INTRODUCTION:The term ‘arrhythmia’ refers to any change from the normal sequence of electrical impulses. The electrical impulses may happen too fast, too slowly or erratically. A heartbeat too fast is called tachycardia and a heartbeat too slow is called bradycardia. The four main types of arrhythmias are premature (extra) beats, supraventricular arrhythmias, ventricular arrhythmias and bradyarrythmias 1.
The types of arrhythmias and their mechanisms is mentioned in Table 1.1 2 . Table 1.1 The therapy of arrhythmia begins with proper diagnosis, since many pharmacological interventions are themselves arryhthmogenic 3.
Despite the emergence of several forms of nonpharmacological therapy for cardiac arrhythmias, antiarrhythmic drugs play an important role in its management 4. Antiarrhythmic drugs (AADs) suppress cardiac arrhythmias through their effects on various ion channels and receptors 5. AADs have been classified by Vaughan Williams and Singh based on the primary electrophysiological action of the drug that may severe to indicate the types of clinical effects and therapeutic utility. The classes of drugs with their action is given in Table 1.2 6 . Table 1.2 The benefit of antiarrhythmic therapy is reduction of arrhythmia related symptoms and reduction in long-term mortality in asymptomatic patients 7.
But ADA carries with it a number of risks like proarrhythmias and systemic toxicity. Aggravation of arrhythmias is a common complication of of antiarrhtymatic drugs therapy. Patients with a history of congestive heart failure or any heart disease are at a greater risk and AADs should be used cautiously in them 8.
Therefore the goals of pharmacologic therapy of cardiac arrhythmia are to provide the maximum benefit in terms of arrhythmia suppression while maintaining patient’s safety 4. To accomplish these goals, a deliberate treatment strategy guided by the morphological criteria of the arrhythmia modified by the rate and duration of complexes, noting symptoms and adhering to the guidelines of AHA/ACC 2017 for the management of arrhythmias is desirable.Arrhythmia Common mechanismPremature atrial, nodal or ventricular depolarisationsUnknownAtrial fibrillationDisorganised functional re-entryAtrial flutterStable re-entrant circuit in the right atriumAtrial tachycardiaEnhanced automaticity, DAD-related automaticity, or re-entry in atriumAV nodal re-entrant tachycardia (PSVT)Re-entrant circuit within or near AV nodeVentricular tachycardiaRe-entry near the rim of the healed MI or DADs triggered by increased sympathetic tone.Ventricular fibrillationDisorganised re-entryClassActionsI.Membrane stabilising agents (Na+ channel blockers)II.Antiadrenergic agentsIII.Agents widening APIV.Calcium channel blockers