A Critical Account of the PharmacoIogical Agents, used to treat Cardiac Dsrhythmias

Abstract

INTRODUCTION: The condition of dysrhythmia may be defined as an irregular cardiac rhythm or a heart rate faster or slower than physiological (22). This disturbed rhythm can be caused by an abnormality in the rate, regularity or site of origin or the conduction of the impulse such that the normal physiological sequence of activation of the atria and ventricles is disturbed (7). Most of the cases of sudden early deaths arising from cardiac infarction are due to onset of dysrhythmias.In the absence of a definite action of verapamil on electrophysiological parameters of myocardial fibres, as already has been discussed, it seems unrealistic to group verapamil into any class, but again it is desirable to classify this drug and other drugs such as prenylämine (22) separately due to its unique mode of action unrelated to other antidysrhythmic drugs. CONCLUSIONS: Many workers beleive that if the precise mechanisms of dysrhythmia were known, it would be easier to select a therapeutic agent with the specific effet necessary to correct the abnorm ality. Unfortunately, the basic knowledge of precise mechanism involved in the genesis of dysrhythmia is still lacking in most of the cases and therefore unanimity of opinion has yet to be reached regarding the pathomechanism of dysrhythmjas. Another factor which should be taken into consideration during the evaluation of these drugs is the concentrations of the drug. As it has been reported that propranolol does not produce any change in AP at the concentration of 0. 1 mg/I but at 0.3 mg/i APD and ERP in Purkinje fibre (14) are decreased.