Temporary segmental renal artery occlusion using reverse phase polymer for bloodless robotic partial nephrectomy.

PURPOSE: Renal vascular clamping with ensuing warm ischemia is typically needed during robotic or laparoscopic partial nephrectomy. We developed a technique for angiographic delivery of the novel intra-arterial reverse thermoplastic polymer LeGoo-XL that allows temporary selective vascular occlusion with normal perfusion of the remaining kidney. MATERIALS AND METHODS: Eight pigs underwent a total of 16 selective angiographic occlusions of the lower pole segmental artery using gel polymer. The technical feasibility of 2 hemostatic techniques, perfusion hemostasis and local plug formation, was assessed in 4 pigs each. Selective ischemia time was recorded and the vascular occlusion site was noted radiographically and laparoscopically. The feasibility of reversing the polymer from solid back to liquid state to allow reperfusion was determined. Pathological analysis of the kidney was completed in these acute model pigs. In the last 2 cases lower pole robotic partial nephrectomy was done using the da Vinci surgical system. RESULTS: Selective lower pole ischemia was achieved in all 8 cases. Perfusion hemostasis yielded an inconsistent duration of occlusion (zero to greater than 60 minutes). Vascular occlusion time using local plug formation was more reliable (17 to 30 minutes) with consistent ability to reverse the plug to liquid state by cold saline flush. Two lower pole robotic partial nephrectomies were completed with minimal blood loss. CONCLUSIONS: We developed a reliable technique of angiographic delivery of gel polymer for temporary vascular occlusion of selective renal artery branches using local plug formation. Ongoing studies are under way to assess technique consistency and the long-term effects of the polymer.

A novel technique for creating solid renal pseudotumors and renal vein-inferior vena caval pseudothrombus in a porcine and cadaveric model.

PURPOSE: We developed a simple means to replicate kidney tumors in an animal and cadaver model that could be used to create pseudotumors of different sizes and locations for use in surgical training. MATERIALS AND METHODS: Various substances were injected ex vivo into the parenchyma of porcine kidneys to identify an optimal pseudotumor model. Renal pseudotumors were created percutaneously and endoscopically using 8 live pigs and a human cadaver model. A renal vein pseudothrombus porcine model was also created by injecting pseudothrombus material into the renal vein after renal hilar clamping. Procedures performed on pseudotumors included robotic partial nephrectomy, percutaneous biopsy and robotic nephrectomy with renal vein thrombectomy. All specimens were analyzed after resection. RESULTS: The most ideal pseudotumor models were created from a mixture of gelatin, Metamucil and methylene blue (metagel) or from Kromopan hydrocolloid. We created 33 tumors 0.5 to 3.5 cm in size (mean 2.8). All tumors were a solid palpable mass on gross examination and ultrasonography revealed clearly visible hyperechoic lesions in 30 of 33. A renal vein tumor pseudothrombus model was successfully created in 3 pigs. We successfully performed robotic excision of pseudotumors, including partial nephrectomy for 16 and radical nephrectomy with renal vein thrombectomy for 3. Percutaneous needle core biopsy under ultrasound guidance was also successfully performed. CONCLUSIONS: We describe what is to our knowledge a novel technique of creating solid renal tumors and tumor thrombi that can be used for training in minimally invasive kidney surgery.