Anaesthesia considerations for cardiac MRI in infants and small children

BACKGROUND: General anaesthesia is frequently necessary in infants and small children undergoing cardiac magnetic resonance imaging (MRI), because of the imaging techniques, MRI environment and potential need for breath-holding to facilitate imaging. Anaesthetizing paediatric patients with congenital heart disease (CHD) for cardiac MRI poses many challenges for the anaesthetist and this report reviews our experience. METHODS: We retrospectively reviewed the anaesthesia and MRI records of all patients who had undergone cardiac MRI between January 2000 and October 2002. RESULTS: A total of 250 children with cardiac disease underwent general anaesthesia for cardiac MRI. ASA classification included class I, 2%; class II; 26%; class III, 60% and class IV, 12%. A total of 168 patients (67%) had undergone previous cardiac surgery, 182 patients (94%) were discharged the same day and 48 patients (19.2%) had cyanotic cardiac defects (SpO2 between 55 and 85%). No scans were interrupted because of low oxygen saturation during breath-hold or haemodynamic instability. No patient was admitted to the hospital from complications related to general anaesthesia, but one inhouse patient from the cardiology ward was admitted to the cardiac intensive care unit (CICU) after the MRI because of cyanosis and low cardiac output. Seven patients from the CICU were on inotropic infusions when they underwent the MRI procedure and two others needed inotropic support after induction of anaesthesia. Five patients had a brief episode of hypotension during the MRI and responded quickly to interventions. CONCLUSION: Our experience demonstrates that general anaesthesia for cardiac MRI can be provided safely in infants and small children with CHD, despite the complexity and pathophysiology of many defects, the frequent breath-holding for image acquisitions and the MRI environment.