Indexing haemodynamic variables in young children.

"CONFLICT OF INTEREST TSS declares no competing interest. LL declares no competing interest."

"Funding information This work was supported by project grants from The Anna & Edwin Berger's Foundation (Lidingö, Sweden) and The Swedish Children Heart Association (Stockholm, Sweden)."

"We performed a single‐centre, retrospective observational cohort study in young children with congenital heart defects undergoing corrective heart surgery of atrial septal and/or ventricle septal defects. The inclusion criteria for this study were written informed parental consent, elective open‐heart surgery and weight less than 15 kilograms. All children included in this study were enrolled from two similar haemodynamic studies, at Lund Children's Hospital from February 2010 to March 2017. These studies were approved and registered by the Ethics Committee of Lund University, Sweden (Dnr 2009/708 and Dnr 2013/636)."