to record a rhythm strip during adenosine administration as well as during vagal maneuvers Once adenosine has been administered, assess the EKG for adequate response of AV or VA dissociation from the adenosine Note signs of AV dissociation, tachycardia termination, slowing, or irregularity of the rhythm The mechanism of tachycardia is often revealed with initiation or termination of the rhythm Administration of adenosine will result in one of three possible outcomes: It may have no effect on the rhythm; it may terminate tachycardia resulting in sinus rhythm; or it may reveal atrial flutter waves or atrial tachycardia during transient blocking of the AV node Tachycardia will resume after adenosine is metabolized ( Fig 86.1 ) In the first case, when adenosine has no effect on the rhythm, it is either because the dose was too low, it was metabolized before it reached the heart, or the rhythm is VT The dose should be doubled and properly administered The higher dose may be given twice If the rhythm is determined to be VT, follow the management of wide complex arrhythmias below In the second case, when adenosine successfully terminates tachycardia, next steps include recording the EKG in sinus rhythm and monitoring on telemetry until admission, transfer, or cardiology consultation If adenosine is successful in terminating tachycardia but it recurs, adenosine may be given again Another option is to administer a longer-acting drug and then repeat conversion with adenosine The third case is when adenosine administration reveals atrial flutter or atrial tachycardia One common pitfall is the assumption that the tachycardia briefly stopped and then restarted in response to adenosine, when in reality adenosine simply unmasked the rhythm by blocking AV conduction to the ventricles, thus making the atrial flutter waves obvious To avoid this pitfall, look for flutter waves or atrial tachycardia P waves during the time of slowing/AV node inhibition ( Figs 86.2 –86.5 ) If adenosine successfully converts SVT to sinus rhythm, but the tachycardia recurs, electrical cardioversion offers no advantage over redosing adenosine In this case, a longer-acting medication is needed If the patient is on chronic antiarrhythmic therapy, consider giving this medication Useful IV medications include procainamide, esmolol, or amiodarone Oral beta-blockers, sotalol, or flecainide may be used Calcium channel blockers should not be used in patients less than years of age, in combination with beta-blockers, or with poor ventricular function Cardiology consultation is advised If adenosine fails to convert tachycardia at all, electrical cardioversion is indicated