Cardiorenal syndrome: definition, classification and recent results of studies on pathogenesis

Abstract

Background: The term cardiorenal syndrome (CRS) has been used without a consistent definition. Since there is a high clinical impact of heart and kidney disease interactions a unified definition of CRS is warranted. Methods: CRS definition and classification proposal by an international group of authors in 2008 is presented. Medline and Index Medicus databases were searched for relevant articles and a current view on the pathogenesis of CRS subtypes as defined in this proposal is given. Results: CRS is defined as a pathophysiologic disorder of the heart and kidneys, whereby acute or chronic dysfunction of one organ induces acute or chronic dysfunction of the other. CRS is divided into 5 subtypes according to the primary failing organ and the time frame of dysfunction. With the CRS type 1 and 2, there are acute and chronic cardiac disorders causing renal injury with hemodynamic disturbances of renal perfusion, especially renal venous congestion being implicated as a major cause. The CRS type 3 and 4 may also be designated as renocardiac syn-napovedromes, as there are acute and chronic kidney diseases leading to cardiac dysfunction. Particularly type 4 CRS encompasses numerous hemodynamic, metabolic and neurohumoral derangements. CRS type 5 reflects a systemic condition causing both cardiac and kidney dysfunction. Conclusions: Unified definition and classification of CRS allows a more comprehensive understanding of complex heart and kidney disease interactions and it is a good platform for future research.