(Dysrhmthmia, Abnormal Heart rhythm, Tachycardia, Bradycardia)
is a term for a large and heterogeneous group of conditions in which there is abnormal electrical activity in the heart. Some Cardiac arrhythmia are life-threatening medical emergencies that can result in cardiac arrest and sudden death. The most commonly observed symptom is abnormal or irregular palpitations, others include Chest pain, Fainting, Paleness, dizziness, Change in pattern of the pulse, sweating, etc.
Cardiac Arrhythmia is associated with Bradycardia - Slow rhythm, Tachycardia- heart rate faster than 100 beats/minute, increased automaticity, Re-entry arrhythmia and Fibrillation.
Cardiac Arrythmia can also result due to some drugs as follows: Amphetamines, Caffeine, Cocaine, Beta blockers, Psychotropics, Sympathomimetics.
- Rapid arrhythmia (greater than 100 beats per minute) are called .
- Slow arrhythmia (slower than 60 beats per minute) are called .
- Irregular heart rhythms are called (as in atrial fibrillation).
Treatment of arrhythmias involves improving the symptoms and reducing emotional and mental stress. The type and seriousness of the condition also decides whether the treatment required is by using medication, making lifestyle changes or undergoing surgical procedures.
The Class of Anti-arrhythmics medications include:
These are classified as Class II antiarrhythmic agents according to the Vaughan Williams classification. Beta-blockers decrease the heart rate and cardiac output, which lowers blood pressure by blocking the effects of adrenalin.
Coronary vasodilators are used for the treatment of coronary insufficiency; heart failure and angina. Products include selective adenosine A2 receptor agonists, calcium antagonists and potassium channel activators.
Sodium channels Blockers are classified as class I Anti arrhythmics agents. Sodium channels Blockers reduce the velocity of the action potential transmission within the heart leading to reduced conduction velocity; negative dromotropy. This can serve as an important mechanism for suppressing tachycardias that are caused by abnormal conduction (e.g., reentry mechanisms). By depressing abnormal conduction, reentry mechanisms can be interrupted.
Potassium channel blockers used in the treatment of cardiac arrhythmia are classified as class III antiarrhythmic agents. These agents do not decrease the conduction velocity, they result in the prolongation of the action potential duration and refractory period, combined with the maintenance of normal conduction velocity, hence prevent re-entrant arrhythmias.
Slow calcium channel blockers are classified as the Class II antiarrhythmic agents. These decrease conduction through the AV node, and shorten phase two (the plateau) of the cardiac action potential and thus reduce the contractility of the heart. However, in contrast to beta blockers, they allow the body to retain adrenergic control of heart rate and contractility.