Efficacy and adverse effects of adenosine in patients of supraventricular tachycardia

Background: Adenosine administered intravenously terminates supraventricular tachycardia (SVT) involving the AV node as part of the reenterant circuit. This study was designed to determine the safety and efficacy of intravenous adenosine in terminating acute episodes of paroxysmal supraventricular tachycardia. Methods and results: A randomized trial to evaluate the dose response in patients receiving Adenosine in the Emergency Department of Punjab Institute of Cardiology Lahore was carried out from March 2003 to August 2003. A total of 100 patients with a tachycardia electrocardiographically consistent with paroxysmal supraventricular tachycardia were entered in to the protocol. The patients received sequential bolus doses of 6, 12 and 18 mgs of Adenosine to terminate SVT with a two minute interval between the injections. Clinical variables and the time interval from the initiation of treatment to the termination of the supraventricular tachycardia were noted and any adverse clinical effects if observed were also recorded. There was a female preponderance of 63% in the study group of total 100 cases. The types of arrhythmias observed among the patients under study included AVNRT (81%), AVRT (12%) and atrial tachycardia (07%). The response to Adenosine therapy revealed (92.5%) in patients of AVNRT, (75%) in patients of AVRT and (42%) in patients of atrial tachycardia. The analysis of adverse effects revealed Facial flushing in (26%) patients, while dyspnoea chest pressure , Bronchospasm and other rhythm disturbances were present in other patients. (30%) patients had no side effects. Conclusions: Adenosine is a safe, effective and rapidly acting drug for terminating SVT and it is associated with very limited number of adverse effects if they occur at all.