Understanding Dexmedetomidine In Infants Post-Operative From Cardiac Surgery

Inclusion Criteria: * Patients must be greater or equal to one month or less than or equal to 24 months of age. * Post operative from cardiac surgery with tracheal intubation/mechanical ventilation in the immediate post-op period. * Planned tracheal extubation within 24 hours post-operatively. * Adequate renal function(1-12 months old creatinine less than or equal to 0.6mg/dL and \>12 months to 24 months creatinine \< or= to 1.0mg/dL) * Adequate liver function(Total bilirubin \< or= 1.5mg/dL and ALT 1-12 months \< or = to 165 U/L and \> 12 months to 24 months \< or = to 90 U/L) * Isolated heart surgery * Informed consent Exclusion Criteria: * Patients who have received another investigational drug within the past 30 days. * Receiving continuous infusions of muscle relaxants in the postoperative setting. * Patients whoo have a positive blood culture without a subsequent negative culture or other evidence of ongoing serious infection. * Patients, who, int he opinion of the investigator may not be able to comply with the safety monitoring requirements of the study. * Patients who show signs or symptoms of elevated intracranial pressure. * Post-operative hypotension based on age. * Preexisting bradycardia based on age. * Heart block * Weight \< 5kg * Patients, who in the opinion of the investigator, are not appropriate candidates for an investigational drug study.