I have heard there is a bit of a struggle between cardiologists and nephrologists; something about the heart vs. the kidneys. any insights for why?

Fluid requirements: I would not characterize this as a struggle between specialties. What you may have heard is a debate about fluid requirements for critically ill patients. Sometimes patients whose hearts are functioning poorly cannot tolerate much fluid, and may need diuretics to eliminate fluid. On the other hand, the kidneys need fluid for optimum function. This can be a complicated critical care issue.

Too wet or too dry?: A weak heart (CHF) would like the cirulation to be "dry" i.e. Less fluid overload, in order to function better. The weak kidneys (chronic kidney disease or acute kidney injury) slows down if the circulation is dry. There is usually a happy medium between the two systems that both cardiologists and nephrologists are looking for. Also, some cardiac medicines slow down kidneys raising some debates.

Connected: Diagnostic procedures and treatments for heart can affect the kidney function and people with severe kidney disease most likely also have cardiac issues.

Heart v kidneys: Hi sinan, most cardiologist and nephrologists live in harmony. However, in certain disease processes, treatments can effect either organ in negative ways. Too much of one medication and the kidneys become angry, not enough and the heart struggles. The kidneys need the heart to pump well to work properly so they are closely tied. Hope that helps.