Venous Congestion And Delirium After Cardiac Surgery

Inclusion Criteria: 1. Patients scheduled to undergo elective cardiac surgery via a midline thoracic incision; 2. ≥18 years; 3. A preoperative MMSE score\>23, without consciousness or language barriers, capable of cooperating with neurological examinations, cognitive function tests, and other assessments of neurological function. Exclusion Criteria: 1. Contraindications for TEE; 2. Emergency cardiac surgery; 3. Major vascular surgery; 4. Redo cardiac surgery; 5. Severe infection requiring continuous antibiotic therapy; 6. Severe preoperative heart failure with left ventricular ejection fraction \< 30%; 7. A critical preoperative state (mechanical circulatory support, extracorporeal membrane oxygenation, current renal replacement therapy, mechanical ventilation, or cardiac arrest necessitating resuscitation); 8. Multi-organ dysfunction; 9. Known conditions that may interfere with the assessment or interpretation of hepatic vein, portal vein blood flow (such as liver cirrhosis or portal vein thrombosis) or the renal vein blood flow (such as urinary tract obstruction); 10. Planned cardiac transplantation or ventricular assist device implantation; 11. Pregnancy; 12. Insufficient ultrasonographic imaging; 13. Restarting CPB after first CPB cessation during surgery; 14. Requirement for cardiac assist devices (ECMO, IABP, or ventricular assist device) after CPB intraoperatively; 15. Neurological or psychiatric diagnoses that may affect cognitive performance or cognitive testing; 16. Documented delirium before surgery.