Pathophysiology of the Cardiorenal Syndromes Types 1–5: Updates from the Eleventh Consensus Conference of the Acute Dialysis Quality Initiative (ADQI)

According to the recent definition proposed by the Consensus conference on Acute Dialysis Quality Initiative Group (Ronco in Cardiorenal Med 1:3–4, 2011), the term cardiorenal syndrome (CRS) has been used to define different clinical conditions in which heart and kidney dysfunction overlap. Type 1 CRS (acute cardiorenal syndrome) is characterized by acute worsening of cardiac function leading to AKI (Ronco in Contrib Nephrol 164:33–38, 2010; Eren et al. in Cardiorenal Med 2:168–176, 2012) in the setting of active cardiac disease such as ADHF, while type 2 CRS occurs in a setting of chronic cardiac decompensation. Type 3 CRS is closely linked to acute kidney injury (AKI), while type 4 represents cardiovascular involvement in patients with chronic kidney disease. Type 5 CRS represents cardiac and renal involvement in several diseases such as sepsis, hepatorenal syndrome, and immune-mediated diseases. Understanding the clinical phenotype of CRS is critical in initiating appropriate therapy and applying the underlying pathophysiologic principles in each subtype to achieve optimal outcomes.