Ischemic renal damage after nephron-sparing surgery in patients with normal contralateral kidney.

BACKGROUND: Although 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. OBJECTIVE: To determine ischemic renal damage after NSS. DESIGN, SETTING, AND PARTICIPANTS: From August 2005 to October 2007, 32 consecutive patients with elective indications underwent NSS. The mean tumor diameter was 2.6 cm. INTERVENTION: Of 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. MEASUREMENTS: We analyzed effective renal plasma flow (ERPF) calculated from (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG-3) renal scintigraphy and renal parenchymal volume (RPV) measured from computed tomography (CT) scan. In addition, we analyzed (99m)Tc-MAG-3 uptake regionally in the surgically non-affected parts. (99m)Tc-MAG-3 and CT scans were performed preoperatively and 1 wk and 6 mo postoperatively. RESULTS AND LIMITATIONS: One week after NSS, ERPF of the operated kidney decreased by 28.7% (from 158.9 to 113.3 ml/min per 1.73 m(2), p<0.001), and RPV decreased by 12.6% (from 149.8 to 131.0 cm(3), p<0.001). These changes were stable for 6 mo. Regional (99m)Tc-MAG-3 uptake of the operated kidney with an ischemic time of > or = 25 min decreased to 61.8% after 1 wk and 70.9% after 6 mo. In contrast, with ischemic times within 25 min, regional (99m)Tc-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. CONCLUSIONS: Although total renal function was almost unaffected before and after NSS, a warm ischemic time of > or = 25 min caused irreversible damage distributed diffusely throughout the operated kidney.