Gut Microbiome and Short-Chain Fatty Acid Alterations After Cardiopulmonary Bypass are Associated with Nutritional and Functional Impairment in Young Children with Congenital Heart Defects

Shoira Abdusalamovna Agzamova,1 Faniya Rashidovna Babadjanova2 1Department of Family Medicine No. 1, Physical Education and Civil Defense, Tashkent State Medical University, Tashkent, Uzbekistan; 2Department of Pediatrics and Neonatology, Urgench State Medical Institute, Urgench, UzbekistanCorrespondence: Faniya Rashidovna Babadjanova, Department of Pediatrics and Neonatology, Urgench State Medical Institute, Urgench, Uzbekistan, Email babadjanovafaniya@gmail.comBackground: Cardiac surgery with cardiopulmonary bypass (CPB) in young children is associated with systemic stress, gastrointestinal dysfunction, and impaired nutritional recovery. The role of gut microbiome disruption and short-chain fatty acid (SCFA) metabolism in these processes remains insufficiently studied.Objective: To evaluate changes in gut microbiome composition, SCFA profiles, and nutritional status in children aged 0– 3 years after CPB, and to assess their association with postoperative feeding intolerance and impaired growth.Methods: This prospective observational study included 20 children undergoing cardiac surgery with CPB. Stool samples were collected preoperatively and during the early postoperative period. Microbiota composition was assessed using culture-based microbiological methods, and fecal SCFA concentrations were measured by gas chromatography. Clinical, anthropometric, and laboratory parameters were assessed, and their associations with CPB characteristics and microbiome alterations were analyzed.Results: The postoperative period was characterized by significant intestinal dysbiosis, including reduced abundance of beneficial bacteria (Bifidobacterium, Lactobacillus, Bacteroides) and decreased SCFA-producing taxa. Fecal butyrate and propionate levels were significantly reduced. These changes were associated with increased intestinal inflammation, feeding intolerance, impaired nutrient absorption, and insufficient weight gain. The severity of dysbiosis correlated with CPB duration.Conclusion: CPB in early childhood is associated with disruption of gut microbiota and reduced SCFA production, which are linked to postoperative feeding intolerance and impaired nutritional recovery. Targeted monitoring and modulation of the gut microbiome may improve clinical outcomes in pediatric cardiac surgery patients.