Post-Marketing Study to Assess the Safety & Efficacy of RenalGuard® Therapy for Prevention CSA-AKI

Inclusion Criteria: 1. Male or female and \>18 years of age 2. Patient able to give written consent 3. Scheduled for the following non-emergent cardiac surgery procedure requiring CPB, isolated or in combination: * coronary artery bypass graft (CABG) * aortic valve replacement or repair alone, with or without aortic root repair * mitral, tricuspid, or pulmonic valve replacement or repair * simultaneous replacement of several cardiac valves * CABG with aortic, mitral, tricuspid, or pulmonic valve replacement or repair * Surgery on the aorta: aortic root and/ or ascending aorta * Atrial fibrillation (AF) ablation surgery if combined with other cardiac procedures. * Atrial septal defect (ASD) closure if combined with other cardiac procedures. * Excision of myxoma if combined with other cardiac procedures 4. Have at least one of the following risk factors for CSA-AKI: * CKD-EPI eGFR 20-59 mL/min/1.73 m² * Age ≥ 75 years * Undergoing combined surgery (e.g. CABG + Valve) * Logistic EuroScore of ≥5 or, Euroscore II of ≥4 or Society of Thoracic Surgeons (STS) Score ≥4 * Left ventricular ejection fraction (LVEF) ≤ 35% by invasive or noninvasive diagnostic cardiac imaging performed within 90 days prior to surgery. * Insulin-requiring diabetes * Non-insulin-requiring diabetes with HbA1C ≥ 6.1% in the last 6 months * Preoperative anemia within 4 weeks of surgery Exclusion Criteria: 1. Patient requiring emergency surgery 2. Surgery to be performed without CPB 3. Patient receiving furosemide at a dose\>100 mg/day orally (or the equivalent dose of an alternative loop diuretic) in the last week 4. Patient who cannot be urethrally catheterize for any reason 5. Patients already dialysis dependent 6. Patients with CKD-EPI eGFR \<20 mL/min/1.73 m² 7. Known or suspected AKI (KDIGO criteria) at the time of screening 8. Patients participating in another interventional drug or device study or have received an investigational drug or device treatment within the last 30 days 9. Pregnant patient, self-reported 10. Patients whose planned surgery to be performed under conditions of circulatory arrest or hypothermia with rectal temperature \< 28°Celsius (82.4° Fahrenheit) 11. Patient with suspected or confirmed bacteraemia, endocarditis, or pyelonephritis at hospital admission 12. Patients with pneumonia, aspiration, or bilateral pulmonary infiltrates from an infectious aetiology reported on chest x-ray or CT scan in the last 7 days 13. Patients in cardiogenic shock or hemodynamic instability which require inotropes or vasopressors or other mechanical devices (Impella Heart Pump, IABP) within 24 hours prior to surgery 14. Patients on extracorporeal membrane oxygenation (ECMO) or durable ventricular assist device (VAD) at the time of screening, or planned use within 24h prior to surgery 15. Patients currently treated with chemotherapy or radiation therapy that may have an impact on kidney function. 16. Patient underwent prior solid organ transplantation 17. Patients underwent major surgery within the last 3 months 18. Any condition which, in the judgement of the investigator, might increase the risk to the patient.