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Temporary Segmental Renal Artery Occlusion Using a Novel Reverse Phase Polymer for Robotic Partial Nephrectomy in a Swine Model
Sara Lenherr, M.D.1, Ali Moinzadeh, M.D.1, Sebastian Flacke, M.D., Ph.D.1, Kathryn Lyall, M.S.2, John Merhige, M.E.M3, Curtis W. Bakal, M.D., M.P.H.1, Jean-Marie Vogel, B.A.3, John A. Libertino, M.D.1, Peter N. Madras, M.D.3.
1Lahey Clinic Medical Center, Burlington, MA, USA, 2Intuitive Surgical, Inc, Sunnyvale, CA, USA, 3Pluromed Inc., Woburn, MA, USA.

BACKGROUND: Renal vascular clamping with ensuing warm ischemia is typically necessary during robotic or laparoscopic partial nephrectomy. We aimed to develop a technique for angiographic delivery of a novel intra-arterial reverse thermoplastic polymer allowing temporary selective vascular occlusion with normal perfusion of the remaining kidney. Ultimately, we assessed the feasibility of robotic lower pole partial nephrectomy of the ischemic portion of kidney.
METHODS: Following IACUC approval, eight pigs underwent 16 selective angiographic occlusions of the lower pole segmental artery using LeGoo-XL™ (Pluromed Inc., Woburn, MA, USA). The novel gel polymer LeGoo-XL™ is a non-toxic, non-ionic polymer with reverse thermosensitive properties. The technical feasibility of 2 hemostatic techniques, perfusion hemostasis (PH, n=4) and local plug formation (LP, n=4) was assessed. Duration of selective ischemia was recorded and location of vascular occlusion was noted radiographically and laparoscopically. Feasibility of reversal of the polymer from solid back to liquid state allowing reperfusion was evaluated. Pathologic analysis of the kidney was completed in these acute model pigs. In the last 2 cases, utilizing the LP injection method, a lower pole robotic partial nephrectomy was completed using the da Vinci® surgical system (Intuitive Surgical, Inc., Sunnyvale, CA).
RESULTS: Selective lower pole ischemia was achieved in all 8 cases. There was excellent correlation of radiographic and laparoscopic assessment of vascular occlusion. The PH technique yielded inconsistent duration of occlusion (0-60 minutes). In some cases, reversal of the polymer from solid form to liquid state was not rapidly achieved. In contrast, duration of vascular occlusion using the LP injection technique was more reliable (17-33 minutes) with consistent ability to quickly reverse the plug back to liquid state by cold saline flush, thus reperfusing the previously ischemic segment. Two lower pole robotic partial nephrectomies were completed with minimal blood loss. Pathologic analysis of the kidney did not show any abnormality after treatment with LeGoo-XL™.
CONCLUSIONS: This limited feasibility trial demonstrates a reliable technique for angiographic delivery of LeGoo-XL™ for temporary vascular occlusion of selective renal artery branches using the LP injection technique. Ongoing studies are underway to assess consistency of the technique and long-term effects of the polymer on renal histology and function in survival studies.


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