Cardiorenal Interactions in Acute Heart Failure; Renal Proximal Tubules in the Spotlight.

BACKGROUND:The maladaptive neurohormonal activation, an integral mechanism in the pathophysiology of heart failure (HF) and cardiorenal syndrome, has a profound impact on renal sodium handling. Congestion is the primary reason for hospitalization of patients with HF and the main target of therapy. As sodium is the main determinant of extracellular volume, the goal is to enhance urinary sodium excretion in order to address excess fluid. The interventions to increase natriuresis have conventionally been focused on distal nephron as the primary segment that counterbalances the effects of loop diuretics. SUMMARY:Recent developments in the field of cardiorenal medicine have resulted in a shift of attention to renal proximal tubules (e.g., emerging evidence on proximal tubular dysfunction beyond handling of sodium). Herein, we discuss the three main mechanisms of sodium transport in the proximal tubules with emphasis on their intrinsic links to one another as well as to more distal transporters of sodium. Then, we provide an overview of the findings of the most recent clinical studies that have tried to enhance the conventional decongestive strategies through simultaneous blockade of these mechanisms. KEY MESSAGE:Interventions aiming at renal proximal tubules have the potential to significantly improve our ability to decongest patients with acute HF.