Application Of Radiofrequency Energy Research Articles

Early Tissue Reaction After Second-Generation Cryoballoon Ablation Evaluated with Intracardiac Echocardiography.

Radiofrequency energy applications immediately produce tissue edema. This study aimed to investigate the acute tissue reaction immediately after second-generation cryoballoon applications using 3-dimensional intracardiac echocardiography (ICE) imaging technology.This study consisted of 10 patients with paroxysmal atrial fibrillation who underwent pulmonary vein isolation (PVI) using second-generation cryoballoons. Ablation was performed with a single 3-minute freeze strategy and exclusively 28-mm balloons. The left atrial and right pulmonary vein (PV) antra geometries were created with 3-dimensional ICE technology before and immediately after the PVI.Out of 20 right PVs, 19 were isolated exclusively with cryoballoons, and one right inferior PV (RIPV) required touch-up ablation. All 10 right superior PVs (RSPVs) were isolated by single cryoballoon applications, and RIPVs were isolated by a mean of 1.2 ± 0.4 applications. The total application time was 171 ± 19 and 203 ± 71 seconds, and nadir balloon temperature was -56.0 ± 4.9 and -53.8 ± 5.4°C for the RSPVs and RIPVs, respectively. In all patients, diffuse wall thickening of the antra and ostium of the right PVs was observed as compared to baseline. The wall thickening was 0-0.25 mm in 3 patients, and 0.25-0.5 mm in the remaining 7. During the median follow-up of 13 [10.2-17.2] months, 8 (80%) patients were free from arrhythmia recurrences. Nine (90%) patients underwent repeat cardiac computed tomography at a median of 6.0 [4.5-12.0] months after the initial procedure, and no PV stenosis was observed in all.Tissue edema and wall thickening appeared in the human left atrium immediately after second-generation cryoballoon ablation.

Catheter ablation of right-sided para-Hisian ventricular arrhythmias using a simple pacing strategy

Ablation of para-Hisian ventricular arrhythmias (PH-VAs) is challenging because of the close relationship of the origin site and His bundle. Using pacing techniques to differentiate the near-field from far-field His activations, thereby avoiding atrioventricular block, has been reported in patients with para-Hisian accessory pathways. We applied the same pacing technique and 3-dimensional mapping to guide radiofrequency (RF) ablation in patients with right-sided PH-VAs and investigated the clinical outcome of such cases. Fourteen patients with right-sided PH-VAs were included in this study. The earliest activation sites were confirmed in the right ventricle on the 3-dimensional map. Pacing with different outputs was performed at the largest His potential site (P1) and the earliest activation site (P2). If the minimum His bundle-right bundle branch-captured output at P2 was higher than that at P1, RF ablation was performed at the site. All the patients in this study had monomorphic premature ventricular contractions (PVCs) with a mean QRS duration of 118.3 ± 8.1 ms. A His-right bundle branch potential with an amplitude of 0.05 ± 0.02 mV was recorded at P2, with a mean distance of 5.97 ± 1.84 mm away from P1. PVCs were successfully eliminated in 13 of 14 patients (92.9%). One patient exhibited persistent right bundle branch block after ablation, and 1 recurrence of ablated PVCs occurred during a median follow-up period of 15 months. Using a simple pacing technique to evaluate the safety of RF energy application led to a high success rate of RF catheter ablation of right-sided PH-VAs without atrioventricular block.

SECCA procedure for anal incontinence and antibiotic treatment: a case report of anal abscess

BackgroundFecal Incontinence (FI) can seriously affect quality of life. The treatment of fecal incontinence starts conservatively but in case of failure, different surgical approaches may be proposed to the patient. Recently several not invasive approaches have been developed. One of these is the radiofrequency (RF) energy application to the internal anal sphincter.Case presentationWe report a rare case of an anal abscess related to a SECCA procedure in a 66-year-old woman affected by gas and FI for twenty years.ConclusionsThe complications post-SECCA procedure reported in literature are generally not serious and often self-limited, such as bleeding or anal pain. This is a case of an anal abscess.We suggest that this finding could consolidate the importance of administering antibiotic therapy to patients and to run a full course of at least 6 days rather than a short-term (24 h) therapy, with the aim to minimize the incidence of this complication.

A new bronchoscopic catheter for the transbronchial ablation of pulmonary nodules

ObjectivesWith the objective of simultaneous bronchoscopic biopsy and ablation of malignant solitary pulmonary nodules, we have developed a flexible monopolar radiofrequency (RF) catheter that can be deployed through the working channel of most bronchoscopes. Materials and MethodsFresh tumor specimens were heated in a water bath to 37 °C, and the RF catheter was inserted into the tumors within the specimen. Temperature sensors were positioned 3 mm, 5 mm and 7 mm from the electrode to measure the temperature of the surrounding tissue every 1 s. The ablation was conducted by applying RF energy for 8 min. The ablated specimens were evaluated by cutting the tissue samples along the top of the device and measuring the ablation zones. ResultsFive ablations were performed in 3 specimens. All of the ablation zones had a major axis length (along the electrode axis) between 18.9 mm and 22.8 mm and a minor axis length (perpendicular to the major axis) between 13.3 mm and 18.0 mm. The temperature data showed that all of the temperature sensors detected 60 °C or higher. These results demonstrate that the RF catheter was capable of generating ablation zones that were locally contained in ex vivo human cancerous lung specimens and that incorporated the tumor tissues. ConclusionWe present the results of a benchtop study demonstrating the local control of ablation achieved using the RF device. This study suggests that the ex vivo ablation of lung malignancy with a new bronchoscopic RF catheter is feasible and that in vivo tumor ablation with this method in humans merits further study.

Intravascular imaging, histopathological analysis, and catecholamine quantification following catheter-based renal denervation in a swine model: the impact of prebifurcation energy delivery.

The purpose of this study was to evaluate the impact of prebifurcation renal denervation in a swine model and assess its safety through optical coherence tomography (OCT). Prebifurcation renal denervation with a multi-electrode catheter was performed in one renal artery of 12 healthy pigs, with the contralateral artery and kidney being used as controls. Angiograms and OCT pullbacks were obtained peri-procedurally and 1 month post procedure. Renal tissue catecholamines were quantified, and the arterial wall and peri-adventitial tissue were analyzed histologically. Intraluminal changes (endothelial swelling, spasm, and thrombus formation) were observed acutely by OCT in most of the treated arteries and were no longer visible at follow-up. Histology revealed a statistically significant accumulation of collagen (fibrosis) and a near absence of tyrosine hydroxylase labeling in the denervated artery, suggesting a clear reduction in nervous terminals. Renal tissue catecholamine levels were similar between both sides, probably due to the low number of ablation points and the renorenal reflex. The present study demonstrates that renal denervation is associated with acute intimal disruptions, areas of fibrosis, and a reduction in nervous terminals. The lack of difference in renal tissue catecholamine levels is indicative of the need to perform the highest and safest number of ablation points in both renal arteries. These findings are important because they demonstrate the histological consequences of radiofrequency energy application and its medium-term safety.

Effect of Bipolar Radiofrequency Energy on Canine Stifle Joint Fluid Temperature.

The aim of this study was to evaluate the effect of bipolar radiofrequency (RF) energy on canine stifle joint fluid temperature. A standard stifle arthroscopy was performed on 15 canine large breed cadaveric stifle joints. A bipolar RF (VAPR III, 2.3-mm side effect electrode; Depuy Mitek, Raynham, Massachusetts, United States) unit was activated in the joint (1) with or without direct tissue contact, (2) with or without additional 18-gauge needle outflow and (3) for 15 and 30 seconds. The joint fluid temperature was monitored with two fibre optic intra-articular sensors. The stifle joint fluid temperature was significantly higher when there was no contact between the tissue and RF probe (mean: 58.6°C with 95% confidence interval [CI]: 53.3-64.0°C) compared with when tissue was contacted (mean: 29.0°C with 95% CI: 26.3-31.6°C). An 18-gauge egress needle had minimal effect on reducing joint fluid temperature. The temperature was higher during the 30-second application of RF energy than the 15-second group. Bipolar RF energy without firm tissue contact rapidly and significantly increased joint fluid temperature beyond the level reported to damage chondrocytes (above 45°C). Caution is required in the use of bipolar RF energy in the canine stifle joint.

Safety and efficacy of delivering high-power short-duration radiofrequency ablation lesions utilizing a novel temperature sensing technology.

Delivery of high-power short-duration radiofrequency (RF) ablation lesions is not commonly used, in part because conventional thermocouple (TC) technology underestimates tissue temperature, increasing the risk of steam pop, and thrombus formation. We aimed to test whether utilization of an ablation catheter equipped with a highly accurate novel TC technology could facilitate safe and effective delivery of high-power RF lesions. Adult male Yorkshire swine were used for the study. High-power short-duration ablations (10-s total; 90 W for 4 s followed by 50 W for 6 s) were delivered using an irrigated force sensing catheter, equipped with six miniature TC sensors embedded in the tip electrode shell. Power modulation was automatically performed when the temperature reached 65°C. Ablation parameters were recorded and histopathological analysis was performed to assess lesion formation. One hundred and fourteen RF applications, delivered using the study ablation protocol in the ventricles of eight swine [53 in the right ventricle (RV), 61 in the left ventricle (LV)], were analysed. Average power delivered was 55.4 ± 5.3 W and none of the ablations resulted in a steam pop. Fourteen out of the 114 (12.3%) lesions were transmural. The mean lesion depth was 3.9 ± 1.1 mm for the 100 non-transmural lesions. Similar ablation parameters resulted in bigger impedance drop (11.6 Ω vs. 9.1 Ω, P = 0.009) and deeper lesions in the LV compared with the RV (4.3 ± 1.2 mm vs. 3.3 ± 0.8 mm, P < 0.001). Delivery of high-power short-duration RF energy applications, facilitated by a novel ablation catheter system equipped with advanced TC technology, is feasible, safe, and results in the formation of effective ablation lesions.

Freedom from pulmonary vein stenosis after multiple applications of epicardial ablation energy

In patients undergoing cardiac surgical procedures, pulmonary vein isolation may be easily accomplished, and it is important to achieve bidirectional conduction block across created lesions. The primary aim of this study was to assess the risk of pulmonary vein stenosis (PVS) after multiple applications of epicardial bipolar radiofrequency energy. Thirty-five consecutive patients who were referred for off-pump coronary revascularization with concomitant pulmonary vein isolation and left atrial appendage occlusion were prospectively included in the study. The ablation protocol provided 8 standard epicardial applications of bipolar energy with additional applications until the acute bidirectional conduction block was achieved. Three to 6 months after surgery, patients underwent computed tomography to assess PVS. In all patients, bidirectional conduction block was achieved across the created lesions. In 31 (89%) patients, conduction block was accomplished after the standard 8 energy applications on each side. In 4 (11%) patients, additional applications of energy were needed. All patients had computed tomography (128 total pulmonary veins) scans, which showed no evidence of PVS. Multiple applications of bipolar radiofrequency energy during off-pump epicardial pulmonary vein isolation did not lead to PVS. Creating bidirectional conduction block using multiple energy applications through created lesions is feasible in all patients using the ablation protocol described.

Reentrant atrial tachycardia originating from the sinus venosa region

A 78-year old woman with palpitation exhibited an atrial tachycardia (AT) of variable cycle lengths resembling atrial fibrillation (AF). Vague centrifugal activation was noted at the sinus venosa region where overdrive pacing demonstrated entrainment with concealed fusion and the stimulus to P wave approximated the electrogram to the P wave interval of 125ms. Application of radiofrequency energy to this site resulted in termination of the AT as well as formation of a fixed block line manifested by the presence of discrete double potentials. These observations indicated the reentrant mechanism of AT originating from the sinus venosa region.

Safety and Efficacy of Cryoablation in Patients With Ventricular Arrhythmias Originating From the Para-Hisian Region

This study aimed to assess the outcome of cryoablation in patients with ventricular arrhythmias (VAs) originating from the para-Hisian region. There are few data regarding the outcome of cryoablation in patients with VAs originating from the para-Hisian region, where there is the risk of injury to the conduction system. The study analyzed all patients undergoing cryoablation at the Mayo Clinic (Rochester, Minnesota) as part of an ablation for VAs originating from the para-Hisian region. The study population consisted of 10 patients (64 ± 15 years of age, 7 men). Cryoenergy was applied after an unsuccessful radiofrequency (RF) ablation in 8 (80%) patients. The VAs were successfully ablated with cryoablation in 7(70%) patients; RF ablation after an unsuccessful cryoablation eliminated the VAs at almost the same location with careful monitoring in 1 patient. The authors could not ablate the actual focus because a transient atrioventricular block developed during cryo- and RF energy applications, which led to an unsuccessful ablation in the remaining 2 patients. Acomplete atrioventricular block occurred during the cryoenergy application in 1 patient, who needed a permanent pacemaker implantation. There were no VA recurrences in 4 of 8 (50%) patients with procedural success during a median follow-up period of 122 days (interquartile range: 43 to 574 days). Cryoablation is clinically effective in some patients with VAs originating from the para-Hisian region, where there is the risk of injury to the conduction system, and therefore should be considered as an alternative to or inaddition to RF ablation in these cases. Cryoablation requires care because it can also lead to major complications.

Ventricular fibrillation induced by radiofrequency energy delivery for premature ventricular contractions arising from the right ventricular outflow tract: is implantablecardioverterdefibrillator indicated?

INTRODUCTION Inadvertently induced ventricular fibrillation (VF) by radiofrequency (RF) energy delivery for premature ventricular complexes (PVCs) is a rare phenomenon; nevertheless, it is crucial to assess long‑term risk of sudden cardiac death in these patients. OBJECTIVES The aim of our study was to define the long‑term prognosis in patients with normal ejection fraction (EF), in whom VF was inadvertently induced by RF energy application during ablation of symptomatic idiopathic PVCs originating from the right ventricular outflow tract (RVOT). PATIENTS AND METHODS Among over 20 000 RF catheter ablations performed at 5 tertiary centers (2008-2016), 6 patients (5 men) had VF induced by RF application to the RVOT. The mean (SD) age of patients was 35.2 (16.8) years. All patients had normal EF (≥60%). We analyzed the risk of malignant ventricular arrhythmias and assessed heart function during follow‑up. RESULTS After ablation, baseline contrast‑enhanced magnetic resonance imaging was performed in 4 of the 6 patients; no area of late gadolinium enhancement was observed. One patient received an implantable cardioverter‑defibrillator (ICD). Exercise tests revealed only rare PVCs. All patients completedthe follow‑up (mean [SD] duration of follow‑up, 64.0 [34.9] months). All patients were alive, with no cases of syncope, documented ventricular tachycardia, or VF. The patient with an ICD received 2 inappropriate high‑voltage therapies. CONCLUSIONS Patients with inadvertently induced VF via RF energy application during ablation of PVCs from the RVOT, who have normal left ventricular function and no electrocardiography abnormalities have good prognosis and low VF risk during long‑term follow‑up. Therefore, ICD placement seems to be not indicated for these patients.

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.

Study to evaluate the immunomodulatory effects of radiofrequency ablation compared to surgical resection for liver cancer.

Introduction: Hepatic cancer is a highly lethal tumour with increasing worldwide incidence. These tumours are characterized by the proliferation of malignant cells, generalised immunosuppression and chronic inflammation marked with an increase in inflammatory markers as a neutrophil-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR) and overexpression of CD4+CD39+ on T lymphocytes. The studies have outlined immunomodulatory changes in liver cancer patients as the plausible explanation for the better survival. The aim of this pilot study was understand the possible immunomodulatory effect of radiofrequency (RF) energy and liver resection (non-radiofrequency based devices; non-RF device) in relation to NLR, PLR and expression of CD4+CD39+ T lymphocytes and compare the magnitude of these changes.Material and Methods: In the present study, 17 patients with hepatic cancer were prospectively divided into treatment groups radiofrequency ablation (RFA group) and Liver resection using non-RF devices (LR group). A blood sample was collected from each patient, one month before and after the procedure and compared with the blood samples of age-matched healthy volunteers for group wise comparison. The Mann-Whitney U test, Mc Nemar test and Wilcoxon rank test were used for statistical comparisons as appropriate.Results: A decrease in NLR was reported after RFA from 4.7±3.3 to 3.8±1.8 (P=0.283), in contrary to an increase from 3.5±2.8 to 4.5±3.2 (P=0.183) in LR group. Likewise, a decrease was discerned in PLR following RFA from 140.5±79.5 to 137±69.2 respectively (P=0.386) and increase in the LR group from 116±42.2 to 120.8±29 respectively (P=0.391). A significant decrease in CD4+CD39+ lymphocytes from 55.8±13.8 to 24.6±21.1 (P=0.03) was observed in RFA group whilst a significant increase was reported in LR group from 47.6±8.8 to 55.7±33.2 (P=0.38).Conclusion: Studies have shown that decrease in the NLR, PLR and expression of CD4+CD39+ on T lymphocytes as the marker of better survival in hepatic cancer patients and our findings have confirmed that these changes can be induced following application of RF energy. Moreover, this could be the explanation of better survival observed in different studies using RFA or other RF-based devices in comparison to non-RF based liver resection techniques. However, further larger studies are needed to confirm these findings.

Ex vivo human bile duct radiofrequency ablation with a bipolar catheter.

Management of the primary and secondary tumors of the bile ducts still remains as a major clinical challenge. Radiofrequency (RF) ablation (RFA) of these tumors is feasible but the effect of RF energy on the human common bile duct (CBD) and surrounding tissues has not been investigated. This pilot study aimed to determine the relationship between RF energy and the depth of ablation in the normal human CBD. The study was performed on fresh ex vivo human biliary-pancreatic tissue which had been resected for a pancreatic cyst or mass. The study was conducted within 15min after resection. A bipolar Habib RFA catheter was placed into the middle of the intact CBD, and three different (5, 7, 10W) power settings were applied over a 90-s period by an RF generator. Gross and histological examinations were performed. The depth of coagulation necrosis in CBD and the effect of RFA on CBD wall and surrounding pancreas tissue were determined by microscopic examination. The study included eight tissue samples. 5W power was applied to three sites and RFA caused only focal epithelial necrosis limited to the CBD mucosa. 7 and 10W were applied to five sites and coagulation necrosis occurred in all cases. Microscopically, necrosis was transmural, involved accessory bile duct glands, and extended to the surrounding pancreatic tissue in four of these cases. Macroscopically, RFA resulted in circumferential white-yellowish color change extending approximately 2cm of the CBD. Bipolar RF energy application with 5W resulted in limited ablation on CBD wall. However, 7 and 10W generated tissue necrosis which extended through the CBD wall and into surrounding pancreas tissue. Endoscopic biliary RFA is an effective technique for local biliary tissue ablation but the use of high energy may injure surrounding tissue.

Thermal latency adds to lesion depth after application of high-power short-duration radiofrequency energy: Results of a computer-modeling study.

The use of ultra-short RF pulses could achieve greater lesion depth immediately after the application of the pulse due to thermal latency. A computer model of irrigated-catheter RF ablation was built to study the impact of thermal latency on the lesion depth. The results showed that the shorter the RF pulse duration (keeping energy constant), the greater the lesion depth during the cooling phase. For instance, after a 10-second pulse, lesion depth grew from 2.05mm at the end of the pulse to 2.39mm (17%), while after an ultra-short RF pulse of only 1 second the extra growth was 37% (from 2.22 to 3.05mm). Importantly, short applications resulted in deeper lesions than long applications (3.05mm vs. 2.39mm, for 1- and 10-second pulse, respectively). While shortening the pulse duration produced deeper lesions, the associated increase in applied voltage caused overheating in the tissue: temperatures around 100 °C were reached at a depth of 1mm in the case of 1- and 5-second pulses. However, since the lesion depth increased during the cooling period, lower values of applied voltage could be applied in short durations in order to obtain lesion depths similar to those in longer durations while avoiding overheating. The thermal latency phenomenon seems to be the cause of significantly greater lesion depth after short-duration high-power RF pulses. Balancing the applied total energy when the voltage and duration are changed is not the optimal strategy since short pulses can also cause overheating.

Initial results of a first-in-human study on the PlasmaWire™ System, a new radiofrequency wire for recanalization of chronic total occlusions.

To examine the safety, efficacy, and efficiency of the PlasmaWireTM System to recanalize coronary chronic total occlusions (CTO) using controlled ablation inside the CTO. The PlasmaWireTM System is a new bipolar radiofrequency (RF) wire system utilizing plasma-mediated ablation to facilitate wire crossing in CTOs. Two independent PlasmaWireTM wires are used in tandem for channel creation by applying RF energy between the tips so as to localize the ablation. Prospective, nonrandomized, single-arm, multicenter study in seven patients with CTOs indicated for percutaneous coronary intervention (PCI). In this study, both wires were antegradely delivered to the distal end of CTO for antegrade re-entry in two cases and bidirectionally (antegrade and retrograde) delivered to the CTO for retrograde re-entry in five cases. In all cases, channel creation was achieved within a few seconds and was confirmed on angiogram or intravascular ultrasound (IVUS) and CTO recanalization was successfully achieved without any major adverse cardiac and cerebrovascular events (MACCE) or other minor complications. The clinical follow-up showed no clinical event at 1 month. The PlasmaWireTM System was shown to be safe and effective in obtaining CTO recanalization through a re-entry channel utilizing plasma-mediated ablation while reducing procedure time. The PlasmaWire™ System is a new bi-polar RF wire system utilizing plasma-mediated ablation for channel creation to facilitate CTO recanalization. This first-in-human study in which seven patients were enrolled was conducted to demonstrate the safety, efficacy, and efficiency of this system for CTO recanalization. Channels through the CTOs were successfully created within a few seconds by applying RF energy between the tips of two independent PlasmaWireTM wires and recanalization was achieved in all cases without any complication. The PlasmaWireTM System may safely facilitate CTO recanalization with less vessel injury and improve initial results of CTO PCI while reducing procedure time.

Sucrose modulation of radiofrequency-induced heating rates and cell death.

Applied radiofrequency (RF) energy induces hyperthermia in tissues, facilitating vascular perfusion This study explores the impact of RF radiation on the integrity of the luminal endothelium, and then predominately explores the impact of altering the conductivity of biologically-relevant solutions on RF-induced heating rates and cell death. The ability of cells to survive high sucrose (i.e. hyperosmotic conditions) to achieve lower conductivity as a mechanism for directing hyperthermia is evaluated. RF radiation was generated using a capacitively-coupled radiofrequency system operating at 13.56 MHz. Temperatures were recorded using a FLIR SC 6000 infrared camera. RF radiation reduced cell-to-cell connections among endothelial cells and altered cell morphology towards a more rounded appearance at temperatures reported to cause in vivo vessel deformation. Isotonic solutions containing high sucrose and low levels of NaCl displayed low conductivity and faster heating rates compared to high salt solutions. Heating rates were positively correlated with cell death. Addition of sucrose to serum similarly reduced conductivity and increased heating rates in a dose-dependent manner. Cellular proliferation was normal for cells grown in media supplemented with 125 mM sucrose for 24 hours or for cells grown in 750 mM sucrose for 10 minutes followed by a 24 h recovery period. Sucrose is known to form weak hydrogen bonds in fluids as opposed to ions, freeing water molecules to rotate in an oscillating field of electromagnetic radiation and contributing to heat induction. The ability of cells to survive temporal exposures to hyperosmotic (i.e. elevated sucrose) conditions creates an opportunity to use sucrose or other saccharides to selectively elevate heating in specific tissues upon exposure to a radiofrequency field.

Investigation of the Feasibility of Radio Frequency Energy for Controlling Insects in Milled Rice

Many studies showed that radio frequency (RF) holds great potential to control insects in grains, while a few more technical issues need to be addressed to further make this technology ready for industrial application. Therefore, the effect of RF heating rate on rice fissure ratio and broken rate, RF heating lethality on immature rice weevils, and RF disinfestation treatment on cooking and eating quality of milled rice was investigated in this study. Results indicated that RF heating rate had no significant influence on rice broken rate, while fast RF heating rate (>7.2 °C/min) had adverse effects on rice fissure ratio, and mild RF heating rate (<5.8 °C/min) had no significant influence on fissure ratio of milled rice. RF treatment (50 °C, 5 min) could completely control immature rice weevils in rough, brown, and milled rice. Even though RF disinfestation treatment (50 °C, 5 min) influenced the cooking quality (water absorption, adhesive strength) of milled rice, it had no significant effect on overall sensory quality. This study provided valuable information for considering the application of RF energy in milled rice process to control insects.

Effects on the Distal Radioulnar Joint of Ablation of Triangular Fibrocartilage Complex Tears With Radiofrequency Energy

This cadaver study investigated the temperature profile in the wrist joint and distal radioulnar joint (DRUJ) during radiofrequency energy (RFE) application for triangular fibrocartilage complex resection. An arthroscopic partial resection of the triangular fibrocartilage complex using monopolar and bipolar RFE was simulated in 14 cadaver limbs. The temperature was recorded simultaneously in the DRUJ and at 6 other anatomic locations of the wrist during RFE application. The mean temperature in the DRUJ was 43.3 ± 8.2°C for the bipolar system in the ablation mode (60 W) and 30.4 ± 3.4°C for the monopolar system in the cut mode (20 W) after 30 seconds. The highest measured temperature in the DRUJ was 54.3°C for the bipolar system and 68.1°C for the monopolar system. The application of RFE for debridement or resection of the triangular fibrocartilage complex in a clinical setting can induce peak temperatures that might cause damage to the cartilage of the DRUJ. Bipolar systems produce higher mean temperatures than monopolar devices. RFE application increases the mean temperature in the DRUJ after 30 seconds to a level that may jeopardize cartilage tissue.

Radiofrequency and Cryo-Ablation Effect on Transvenous Pacing and Defibrillatory Lead Integrity: An In Vitro Study.

Medical societies and cardiac implantable electronic device (CIED) manufacturers recommend avoiding close or direct contact between the body of transvenous leads and ablation catheters used to treat cardiac arrhythmias. These recommendations are made despite the lack of clinical studies. However, the target myocardium for successful ablation can be contiguous to CIED leads. We examine in vitro the effects of direct application of radiofrequency (RF) and cryo-ablation energy on the integrity and functionality of CIED leads (excluding the pacing electrodes and defibrillation coils). A saline bath was created to mimic the body milieu. CIED leads, including all commercially available lead insulation materials, were connected to a CIED pulse generator and placed in direct contact with an ablation catheter in the tissue bath. RF and cryo-ablation energy were delivered under various conditions, including maximal ablation power, temperature, and impedance via the RF generator. CIED lead functionality, reflective of conductor integrity, was evaluated through lead impedance monitoring during ablation. CIED leads were then visually inspected, and examined with optic and electron microscopy as per protocol. A total of 42 leads were studied. All leads showed the absence of insulation damage at the site of ablation visually and with microscopy. Lead functionality was also preserved in all leads. Catheter ablation in contact with CIED leads using radiofrequency or cryo-ablation in vitro did not affect lead body integrity and function despite aggressive ablation settings. It may be reasonable to perform ablation in contact with the body of CIED leads when clinically necessary.