1 of 4 Abstract—Hepatic resection is the current standard treatment for hepatic malignancies. During hepatic resection part of the liver containing the tumor is surgically removed. This type of surgery is associated with high blood loss of ~1 L. Blood loss is associated with increased complication rates, prolonged hospital stay and reduced patient survival, especially when transfusion is required. We present a device that allows coagulation of a plane of tissue 1 to 2 cm wide, including coagulation of large vessels. This enables reduction of blood loss to a minimum by performing surgery along the coagulated tissue plane. The device consists of a linear array of radiofrequency (RF) electrodes 1.5 cm apart. By application of RF current in bipolar mode between two adjacent electrodes, temperatures close to 100 °C are obtained in-between electrodes enabling coagulation of large vessels. Rapid switching of applied current between all adjacent electrode pairs enables rapid heating of a tissue slice. We present a prototype device including results from ex vivo and in vivo experiments. Keywords—Ablation, resection, liver, radiofrequency, electrodes, coagulation I. INTRODUCTION Surgical resection is the current standard treatment for both primary and metastatic liver cancer. Depending on technique, either one of the two liver lobes is surgically removed (anatomical resection), or part of a lobe is removed (partial resection). Surgical resection is associated with high interoperative blood loss, with mean blood loss between 600 mL and 1300 mL [1, 2], with 28 to 47% of the patients requiring blood transfusion [1, 3]. Several studies have shown that blood loss correlates adversely with length of hospital stay, complication rate, and patient survival [4, 5]. Especially when transfusion is required, patient prognosis is affected detrimentally, probably due to immunosuppression [6]. Further reduction in interoperative blood loss is therefore advocated by many surgeons. Several recent studies suggested the use of radiofrequency (RF) or microwave ablation to assist hepatic resection [7, 8]. A plane of tissue is coagulated by sequential application of conventional RF or microwave ablation devices, after which resection is performed along the coagulated tissue plane. Using this technique, blood loss can be significantly reduced to a mean of 30 mL for RF-assisted resection [7]. Currently there are a number of limitations to this technique. Conventional RF and microwave applicators cannot coagulate vessels larger than 3 mm diameter. These vessels have to be attended to separately. Furthermore, a large number of ablations are required resulting in considerably longer procedural time of up to several hours. In this study we present a device that potentially allows coagulation of a tissue slice within 3 min, while also coagulating larger vessels than currently possible. II. METHODOLOGY A. Computer models We created 2-D computer models of two needle- and two blade-electrodes at different distances of 1.5, 2 and 2.5 cm. We solved the bioheat transfer equation similar to previous studies [9], and determined tissue temperature distribution after 3 min simulated ablation employing temperature control to limit maximum tissue temperature to 100 °C. From these models we chose 1.5 cm as the optimal distance for subsequent experiments. We further determined tissue temperature created by an array of needle electrodes, where power is applied simultaneously between all electrodes and a ground pad. B. Bipolar RF application with 2 electrodes We custom made blade electrodes (5 × 0.5 mm, 10 cm long) from stainless steel, and separated them 1.5 cm apart guided by a Teflon guide (similar to Fig. 1). Initial computer modeling studies showed that blade electrodes provide higher tissue temperatures compared to needle electrodes. Figure 1. Array of blade electrodes (5 × 0.5 mm), 1.5 cm apart. The distance between two electrodes used in bipolar mode was also determined by computer modeling studies. We A device for radiofrequency assisted hepatic resection D. Haemmerich 1,2 , D. J. Schutt 1 , J. A. Will 3 , R. M. Striegel 2 , J. G. Webster 1 , D. M. Mahvi 2 1 Department of Biomedical Engineering, University of Wisconsin-Madison, WI, USA 2 Department of Surgery, University of Wisconsin-Madison, WI, USA 3 Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, WI, USA