Intestinal Tissue Fusion Based on Radiofrequency Energy / 医用生物力学

Objective The ileum of porcine intestines with radiofrequency (RF) energy was fused through a novel linkage-type pressure controlled electrode, so as to verify feasibility and security of intestinal reconstruction in the RF energy tissue fusion technology. Methods Fresh porcine intestines were fixed on negative electrode in the order of ‘mucosa-serosa’, and then different compressive pressures （497，796，995，1 194，1 492 kPa）and RF energy were applied to the tissues through positive electrode of pressure cone to complete intestinal anastomosis. Biomechanical properties of the fused area were studied by tensile strength and bursting pressure test, and the thermal diffusion and tissue microstructure also studied. ResultsThe anastomotic tensile strength and bursting pressure could reach （8.73±1.11） N and （8.29±0.41） kPa, respectively, when the energy output power, pressure and welding time were 160 W, 995 kPa and 13 s, respectively, and an intact microstructure with little free collagen in the fused area could be observed. Conclusions The technology of RF energy-based tissue fusion could accomplish fast and stable intestinal tract reconstruction, showing great potential in clinical application. It is of great significance to shorten the operation time, simplify the operation process and improve the operation quality.

Advancement in liver laparoscopic resection - development of a new surgical device

Liver resection is the standard treatment for any liver lesion. Laparoscopic liver resection is associated with lower intra-operative blood loss and fewer complications than open resection. Access to the posterior part of the right liver lobe is very uncomfortable and difficult for surgeons due the anatomic position, especially when employing laparoscopic surgery. Based on these experiences, a new laparoscopic device was developed that is capable of bending its long axis and allowing the application of radiofrequency energy in areas that were not technically accessible. The device is equipped with four telescopic needle electrodes that cause tissue coagulation after the delivery of radiofrequency energy. Ex vivo testing was performed in 2012 and 2014 at the University Hospital, Ostrava, on a porcine liver tissue. The main goal of this testing was to verify if the newly proposed electrode layout was suitable for sufficient tissue coagulation and creating a safety zone around lesions. During the ex vivo testing, the material of needle electrodes was improved to achieve the lowest possibility of adhesion. The power supply was adjusted from 20 to 120 W and the ablation time, which varied from 10 to 110 s, was monitored. Subsequently, optimal power delivery and time for coagulation was determined. This experimental study demonstrated the feasibility and safety of the newly developed device. Based on the ex vivo testing, LARA-K1 can create a safety zone of coagulation. For further assessment of the new device, an in vivo study should be performed.

Reconsideration of Gastroesophago-larygotracheal Syndrome and Progress of Endoscopic Radiofrequency Energy Delivery for Gastroesophageal Reflux Disease / 中国微创外科杂志

[Summary] As the gradual deepening understanding of gastroesophageal reflux disease ( GERD ) , more extraesophageal symptoms are noted .The concept and therapeutic strategy for GERD has also undergone a quiet revolution over recent years .The application of proton pump inhibitor ( PPI) has been a landmark of medical treatment for GERD , and the invention of laparoscopic fundoplication and endoscopic radiofrequency energy delivery to the lower esophageal sphincter are marking a new era of comprehensive therapy for GERD .Good short and long term outcomes have been obtained since endoscopic radiofrequency energy delivery to the lower esophageal sphincter was applied on typical symptoms of GERD .Furthermore, the technique has also been successfully used in treating extraesophageal symptoms induced by proximal reflux in China .With more simple and less invasive features compared with anti-reflux surgery, the radiofrequency procedure has broad application prospects .

The Effects of Radiofrequency Energy on Human Articular Cartilage: The Effect of Power Setting and Mode of Treatment on Chondrocyte Viability / 대한정형외과학회잡지

PURPOSE: The objective of this study was to investigate the effects of radiofrequency energy on human chondrocyte viability, and to correlate confocal laser microscopy fluorescence to sulfate uptake and to the histological integrity of articular cartilage. MATERIALS AND METHODS: The chondroplasty procedure for chondromalacic articular cartilage was performed using a 3.0-mm ArthroWand (Arthroscopic Electrosurgery System, ArthroCare Corporation) on fresh human articular cartilage. Radiofrequency energy was applied to the cartilage surface through the probe at a velocity of 10-mm per second in contact and non-contact mode. Three power settings were used. The treated cartilage was analyzed for chondrocyte viability by confocal laser microscopy and (35)S uptake. RESULTS: Confocal laser microscopy demonstrated partial-thickness chondrocyte death irrespective of treatment method. No mode of treatment or radiofrequency energy power setting resulted in full-thickness chondrocyte death. The depth of cartilage ablation was increased in the treated areas in contact mode in proportion to the power level and the time of treatment. No statistically significant difference in radiolabeled sulfate uptake of the specimens was observed with respect to the treatment modes and power settings. CONCLUSION: The extent of chondrocyte death by radiofrequency energy was not as significant as reported previously when the probe was moved at the speed of 10 mm/sec. Radiofrequency energy may be useful to treat chondromalacic cartilage in a contact mode using a proper energy level and delivery time.

The Effect of Radiofrequency Energy-Induced Thermal Shrinkage on Anterior Cruciate Ligament: An in Vitro Biomechanical Study Using a Rabbit Model

Recently, devices using radiofrequency energy have been developed for arthroscopic soft tissue ablation and shrinkage. The purpose of this study was to evaluate effect of radiofrequency energy on the biomechanical competence of thermal shrinkage of anterior cruciate ligament and was to demonstrate a new approach for radiofrequency energy, applying to ligamentous tissue in a dynamic fashion. Twelve New Zealand White rabbits, were divided into two experimental groups by right and left hindlimbs. Thermal shrinkage of the anterior cruciate ligament of rabbits produced using radiofrequency energy generator(N=12, group I). And untreated control group(N=12, group II). The percent shrinkage was calculated from the change of length of anterior cruciate ligament after radiofrequency energyinduced thermal shrinkage. The maximal tensile stress and linear stiffness of anterior cruciate ligament as biomechanical competence were assessed. The results obtained were as follows: 1. In the group I the percentage of shrinkage was 29.50Fo on the average. 2. The average of maximal tensile stress to failure was 271.24 kN in group I and 283.50 kN in group II. There was no significant difference(p=0.24) in the maximal tensile stress between two groups. 3. The average of linear stiffness in group I(179.16kN/mm) was higher than that of group II(148.20kN/mm). But there was no significant difference(p=0.078) between two groups. This study shows that radiofrequency energy appears to be safe to use on therma1 shrinkage of anterior cruciate ligament, which necessitate a mechanical tensile strength.

The Tissue Damage due to Radiofrequency Energy in Bovine Skeletal Muscle

BACKGROUND: Radiofrequency(RF) catheter ablation has rapidly emerged as the treatment of choice for symptomatic reentrant arrythmia associated with accessory pathway or atrioventricular node conduction. Rarely RF catheter ablation therapy can produce the cardiac perforation, ventricular function insufficiency and arrythmia. So, the purpose of this study was to determine the correlation between the RF energy and muscle injury. METHODS: Bovine skeletal muscle was immersed in normal saline, and the entire chamber was heated to 36-37degrees C by water bath. The 4mm tip 7 Fr electrode catheter was placed horizontally on the skeletal muscle surface withoup pressure. RF energy was delicered to tissue for the pulse duration of 10, 20, 30, 40, 50, 60 seconds and voltage of 10, 15, 20, 25, 30, 35, 40, 45volt and total 432 lesions were produced. Horizontal, vertical lesion diameters and depths were measured, and the area and volume of lesion were calculated. RESULTS: Increasing voltage and duration of RF increased the horizontal and vertical diameter, depth, area and volume of lesion(p<0.0001). The RF pulse duration and voltages made lesion below 5mm depth were 45volt applied dbelow 20seconds, 40volt applied below 25seconds, 35volt applied below 32seconds, 30volt applied below 38seconds, 25volt applied during any duation of time. CONCLUSION: So, for prevention of undesirable tissue damage, the adequate pulse duration and voltage of RF must to be delivered to tissue.

The Selective Radiofrequency Catheter Ablation in Patients with AV Nodal Reentrant Tachycardia

BACKGROUND: The catheter ablation using radiofrequency(RF) energy in patients with AV nodal reentrant tachycardia(AVNRT) has been proved as a safe and effective nonpharmacologic therapeutic modality. The selective ablation of slow pathway is now becomming a standard treatment in patients with AVNRT because of its high success rate and negligible AV block risk. In our study, we demonstrated the feasibility, success rate and complications of selective radiofrequency catheter ablation of fast pathway or slow pathway for the treatment of AV nodal reentrant tachycardia. METHODS: Among patients diagnosed as AVNRT by electrophysiologic study, total 21 patients (M : F=11 :10, mean age ; 39 years old) were included in this study. Selective RF ablation of fast pathway was performed in 9 patients and selective RF ablation of slow pathway in 12 patients. The RF generator used in this study was Osypka HAT 200 model and catheters were 6F or 7F steerable catheters with 4 mm distal tip. RESULTS: The successful selective abation was achieved in 18 of 21 patient(86%). The success rate of selective ablation of fast pathway was 67%(6/9 patients) and that of slow pathway was 100%(12/12). The complication(complete AV block) was occurred in one patient in slective ablation of fast pathway but there was no AV block in selective ablation of slow pathway. During follow-up, there was one recurrence in patients treated by selective ablation of fast pathway(mean F/U : 17 months) but there has been no recurrence yet in patients treated by selective ablation of slow pathway(mean F/U : 6 months). The procedural feasibility between two ablation methods in terms of total procedure time, fluoroscopic time and number of RF applications was not differrent significantly. CONCLUSION: The RF ablation in patients with AV nodal reentrant tachycardia is a safe and a effective nonpharmacologic therapeutic modality. Especially, the selective RF ablation of slow pathway is a promising therapeutic modality in patients with AV nodal reentrant tachy cardia.

Ablação por cateter em pacientes com arritmias cardíacas refratárias utilizando técnicas de radiofrequência / Catheter ablation of refractory cardiac arrhythmias by radiofrequency current

Objetivo: Descrever a experiência inicial do Setor Eletrofisiologia Clínica da Escola Paulista de Medicina com as técnicas de ablaçäo por radiofreqüência. Métodos - Vinte pacientes com arritmias refratárias ao tratamento clínico foram submetidos a estudo eletrofisiológico para diagnóstico e ablaçäo por radiofreqüência dos circuitos de suas arritmias. Dez pacientes eram homens e 10 mulheres com idades variando de 13 a 76 anos (média de 42,4 anos). Dezenove pacientes apresentavam taquiarritmias supraventriculares: 1 taquicardia atrial e 1 fibrilaçäo atrial com resposta ventricular rápida, 5 pacientes com taquicardia reentrante nodal e 12 pacientes com taquicardia reentrante atrioventricular. Um pacientes apresentava taquicardia ventricular de via de saída de ventrículo direito. Resultados - O tempo médio do procedimento foi de 4,17 horas e o número de aplicaçöes variou de 1 a 10 (média de 3,4 aplicaçöes), 30 - 40 V cada. Obteve-se sucesso em 18/20 (90%) dos pacientes, sendo que em 15/18 (83%) dos pacientes tratados com sucesso, o procedimento diagnóstico e terapêutico foi feito só exame. Um paciente apresentou oclusäo arterial aguda relacionada ao procedimento, necessitando de trombectomia por cateter de Fogarty. Durante um seguimento médio de 4 meses nenhum paciente apresentou recorrência de taquicardia. Conclusäo - Os resultados da experiência inicial das técnicas de ablaçäo por radiofreqüencia em nosso meio sugerem que esse proceimento possa beneficiar um grande número de pacientes com taquiarritmias

Purpose - evaluate the efficacy of radiofrequency catheter ablation in patients with refractory cardiac arrhythmias. Methods - Twenty patients with refractory cardinc arrhythmias were undertaken to electrophysiologic studies for diagnosis and radiofrequency catheter ablation of their reentrant arrhythmias. Ten patients were men and 10 women with ages varyingfrom 13 to 76 years (mean = 42,4 years).Nineteen patients had supraventricular tachyarrhythmias: One patient had atrial tachycardia and 1 atrial fibrillation with rapid ventricular rate, 5 patients had reentrant nodal tachycardia, 12 patients had reentrant atrioventricular tachycardia and 1 patient had right ventricular outflow tract tachycardia. Results - the mean time of the procedure was 4,1 hours. The radiofrequency current energy applied was 40-50 V for 30-40 seconds. Ablation was successful in 18/20 (90%) patients; in 15/18 (83%) of sucessfully treated patients the same study was done for diagnosis and radiofrequency ablation. One patient had femoral arterial occlusion and was treated with no significant sequelae. During a mean follow-up of 4 months no preexcitacion or reentrant tachycardia occurred. Conclusions - the results of our experience with radiofrequency catheter ablation of cardiac arrhythmias suggest that this technique can benefit an important number of patients with cardiac arrhythmias

Transcatheter Modification of Atrioventricular Junction With Radiofrequency Energy for Control of Atrioventricular Nodal Reentrant Tachycardia / 中国介入心脏病学杂志

Transcatheter atrioventricular (AV) junction ablation with radiofrequency energy was performed in five patients with AV nodal reentrant tachycardia. Disappearance of ventriculoa-trial condcution in all patients was showed and no dual pathway was observed in four patients, in whom three patients occurred first degree AV block after ablation. No tachycardia was showed in all patients in the electrophysiology test and in follow-up of 1. 5-12. 5 months. The results sug-gested that the application of radiofrequency energy may be a suitable and safe therapeutic mothed for modification of AV nodal conduction in patients with AV nodal reentrant tachycardia.