A Study to Understand How Cardiac Surgery-associated Acute Kidney Injury Develops in Participants Who Undergo Heart Surgery With the Use of Heart-lung Machine

Researchers are looking for a better way to treat and prevent cardiac surgery-associated acute kidney injury (CSA-AKI) in people who undergo heart surgeries. CSA-AKI is a common complication in people undergoing heart surgeries, where the kidneys stop working properly. CSA-AKI risk factors include older age and alongside diseases such as kidney disease and diabetes. Longer time with heart-lung machine during heart surgeries also increases the occurrence of CSA-AKI. In this study, researchers want to better understand how CSA-AKI develops (also known as the mechanisms involved in the development of CSA-AKI) in people under heart surgeries, the presence of certain biomarkers in the body, especially with a focus on the early hours and days after the surgery. (A biomarker is a biological molecule found in blood, other body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease.) These biomarkers will be compared in participants who develop CSA-AKI within a week after heart surgery with the participants who do not develop CSA-AKI. The relationship with biomarkers will be determined by examining participants' blood and urine samples before and after surgery. This may help researchers better understand CSA-AKI, identify potential treatment targets and develop possible treatments to prevent CSA-AKI. Participants in this study will be people who have heart surgery already scheduled by their own doctors and have a risk of developing CSA-AKI. Participants will not receive any treatment as part of this study. They will undergo the heart surgery and related medical processes as per their normal medical treatment and management. Each participant will be in the study for up to 2 months. During the study, the doctors and their study team will: * collect participants' blood and urine samples before and after surgery * assess participants' medical records and test reports during hospitalization * monitor overall health of the participants throughout the study