In order to optimize temperature monitoring, the mean of temperature measured by Copper-CuNi thermocouple (TC) was compared with the actual temperature. By the use of the temperature response curve of TC, the data from monitoring temperature were analyzed in regard to the depth of installation, the diameter of TC hole and the material of ablation electrode. The accuracy and real-time of TC with a depth of 3.5 mm were better than those of 2.5 mm or 3 mm, when TC was installed in the ablation electrode TC hole. However, the difference of real-time performance was not obvious. When TC was installed in different TC holes with diameter of 0.44 mm, 0.42 mm, 0.33 mm respectively, TC with the diameter of 0.33 mm TC hole was noted to be of higher accuracy and better real-time to response temperature, compared with others. In terms of material quality, the slope of platinum temperature response curve was greater than that of stainless steel, while the accuracy of sensor temperature changed inconspicuously. As a result, the monitoring device of temperature should be put to the heat source as nearly as possible. Also, platinum ablation electrode with better thermal conductivity should be chosen.
Catheter Ablation ; instrumentation ; methods ; Electrodes ; Equipment Design ; Humans ; Platinum ; Temperature

Catheter Ablation ; instrumentation ; methods ; Humans ; Tachycardia, Supraventricular ; therapy

The combination of the cryosurgery using LN2 and intelligent RF ablation therapeutic instrument based on the theory of local destruction is introduced in this paper, and this alternating therapy is believed to have a better controlling effect on tumor ablation. In heating period, a fuzzy algorithm is used to control the RF power to realize a more smoothly heating process to the target area.
Catheter Ablation ; instrumentation ; methods ; Cryosurgery ; instrumentation ; Equipment Design ; Humans ; Hyperthermia, Induced ; instrumentation ; methods ; Neoplasms ; surgery

Although surgical resection remains the best option as potentially curative therapy for hepatocellular carcinoma, radiofrequency thermal ablation has begun to receive much attention as an effective minimally invasive technique for the local control of unresectable malignant hepatic tumors. Most recent radiofrequency devices equipped with a powerful generator and larger needle electrode permit larger thermal lesions, up to 5 cm in diameter, with a single ablation. In this article, the author reviews the technical developments and early clinical results obtained with radiofrequency ablation techniques.
Aged ; Carcinoma, Hepatocellular/*surgery ; *Catheter Ablation/instrumentation/methods ; Female ; Human ; Liver Neoplasms/*surgery ; Male ; Middle Age

OBJECTIVE: To determine the in vivo efficiency of monopolar radiofrequency ablation (RFA) using a dual-switching (DS) system and a separable clustered (SC) electrode to create coagulation in swine liver. MATERIALS AND METHODS: Thirty-three ablation zones were created in nine pigs using a DS system and an SC electrode in the switching monopolar mode. The pigs were divided into two groups for two experiments: 1) preliminary experiments (n = 3) to identify the optimal inter-electrode distances (IEDs) for dual-switching monopolar (DSM)-RFA, and 2) main experiments (n = 6) to compare the in vivo efficiency of DSM-RFA with that of a single-switching monopolar (SSM)-RFA. RF energy was alternatively applied to one of the three electrodes (SSM-RFA) or concurrently applied to a pair of electrodes (DSM-RFA) for 12 minutes in in vivo porcine livers. The delivered RFA energy and the shapes and dimensions of the coagulation areas were compared between the two groups. RESULTS: No pig died during RFA. The ideal IEDs for creating round or oval coagulation area using the DSM-RFA were 2.0 and 2.5 cm. DSM-RFA allowed more efficient RF energy delivery than SSM-RFA at the given time (23.0 +/- 4.0 kcal vs. 16.92 +/- 2.0 kcal, respectively; p = 0.0005). DSM-RFA created a significantly larger coagulation volume than SSM-RFA (40.4 +/- 16.4 cm3 vs. 20.8 +/- 10.7 cm3; p < 0.001). Both groups showed similar circularity of the ablation zones (p = 0.29). CONCLUSION: Dual-switching monopolar-radiofrequency ablation using an SC electrode is feasible and can create larger ablation zones than SSM-RFA as it allows more RF energy delivery at a given time.
Animals ; Catheter Ablation/*instrumentation/*methods ; *Electrodes ; Feasibility Studies ; Liver/*surgery ; Male ; Sus scrofa ; Time Factors

OBJECTIVE: To compare the in-vitro efficiency of dual-switching monopolar (DSM) radiofrequency ablation (RFA) using a separable clustered electrode (Octopus(R) electrodes) with consecutive monopolar (CM) and switching monopolar (SM) RFA techniques to create an ablative zone in the explanted bovine liver. MATERIALS AND METHODS: For DSM-RFA, we used a prototype, three-channel, dual generator RFA Unit and Octopus(R) electrodes with three, 17 gauge internally cooled electrodes. The RFA Unit allowed simultaneous radiofrequency (RF) energy delivery to two electrodes of the Octopus(R) electrodes as well as automatic switching among the three electrode pairs according to the impedance changes. RF energy was sequentially applied to one of the three electrodes for 24 minutes (group A; CM mode, n = 10) or alternatively applied for 12 minutes (group B; SM mode, n = 10) or concurrently applied to a pair of electrodes for 12 minutes (group C; DSM mode, n = 10) in explanted bovine livers. Changes in the impedance and current during RFA as well as the dimensions of the thermal ablative zones were compared among the three groups. RESULTS: The mean, delivered RF energy amounts in groups A, B, and C were 63.15 +/- 8.6 kJ, 72.13 +/- 5.4 kJ, and 106.08 +/- 13.4 kJ, respectively (p < 0.001). The DSM mode created a significantly larger ablation volume than did the other modes, i.e., 68.1 +/- 10.2 cm3 (group A), 92.0 +/- 19.9 cm3 (group B), and 115.1 +/- 14.0 cm3 (group C) (p < 0.001). The circularity in groups A, B, and C were 0.84 +/- 0.06, 0.87 +/- 0.04 and 0.90 +/- 0.03, respectively (p = 0.03). CONCLUSION: DSM-RFA using Octopus(R) electrodes can help create large ablative zones within a relatively short time.
Analysis of Variance ; Animals ; Catheter Ablation/*instrumentation/methods ; Cattle ; Electric Impedance ; Electrodes ; Equipment Design ; Liver/*surgery

OBJECTIVETo analyze the transmural lesions of different parts of the pig heart atrium received different times of ablation applied with Atricure bipolar radiofrequency system.

METHODSSix fresh (ex vivo time<20 min) pig hearts with atrium preserved intact were used as the experimental objects and experimental groups were divided according to the ablation position. The Atricure bipolar radiofrequency system was applied in the ablation of the parts of the atrium, such as posterior wall of left atrium, anterior wall of left atrium, anterior wall of right atrium and posterior wall of left atrium close to mitral posterior ring. Ablate the position of the atrium lengthened about 2.0 cm with the same thickness with an interval of 0.5 cm for 4 times respectively, also recording the time of every ablation. For each part and each time of ablation, the ablated atrial tissue was preserved with 4% formaldehyde and 5% glutaraldehyde, and was sent for observation under light microscope and transmission electron microscope. The ablation time and lesion were analyzed statistically.

RESULTSIn the same position of the atrium, ablation time decreased with the times of the ablation, in different position of the atrium with same time of ablation, time showed a positive proportion with the thickness of the atrium.

CONCLUSIONSAtricure bipolar radiofrequency system is very safe and efficient, also convenient for manipulation. With regard to the relatively thinner part of the atrium, such as posterior wall and anterior wall of left atrium, at least two times of ablation can ensure transmural lesion of the atrial tissue, but to the position of the atrium such as anterior wall of right atrium and posterior wall of left atrium close to mitral posterior ring, 3 to 4 times of ablation can ensure transmural lesion of the atrial tissue.

Radio frequency ablation has become a valuable method in treating cancers or tumors for its wide adaptability, better efficacy, convenience and safety. This paper introduces the research and development of a multipolar RF tumor therapy system based on the technology of destroying hypoxic cell. This is an intellectualized tumor curing system.
Animals ; Catheter Ablation ; instrumentation ; methods ; Electrodes ; Equipment Design ; Mice ; Mice, Nude ; Neoplasms, Experimental ; therapy ; Software Design

The therapeutic options for benign prostatic hyperplasia (BPH) can be divided into medicinal, surgical and minimally invasive treatments. The minimally invasive treatment of BPH is gradually accepted by more and more urologists for its advantages of less damage, good effect, quick recovery and easy acceptance by patients, which includes transurethral needle ablation of the prostate (TUNA), transurethral microwave therapy (TUMT), photoselective laser vaporization of the prostate (PVP), holmium laser enucleation of the prostate (HOLEP) and so on. This article updates the advances in the minimally invasive treatment.
Catheter Ablation ; Humans ; Male ; Minimally Invasive Surgical Procedures ; instrumentation ; methods ; Prostatic Hyperplasia ; surgery ; therapy ; Transurethral Resection of Prostate ; instrumentation ; methods

The development of a RF ablation therapeutic instrument based on improved PID algorithm is introduced here. It is based on the theory of radio frequency local destruction. By adopting the improved PID temperature control algorithm, the problem of the temperature control precision reduction due to tumor tissue characteristic changing by heating has been solved, thus ensuring homogeneous and smooth radio frequency heating to tumor foci. Experiments demonstrate that the new algorithm has strong adaptability and anti-disturbance capability, the equipment works stably and reliably, and can control therapeutic temperature precisely (+/- 2 degrees C), which indicates a good clinical application value.
Algorithms ; Calorimetry ; instrumentation ; methods ; Catheter Ablation ; instrumentation ; methods ; Electrodes ; Equipment Design ; Humans ; Hyperthermia, Induced ; instrumentation ; methods ; Information Storage and Retrieval ; Neoplasms ; therapy ; Software ; Temperature