Inclusion Criteria:  Adult patients undergoing cardiac surgery with CPB Cardiac index 2.1l/min per square meter Written informed consent D-renin (difference between post- and preoperative) ≥ 3.7 µU/ml 4 h after CPB Postoperative hypotension requiring vasopressors  Exclusion Criteria:  Preexisting AKI (stage 1 and higher) Patients with cardiac assist devices Pregnant women, nursing women and women of childbearing potential Known (Glomerulo-) Nephritis, interstitial nephritis or vasculitis chronic kidney disease with eGFR (estimated glomerular filtration rate) < 30 ml/min Dialysis dependent chronic kidney disease Prior kidney transplant within the last to 12 months Emergency surgery in the context of an acute coronary syndrome Hypersensitivity to the active substance, or to any of the excipients of the study medication Bronchospasm Liver failure Mesenteric ischemia Participation in another intervention trial in the past 3 months Persons with any kind of dependency on the investigator or employed by the institution responsible or investigator Persons held in an institution by legal or official order