Endovascular temporary vessel occlusion with a reverse-thermosensitive polymer for bloodless minimally invasive renal surgery.

PURPOSE: To demonstrate the feasibility of reversible vessel embolization with angiographic guidance for delivery of a rapid reverse-thermosensitive polymer to provide hemostasis as an aid for minimally invasive renal surgery in a porcine model. MATERIALS AND METHODS: After isolation of the left kidney of seven anesthetized pigs (50-70 kg) with a surgical robot, a renal angiogram of both kidneys was obtained. A 5-F angiographic catheter was used to selectively embolize a lower-pole segmental artery of the right and left kidney with a thermosensitive polymer (LeGoo-XL). Distal and proximal embolization of the target vessel was compared. Degree and duration of hemostasis and reversibility was determined. After complete hemostasis was obtained angiographically, a partial robotic lower-pole nephrectomy was performed on the left kidney only. RESULTS: Only proximal embolization provided controllable hemostasis. A 20% polymer concentration in a buffer solution of 40% saline solution and 40% iodine contrast medium by weight injected at room temperature resulted in a reproducible embolus for more than 30 minutes, the time needed to perform a partial nephrectomy. The radiographic appearance of the embolus was used to determine the total amount of polymer needed. Cold saline solution completely dissolved any residual polymer at the end of surgery. CONCLUSIONS: Proximal arterial occlusion with a thermosensitive polymer can be rapidly reversed with selective intraarterial infusion of chilled saline solution. Preceding nephron-sparing surgery with transcatheter embolization of the relevant branch of the renal artery with the polymer can facilitate the procedure and ought to be investigated further.

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.