Acute Calcineurin Inhibitor Nephrotoxicity Diagnosed Using Kidney Doppler Ultrasonography After Heart Transplant: A Case Report

Abstract

Acute calcineurin inhibitor (CNI) nephrotoxicity is a common complication associated with CNI exposure. However, it can be difficult to diagnose. Herein, we report a case of acute CNI nephrotoxicity after heart transplant that was visualized using kidney Doppler ultrasonography. A 38-year-old female patient underwent heart transplant 5 years after the use of left ventricular assist device support because of advanced heart failure due to ischemic cardiomyopathy. Corticosteroids, tacrolimus, and mycophenolate mofetil were administered as immunosuppressive regimens postoperatively. The patient gradually developed kidney dysfunction despite a favorable perioperative clinical course and hemodynamics. Serum creatinine increased to 1.89 mg/dL on postoperative day (POD) 9, and the kidney Doppler ultrasonography examination showed severely reduced blood flow in the renal and renal segmental arteries, indicating acute CNI nephrotoxicity due to vasoconstriction of the renal arterioles. After the cessation of tacrolimus, kidney function returned to baseline levels within 2 days, and the kidney Doppler ultrasonography examination on POD 19 revealed a significant increase in blood flow in the renal and renal segmental arteries. Basiliximab followed by everolimus were administered as alternative immunosuppressants. No organic stenosis of the renal artery was detected on the kidney magnetic resonance angiography, and the patient was discharged on POD 51, without any other adverse events, including rejection. Although CNIs are widely used after heart transplant, acute nephrotoxicity should always be considered. After heart transplant, a kidney Doppler ultrasonography should be performed routinely and promptly if there are any clinical manifestations related to kidney function.