"Cardio-renal syndromes" (CRS) are disorders of the heart and kidneys whereby 
acute or chronic dysfunction in one organ may induce acute or chronic 
dysfunction of the other. The current definition has been expanded into five 
subtypes whose etymology reflects the primary and secondary pathology, the 
time-frame and simultaneous cardiac and renal co-dysfunction secondary to 
systemic disease: CRS type I: acute worsening of heart function (AHF-ACS) 
leading to kidney injury and/or dysfunction. CRS type II: chronic abnormalities 
in heart function (CHF-CHD) leading to kidney injury or dysfunction. CRS type 
III: acute worsening of kidney function (AKI) leading to heart injury and/or 
dysfunction. CRS type IV: chronic kidney disease (CKD) leading to heart injury, 
disease and/or dysfunction. CRS type V: systemic conditions leading to 
simultaneous injury and/or dysfunction of heart and kidney. These different 
subtypes may have a different pathophysiological mechanism and they may 
represent separate entities in terms of prevention and therapy.