combination) to control rate until the patient is fully assessed for a possible clot in the left atrium Calcium channel blockers are not given to patients less than years of age Amiodarone or sotalol are commonly used for chronic control atrial fibrillation and when used acutely may cause conversion to sinus rhythm Wide Complex, Irregular Tachycardia A wide rhythm, which is irregularly irregular may be VT or atrial fibrillation with Wolff–Parkinson–White (WPW) and will require cardioversion/defibrillation Assess for hemodynamic stability and proceed according to the PALS algorithms WPW with atrial fibrillation should be cardioverted, just as for atrial fibrillation without WPW Do not give adenosine to any patient with a wide complex irregular rhythm (see adenosine below) Narrow Complex, Regular Tachycardia Evaluation of a relatively stable patient with narrow complex tachycardia, includes asking the patient to perform a vagal maneuver while recording the rhythm An external defibrillator/pacer should be available The vagal technique chosen should be appropriate for the age of the patient In infants, knee to chest position, rectal stimulation with a thermometer, or the diving reflex may be used To elicit the diving reflex in an infant, gently place a slurry of ice and water in a plastic bag over the nose and eyes of the patient for no more than 35 seconds Older children and adolescents may perform knee to chest, hold their breath, immerse their face in cold water, or bear down If vagal maneuvers are unsuccessful in converting tachycardia to sinus rhythm, IV access should be obtained for administration of adenosine Adenosine is the drug of choice in regular, narrow complex tachycardia It is an amino acid that is rapidly metabolized by erythrocytes and the endothelium, giving it a half-life of about seconds Therefore, adenosine must be delivered via a large-bore IV placed as close to the heart as possible, followed by rapid or simultaneous flush of 10 mL normal saline to ensure that the medication reaches the heart before it is metabolized The starting dose of adenosine is 0.1 mg/kg IV, followed by 0.2 mg/kg IV as needed three times In patients weighing more than 50 kg, give mg IV followed by 12 mg IV One-third to one-half of the normal adenosine dose should be used when given to heart transplant recipients Adenosine has reportedly been effective when administered through an intraosseous line but results are inconsistent Adenosine briefly blocks conduction in the atrioventricular (AV) node causing disruption of any tachycardia circuit that depends on AV nodal conduction for perpetuation of the tachycardia Interpretation of the adenosine’s effect on conduction cannot be analyzed on the bedside monitor screens, so it is important