Blunted renal vasoconstriction in patients with subclinical contrast-induced renal injury

Contrast media are considered to cause acute kidney injury by activating various factors that induce renal vasoconstriction. We analysed the renal microvascular haemodynamic response using the Doppler flow wire method. Then changes in urinary liver-type fatty acid-binding protein levels following contrast medium administration were compared between groups with or without a micro-injury of the kidney. In the group without renal micro-injury, the average peak velocity (APV) decreased significantly, whereas the renal artery resistance index (RI) increased significantly following contrast medium administration. In contrast, there was no significant change in either the APV or RI in the group with a renal micro-injury. A blunted microvascular response was found in the micro-injury group, whereas microvascular resistance increased in the non-micro-injury group.