About esmololbeta1 selective adrenergic blocking agent, class ii antiarrhythmic agent, antiarrhythmic agent.mechanism of action of esmololesmolol is an ultra short acting cardio selective beta-1 adrenergic antagonist. it has negative chronotropic effects on heart. it decreases oxygen consumption- cardiac work and aortic pressure. it decreases nor adrenaline and renin releases. it decreases central sympathetic out flow. in sympathetic over activity, it prolongs systole by retarding conduction. the drug decreases bp in hypertensive individuals- both systolic and diastolic bp is reduced. it exerts class-2 anti arrhythmic properties and suppress adrenergically mediated ectopic activity.