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Radiofrequency
Kinds of Radiofrequency Terms modified by Radiofrequency Selected AbstractsINLINE RADIOFREQUENCY ABLATION-ASSISTED LAPAROSCOPIC LIVER RESECTION: FIRST EXPERIMENT WITH STAPLING DEVICEANZ JOURNAL OF SURGERY, Issue 6 2007Peng Yao Background: In liver surgery, the increase in advancement of laparoscopic equipment has allowed the feasibility and safety of complex laparoscopic liver resection. However, blood loss and the potential risk of gas embolism seem to be the main obstacles. In this study, we successfully used the InLine radiofrquency ablation (RFA) device to carry out laparoscopic hand-assisted liver resection in pigs. Methods: Under general anaesthesia with tracheal intubation, pigs underwent InLine RFA-assisted laparoscopic liver resection. After installation of Hand Port and trocars, the InLine RFA device was introduced through Hand Port system and inserted into the premarked resection line. Then the generator was turned on and the power was applied according to the power setting. The resection was finally carried out using diathermy or stapler. For the control group, resection was simply carried out by diathermy or stapler. Results: Eight Landrace pigs underwent 23 liver resections. Blood loss was reduced significantly in the InLine group (P < 0.001) when compared with control group in both surgical methods (diathermy and stapler). Conclusion: In this study, we successfully carried out InLine RFA-assisted laparoscopic liver resection in both stapled and diathermy group. We showed that there was a highly significant difference between InLine and other liver resection techniques laparoscopically. [source] Animal Model to Explain Fat Atrophy Using Nonablative RadiofrequencyDERMATOLOGIC SURGERY, Issue 2 2007IŃIGO DE FELIPE MD First page of article [source] Treatment of Nevoid Hyperkeratosis of the Nipple and Areola Using a Radiofrequency Surgical UnitDERMATOLOGIC SURGERY, Issue 6 2005Irfan Özyazgan MD Background. Nevoid hyperkeratosis of the nipple and areola (NHNA) is a rare condition of unknown etiology. Verrucous thickening and pigmentation of the nipple and areola are the main features of the condition. Different therapeutic options, both medical and surgical, have been described. Objective. To use a radiofrequency surgical unit to treat an NHNA case, which was unresponsive to keratolytic therapy. Materials and Methods. The lesions of the nipple and areolas were excised tangentially with a diamond-shaped electrode of a radiofrequency surgical unit under local anesthesia. Results. The patient had a good cosmetic appearance after the treatment, and there was no recurrence at the ninth postoperative month. Conclusion. Radiofrequency for tangential excision in the treatment of NHNA lesions that have not responded to medical therapy can be an alternative surgical method. [source] Noninvasive Lower Eyelid Blepharoplasty: A New Technique Using Nonablative Radiofrequency on Periorbital SkinDERMATOLOGIC SURGERY, Issue 2 2004Javier Ruiz-esparza MDArticle first published online: 3 FEB 200 Background. Laxity and rhytids of the lower eyelids are common cosmetic concerns. Historically, correction has either been surgical through either transcutaneous or transconjunctival blepharoplasty or ablative through laser resurfacing or chemical peeling. Therapeutic options usually require significant postoperative healing and have the potential risk of scarring ectropion or pigmentary loss. Objective. To report the use of a new technique that uses nonablative radiofrequency (NARF) to tighten noninvasively and nonsurgically the flaccid skin of the lower eyelids by treating the periorbital area to produce cosmetic improvement. Methods. Nine patients with skin flaccidity of the lower eyelids had a single treatment session with NARF in a small area of skin in the periorbital region, specifically the zygomatic and/or temporal areas. All patients were treated with topical anesthesia only. The treatment lasted approximately 10 minutes. No postoperative care was required. Results. All of the nine patients in the study achieved cosmetic improvement of the eyelids ostensibly through skin contraction. All patients were able to return to their normal routines immediately. Although the results were gradual, patient satisfaction was remarkable. No complications were seen in this study. Conclusion. This new procedure using NARF was successful in providing a safe, noninvasive, cosmetic improvement in these patients with excessive skin laxity of the lower eyelids. Postoperative morbidity, including down time and complications, was not seen. [source] Comparison of Endovenous Radiofrequency Versus 810 nm Diode Laser Occlusion of Large Veins in an Animal ModelDERMATOLOGIC SURGERY, Issue 1 2002Robert A. Weiss MDArticle first published online: 27 FEB 200 background. Endovenous occlusion using radiofrequency (RF) energy has been shown to be effective for the elimination of sapheno-femoral reflux and subsequent elimination of varicose veins. Recently, endovenous laser occlusion has been introduced with initial clinical reports indicating effective treatment for varicose veins. However, in our practice we note increased peri-operative hematoma and tenderness with the laser. Little is known regarding the mechanism of action of this new laser vein therapy. objective. To better understand the mechanism of action of endovenous laser vs. the endovenous RF procedure in the jugular vein of the goat model. methods. A bilateral comparison was performed using 810 nm diode laser transmitted by a bare-tipped optical fiber vs. the RF delivery by engineered electrodes with a temperature feedback loop using a thermocouple (Closure procedure) in three goat jugular veins. Immediate and one-week results were studied radiographically and histologically. Temperature measurements during laser treatment were performed by using an array of up to five thermocouples, spaced 2 mm apart, placed adjacent to a laser fiber tip during goat jugular vein treatment. results. Immediate findings showed that 100% of the laser-treated veins showed perforations by histologic examination and immediate contrast fluoroscopy. The RF-treated side showed immediate constriction with maintenance of contrast material within the vein lumen and no perforations. The difference in acute vein shrinkage was also dramatic as laser treatments resulted in vein shrinkage of 26%, while RF-treated veins showed a 77% acute reduction in diameter. At one week, extravasated blood that leaked into the surrounding tissue of laser treated veins acutely, continued to occupy space and impinge on surrounding structures including nerves. For the laser treatment, the highest average temperature was 729°C (peak temperature 1334°C) observed flush with the laser fiber tip, while the temperature feedback mechanism of the RF method maintains temperatures at the electrodes of 85°C. conclusion. Vein perforations, extremely high intravascular temperatures, failure to cause significant collagen shrinkage, and intact endothelium in an animal model justify a closer look at the human clinical application of the 810 nm endovenous laser technique. Extravasated blood impinging on adjacent structures may theoretically lead to increased peri-operative hematoma and tenderness. Further study and clinical investigation is warranted. [source] Radiofrequency ablation-assisted liver resection: review of the literature and our experienceHPB, Issue 4 2006Peng Yao Abstract Background: Surgical resection is the best established treatment known to provide long-term survival and possibility of cure for liver malignancy. Intraoperative blood loss has been the major concern during major liver resections, and mortality and morbidity of surgery are clearly associated with the amount of blood loss. Different techniques have been developed to minimize intraoperative blood loss during liver resection. The radiofrequency ablation (RFA) technique has been used widely in the treatment of unresectable liver tumors. This review concentrates on the use of RFA to provide an avascular liver resection plane. Methods and results: The following review is based on two types of RFA device during liver resection: single needle probe RFA and the In-Line RFA device. Conclusion: Liver resection assisted by RFA is safe and is associated with very limited blood loss. [source] Surgical Ablation of Permanent Atrial Fibrillation by Means of Maze Radiofrequency:JOURNAL OF CARDIAC SURGERY, Issue 5 2004Mid-Term Results We report our experience with a biatrial pattern of lesions based on the use of epicardial and endocardial radiofrequency ablation in an effort to minimize maze procedure. Method: In 85 patients undergoing cardiac surgery for established permanent atrial fibrillation (>3 months), a biauricular pattern of epicardic,endocardic maze lesions was performed. The main surgical procedures were diverse: 42 mitral valve surgeries, 7 mitrotricuspid valves, 18 mitroaortics, 4 mitroaortic and tricuspids, 2 aortic valves, 3 CABGs, 5 CABG and valve procedures, and 4 atrial septal defects. The mean age of the patients was 61 ± 12 (range 39,78). The mean duration of atrial fibrillation was 5.8 years (range 0.3 to 24). Results: Sixty-two (72.9%) patients presented postoperative supraventricular arrhythmia. Hospital mortality was seen in five patients (5.8%). Two patients died after a 12-month mean follow-up (range 2 to 32). A total of 14.1% of patients remained with their previous atrial fibrillation and 85.9% recovered and maintained sinus rhythm, with two patients having a permanent pacemaker. A total of 56% patients have been followed-up for a period of more than 6 months, and among them prevalence of sinus rhythm is 87.5%. Echocardiography detected biauricular contraction in 65% of them. After analyzing the data, factors involved in postoperative recurrence of atrial fibrillation after radiofrequency surgery were oldness of the atrial fibrillation (p < 0.01) and pre and postoperative left auricle volume (p < 0.04). Conclusion: Intraoperative radiofrequency has permitted us to perform the maze procedure in a simple way, with a low surgical morbid-mortality. We have obtained an 85.9% electrographic effectiveness and a 65% recovery of atrial contraction. Postoperative incidence of arrhythmia is the main postoperative problem. [source] Gold-Tip Electrodes,A New "Deep Lesion" Technology for Catheter Ablation?JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2005In Vitro Comparison of a Gold Alloy Versus Platinum, Iridium Tip Electrode Ablation Catheter Radiofrequency (RF) catheter ablation is widely used to induce focal myocardial necrosis using the effect of resistive heating through high-frequency current delivery. It is current standard to limit the target tissue,electrode interface temperature to a maximum of 60,70°C to avoid char formation. Gold (Au) exhibits a thermal conductivity of nearly four times greater than platinum (Pt,Ir) (3.17 W/cm Kelvin vs 0.716 W/cm Kelvin), it was therefore hypothesized that RF ablation using a gold electrode would create broader and deeper lesions as a result of a better heat conduction from the tissue,electrode interface and additional cooling of the gold electrode by "heat loss" to the intracardiac blood. Both mechanisms would allow applying more RF power to the tissue before the electrode,tissue interface temperature limit is reached. To test this hypothesis, we performed in vitro isolated liver and pig heart investigations comparing lesion depths of a new Au-alloy-tip electrode to standard Pt,Ir electrode material. Mean lesion depth in liver tissue for Pt,Ir was 4.33 ± 0.45 mm (n = 60) whereas Au electrode was able to achieve significantly deeper lesions (5.86 ± 0.37 mm [n = 60; P < 0.001]). The mean power delivered using Pt,Ir was 6.95 ± 2.41 W whereas Au tip electrode delivered 9.64 ± 3.78 W indicating a statistically significant difference (P < 0.05). In vitro pig heart tissue Au ablation (n = 20) increased significantly the lesion depth (Au: 4.85 ± 1.01 mm, Pt,Ir: 2.96 ± 0.81 mm, n = 20; P < 0.001). Au tip electrode again applied significantly more power (P < 0.001). Gold-tip electrode catheters were able to induce deeper lesions using RF ablation in vitro as compared to Pt,Ir tip electrode material. In liver and in pig heart tissue, the increase in lesion depth was associated with a significant increase in the average power applied with the gold electrode at the same level of electrode,tissue temperature as compared to platinum material. [source] Catheter Ablation of Ventricular Tachycardia in Remote Myocardial Infarction:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2003Substrate Description Guiding Placement of Individual Linear Lesions Targeting Noninducibility Introduction: The aim of this study was to describe the arrhythmogenic substrate in postinfarction patients with ventricular tachycardia (VT) guiding the placement of individual strategic linear lesions transecting all potential isthmuses using target area maps with limited mapping points to allow short procedure times. Methods and Results: In 28 patients with pleomorphic, unstable, and/or incessant VT, electroanatomic voltage mapping was performed in conjunction with limited sinus rhythm mapping, pace mapping, and activation mapping. Radiofrequency (RF) energy was applied directly within the low-voltage areas of the chronically infarcted areas or in the border zone. Ablation lines typically were perpendicular to the course of the presumed central common pathways. The maps consisted of 63 ± 30 mapping points. An average lesion line length of 46 ± 21 mm was placed with 17 ± 7 RF pulses. Twenty-two (79%) of the 28 patients were rendered completely noninducible at the end of the procedure. Procedure time measured 134 ± 41 minutes. No major complications were observed. Six (27%) of 22 patients who were rendered completely noninducible experienced VT recurrence during follow-up versus 4 (67%) of 6 patients who were still inducible after ablation (P = 0.06). Conclusion: Individually tailored substrate description guiding the placement of linear lesion lines transecting potential isthmuses rendered 80% of the patients completely noninducible. The construction of regional target area maps allowed short procedure times, with a resulting low incidence of complications in these critically ill patients. (J Cardiovasc Electrophysiol, Vol. 14, pp. 675-681, July 2003) [source] Clinical Usefulness of a Multielectrode Basket Catheter for Idiopathic Ventricular Tachycardia Originating from Right Ventricular Outflow TractJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2001TAKESHI AIBA M.D. Basket Catheter in Idiopathic VT.Introduction: It often is difficult to determine the optimal ablation site for idiopathic ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT) when the VT or premature ventricular complex (PVC) does not occur frequently. The aim of our study was to evaluate the usefulness of a multielectrode basket catheter for ablation of idiopathic VT originating from the RVOT. Methods and Results: Radiofrequency (RF) catheter ablation was performed using a 4-mm tip, quadripolar catheter in 50 consecutive patients with 81 VTs originating from the RVOT with (basket group = 25 patients with 45 VTs) or without (control group = 25 patients with 36 VTs) predeployment of a multielectrode basket catheter composed of 64 electrodes. Deployment of the multielectrode basket catheter was possible and safe in all 25 patients in the basket group. Ablation was successful in 25 (100%) of 25 patients in the basket group and in 22 (88%) of 25 patients in the control group. The total number of RF applications and the number of RF applications per PVC morphology did not differ between the two groups. However, both the fluoroscopic and ablation procedure times per PVC morphology were shorter in the basket group than in the control group (36.8 ± 14.1 min vs 52.0 ± 32.5 min, P = 0.04; 60.0 ± 14.6 vs 81.5 ± 51.2 min, P = 0.05). This difference was more pronounced in the 29 patients in whom VT or PVC was not frequently observed. Conclusion: The multielectrode basket catheter is safe and useful for determining the optimal ablation site in patients with idiopathic VT originating from the RVOT, especially in those without frequent VT or PVC. [source] Bimodal RR Interval Distribution in Chronic Atrial Fibrillation:JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 5 2000Impact of Dual Atrioventricular Nodal Physiology on Long-Term Rate Control after Catheter Ablation of the Posterior Atrionodal Input Bimodal RR Interval Distribution, Introduction: Radiofrequency (RF) catheter modification of the AV node hi patients with atrial fibrillation (AF) is limited by an unpredictable decrease of the ventricular rate and a wish incidence of permanent AV block, A bimodal RR histogram has been suggested to serve as a predictor for successful outcome but the corresponding AV node properties have never been characterized, We hypothesized that a bimodal histogram indicates dual AV nodal physiology and predicts a better outcome after AV node modification in chronic AF. Methods and Results: Thirty-seven patients were prospectively subdivided into two groups according to the RR histogram of 24-hour ECC monitoring, Before to RF ablation, internal cardioversion and programmed stimulation were performed, Among the 22 patients (group I) with a bimodal RR histogram, dual AV nodal physiology was found in 17 (779f) patients, Ablation significantly decreased ventricular rate with loss of the peak of short RR cycles after ablation (mean and maximal ventricular rates: 32% and 35% rate reduction, respectively; P < 0,01), In 15 patients with a unimodal RR histogram (group II), dual AV nodal physiology was found in 2 (13%), and rate reductions were 16% and 17%, respectively, At 6 months, 3 (14%) patients in group 1 and 6 (40%) in group II underwent elective AV nodal ablation with pacemaker implantation due to intolerable rapid ventricular response to AF. Conclusion: Bimodal RR interval distribution during chronic AF suggests the presence of dual AV nodal physiology and predicts a better outcome of RF ablation of the posterior atrionocdal input. [source] Catheter Ablation of Chronic Atrial Fibrillation Targeting the Reinitiating TriggersJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2000MICHEL HAĎSSAGUERRE M.D. Trigger Ablation in Chronic AF. Introduction: We assessed the mode of reinitiation of atrial fibrillation (AF) after cardioversion and the efficacy of ablating these foci of reinitiation in patients with chronic AF. Methods and Results: Fifteen patients, 7 with structural heart disease, underwent mapping and catheter ablation of drug-resistant AF documented to he persistent for 5 ± 4 months. In all patients, cardioversion was followed by documentation of P on T atrial ectopy and early recurrence, which allowed mapping of the reinitiating trigger or the source of ectopy. Radiofrequency (RF) ablation was performed at pulmonary vein (PV) ostia using a target temperature of 50°C and a power limit of 30 to 40 W, with the endpoint being interruption of all local muscle conduction. A total of 32 arrhythmogenic PVs and 2 atrial foci (left septum and left appendage) were identified: 1, 2, and 3 or 4 PVs in 5, 3, and 6 patients. RF applications at the ostial perimeter resulted in progressively increasing delay, followed by abolition of PV potentials in 8, but potentials persisted in 6. A single ablation session was performed in 7 patients and 8 underwent two or three sessions because of recurrence of AF; ablation was directed at the same source due to recovery of local PV potential or at a different PV. No PV stenosis was noted either acutely or at repeated follow-up angiograms. Nine patients (60%) were in stable sinus rhythm without antiarrhythmic drugs at follow-up of 11 ± 8 months. Anticoagulants were interrupted in 7 patients. Conclusion: PVs are the dominant triggers reinitiating chronic AF in this patient population. Elimination of PV potentials by ostial RF applications results in stable sinus rhythm in 60%. A larger group and longer follow-up are needed to investigate further the role of trigger ablation in curative therapy for chronic AF. [source] Transverse relaxation time (T2) mapping in the brain with off-resonance correction using phase-cycled steady-state free precession imagingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2009Sean C.L. Deoni PhD Abstract Purpose To investigate a new approach for more completely accounting for off-resonance affects in the DESPOT2 (driven equilibrium single pulse observation of T2) mapping technique. Materials and Methods The DESPOT2 method derives T2 information from fully balanced steady-state free precession (bSSFP) images acquired over multiple flip angles. Off-resonance affects, which present as bands of altered signal intensity throughout the bSSFP images, results in erroneous T2 values in the corresponding calculated maps. Radiofrequency (RF) phase-cycling, in which the phase of the RF pulse is incremented along the pulse train, offers a potential method for eliminating these artifacts. In this work we present a general method, referred to as DESPOT2, with full modeling (DESPOT2-FM), for deriving T2, as well as off-resonance frequency, from dual flip angle bSSFP data acquired with two RF phase increments. Results The method is demonstrated in vivo through the acquisition of whole-brain, 1 mm3 isotropic T2 maps at 3T and shown to provide near artifact-free maps, even in areas with steep susceptibility-induced gradients. Conclusion DESPOT2-FM offers an efficient method for acquiring high spatial resolution, whole-brain T2 maps at 3T with high precision and free of artifact. J. Magn. Reson. Imaging 2009;30:411,417. © 2009 Wiley-Liss, Inc. [source] Is Pulsed Radiofrequency a Neuromodulation Technique?NEUROMODULATION, Issue 1 2003David Abejón [source] Use of Radiofrequency Perforation for Lead Placement in Biventricular or Conventional Endocardial Pacing after Mustard or Senning Operations for D-Transposition of the Great ArteriesPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 9 2009SANTABHANU CHAKRABARTI M.D. Background: Endocardial pacemaker lead placement can be challenging after Mustard and Senning operations for transposition of the great arteries (D-TGA), if there is atresia of the systemic venous pathways and because the coronary sinus cannot be used for cardiac resynchronization therapy. Radiofrequency (RF)-assisted perforation techniques have been used in congenital heart disease but have not been reported for use in pacemaker implantation. Methods and Results: We describe RF perforation of an atretic superior systemic venous pathway and systemic venous baffles in three patients after Senning and Mustard operations to implant endocardial pacing systems to achieve conventional or biventricular pacing. Conclusions: RF-energy-assisted perforation is feasible and effective tool to facilitate endocardial lead placement during dual-chamber and biventricular pacemaker implantation in patients with Mustard or Senning operations for D-TGA. [source] Comparison of the Healing Mechanisms of Myocardial Lesions Induced by Dry Radiofrequency and Microwave Epicardial AblationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2006ROSA HENRIQUES DE GOUVEIA Background: Histological assessment of the evolution of lesions induced on a pig's left atrium by microwave (MW) epicardial applications and comparison with dry radiofrequency (RF) lesions. Methods: MW (40 W, 40 seconds) and dry RF (80°C, 2 minutes) were epicardially applied on nine pigs' left atrium. Samples were procured following application (n = 2), at day 3 (n = 2), day 7 (n = 2), day 14 (n = 2), and at 1 month (n = 1). They were fixed in formalin, embedded in paraffin, sectioned (2 ,), stained with histochemical dyes, immunomarked, and histologically analyzed. Results: Histological features of acute stage MW lesion are interstitial hemorrhage, adipose, and muscular tissues' coagulation necrosis, thrombosis of myocardial interstitium small vessels at damaged and optically undamaged areas, epicardial coronary branches, and endocardial parietal thrombosis. Day 3,lymphohistiocytic infiltration (lysosyme+) highlights lesion limits. Day 7,lymphohistiocytic infiltration increases, multi-nucleated giant cells appear surrounding/fagocyting necrotic tissue. Neovessels and scarce myofibroblasts appear. Lesion edges are now better defined. Day 14,myofibroblastic proliferation (actin++, vimentin+) creates "young" scar tissue, as in "healing by second intention." Lesions are deeper and wider than appeared at acute stage. One month,dense fibrous tissue scar appears. Endothelial cells covering endocardium are morphologically intact. RF lesions are histologically identical to MW's, although no vessel thrombosis was identified at acute optically undamaged areas and cytomorphologic elements emerge at later stages in the healing process. Conclusions: (1) Microwave scars are deeper and wider than the lesions observed at the acute stage. (2) Evolution of microwave lesions is faster and induces broader scars than dry radiofrequency. (3) Scar formation (both energies) is "healing by second intention." (4) Endocardial thrombosis may occur despite morphologically intact endothelium. [source] Feasibility of Pulmonary Vein Ostia Radiofrequency Ablation in Patients with Atrial Fibrillation: A Multicenter Study (CACAF Pilot Study)PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p2 2003GIUSEPPE STABILE STABILE, G., et al.: Feasibility of Pulmonary Vein Ostia Radiofrequency Ablation in Patients with Atrial Fibrillation: A Multicenter Study (CACAF Pilot Study)Radiofrequency (RF) catheter ablation has been proposed as a treatment of atrial fibrillation (AF). Several approaches have been reported and success rates have been dependent on procedural volume and operator's experience. This is the first report of a multicenter study of RF ablation of AF. We treated 44 men and 25 women with paroxysmal(n = 40)or persistent(n = 29), drug refractory AF. Circular pulmonary vein (PV) ostial lesions were deployed transseptally, during sinus rhythm(n = 42)or AF(n = 26), under three-dimensional electroanatomic guidance. Cavo-tricuspid isthmus ablation was performed in 27 (40%) patients. The mean procedure time was215 ± 76minutes (93,530), mean fluoroscopic exposure32 ± 14minutes (12,79), and mean number of RF pulses per patient56 ± 29(18,166). The mean numbers of separate PV ostia mapped and isolated per patient were3.9 ± 0.5, and3.8 ± 0.7, respectively. Major complications were observed in 3 (4%) patients, including pericardial effusion, transient ischemic attack, and tamponade. At 1-month follow-up, 21 of 68 (31%) patients had had AF recurrences, of whom 8 required electrical cardioversion. After the first month, over a mean period of9 ± 3(5,14) months, 57 (84%) patients remained free of atrial arrhythmias. RF ablation of AF by circumferential PV ostial ablation is feasible with a high short-term success rate. While the procedure and fluoroscopic exposure duration were short, the incidence of major cardiac complications was not negligible. (PACE 2003; 26[Pt. II]:284,287) [source] In Reply to Pulsed RadiofrequencyPAIN MEDICINE, Issue 4 2007Nikolai Bogduk MD No abstract is available for this article. [source] Pulsed Radiofrequency: Current Clinical and Biological Literature AvailablePAIN MEDICINE, Issue 5 2006Alex Cahana MD, DAAPM ABSTRACT Objective., Pulsed radiofrequency, where short bursts of radiofrequency energy are applied to nervous tissue, has been used by pain practitioners as a non- or minimally neurodestructive technique, alternative to radiofrequency heat lesions. Clinical advantages and mechanisms of this treatment remain unclear. The objective of this study was to review current clinical and laboratory data. Design., We systematically searched the MEDLINE database (PubMed) and tables of contents of electronically available pain journals. Reference lists of relevant reports and international scientific pain congress abstract books were also hand searched. Only those reports on pulsed radiofrequency were withheld. Results., The final analysis yielded 58 reports on the clinical use of pulsed radiofrequency in different applications: 33 full publications and 25 abstracts. We also retrieved six basic science reports, five full publications, and one abstract. Conclusions., The accumulation of these data shows that the use of pulsed radiofrequency generates an increasing interest of pain physicians for the management of a variety of pain syndromes. Although the mechanism of action has not been completely elucidated, laboratory reports suggest a genuine neurobiological phenomenon altering the pain signaling, which some have described as neuromodulatory. No side effects related to the pulsed radiofrequency technique were reported to date. Further research in the clinical and biological effects is justified. [source] Intradiscal High-Voltage, Long-Duration Pulsed Radiofrequency for Discogenic Pain: A Preliminary ReportPAIN MEDICINE, Issue 5 2006Alexandre Teixeira MD ABSTRACT Background., Intradiscal radiofrequency, with the electrode placed in the center of the nucleus pulposus, has been a controversial procedure in patients with discogenic pain. Possibly the effect has not been due to the production of heat, but to exposure to electric fields. Design., We have investigated the effect of high-voltage, long-duration intradiscal pulsed radiofrequency in patients with one-level discogenic low back pain, as confirmed by discography. Outcome Measure., The pain intensity score on a 0,10 numeric rating scale (NRS) was taken as outcome measure. Patients., Eight patients were reported. The mean duration of pain was 6.3 years (range 0.5,16, median 4). The mean NRS score was 7.75 (range 5,9). Disc height was reduced 60% in one patient and up to 30% in the others. Intervention., A 15-cm, 20-gauge needle with a 15-mm active tip was placed centrally in the disc. Pulsed radiofrequency was applied for 20 min at a setting of 2 × 20 ms/s and 60 V. Results., There was a very significant fall in the NRS scores over the first 3 months (P < 0.0001). On an individual basis, all patients had a fall of the NRS score of at least 4 points at the 3-month follow-up. A follow-up of 12.8 months (range 6,25, median 9) was available for five patients. All these patients are now pain free, except for one patient with an NRS score of 2. Conclusion., It is concluded that this method merits a controlled, prospective study. [source] Technical Aspects of RadiofrequencyPAIN PRACTICE, Issue 3 2002M. Sluijter MD If the resulting current flows through a percutaneously introduced electrode, heat will be produced around the electrode because the body tissue acts as a resistor. RF can, therefore, be used to ablate nervous tissue in the treatment of chronic pain. This method has gained acceptance for percutaneous cordotomy and for the treatment of trigeminal neuralgia. For spinal pain, the method had little success initially, but since the introduction of small diameter instrumentation, the results have markedly improved. he mechanism of action of RF has not been challenged until recently even though there was awareness that some observations were not consistent with the heat concept. The formation of heat is not the only occurrence during RF treatment, however. The tissue surrounding the electrode is also exposed to the RF electric field. This exposure has a biological effect as has been demonstrated both in cells in a cell culture and in the exposure to RF of dorsal root ganglia, resulting in transsynaptal induction of early gene expression in the dorsal horn. The mode of action of RF is, therefore, uncertain at the moment. The method of pulsed RF is based on the concept that the production of heat has been a by-product of RF treatment and that the clinical effect is due to exposure to the electric field. In pulsed RF, the generator output is interrupted to allow for the elimination of heat in the silent period. The early results have been encouraging, but the results of controlled, prospective studies are not yet available. Since there are now 2 almost diametrically opposed views on the mode of action of RF, it is difficult to give recommendations for treatment. The decision is easy for indications for which heat RF has traditionally been contraindicated such as the treatment of peripheral nerves and trigger points. When the application of heat carries a potential risk, for instance if the dorsal root ganglion is the target structure, the use of pulsed RF is also recommended. As for the medial branch the situation is controversial. Since there are controlled studies available showing the effect of heat lesions, it is recommended that the technique should not be changed until further studies have been completed. Finally, the equipment for RF treatment is described and safety issues are discussed. [source] Mobile phone exposure and spatial memoryBIOELECTROMAGNETICS, Issue 1 2009Clairy Wiholm Abstract Radiofrequency (RF) emission during mobile phone use has been suggested to impair cognitive functions, that is, working memory. This study investigated the effects of a 2,1/2 h RF exposure (884 MHz) on spatial memory and learning, using a double-blind repeated measures design. The exposure was designed to mimic that experienced during a real-life mobile phone conversation. The design maximized the exposure to the left hemisphere. The average exposure was peak spatial specific absorption rate (psSAR10g) of 1.4 W/kg. The primary outcome measure was a "virtual" spatial navigation task modeled after the commonly used and validated Morris Water Maze. The distance traveled on each trial and the amount of improvement across trials (i.e., learning) were used as dependent variables. The participants were daily mobile phone users, with and without symptoms attributed to regular mobile phone use. Results revealed a main effect of RF exposure and a significant RF exposure by group effect on distance traveled during the trials. The symptomatic group improved their performance during RF exposure while there was no such effect in the non-symptomatic group. Until this new finding is further investigated, we can only speculate about the cause. Bioelectromagnetics 30:59,65, 2009. © 2008 Wiley-Liss, Inc. [source] Radiofrequency (RF) effects on blood cells, cardiac, endocrine, and immunological functionsBIOELECTROMAGNETICS, Issue S6 2003David R. Black Abstract Effects of radiofrequency electromagnetic fields (RFEMF) on the pituitary adrenocortical (ACTH), growth (GH), and thyroid (TSH) hormones have been extensively studied, and there is coherent research on reproductive hormones (FSH and LH). Those effects which have been identified are clearly caused by heating. The exposure thresholds for these effects in living mammals, including primates, have been established. There is limited evidence that indicates no interaction between RFEMF and the pineal gland or an effect on prolactin from the pituitary gland. Studies of RFEMF exposed blood cells have shown that changes or damage do not occur unless the cells are heated. White cells (leukocytes) are much more sensitive than red cells (erythrocytes) but white cell effects remain consistent with normal physiological responses to systemic temperature fluctuation. Lifetime studies of RFEMF exposed animals show no cumulative adverse effects in their endocrine, hematological, or immune systems. Cardiovascular tissue is not directly affected adversely in the absence of significant RFEMF heating or electric currents. The regulation of blood pressure is not influenced by ultra high frequency (UHF) RFEMF at levels commonly encountered in the use of mobile communication devices. Bioelectromagnetics Supplement 6:S187,S195, 2003. © 2003 Wiley-Liss, Inc. [source] Percutaneous radiofrequency thermoablation as an alternative to surgery for treatment of liver tumour recurrence after hepatectomyBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 6 2002Dr D. Elias Background: Radiofrequency (RF) current, converted into heat through ion agitation and friction, can destroy liver tumours by means of coagulation necrosis. This study assessed whether percutaneous RF ablation is a useful and safe technique for the treatment of liver tumour recurrence after hepatectomy. Methods: Forty-seven patients presenting with local recurrence after hepatectomy for malignant tumours (29 with colorectal secondaries) were treated with percutaneous RF ablation instead of repeat hepatectomy. RF thermal ablation was performed under image guidance for 12,15 min. This group represented 63 per cent of 75 patients treated with curative intent for liver recurrence in the same time interval. The other 28 patients underwent repeat hepatectomy. Results: The mean(s.d.) number of liver metastases destroyed was 1·4(0·7) (range 1,3) and their diameter was 21(8) (range 9,35) mm. Twenty-six patients presented with liver recurrence at least once but up to three times after the initial RF application. Incomplete local RF treatment was observed in six of 47 patients. Fifteen patients developed extrahepatic recurrence. The mean(s.d.) interval between RF ablation and the last follow-up visit was 14·4(10·1) (range 5·5,40) months. One death and three major complications occurred. Survival rates at 1 and 2 years were 88 and 55 per cent respectively. A retrospective study of the authors' database over two similar consecutive periods showed that RF ablation increased the percentage of curative local treatments for liver recurrence after hepatectomy from 17 to 26 per cent and decreased the proportion of repeat hepatectomies from 100 to to 39 per cent. Conclusion: Percutaneous RF treatment increases the number of patients eligible for curative treatment. It should be preferred to repeat hepatectomy when feasible and safe because it is less invasive. Repeat hepatectomy is indicated only when percutaneous RF ablation is contraindicated or fails. © 2002 British Journal of Surgery Society Ltd [source] Radiofrequency field-induced thermal cytotoxicity in cancer cells treated with fluorescent nanoparticles,CANCER, Issue 13 2010Evan S. Glazer MD Abstract BACKGROUND: Nonionizing radiation, such as radiofrequency field and near infrared laser, induces thermal cytotoxicity in cancer cells treated with gold nanoparticles. Quantum dots are fluorescent semiconducting nanoparticles that were hypothesized to induce similar injury after radiofrequency field irradiation. METHODS: Gold nanoparticles and 2 types of quantum dot (cadmium-selenide and indium-gallium-phosphide) conjugated to cetuximab (C225), a monoclonal antibody against human epidermal growth factor receptor (EGFR)-1, demonstrated concentration-dependent heating in a radiofrequency field. The authors investigated the effect of radiofrequency field exposure after targeted nanoparticle treatment in a coculture of 2 human cancer cell lines that have differential EGFR-1 expression (a high-expressing pancreatic carcinoma, Panc-1, and a low-expressing breast carcinoma, Cama-1). RESULTS: Radiofrequency revealed that Panc-1 or Cama-1 cells not containing gold nanoparticles or quantum dots had a viability of >92%. The viability of Panc-1 cells exposed to the radiofrequency field after treatment with 50 nM Au-C225 was 39.4% ± 8.3% without injury to bystander Cama-1 cells (viability was 93.7% ± 1.0%; P , .0006). Panc-1 cells treated with targeted cadmium-selenide quantum dots were only 47.5% viable after radiofrequency field exposure (P<.0001 compared with radiofrequency only Panc-1 control cells). Targeted indium-gallium-phosphide quantum dots decreased Panc-1 viability to 58.2% ± 3.4% after radiofrequency field exposure (P = ,.0004 compared with Cama-1 and Panc-1 controls). CONCLUSIONS: The authors selectively induced radiofrequency field cytotoxicity in Panc-1 cells without injury to bystander Cama-1 cells using EGFR-1,targeted nanoparticles, and demonstrated an interesting bifunctionality of fluorescent nanoparticles as agents for both cancer cell imaging and treatment. Cancer 2010. © 2010 American Cancer Society. [source] Visual Support for Interactive Post-Interventional Assessment of Radiofrequency Ablation TherapyCOMPUTER GRAPHICS FORUM, Issue 3 2010Christian Rieder Abstract Percutaneous radiofrequency (RF) ablation is a minimally invasive, image-guided therapy for the treatment of liver tumors. The assessment of the ablation area (coagulation) is performed to verify the treatment success as an essential part of the therapy. Traditionally, pre- and post-interventional CT images are used to visually compare the shape, size, and position of tumor and coagulation. In this work, we present a novel visualization as well as a navigation tool, the so-called tumor map. The tumor map is a pseudo-cylindrical mapping of the tumor surface onto a 2D image. It is used for a combined visualization of all ablation zones of the tumor to allow a reliable therapy assessment. Additionally, the tumor map serves as an interactive tool for intuitive navigation within the 3D volume rendering of the tumor vicinity as well as with familiar 2D viewers. [source] Particle in Cell Simulation of Low Temperature Laboratory PlasmasCONTRIBUTIONS TO PLASMA PHYSICS, Issue 8-9 2007K. Matyash Abstract Several applications of PIC simulations for understanding basic physics phenomena in low-temperature plasmas are presented: capacitive radiofrequency discharges in Oxygen, dusty plasmas and negative ion sources for heating of fusion plasmas. The analysis of these systems based on their microscopic properties as accessible with PIC gives improved insight into their complex behavior. These studies are results of joint efforts over about one decade of research groups from Greifswald University, Germany; Bari University, Italy; Keio University, Japan and Innsbruck University, Austria. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Results of a Survey of 5,700 Patient Monopolar Radiofrequency Facial Skin Tightening Treatments: Assessment of a Low-Energy Multiple-Pass Technique Leading to a Clinical End Point AlgorithmDERMATOLOGIC SURGERY, Issue 8 2007FRCP, FRCPC, JEFFREY S. DOVER MD INTRODUCTION Monopolar radiofrequency is an effective means of nonsurgical facial skin tightening. OBJECTIVE The objective of this study was to determine whether using larger tips at lower energy and multiple passes, using patient feedback on heat sensation and treating to a clinical end point of visible tightening, would yield better results than single passes with small tips at high energy, as measured by patient and physician satisfaction. METHODS Fourteen physicians from four specialties were surveyed to determine the answers to the following three questions. (1) Is patient's feedback on heat sensation a valid and preferred method for optimal energy selection? (2) Do multiple passes at moderate energy settings yield substantial and consistent efficacy? (3) Is treating to a clinical end point of visible tightening predictable of results? RESULTS A total of 5,700 patient treatments were surveyed. Comparisons were made using the original algorithm of high-energy, single pass to the new algorithm of lower energy and multiple passes with visible tightening as the end point of treatment. Using the original treatment algorithm, 26% of patients demonstrated immediate tightening, 54% observed skin tightening 6 months after treatment, 45% found the procedure too painful, and 68% of patients found the treatment results met their expectations. With the new multiple-pass algorithm, 87% observed immediate tightening, 92% had the tightening six months after treatment, 5% found the procedure too painful, while 94% found the treatment results met their expectations. CONCLUSIONS Patient feedback on heat sensation is a valid, preferable method for optimal energy selection in monopolar radiofrequency skin-tightening treatments. [source] A Randomized Trial to Determine the Influence of Laser Therapy, Monopolar Radiofrequency Treatment, and Intense Pulsed Light Therapy Administered Immediately after Hyaluronic Acid Gel ImplantationDERMATOLOGIC SURGERY, Issue 5 2007MITCHEL P. GOLDMAN MD BACKGROUND Hyaluronic acid-based dermal fillers, such as hyaluronic acid gel (Restylane, Q-Medical AB, Uppsala, Sweden), are widely used for tissue augmentation of the nasolabial folds. Additional dermatologic treatments using infrared light, radiofrequency (RF), and intense pulsed light (IPL) are also important tools for facial rejuvenation. This study was designed to evaluate whether these therapies could be safely administered immediately after hyaluronic acid gel treatment without compromising the effect of the dermal filler. OBJECTIVE The objective of this study was to confirm or refute any possible subtractive effects of augmentation of the nasolabial folds when followed by 1,320-nm Nd:YAG laser, 1,450-nm diode laser, monopolar RF, and/or IPL treatments. METHODS Thirty-six patients with prominent nasolabial folds were treated with hyaluronic acid gel implantation on one side of the face and hyaluronic acid gel followed by one of the nonablative laser/RF/IPL therapies on the contralateral side of the face. RESULTS There were no statistically significant differences between wrinkle severity or global aesthetic scores for hyaluronic acid gel implantation alone and hyaluronic acid gel with laser/RF/IPL treatment at any time point. In a small sample, histologic changes were not apparent after laser/RF/IPL treatment. CONCLUSIONS Based on this small pilot study, laser, RF, and IPL treatments can safely be administered immediately after hyaluronic acid gel implantation without reduction in overall clinical effect. [source] Near Painless, Nonablative, Immediate Skin Contraction Induced by Low-Fluence Irradiation with New Infrared Device: A Report of 25 PatientsDERMATOLOGIC SURGERY, Issue 5 2006JAVIER RUIZ-ESPARZA MD BACKGROUND Nonablative radiofrequency (NARF) has been the only method for producing noninvasive skin tightening. Nevertheless, significant pain during the procedure is an important downside of this technology. A new nonablative medical device, Titan (Cutera, Inc., Brisbane, CA, USA), capable of fluences much lower than those possible with NARF, was tested as a less painful alternative. OBJECTIVES To produce skin contraction leading to lifting of eyebrows and/or improvement of lower face and neck skin laxity using fluences below pain levels. PATIENTS AND METHODS Twenty-five patients were treated. Standardized photographs were obtained preoperatively, after a few days, a few weeks, and up to 12 months after the procedure. RESULTS Immediate changes were obtained in 22 of 25 patients. Examination of photographs revealed that the initial improvement was maintained throughout the follow-up period. CONCLUSION Immediate true skin contraction persisting through the immediate, intermediate, and long-term follow-up was found in the vast majority of patients in this group. Edema as an artifact simulating immediate improvement was excluded by serial photographs taken during the follow-up period. Skin contraction occurred at low fluences, below the threshold of pain. This, to the best of our knowledge, has not been previously described in the medical literature. [source] | |||||||||||||||||||||||||||||||||||||