SVT is the most common dysrhythmia in the pediatric population. Infants or children usually present with a history of poor feeding, rapid breathing, and irritability or pallor. The origin of the arrhythmia is above the bundle of His and most often uses an accessory pathway to complete the circuit. An electrical impulse travels down the AV node and activates the ventricle but goes back up the accessory pathway to depolarize the atrium again. This is seen on EKG as a narrow complex tachycardia at rates of 230–300/min. Adenosine is the safest and fastest acting antiarrhythmic agent that blocks the AV node and breaks the circuit. Verapamil, a calcium channel blocker, is contraindicated in infants younger than 1 year because it can cause hypotension and cardiovascular collapse. Vagal stimulation via carotid massage is not recommended in young children. In a patient who is symptomatic, oral digoxin is not the drug of choice as it takes sometime to work. Its use may also enhance conduction in the accessory pathway especially in patients with WPW. Cardioversion is used for unstable patients at 0.5–1.0 J/kg, not 4 J/kg. New onset SVT should be hospitalized for further evaluation and management.