The Cardiorenal Syndrome

This special issue of the International Journal of Nephrology is the first nephrology journal edition devoted solely to the discussion of the cardiorenal syndrome and represents a landmark state-of-the-art discussion on such pathological entity. The cardiorenal syndrome (CRS) was first officially defined at a consensus conference of the Acute Dialysis Quality Initiative in 2009 [1]. This definition was made in the attempt to characterize and classify the various connections between acute and chronic heart and kidney disease. Although well known, heart and kidney interactions had not been clearly defined in the past nor were they completely elucidated and classified. The consensus conference defined 5 forms of heart-kidney interaction that would lay the foundation for both a common language in describing patients suffering from these syndromes as well as forming a schema for further research. The consensus conference recognized that communication between the heart and kidneys occurs through a variety of pathways that in the healthy state modulate cardiac output, vascular tone, maintenance of volume state, and excretion of waste products. However, a change in the performance of one of these organs elicits a cascade of mediators that affects the other and leads to a spiral of mutual organ dysfunction.