Experimental Radiofrequency Ablation Of The Tissues Near The Main Vessels Located In Hepatic Hilar

Hepatocellular carcinoma is commonly seen cancer of the liver with high malignant potential. At time of accurate diagnosis, the cancer has progressed to mid and late stages and quite often accompanies cirrhosis of the liver. Curative surgical excision of the malignancy is low and furthermore the liver is also the most common site of metastatic spread of cancer from the gastrointestinal tract. Even though many cancers are located in the hepatic window, only 10 to 15 percent of cases will involve successful surgical resection. Therefore, even though surgery is the best option for hepatocellular carcinoma, due to its limited criteria, it is hard to satisfy clinical need.With advances in CT scans and laproscopic techniques, series of tumor reducing techniques were introduced including percutaneous ethanol injection (PEI), cryoablation, laser thermal therapy, microwave, focal ultrasound and Radiofrequency Ablation (RFA). RFA is a new technique developed recently as a method of minimaltrauma therapy in treating tumors. Due to its minimal damage to surrounding liver tissues, ease of usage, decreasing patient pain, safety, and fast recovery time RFA is gaining more and more attention among surgeons.Radiofrequency involves a high frequency alternating current that moves at the tip of an electrode that is applied to the tumor. The ions inside the tumor will attempt to follow the changes in the alternating current resulting in frictional heating of the tissue itself. As cells continue to heat up, tissue death and necrosis will surround the electrode. Early RFA electrodes have a small diameter of therapeutic area (1 to 1.5 cm) at its tip thus limited its usage in therapy. The next generation of electrodes was improved with changes in electrode morphology (such as umbrella shaped) and vacuum electrode with cold water circulation. These changes improve the diameter of the therapeutic area to 3 -5 cm. however, for tumors sized beyond 5 cm limited therapeutic effects were seen.In animal experiments and clinical data shows that blockage of the portal vein (Pringle maneuver) can increase the RFA therapeutic area. The mechanism is due to decreasing the amount of blood flow to the liver will cause a decrease in "heat-sink" affect. This method improves the heat penatrance in the tissue creating a larger therapeutic effect. However, at the same time, the major vessels in the liver may suffer vessel wall damage due to the absence of protective cooling effect of blood flow.Tumors that are located in the hepatic hilar are in close proximity to neighboring structures veins and hepatic artery so the "heat- sink" affect is even more evident. This experiment using animal experiments will attempt to answer the follow questions.1. Are hepatic tumors surrounding the portal vein has an increased difficulty in treatment with RFA? 2. If the portal vein was blocked, what is the efficacy of RFA on the tumors surrounding the blood vessels? 3. How does RFA effect the homodynamic of the liver and the entire body?Method and Materials19 live domestic pigs (between 35 to 40 Kg) divided into 5 groups (as illustrated) with short term observation defined as 3 hours, and long term observation defined as7 days.RFA used PE-D(20)(2) model vacuum cold circulation single loop electrode andinserted 5 mm from the left branch of the hepatic vein ( illustration 3). Cool-tip RFsystem was utilized and 12 minutes radio frequency was performed. The opposing group has the portal vein circulation clamped for 12 minutes. Left hepatic artery, and the portal vein's blood flow was determined using Titan High-Resolution Ultrasound System, conglutination is determined via NZ-02 Awl-plank Conglutination Instrument, and liver function is determined by Au 2700 Biochemistry Analyse Apparatus. Tissue samples were stained (H-E stain) then viewed under Olympus microscope. Venous wall cell samples were taken from the Portal vein and viewed under TECNA 110 electron microscope (EM) and Cambridge S260 scanning electron microscope (SEM). Data result were analyzed using t test via SPSS 12.0 sof...