The cardiorenal syndrome in heart failure.

The frequently occurring condition of renal failure in heart failure (HF) has been termed the cardiorenal syndrome. However, the importance of renal insufficiency in HF has only been embraced in the last decade, and therefore, the pathophysiology of cardiorenal failure is still poorly understood. The main driving force of renal failure in HF is probably hemodynamic derangement, with both reduced renal perfusion and increased venous pressure as the most important driving forces. Different cardiorenal connectors may modulate this relationship. Furthermore, renal failure is not only limited to reduced filtration but also includes glomerular hypertension and tubulointerstitial hypoxia, leading to loss of glomerular integrity and tubular damage. Recognition of these key pathophysiologic pathways in the concept of the cardiorenal syndrome is needed to value the interrelationship and incremental contribution of different risk markers and possible new treatments to improve renal function and outcome in this complex and bidirectional interplay between the heart and the kidney.