system:
-Abnormal (extra) signals may occur.
-Electrical signals may be blocked or slowed.
-Electrical signals travel in new or different pathways through the heart.
Some common causes of abnormal heartbeats are:
-Abnormal levels of potassium or other substances in the body
-Heart attack, or a damaged heart muscle from a past heart attack
-Heart disease that is present at birth (congenital)
-Heart failure or an enlarged heart
-Overactive thyroid gland
Arrhythmias may also be caused by some substances or drugs, including: alcohol, caffeine, or stimulant drugs, heart or blood pressure medicines, cigarette smoking (nicotine), drugs that mimic the activity of your nervous system and medicines used for depression or psychosis.
Sometimes medicines used to treat one type of arrhythmia will cause another type of abnormal heart rhythm.
Some of the more common abnormal heart rhythms are:
-Tachycardia: supraventricular tachycardia (SVT) or ventricular tachycardia (ventricular fibrillation).
-Bradycardia: sinus node dysfunction or heart block.
Other classification: Arrhythmias originating in the Atria:
-Atrial fibrillation.
-Atrial flutter.
-Supraventricular tachycardias (PSVT).
-Wolff-Parkinson-White syndrome.
-Premature supraventricular contraction or premature atrial contraction (PAC).
-Sick sinus syndrome.
-Sinus arrhythmia.
-Sinus tachycardia.
-Multifocal atrial tachycardia.
Arrhythmias originating in the Ventricles:
-Premature ventricular contraction (PVC)
-Ventricular Fibrillation
-Ventricular tachycardia.
Symptoms
An arrhythmia may be present all of the time or it may come and go. You may or may not feel symptoms when the arrhythmia is present. Or, you may only notice symptoms when you are more active.
Symptoms can be very mild, or they may be severe or even life-threatening.
Common symptoms that may occur when the arrhythmia is present include: chest pain, fainting, light-headedness, dizziness, paleness, shortness of breath or sweating.
Treatment
When an arrhythmia is serious, you may need urgent treatment to restore a normal rhythm. This may include:
-Electrical "shock" therapy (defibrillation or cardioversion)
-Implanting a short-term heart pacemaker
-Medicines given through a vein (intravenous) or by mouth.
Sometimes, better treatment for your angina or heart failure will lower your chance of having an arrhythmia.
Medicines called anti-arrhythmic drugs may be used:
-To prevent an arrhythmia from happening again
-To keep your heart rate from becoming too fast or too slow
Other treatments to prevent or treat abnormal heart rhythms include: cardiac ablation, implantable cardiac defibrillator or a pacemaker.
ANTI-ARRHYTMIC DRUGS
-Adenosine: rapid reversion to sinus rhythm of paroxysmal supraventricular tachycardias. (Adenocor).
-Amiodarone hydrochloride: treatment of arrhythmias particularly when other drugs are ineffective or contraindicated. (Cordarone).
-Disopyramide: for ventricular or supraventricular arrhythmias. (Rythmodan).
-Flecainide acetate (Tambocor).
-Propafenone hydrochloride: for ventricular arrhythmias and paroxysmal supraventricular tachyarrhythmias. (Arythmol).
-Lidocaine hydrochloride: for ventricular arrhythmias. (Minijet Lignocaine).
BETA-ADRENOCEPTOR BLOCKING DRUGS
Indicated for hypertension, angina, myocardial infarction, arrhythmias, heart failure and thyrotoxicosis among others.
-Propanolol hydrochloride (Inderal).
-Acebutolol (Sectral).
-Atenolol (Tenormin, with diuretic: Co-tenidone, Kalten, Tenoret 50 and Tenoretic, with calcium-channel blocker: Beta-adalat and Tenif).
-Bisoprolol fumarate (Cardicor, Emcor).
-Carvedilol (Eucardic).
-Celiprolol hydrochloride (Celectol).
-Esmolol hydrochloride (Brevibloc).
-Labetalol hydrochloride (Trandate).
-Metoprolol tartrate (Betaloc, Lopresor).
-Nadolol (Corgard).
-Nebivolol (Nebilet).
-Oxprenolol hydrochloride (Trasicor, with diuretic: Trasidex).
-Pindolol (Visken, with diuretic: Viskaldix).
-Sotalol hydrochloride (Beta-cardone, Sotacor).
-Timolol maleate (Betim, with diuretic: Prestim).
Sources:
-http://www.nlm.nih.gov/medlineplus/
-http://umm.edu/programs/heart/services/conditions/arrhythmias/types
-BNF 57 March 2009
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