The most common tachyarrhythmias in childhood are narrow QRS complex tachyarrhythmias.The tesla pops majority of these are supraventricular tachycardia (SVT).If electrocardiography is inconsistent with typical SVT, another underlying arrhythmia floor mat alarm for elderly should be considered.In this case, a patient with narrow complex tachycardia who was diagnosed with atrial flutter after adenosine was presented to increase awareness on the subject.