MMP2 and congenital heart disease: The aim of this research was to investigate the role of MMP-2, MMP-9, TIMP-1, and TIMP-2 in the etiopathogenesis of VSD using urine samples as an innovative, non-invasive approach, and to determine if their concentrations in urine can be used as biomarkers for predicting the spontaneous course of this congenital heart defect.