Ischemic Renal Damage after Nephron-Sparing Surgery in Patients with Normal Contralateral Kidney

BackgroundAlthough nephron-sparing surgery (NSS) has been reported not to affect total renal function, the functional damage of the operated kidney is masked by the contralateral kidney in elective indications.ObjectiveTo determine ischemic renal damage after NSS.Design, setting, and participantsFrom August 2005 to October 2007, 32 consecutive patients with elective indications underwent NSS. The mean tumor diameter was 2.6 cm.InterventionOf our patients, the open surgery was performed in 20 patients, and laparoscopic surgery was performed in 12 patients. NSS was performed by hilar clamping with a warm ischemic time of 24.3 min.MeasurementsWe analyzed effective renal plasma flow (ERPF) calculated from 99mTc-mercaptoacetyltriglycine (99mTc-MAG-3) renal scintigraphy and renal parenchymal volume (RPV) measured from computed tomography (CT) scan. In addition, we analyzed 99mTc-MAG-3 uptake regionally in the surgically non-affected parts. 99mTc-MAG-3 and CT scans were performed preoperatively and 1 wk and 6 mo postoperatively.Results and limitationsOne week after NSS, ERPF of the operated kidney decreased by 28.7% (from 158.9 to 113.3 ml/min per 1.73 m2, p < 0.001), and RPV decreased by 12.6% (from 149.8 to 131.0 cm3, p < 0.001). These changes were stable for 6 mo. Regional 99mTc-MAG-3 uptake of the operated kidney with an ischemic time of ≥25 min decreased to 61.8% after 1 wk and 70.9% after 6 mo. In contrast, with ischemic times within 25 min, regional 99mTc-MAG-3 uptake was 87.4% after 1 wk and 94.4% after 6 mo. This is a relatively small study, and the follow-up period is short. A larger sample size and longer follow-up may be required.ConclusionsAlthough total renal function was almost unaffected before and after NSS, a warm ischemic time of ≥25 min caused irreversible damage distributed diffusely throughout the operated kidney.