Understanding Dexmedetomidine in Neonates After Open Heart Surgery

Inclusion Criteria: * Patients must be less than or equal to 1 month old. * Postconceptual age must be \> or equal to 37 weeks on the day of surgery. * Postoperative from cardiac surgery with tracheal intubation/mechanical ventilation in the immediate post-op period. * Planned tracheal extubation within 24 hrs post-op. * Adequate renal function (serum creatine \< or equal to 1.5mg/dL) * Adequate liver function (ALT \< or equal to 165 U/L) * Isolated heart surgery * Informed consent Exclusion Criteria: * Patients who have received another investigational drug since birth. * Patients receiving continuous infusions of muscle relaxants in the post-op setting. * Pateints who have a positive blood culture without a subsequent negative culture of other evidence of ongoing serious infection. * Patients who show signs and symptoms of elevated intracranial pressure. * Post-op hypotension defined by post conceptual age. * Pre-existing bradycardia defined by age * Heart block * Weight \< 2kg * Patients who, in the opinion of the investigator, are not appropriate candidates for an investigational drug study