Cardiorenal syndrome: still not a defined entity.

Because of the increasing incidence of cardiac failure and chronic renal failure due to the progressive aging of the population, the extensive application of cardiac interventional techniques, the rising rates of obesity and diabetes mellitus, coexistence of heart failure and renal failure in the same patient are frequent. More than half of subjects with heart failure had renal impairment, and mortality worsened incrementally across the range of renal dysfunctions. In patients with heart failure, renal dysfunction can result from intrinsic renal disease, hemodynamic abnormalities, or their combination. Severe pump failure leads to low cardiac output and hypotension, and neurohormonal activation produces both fluid retention and vasoconstriction. However, the cardiorenal connection is more elaborate than the hemodynamic model alone; effects of the renin-angiotensin system, the balance between nitric oxide and reactive oxygen species, inflammation, anemia and the sympathetic nervous system should be taken into account. The management of cardiorenal patients requires a tailored therapy that prioritizes the preservation of the equilibrium of each individual patient. Intravascular volume, blood pressure, renal hemodynamic, anemia and intrinsic renal disease management are crucial for improving patients' survival. Complications should be foreseen and prevented, looking carefully at basic physical examination, weight and blood pressure monitoring, and blood, urine urea and electrolytes measurement.