Cardio renal syndromes 2015: Is there a silver lining to the dark clouds?

Kidneys have a pivotal role in maintaining our homeostasis. Kidneys and heart work in tandem to maintain volume homeostasis. Heart failure impacts renal function in many ways including renal hypo perfusion but also due to increased venous pressure along with stimulation of various neuro-humoral responses. Renal failure induces cardiac damage and dysfunction by causing volume overload, inflammation and cardiomyocyte fibrosis. Concomitant comorbidities like Hypertension and Diabetes also play important role resulting in Cardiorenal Syndrome (CRS). Acute Dialysis Quality Initiative, 2007 recognized the bidirectional nature and different manifestations of CRS in acute and chronic settings. Diuretics are the most common drugs to treat the most common symptoms of CRS i.e., peripheral edema and pulmonary congestion. Diuretics could nevertheless contribute to worsening renal function (WRF). Initially it was accepted that WRF during the course of treatment of acute decompensated heart failure (ADHF) uniformly resulted in worse prognosis. However, in view of a few recent studies, the significance of WRF early in response to treatment of ADHF is being debated. The optimal dose and method of delivery of diuretics is still undecided. Isolated ultrafiltration does not improve renal function in patients with CRS despite the early promise. A large, multicentre trial ruled out any survival benefits with Recombinant Brain Natriuretic Peptide (Nesiritide). Despite good physiological basis and early promise with smaller studies, many drugs like Dobutamine, Rolofylline and Tolvaptan failed to show survival benefit in larger studies. However, two recent studies involving Relaxin and Neprilysin have shown good survival advantage. There had been little progress in treatment of CRS until studies involving Relaxin and Neprilysin inhibitor combination with ARB were published. There may after all, be a glimmer of hope in the field of CRS bogged by multiple negative studies. Keywords: Acute Decompensated Heart Failure (ADHF), Acute Dialysis Quality Initiative (ADQI), Anemia, Cardiorenal anemia, Atrial Natriuretic Peptide (ANP), Blood Urea Nitrogen (BUN), Brain-type Natriuretic Peptide (BNP), Cardio Renal Syndrome (CRS), Central Venous Pressure (CVP), Congestive Heart Failure (CHF), Diuretic Resistance (DR), Estimated Glomerular Filtration Rate (eGFR), Heart Failure (HF), Intra-abdominal Pressure (IAP), Juxta glomerular (JG) apparatus, Left Atrium (LA), Left Ventricular Ejection Fraction (LVEF), Neprilysin inhibitor, Neprilysin, Relaxin, Renin-Angiotensin- Aldosterone System (RAAS), Sacubitril, Serelaxin, Sympathetic Nervous System(SNS), Ultrafiltration (UF), Worsening Renal Function (WRF).