Cardiorenal syndrome (CRS) includes a broad spectrum of diseases within which 
both the heart and kidneys are involved, acutely or chronically. An effective 
classification of CRS in 2008 essentially divides CRS in two main groups, 
cardiorenal and renocardiac CRS, based on primum movens of disease (cardiac or 
renal); both cardiorenal and renocardiac CRS are then divided into acute and 
chronic, according to onset of disease. The fifth type of CRS integrates all 
cardiorenal involvement induced by systemic disease. This article addresses the 
pathophysiology, diagnosis, treatment, and outcomes of the 5 distinct types of 
CRS.