Global metabolomic profiling of congenital heart defects and controls

Patients were enrolled into biobank programs at two separate institutions. A small volume of blood (1 mL) was collected in EDTA-coated tubes in the first month of the NICU hospitalization and prior to any cardiac surgery for CHD cases. EDTA tubes were centrifuged within six hours of collection at 1,850 g for 10 minutes at 4⁰C. Approximately 100 to 200 μL of plasma was extracted without disturbing the buffy coat and stored at -80⁰C. Patients from both institutions were selected and divided into three groups based on cardiac phenotype: cyanotic CHD, non-cyanotic (normoxic) CHD, and normoxic controls without CHD. Inclusion criteria for control patients were the absence of cardiopulmonary anomalies, gestational age greater than 32 weeks, absent or minimal respiratory support, as defined as non-invasive respiratory support with fractional inspired oxygen (FiO₂) of 21% (room air) with maintained normal oxygen saturations. Exclusion criteria were syndromic genetic conditions, mechanical ventilation, or requirement of supplemental oxygen (FiO₂ > 21%). Global plasma metabolite profiling (UPLC-MS/MS) was performed on cyanotic CHD patients (n = 27), non-cyanotic CHD (n = 11), and normoxic controls without CHD (n = 12).