26-year-old woman complains of the abrupt onset of her chest pounding. She is diagnosed with paroxysmal atrial tachycardia. Which of the following is the most effective agent for conveing paroxysmal atrial tachycardia to normal sinus rhythm

DRUGS FOR PSVT An attack of PSVT can be terminated by reflex vagal stimulation through Valsalva maneuver, splashing ice cold water on face, hyperflexion (head between knees), etc. Alternatively, or if it does not work, the drug of choice is adenosine (i.v.). Other alternatives are i.v. injection of verapamil/diltiazem/esmolol. Advantages of adenosine for termina-tion of PSVT are: * Efficacy equivalent to or better than verapamil. * Action lasts < 1 min; adverse effects (even cardiac arrest, if it occurs) are transient. * No haemodynamic deterioration; can be given to patients with hypotension, CHF or those receiving b blockers. Verapamil is contra-indicated in these situations. * Safe in wide QRS tachycardia (verapamil is unsafe). * Effective in patients not responding to verapamil. Adverse effects:- Transient dyspnoea, chest pain, fall in BP and flushing, ventricular standstill for few sec or VF occurs in some patients. Bronchospasm may be precipitated in asthmatics; verapamil is the drug of choice for such patients. Ref:- kd tripathi; pg num:-536