DOES LEVOSIMENDAN OFFER RENAL PROTECTION DURING OFF PUMPCORONARY ARTERY BYPASS GRAFTING SURGERY? USE OF PLASMA NEUTROPHIL GELATINASE-ASSOCIATED LIPOCALIN(NGAL) AS AN EARLY MARKER OF AKI

Abstract

Acute renal injury (AKI) is a severe complication that occurs in 3.5-31.0% of patients undergoing on/off pump cardiac surgery.1 Manipulations of heart during off pump Coronary Artery Bypass Grafting (CABG) causes hemodynamic instability which leads to reduction in cardiac output which can cause AKI in postoperative period.2 The occurrence of AKI in patients undergoing cardiac surgery raises the mortality rate from 0.4-4.4% to 1.3-22.3% making severe postoperative AKI an independent risk factor for mortality that results in an 8-fold increase in the risk of death.1 The early identification of patients at risk of developing AKI after cardiac surgery is an important strategy for improving the care of such patients during the intraoperative and postoperative periods.1
Serum creatinine is not an early or reliable marker for AKI as it takes time to rise. Human
neutrophil gelatinase - associated lipocalin (NGAL) was initially identified as a protein isolated
from the secondary granules of human neutrophils.3 In 2005, Mori et al. clarified that NGAL accumulates in the human kidney cortical tubules and in the blood and urine after nephrotoxic and ischemic injury. 4 and Mishra et al. reported that the NGAL concentration in urine and serum represents a sensitive, specific, and highly predictive early biomarker for acute renal injury after cardiac surgery. 5 Levosimendan acts by increasing the calcium sensitivity of myocardial cells (inotropy) and opening the ATP sensitive K+ channels (vasodilation). The action on K+ channels in mitochondria seems to have a protective effect on myocardial, renal and other organs from ischemic injury.6 We hence hypothezised that in off-pump CABG the renal-protective effect of levosimendan can be predicted by measurement of N-GAL levels.