Improving Care for Children With Congenital Heart Disease.

Inclusion Criteria: * obtained written informed consent prior to enrolment * resident within participating healthcare regions in Sweden during study * age 0-17 years at enrolment * Controls: No evidence of congenital heart disease and no history of cardiovascular disease * Cases: congenital heart lesions prior to open heart surgery or cardiac catheter intervention with grouping into i.e. ventricular septal defects and atrial septal defects, complex and critical cases requiring infant surgery or patency of the arterial duct to maintain the circulation postnatally. Exclusion Criteria: * inability to obtain written informed consent prior to study enrolment and/or comply with study protocol * non-resident in participating healthcare regions of Sweden during study * age more than 17 years at enrolment * presence of congenital heart disease where the lesion has already been treated by open heart surgery or cardiac catheter intervention * participation in other research study with conflicting aims / interests