Radio-frequency Technique Research Articles

Modification of Poly(propylene) Membranes for Electrochemical Cells by Low-Temperature Plasma Treatment

Poly(propylene) membranes for battery systems were modified by surface oxidation using radio frequency (RF) and microwave (MW) plasma techniques. The plasmas were generated in two different gases: O2 and CO2. Impedance spectroscopy, time-dependent contact angle measurements and pure water permeability were utilized to characterize the properties of the membranes. It was found that the best improvement in ion conductivity (an increase by four orders of magnitude) was achieved using the O2 MW plasma. Wettability of the membrane surface and the water permeability through the membrane also increase distinctly after such a treatment.

Image-guided multipolar radiofrequency ablation of liver tumours: initial clinical results

The local effectiveness and clinical usefulness of multipolar radiofrequency (RF) ablation of liver tumours was evaluated. Sixty-eight image-guided RF sessions were performed using a multipolar device with bipolar electrodes in 53 patients. There were 45 hepatocellular carcinomas (HCC) and 42 metastases with a diameter < or =3 cm (n = 55), 3.1-5 cm (n = 29) and >5 cm (n = 3); 26 nodules were within 5 mm from large vessels. Local effectiveness and complications were evaluated after RF procedures. Mean follow-up was 17 +/- 10 months. Recurrence and survival rates were analysed by the Kaplan-Meier method. The primary and secondary technical effectiveness rate was 82% and 95%, respectively. The major and minor complication rate was 2.9%, respectively. The local tumour progression at 1- and 2-years was 5% and 9% for HCC nodules and 17% and 31% for metastases, respectively; four of 26 nodules (15%) close to vessels showed local progression. The survival at 1 year and 2 years was 97% and 90% for HCC and 84% and 68% for metastases, respectively. Multipolar RF technique creates ablation zones of adequate size and tailored shape and is effective to treat most liver tumours, including those close to major hepatic vessels.

Bipolar radiofrequency treatment for snoring with mild to moderate sleep apnea: a comparative study between the radiofrequency assisted uvulopalatoplasty technique and the channeling technique

We compared radiofrequency techniques used in the treatment of snoring and obstructive sleep apnea [radiofrequency assisted uvulopalatoplasty (RAUP) and channeling] as regard the efficacy and morbidity. A pilot, prospective randomized single blinded study was conducted on 40 patients in the ENT Department, Kasr Al-Aini Hospital, Cairo University during the period from April to December 2003. Patients were randomized into two groups each consisting of 20 patients. The first group was treated by submucosal channeling of the palate, while the second group was treated by radiofrequency assisted uvulopalatoplasty (RAUP). Patients were followed for 4 months, filling a questionnaire in a standard visual analogue score pattern. Assessment was done prior to the surgery and was repeated 3, 10 days and 3 weeks postoperatively. Visual analogue scores were done for the following parameters: pain, speech deficits, dysphagia, and snoring (by the bed partner). Polysomnography was done pre to intervention and was repeated 4 months postoperatively. This work confirms the favorable effects of radiofrequency in the treatment of patients with snoring and mild to moderate obstructive sleep apnea (OSA) particularly on snoring, confirming the results of the previous studies and highlighting the more rapid relief of snoring and apnea in RAUP group compared to channeling group but with more postoperative pain and morbidity.

P141: Necrotic peripheral arterial plaque is associated with mortality after amputation

Introduction: Severe peripheral arterial disease (PAD) can lead to amputation and premature mortality. Our objective was to compare clinical data and arterial plaque morphology in alive patients versus dead patients after amputation. Methods: Lower extremity arterial specimens were obtained from patients that underwent either an above (n=44) or below knee (n=23) amputation between 2004-06. These specimens were pressure perfused and imaged using intravascular ultrasound (IVUS) ex vivo. Sequential IVUS data obtained at known intervals throughout the vessel length were analyzed with radio-frequency techniques for quantification of plaque composition, plaque volume, and total vessel volume.

Pulmonary Atresia With Intact Ventricular Septum. Perforation and Pulmonary Vavuloplasty Using a Modified Mechanical Technique. Medium-Term Follow-Up

In patients with pulmonary atresia with intact ventricular septum (PAIVS), radiofrequency-assisted perforation of the valve is the most widely used initial therapy when the anatomy is favorable. We report our experience with a modified mechanical technique that gave good results. Between November 2001 and October 2006, valve opening was carried out successfully in 11 consecutive neonates with a favorable anatomy (i.e., Alwi groups A and B, and tricuspid valve Z-score -1.1 [1.3]). The technique involved snare-assisted anterograde or retrograde perforation with the soft tip of a special guidewire used for chronic total coronary artery occlusions, use of an arteriovenous loop, and progressive balloon dilatation from a diameter of 2 mm to a maximum diameter of 9.6 [1.2] mm. Valve opening was achieved in all patients, and right ventricular (RV) systolic pressure fell from 97 [17] mmHg to 48 [13] mmHg (P< .001). No pericardial effusion or cardiac tamponade was observed, though one neonate died 24 hours after the procedure due to pulmonary embolism. Six patients (54%) were discharged without any further intervention, while 4 (36%) required an additional increase in pulmonary blood flow. During the follow-up period of 25 [21] months, two patients died. Eight (72%) survived and were in New York Heart Association functional class 1. Two required additional surgery on the outflow tract, one of whom also needed a one-and-a-half ventricular repair. Data indicate that the valves remain open as RV structures grow, though without any change in the tricuspid valve Z-score. Pulmonary valvuloplasty using a mechanical technique proved effective in patients with PAIVS. Modification of the standard mechanical technique by using the soft tip of a special guidewire used for chronic total coronary artery occlusions was less aggressive and improved results. In patients with a favorable anatomy, results were comparable to those obtained using the radiofrequency technique.

Lumbar Sympathectomy by Laser Technique

Two common syndromes in which sympathetic pain appears to be the cause are causalgia and reflex sympathetic dystrophy. In the past, permanent interruption of the lumbar sympathetic chain has been accomplished by open surgery or phenol or alcohol injection. Subsequently, percutaneous lumbar sympathectomy by radiofrequency lesions involved less morbidity. The Holmium: YAG laser has now been found to be even more effective and longer lasting than the radiofrequency technique. An increasing number of patients are seeking medical treatment for pain associated with sympathetic nervous system. Two common syndromes in which sympathetic pain appears to be the cause are causalgia and reflex sympathetic dystrophy. True causalgia follows partial injury to a major nerve trunk such as the sciatic nerve or its large branches. Reflex sympathetic dystrophy may occur following minor trauma to the neural structures that accompany fractures, soft-tissue injuries, and surgical incisions. Clinical characteristics include burning, poorly localized dermatomal distribution of stabbing pain, hyperesthesia, vasomotor alterations leading to trophic changes, changes in skin temperature, alteration of sweating patterns, piloerection, and swelling. Other conditions complicated by sympathetic dysfunction are amputation stump pain, circulatory insufficiency in the legs, arteriosclerotic disease of the lower limbs, intermittent claudication, and arterial embolism. Following endoscopic or percutaneous discectomy, some patients experience a burning pain with skin trophic changes and allodynia due to irritation of the sympathetic nervous system during manipulation of surrounding structures. This procedure, performed in patients who present with symptoms of causalgia following discectomy is highly effective in relieving this type of pain. METHODS AND MATERIALS Anatomically, the lumbar sympathetic chain lies at the anterolateral border of the vertebral bodies (fig 1). The aorta is positioned anteriorly and slightly medial to the chain on the left side. The inferior vena cava is more closely approximated to the chain on the right in an anterior plane. Many other small lumbar arteries and veins are positioned near the sympathetic chain. The psoas muscle is situated posteriorly. Blockade of the sympathetic nerves can also be performed with spinal, epidural or peripheral nerve blocks, but relief of pain after lumbar sympathetic block will definitely confirm the painful etiology as sympathetically mediated. Most fibers headed for the lower extremity pass through the second and third lumbar ganglia, so that a sympathetic block placed at the L4 level provides almost complete sympathetic denervation to the lower extremity. The pain relief obtained is usually immediate and can be long-lasting, outlasting the duration of action of the local anesthetic. If the pain relief is transient, then sympathetic denervation can be performed with laser. Lumbar Sympathectomy by Laser Technique

High Rate Deposition of Amorphous Silicon Based Solar Cells using Modified Very High Frequency Glow Discharge

AbstractWe report our recent progress on high rate deposition of hydrogenated amorphous silicon (a-Si:H) and silicon germanium (a-SiGe:H) based n-i-p solar cells. The intrinsic a-Si:H and a-SiGe:H layers were deposited using modified very high frequency (MVHF) glow discharge. We found that both the initial cell performance and stability of the MVHF a-Si:H single-junction cells are independent of the deposition rate up to 15 Å/s. The average initial and stable active-area cell efficiencies of 10.0% and 8.5%, respectively, were obtained for the cells on textured Ag/ZnO coated stainless steel substrates. a-SiGe:H single-junction cells were also optimized at a rate of ~10 Å/s. The cell performance is similar to those made using conventional radio frequency technique at 3 Å/s. By combining the optimized component cells made at 10 Å/s, an a-Si:H/a-SiGe:H double-junction solar cell with an initial active-area efficiency of 11.7% was achieved.

Pediatric Tonsillotomy with Radiofrequency Technique: Long‐Term Follow‐Up

Compare the effects of partial tonsil resection using a radiofrequency technique, tonsillotomy (TT), with total tonsillectomy (TE, blunt dissection) after 1 and 3 years. Compare frequency of relapse in snoring or infections and possible long-term changes in behavior among TT children with those in TE children. Ninety-two children (5-15 yr) randomized to TT (n = 49) or TE (n = 43) groups because of obstructive problems with or without recurrent tonsillitis. One year after surgery, general health, degree of obstruction, history of infections, and behavior were investigated using two questionnaires, the Qu1 and Child Behavior Checklist, as well as an ENT visit. After 3 years, two questionnaires, Qu2 and the Glasgow Children's Benefit Inventory, were answered by mail. : After 1 year, both groups were in good health. The effect on snoring and total behavior was the same for both groups, and the rate of recurrence of infections was not higher in the TT group. After 3 years, two children in the TT group were tonsillectomized (4%, 2/49), one because of peritonsillitis and another because of increased snoring. Otherwise, no differences existed between the groups in general health, snoring, or number of infections. Removing only the protruding parts of the tonsils has the same beneficial long-term effect on obstructive symptoms and recurrent throat infections as complete TE in the majority of cases. The need for re-operation is low; therefore, it appears inadvisable to follow the current common practice of routinely removing the whole tonsil given its higher morbidity and risk for serious complications.

Partial discharge current pulses in SF6 and the effect of superposition of their radiometric measurement

The practical advantages of employing non-contact radio frequency (RF) methods for detecting partial discharges (PDs) in high voltage equipment have led to significant effort being focused on the diagnosis of electrical plants using RF techniques. This has particularly been the case for gas insulated substations, which use sulphur hexafluoride (SF6) as an insulating medium. One of the most important challenges facing RF diagnostics is the problem of relating the RF emissions to some measure of severity of the PD. Previous work has established that the amplitude or energy of RF signals radiated from a PD source is strongly dependent on the rate of change of current in the PD pulse. In this paper, measurements of PD current pulses in SF6 are presented for a point-plane configuration using an extremely wide bandwidth (13 GHz) measurement system. By this means, PD pulse shapes have been recorded with better resolution than has previously been possible and rise times have been measured with a high degree of accuracy. The results show a considerable variation in pulse shape, with the minimum rise time measured being 35 ps. With this high time-domain resolution, we have been able to distinguish features within the PD pulses that will affect the energy of the radiated RF signal. In particular, the current pulses tend to occur in bursts of up to ten individual pulses in as little as 1 ns, which will excite multiple RF signals in rapid succession. The effect of superposition of RF waveforms has been investigated by studying the variation in detected RF energy with respect to the time delay between PD pulses. It was found that when two PDs occur within a short period (< 150 ns) the combined energy of the resulting RF pulse has the potential to vary by ±30% of that resulting from two equivalent PD pulses with a wider pulse spacing (≫ 150 ns). In terms of a practical monitoring system concerned with order-of-magnitude variations; this is not considered to pose a major problem for the RF technique.

Pulsed Radiofrequency: Current Clinical and Biological Literature Available

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. 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. 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. 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.

P.368 Arthroscopic radiofrequency techniques for treatment of TMJ internal derangements. Preliminary results

P.368 Arthroscopic radiofrequency techniques for treatment of TMJ internal derangements. Preliminary results

Calcium-channel blockers and beta-blockers are associated with decreased atherosclerotic plaque size and altered morphology

METHODS: Twenty-two patients with PAD underwent intravascular ultrasound (IVUS). IVUS data was analyzed with radiofrequency techniques for quantification of plaque composition, plaque volume and total vessel volume. Associations between plaque characteristics and clinical variables including age (68.8 / 19.6 years), gender (77% male), smoking (73% current smoker), hyperlipidemia (36%), diabetes (36% type I), hypertension (82%), obesity (23%) and coronary artery disease (64%) were evaluated. Similar evaluations were made with medication use including antihyperlipidemic agents (77%), beta-blockers (55%), angiotensin converting enzyme inhibitors (45%), and calcium-channel blockers (36%). Univariate and multivariate analyses were performed using t-test, Pearson’s correlation, and F-tests. Results are expressed as mean / SEM.

Cirugía renal conservadora de nefronas como tratamiento de rescate tras fracaso de la termoablación mediante radiofrecuencia en paciente monorreno con adenocarcinoma renal

To describe the technique of renal radiofrequency (RF) thermal ablation. Case report of a successful nephron-sparing surgery after failure of the RF thermal ablation of a renal adenocarcinoma in a patient with a single kidney. A patient presenting with a renal adenocarcinoma in a single left kidney was treated by RF thermal ablation. The failure of the technique was patent on follow-up after demonstration of a central area of necrosis surrounded by a peripheral contrast enhancing area. Nephron sparing surgery was indicated as salvage procedure. Surgical excision of the tumor with a safety margin, without renal pedicle clamping was undertaken. Fat tissue and hemostatic synthetic material were placed in the surgical bed. Pathology report: renal adenocarcinoma with changes secondary to central necrosis. Twenty-four month postoperative follow-up: fatty renal nodule with small fibrous tracts inside in the area of the tumor. No evidence of contrast enhancing areas. Normal renal function (sCr 0.7 mg/dl, urea 24 mg/dl). Radiofrequency thermal ablation is a relatively new technique. Its oncological efficacy greatly depends on appropriate case selection. One of its main caveats is achieving an area of tissue ablation enough to completely destroy the tumor. When the technique fails, renal surgery (nephron sparing or not) seems to be the most recommended alternative.

Asymptomatic Liver Mass

Asymptomatic Liver Mass

Extensibility and scanning electron microscopy evaluation of 5 pediatric anterior capsulotomy techniques in a porcine model

To compare the extensibility and scanning electron microscopy (SEM) of 5 currently used pediatric anterior capsulotomy techniques: vitrectorhexis, manual continuous curvilinear capsulorhexis (CCC), can-opener, radio frequency diathermy, and plasma blade in a porcine model. Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. Extensibility was determined by stretching each capsulotomy until it ruptured and measuring it by calculating the mean stretch-to-rupture circumference of each capsulotomy (20 eyes per technique) as a percentage of its baseline circumference. Edge characteristics were evaluated using SEM. The mean extensibility of each technique tested (vitrectorhexis 161%, CCC 185%, can opener 149%, radio frequency 145%, plasma blade 170%) was significantly different (P<.001, 1-way analysis of variance). The SEM examination found that the vitrectorhexis had a scalloped edge with the whole edge rolled over, presenting a smooth surface toward the inside of the capsulotomy; the manual CCC produced the smoothest edge, with no irregularities noted; the can-opener edge was irregular, showing each puncture of the needle had created a small arc, with occasional regions of the edge rolled over in a "hit-and-miss" fashion; the radio-frequency diathermy capsulotomy edge was ragged, rough, and irregular; and the plasma blade capsulotomy edge was rougher than the manual CCC, but there were fewer irregularities than the radio-frequency diathermy edge had. The manual CCC technique produced the most extensible porcine capsulotomy, followed by the plasma blade, vitrectorhexis, can-opener, and radio-frequency techniques, in a porcine model. The manual CCC technique also produced the smoothest anterior capsulotomy edge according SEM evaluation.

Abstracts for the British Congenital Cardiac Association Annual Meeting: The Barbican, London, 24–25 November 2005: Poster Presentations: ECMO support for lifethreatening arrhythmia in infancy permits successful radiofrequency treatment

The majority of arrhythmias presenting in infancy cardiovert readily or rapidly respond to conventional medical therapy. A small number prove highly refractory to anti-arrhythmic medications. Myocardial performance may be severely compromised by the combination of fast heart rate and negatively inotropic drugs. Some babies die. We have recently supported 2 babies with refractory arrhythmias on ECMO, both to pursue drug therapy and eventually, to support the circulation during radiofrequency ablation, with very successful results. The first patient was a 2.5 kg neonate presenting with collapse secondary to atrial ectopic tachycardia with a rate of 300/minute. Myocardial function was severely impaired. The arrhythmia was adenosine resistant and after iv amiodarone loading had no effect, esmolol infusion was started. This produced profound hypotension and the arrhythmia rapidly recommenced after DC cardioversion. In the face of such severe haemodynamic disturbance, VA ECMO was instituted. Further anti-arrhythmics were tried on-circulatory support, but the arrhythmia was incessant despite multiple DC cardioversions. Therefore radiofrequency ablation of the atrial ectopic focus was attempted on ECMO support. This was achieved uneventfully and the myocardial function rapidly improved, with decannulation 24 hours later. Unfortunately the arrhythmia recurred 2 weeks later, but was successfully treated by further ablation without ECMO. The child remains well with normal development on no medication. An 11-month-old baby presented to the GP with acute onset of lethargy and poor feeding and a heart rate of 350 bpm was noted! This was a broad complex tachycardia with independent p wave activity (confirmed with adenosine); ie ventricular tachycardia. Although initially well tolerated, the tachycardia resisted DC “cardioversion” even up to 60 J. Progressive and severe myocardial dysfunction and hypotension ensued, exacerbated by any attempts at drug therapy. The patient was therefore placed on VA ECMO. Some slowing of the ventricular rhythm was achieved with amiodarone and flecainide. The patient was then decannulated but the rapid arrhythmia recurred and ECMO was reinstituted. Electro-physiological mapping was then undertaken on ECMO support. NAVEX mapping identified a right ventricular outflow tract focus. This was resistant to conventional RF energy but was eventually successfully ablated with a “Cool-tip” catheter. Myocardial function improved rapidly, the patient was decannulated after 48 hours observation and there has been no recurrence of the arrhythmia since discharge. Although viewed as a very invasive technique, VA ECMO support here has prevented two otherwise unavoidable deaths in babies with conditions readily treated by radio-frequency techniques in older children. Not only did ECMO permit institution of aggressive drug therapy but also safely supported catheter interventions in very small patients. ECMO support should be considered early for small patients with refractory arrhythmias, before irreversible neurological compromise ensues. It could also be used electively to permit radiofrequency ablation in children whose size causes concern for safe catheter manipulation.

MRI Features After Radiofrequency Ablation of Osteoid Osteoma with Cooled Probes and Impedance-Control Energy Delivery

The purposes of our study were to determine the temporal changes in MR signal in bone after radiofrequency ablation of osteoid osteoma and the size of the zone of marrow signal change produced by the radiofrequency technique and to compare the size of the zone with published data for radiofrequency ablation with manual-control protocols. Radiofrequency ablation was performed in 10 patients with a clinical and radiologic diagnosis of osteoid osteoma. A cooled radiofrequency probe was inserted in the nidus. Twelve minutes of radiofrequency energy was applied from a 200-W radiofrequency generator in an impedance-control setting. MRI with multiplanar turbo spin-echo T1-weighted and STIR sequences was performed at 1, 7, and 28 days after the procedure in seven patients. The three remaining patients had follow-up imaging at 28 days only. The images were reviewed by two radiologists who categorized the imaging features and measured the marrow zone of signal alteration when visible. The size of the zone of marrow signal change produced by the radiofrequency technique was compared with published data for radiofrequency ablation with manual-control protocols. A 1-mm band of homogeneous altered marrow signal distributed symmetrically parallel to the entire probe tract was seen earliest, at 1 day, in the femoral neck lesion treated with the 2-cm probe. The band was low signal on the T1 sequence and high signal on the STIR sequence, and the diameter of the zone was 27 mm. By 7 days, five of the seven treated bones showed a band of marrow signal alteration. By 28 days, all 10 treated bones had a band of marrow signal alteration. The interband distance at 90 degrees to the probe measured on STIR images at 28 days was a mean of 20.9 mm (confidence interval, 16.1-25.7 mm [p < 0.05]; range +/- measurement error, 10.5-35 +/- 1.64 mm) with a 1-cm probe and 30.5 mm (measurement error, +/- 0.78 mm) on T1 images without contrast material when a 2-cm exposed-tip probe was used. Higher-output generators with impedance-control software and internally cooled radiofrequency probes with longer exposed tips produce larger zones of marrow signal change than expected with manual-control protocols. MRI allows detection of temporal marrow signal change after radiofrequency ablation. The marrow signal change with a high-energy delivery protocol is larger than manual-control protocols.

Pediatric Tonsillotomy With the Radiofrequency Technique: Less Morbidity and Pain

Pediatric Tonsillotomy With the Radiofrequency Technique: Less Morbidity and Pain

Haut und Haar

Anti-aging medicine is dedicated to the advancement of technology to detect, prevent, and treat aging related disease and to promote research into methods to retard and optimize the aging process. Dermatology offers good basics for rational preventive and therapeutic anti-aging strategies. The role of the skin in anti-aging medicine is not merely that aging is most obvious on the skin, but that the skin is a highly accessible and unique organ that offers unequaled opportunities to the gerontologist for the study of age-related effects. The study of skin aging focuses on two main streams of interest: On one hand, the esthetic problem and its management; on the other, the biological problem of aging in terms of microscopic, biochemical, and molecular changes. Probably the same molecular mechanisms underlying the aging of skin and its appendages, including the pigmentary system, underlie age-dependent degenerative changes of the inner organs and entire organism. The skin and hair are subject to intrinsic or physiologic aging, and extrinsic or premature aging due to external factors. Intrinsic factors are related to individual genetic and epigenetic mechanisms with interindividual variation. Extrinsic factors include ultraviolet radiation and cigarette smoking. Primary prevention encompasses measures that are taken before the aging process has started, secondary prevention when the first signs of aging have come into sight. Eventually, tertiary measures are aimed at correcting established signs of aging. Prevention starts with photoprotection and avoidance of cigarette smoking. In dermatologic practice sun protecting agents, dermocosmetic substances, hair growth promoting agents, and anti-aging compounds play an ever increasing role. Finally, tertiary anti-aging measures include minimally invasive cosmetic procedures such as chemical peels, microdermabrasion, soft tissue fillers, non-ablative laser rejuvenation, radiofrequency techniques and botulinum toxin, as well as laser skin resurfacing and corrective surgical procedures, including autologous hair transplantation.

Pulsed Radiofrequency

Pulsed Radiofrequency