The general definition has been expanded into five subtypes: CRS type 1 = acute worsening of heart function (acute heart failure-acute coronary syndrome) leading to kidney injury and/or dysfunction; CRS type 2 = chronic abnormalities in heart function (chronic heart failure-chronic heart disease) leading to kidney injury or dysfunction; CRS type 3 = acute worsening of kidney function (acute kidney injury) leading to heart injury and/or dysfunction; CRS type 4 = chronic kidney disease (chronic kidney disease) leading to heart injury, disease and/or dysfunction; and CRS type 5 = systemic conditions leading to simultaneous injury and/or dysfunction of heart and kidney.