Numerous organ systems are closely connected. Normally, this connection should maintain the homeostasis and optimal functioning of the human body. In pathology, however, the affected organ can initiate and perpetuate structural and functional disorders in the other organs, which it is connected with. Thus, heart and kidney disorders frequently coexist in the same patient in the acute or chronic phase. Observational and clinical studies have succeeded in demonstrating that acute/chronic heart disease can directly contribute to the development or progression of acute / chronic renal disease and vice versa.