#3859 Prolonged renal ischemia: time is ticking

Abstract Background and Aims Renal ischemia can be a potentially reversible cause of kidney failure. Early intervention (within hours to a couple of days) offers the best chance for kidney recovery after ischemic injury. The kidneys' ability to recover diminishes significantly with prolonged ischemia, as ischemic injury can progress to irreversible kidney damage, such as acute tubular necrosis (ATN), fibrosis, and nephron loss. However, there are some reports of successful kidney revascularization after prolonged kidney ischemia, sometimes leading to partial or limited functional recovery. This recovery is highly dependent on the degree of ischemic injury and the viability of the kidney tissue. Method The patient's medical records were reviewed and summarized. Results We report the case of a 70-year-old male patient with a history of hypertension and valvular and ischemic cardiopathy, who was admitted for aortic conduit and aortic valve replacement revision following the detection of an ascending aorta aneurysm. The procedure was complicated by a complex aortic dissection extending to the abdominal aorta, encompassing the emergence of both renal arteries. The patient became hemodynamically unstable and anuric and was admitted to the intensive care unit for monitoring. CT angiography revealed that the right renal artery was emerging from the false lumen, and the left renal artery was stenotic due to the dissection extending to the proximal part of this artery. The renogram showed delayed enhancement of the renal parenchyma, and renal Doppler ultrasound revealed no flow in the right renal artery and severely reduced flow in the left renal artery. Due to infectious and neurological complications, renal artery intervention was not feasible, and the patient remained anuric, dependent on continuous venovenous hemodiafiltration for 19 days. Once the patient became stable enough, renal angiography was performed, demonstrating partial patency of the left renal artery and virtually complete occlusion of the right renal artery. An endoprosthesis was placed in the right renal artery, restoring patency after the procedure. The patient became independent of renal replacement therapy 5 days later and continued to regain kidney function, reaching a minimum serum creatinine level of 1.3 mg/dL. Conclusion Although the chances of recovery from kidney failure sharply decrease after a few hours, there may still be a role for intervention, even in cases of prolonged ischemia. These patients should be carefully selected, preferably in the case of incomplete occlusions without clear imaging evidence of irreversible damage. We still lack the tools to accurately assess the extent and reversibility of kidney damage; therefore, more precise functional studies are needed, as there is often a mismatch between imaging findings, the actual patency of the renal arteries, and the cellular response to ischemia. Cases like these, although anecdotal, cast doubt on our current ability to predict the renal outcome of acute vascular kidney injury and our reluctance to intervene.