Monitoring Renal Blood Flow Using Contrast Enhanced Ultrasound in Predicting Acute Kidney Injury After Exposure to Iodinated Contrast Agent

What will be done in this protocol? Specific to Aim 1: To investigate the correlation between changes in RBF after exposure to iodinated contrast agent, measured by CEU, on occurrence of acute kidney injury (AKI) in a population of subjects at risk for CN.

Procedures: Subjects with an estimated glomerular filtration rate (eGFR), measured by the Modification of Diet in Renal Disease (MDRD) formula, between 30 - 60 ml/min/1.73 m2 who are scheduled for a coronary angiogram will be enrolled in this study. These subjects are considered to be at higher risks of CN. It is important to clarify that all subjects are scheduled for a coronary angiography for clinical reasons before enrollment in this study. Coronary angiography is not a part of interventions of this protocol. The decision regarding the need for coronary angiography and the strategies for its prevention are made by the subjects' healthcare providers and not the research team.

The details of protocol will be discussed with all interventional cardiologists and permission will be obtained to discuss study details with potential subjects. Eligible subjects will be identified by searching the electronic medical record of individuals who are listed in the cardiac catheterization laboratory schedule for inclusion and exclusion criteria. Subjects who appear to qualify for study participation based on medical record review the inclusion and exclusion criteria will be approached. The details of the study goals, procedures and risks will be discussed with each individual and questions will be answered. The subjects will then be asked to sign the informed consent form. They will then be enrolled in the study.

Since undergoing an X-ray examination or exposure to iodinated contrast media are contraindicated in pregnancy, we assume all women of child bearing age having a test to rule out pregnancy before enrolling in the study. If this test is not done, we will contact the subject's cardiologist and arrange for it as a part of clinical care and not a research related procedure.

At the time of enrollment data on subjects' age, race, gender, ethnicity, history of coronary artery disease, diabetes and congestive heart failure will be collected. Subjects with a history of heart failure will be asked about presence of symptoms of heart failure such as shortness of breath at rest or with activities, fatigue, palpitation and dyspnea. This information will be used to identify the New York Heart Association (NYHA) class of heart failure which is considered a risk factor for CN. List of medications used by subjects will also be recorded. Vital signs will be recorded.