Retrospective Palivizumab Study in Children With Hemodynamically Significant Congenital Heart Disease

Inclusion Criteria: 1. Subject must have documented hemodynamically significant congenital heart disease (Note: Children with uncomplicated small atrial or ventricular septal defects or patent ductus arteriosus are not eligible). 2. Subject must have unoperated or partially corrected congenital heart disease. 3. Subject must have received at least one dose of palivizumab for prophylaxis during the Respiratory Syncytial Virus season - September 1 through April 30 (CASES), or would have been considered eligible for palivizumab prophylaxis (CONTROLS). 4. Subject must be \< 24 months of age at the time of the first dose of palivizumab prophylaxis (CASES) or \< 32 months of age at the end of the assigned Respiratory Syncytial Virus season in which they would have been eligible to receive palivizumab if the drug had been approved in the European Union (CONTROLS). 5. Subject's parent, guardian, or legal representative has voluntarily signed and dated a Release of Information Form to allow the review of medical records and collection of pertinent study data. Exclusion Criteria: 1. Subject was contraindicated for treatment with palivizumab according to the current European product label. 2. Subject had full correction of Congenital Heart Disease. 3. Subject received palivizumab before approval for use in Congenital Heart Disease (CASES), or subject received palivizumab at any time (CONTROLS). 4. Subject has already been included in this study in a prior Respiratory Syncytial Virus season.