Hemodynamically, the kidney is at the heart of cardiorenal syndrome

TREATMENT IS CHALLENGING

The treatment of cardiorenal syndrome is challenging. It is often accompanied by heightened azotemia, diuretic resistance, electrolyte abnormalities, and a spectrum of hemodynamic disarray. As Thind et al point out, there is, unfortunately, no firmly established treatment. While “sequential nephron blockade” (pharmacologically blocking multiple sites on the nephron simultaneously) is theoretically promising, there are no rigorously studied therapeutic strategies with proven efficacy.

On the other hand, mechanical removal of isotonic fluid with ultrafiltration showed early promise in decompensated heart failure, but enthusiasm diminished with results from the Cardiorenal Rescue Study in Acute Decompensated Heart Failure (CARRESS-HF) trial.²⁰ Ultrafiltration was roughly equivalent to aggressive pharmacologic therapy for fluid loss, was associated with higher serum creatinine levels, and was more challenging to administer.

Equally uncertain is the benefit of inotropic or vasoactive therapy, which directly alters cardiac hemodynamics. Low-dose dopamine or low-dose nesiritide is of no benefit toward enhancement of decongestion or renal protection when added to standard diuretic therapy.²¹ Furthermore, routine use of ino­tropes is fraught with more arrhythmias and hypotension and is associated with dismal long-term outcomes.^22,23

Alternative therapies that act directly on renal physiology—eg, rolofylline, a selective adenosine A1 receptor antagonist that may enhance renal blood flow, augment natriuresis, and break diuretic resistance—have been similarly disappointing.²⁴

With so much uncertainty, more investigation into novel treatments for cardiorenal syndrome is clearly warranted.

However, because venous congestion is the hemodynamic hallmark of acute cardiorenal syndrome (increasing P_B), reducing central venous pressure remains the cornerstone treatment for cardiorenal syndrome. Additionally, efforts to preserve renal perfusion and avoid hypotension are prudent to maintain glomerular capillary hydrostatic pressure (P_G).

In light of these considerations, there is no “one size fits all” for the treatment of cardiorenal syndrome. Treatment should be based on thoughtful individualized strategies tailored to the underlying cardiorenal pathophysiology, and with the understanding that the kidney is at the heart of the matter.