Experimental Study Of Using Focused Ultrasound Surgical Clamp Combined With Pringle Maneuver Or Sonovue For Bloodless Partial Hepatectomy

OBJECTIVE: To investigate the safety, efficacy and feasibility of using focused ultrasound surgical clamp (FUSC) combined with either Pringle maneuver or SonoVue for partial hepatectomy, and to provide significant data for a novel hepatic surgical instrument and its clinical application. METHODS: (1)Twelve healthy goats were randomly divided into a FUSC group (n=6) and a Pringle maneuver + FUSC group (n=6). A FUSC was comprised of two ultrasound transducers fixed on a forceps-like handle. The directions of focused ultrasound beams produced by both transducers were opposite, with the same central axes. Ultrasound energy was continuously delivered by two transducers to ablate liver tissue located between both transducers. The frequency was 1.6MHz, and the acoustic power was 150W. All goats in both groups underwent laparotomy, and then the liver was totally exposed for an ablative procedure. In the control group FUSC was only used for ablating a predetermined liver tissue along with a resection line before partial hepatectomy; while in the Pringle maneuver+ FUSC group FUSC was performed immediately after the Pringle maneuver for the liver ablation, followed by partial hepatectomy. FUSC exposure time, blood loss, operation time required for the hepatectomy and the cross-section area of the resected liver were recorded. Histological changes were observed in the removed liver, and 10ml blood samples were collected in each goat to measure blood cells and hepatic and renal functions after surgical procedure. All goats were followed up for complications and survival. (2)Twelve healthy goats were randomly divided into a FUSC group (n=6) in which FUSC was only used for the liver ablation, and a SonoVue + FUSC group (n=6) in which FUSC was performed immediately after iv injection of ultrasound contrast agent SonoVue. FUSC ablation was the same as Part one, and all animals in both groups received partial hepatectomy immediately after ablation. Similar observation was performed in both groups to investigate the changes in histology, FUSC exposure time, blood loss, operation time, liver and kidney functions, complications and survival after interventional procedure. RESULTS: (1)Mean blood loss and mean operative time were 16.9±4.2 ml and 424±27s in the FUSC group, and 11.9±2.6ml and 281±17s in the Pringle maneuver + FUSC group respectively. There was a significant difference of average blood loss per unit area (P< 0.05) and average FUSC exposure time per unit area (P < 0.05) between two groups. After surgical procedure, all animals survived well, and no complications were observed during follow-up period. Pathological examination showed coagulation necrosis of the targeted liver tissue, and small blood vessels were severely destroyed, with the occlusion of the ablated vessels. There was a transient increase of serum ALT, AST, TB and DB levels postoperatively in all goats, and they reduced to a normal level 7 days after surgical procedure. (2)Compared to the values in the FUSC group, mean blood loss and mean operative time were 16.3±3.5ml and 374±12s in the SonoVue + FUSC group. A statistical difference of average FUSC exposure time per unit area (P < 0.05) was significantly observed between two groups. But, there was no significant difference of average blood loss per unit area (P >0.05) in both groups. In addition to the same pathological findings within the destroyed liver cells and small blood vessels in the Part one, there were 0.02-0.2mm and microbubbles and vacuoles with irregular shapes in the treated tissues. Liver function changes were similar to the Part one, and all goats survived well with no complications during follow-up period.CONCLUSIONS: (1)FUSC combined with Pringle maneuver for partial hepatectomy is safe, feasible and effective. It can significantly reduce blood loss, decrease operation time and be easy to be performed during surgical procedure. (2)As a new generation microbubble contrast agent, SonoVue can significantly enhance the cavitation effects of FUSC on the targeted liver, resulting in the improvement of FUSC efficiency and the decrease of operation time. FUSC combined with SonoVue for partial hepatectomy is safe, feasible and effective.